Default water allocation limits for selected catchments in the Canterbury Region

Transcription

1 Default water allocation limits for selected catchments in the Canterbury Region Prepared for Environment Canterbury July August a.m.

2 Authors/Contributors: Paul Franklin Ton Snelder Jani Diettrich Doug Booker For any information regarding this report please contact: Paul Franklin Scientist Freshwater Ecology National Institute of Water & Atmospheric Research Ltd Gate 10, Silverdale Road Hillcrest, Hamilton 3216 PO Box 11115, Hillcrest Hamilton 3251 New Zealand Phone Fax NIWA Client Report No: HAM Report date: July 2012 NIWA Project: ENC12524 All rights reserved. This publication may not be reproduced or copied in any form without the permission of the copyright owner(s). Such permission is only to be given in accordance with the terms of the client s contract with NIWA. This copyright extends to all forms of copying and any storage of material in any kind of information retrieval system. Whilst NIWA has used all reasonable endeavours to ensure that the information contained in this document is accurate, NIWA does not give any express or implied warranty as to the completeness of the information contained herein, or that it will be suitable for any purpose(s) other than those specifically contemplated during the Project or agreed by NIWA and the Client. 2 August a.m.

3 Contents Executive summary Introduction Background Scope Limits for Water Allocation Methods EFSAP model description Applying EFSAP in Canterbury Results Proposed NES rules Spatial patterns Decision space diagrams Discussion Consequences of proposed NES default limits Use of decision space figures for limit setting Limitations Conclusions Acknowledgements References Appendix A Habitat model parameters Tables Table 1: Indicator species used for EFSAP simulations in Canterbury. 21 Table 2: Definition of spatial management units for default allocation limits in Canterbury. 31 Table 3: Summary of decision space diagrams presented. 34 Table 4: Summary of the consequences of applying the proposed NES default limits to each of the three management units. 49 Table 5: Species for which generalised habitat models are available in New Zealand. 59 Default water allocation limits for selected catchments in the Canterbury Region

4 Figures Figure 1: Schematic diagram of aspects of limit setting based on flow duration curve and flow-habitat relationships. 12 Figure 2: An example of annual and monthly FDCs for a network segment. 15 Figure 3: WUA versus flow curves for adult brown trout and brown trout fry for a network segment (mean flow = 20 m 3 s -1 ). 16 Figure 4: Location of ECan catchments of interest for determination of default water allocation limits. 20 Figure 5: Maps showing the reliability at management flow in the catchments of interest under the proposed NES large river rules. 24 Figure 6: Maps showing the reliability at minimum flow in the catchments of interest under the proposed NES large river rules. 25 Figure 7: Maps showing the change in habitat for adult brown trout in the catchments of interest under the proposed NES large river rules. 26 Figure 8: Maps showing the change in food producing habitat in the catchments of interest under the proposed NES large river rules. 27 Figure 9: Maps showing the change in habitat for bluegill bullies in the catchments of interest under the proposed NES large river rules. 28 Figure 10: Variation in reliability at management and minimum flows across all locations of interest. 29 Figure 11: Variation in habitat response across all locations of interest for the three indicators. 30 Figure 12: Density plots showing variation in reliability within and between the three management units. 32 Figure 13: Density plots showing the variation in consequences for instream habitat within and between management units. 33 Figure 14: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for reliability at management flow. 35 Figure 15: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for reliability at minimum flow. 36 Figure 16: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for change in adult brown trout habitat (% of habitat available at MALF). 37 Figure 17: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for change in food producing habitat (% of habitat available at MALF). 38 Figure 18: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for change in bluegill bully habitat (% of habitat available at MALF). 39 Figure 19: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for reliability at management flow. 40 Figure 20: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for reliability at minimum flow. 41 Figure 21: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for change in adult brown trout habitat (% of habitat available at MALF). 42 Figure 22: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for change in food producing habitat (% of habitat available at MALF). 43 Figure 23: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for change in bluegill bully habitat (% of habitat available at MALF). 44 Figure 24: All catchments other than the Clarence decision space diagrams for reliability at management flow. 45 Figure 25: All catchments other than the Clarence decision space diagrams for reliability at minimum flow. 46 Default water allocation limits for selected catchments in the Canterbury Region

5 Figure 26: All catchments other than the Clarence decision space diagrams for change in bluegill bully habitat (% of habitat available at MALF). 47 Figure 27: All catchments other than the Clarence decision space diagrams for change in food producing habitat (% of habitat available at MALF). 48 Figure 28: Interpreting the decision space diagram summary statistics. 50 Figure 29: Illustration of evaluating objectives for multiple values and determining range of limits that satisfy all objectives. 52 Reviewed by: Approved for release: N. Norton H. Rouse Formatting checked by Default water allocation limits for selected catchments in the Canterbury Region 5

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7 Executive summary Environment Canterbury (ECan) is currently developing a new Land and Water Plan that will establish limits for the allocation of water across the Canterbury region. In the catchments where demand for water abstraction is relatively lower, default or interim limits are required. The objective of these limits is to provide a specific level of environmental protection, while enabling out-of-channel water use at specified levels of availability and reliability. To achieve this, limits must include at least minimum flows (the flow below which no water can be abstracted) and total allocation (the total quantity of water that can be abstracted upstream of any location). Default limits can be defined using rules of thumb that are based on hydrological indices, such as the mean annual low flow (MALF). This is the approach that is taken by the proposed National Environmental Standard for Ecological Flows and Water Levels (proposed NES; MfE 2008). Rules of thumb are easily applied, but there are two main disadvantages. Firstly, the consequences for both environmental values and out-of-channel water users (i.e., availability and reliability) are not clearly articulated, making justification of the rules difficult. Secondly, the consequences are spatially variable because flow regimes and the relationship between environmental protection and flow are spatially variable. The Environmental Flows Strategic Allocation Platform (EFSAP) provides a method to evaluate the consequences of setting different water resource use limits across all parts of a catchment or region, including those for which detailed information is not available. It integrates scientific tools to enable the concurrent evaluation of consequences for instream habitat and reliability of supply for out-of-channel water uses, accounting for the interaction between the flow regime, minimum flow and total allocation limits at all locations. In this study we used EFSAP to simulate the consequences of various potential sets of limits (i.e., minimum flows and total allocations) for all river and stream reaches in specified catchments in the Canterbury region where interim default allocation limits are required. A range of alternative scenarios, both more environmentally conservative and more resource use enabling than the proposed NES rules, were simulated. ECan defined forty eight catchments to be assessed that included smaller catchments in South Canterbury, all catchments on Banks Peninsula, some small coastal catchments in North Canterbury, and the catchment of the Clarence River that lies within the Canterbury region. All stream segments within these catchments were assessed. The indicator species selected for analysis were adult brown trout (Salmo trutta), bluegill bully (Gobiomorphus hubbsi) and drift food producing habitat. These were selected based on their presence and value in the locations of interest, and because they require relatively large flows to provide adequate habitat. EFSAP is based on the analysis of flow duration curves (FDCs). In this study we used the annual FDC and the February FDC to represent the average consequences and the consequences under the most restrictive summer conditions respectively. Based on the annual FDC, reliability at management flow (minimum flow plus total allocation) under the proposed NES large river rules (minimum flow 80% MALF; total allocation 50% MALF) is generally higher in the northern catchments and Banks Peninsula, and lower in the southern catchments. However, despite the spatial variability between the catchments of interest, the vast majority of locations have a reliability of supply between 70 and 90%. Under Default water allocation limits for selected catchments in the Canterbury Region 7

8 low flow conditions in February, the reliability of supply at the management flow under the proposed NES large river rules improves in some areas, but declines in others. The result is much greater spatial variation in the consequences, with the majority of sites having a reliability of supply in February between 40 and %. The spatial patterns of consequences for instream habitat appeared to be similar across all three indicator species and also similar between the annual and February FDC. At some locations, habitat availability increased relative to that available at MALF under the proposed NES large river rules. The majority of locations, however, displayed a loss of habitat, which was typically greater under the annual FDC than the February FDC. The high spatial variation in the consequences, particularly for habitat, justified defining spatially discrete management units for setting default water limits. Three management units were defined: Clarence large river (all river segments in the Clarence catchment with mean flow greater than 5 m 3 s -1 ), Clarence small river (all river segments in the Clarence catchment with mean flow less than 5 m 3 s -1 ) and all other catchments of interest. Within these management units, variability in the consequences for instream physical habitat was more uniform for all three indicator species. ECan have defined objectives for reliability of supply and retention of physical habitat: 1. median annual reliability at management flow of at least 95% 2. median annual reliability at minimum flow of at least 95%, and 3. median annual reduction in physical habitat of no greater than 25% of the habitat available at MALF. The combinations of limits that satisfy these objectives were obtained for all management units from the results of the EFSAP simulations and are presented in the report. For all management units there are a number of combinations of limits that satisfy all the objectives. There is, therefore, the requirement to make additional value judgements and balance the needs of competing values to define the final choice of limits. This trade-off process can be facilitated by using the EFSAP outputs to transparently communicate how the consequences of different water resource use limits vary. This is achieved through the use of decision space diagrams which have been designed to simply illustrate the relative consequences of different combinations of limits for each value. It must also be recognised that EFSAP does not evaluate all values that may be relevant for a given location. It also does not explicitly consider flow variability, or the temporal sequencing on flows. It is also based on the assumption that instream physical habitat at low flows is limiting. These factors must therefore be considered when determining the most appropriate combination of limits. However, despite these limitations, EFSAP provides a robust and defensible approach to evaluating the relative merits of different combinations of limits and therefore will allow ECan to more transparently communicate and set water resource limits that meet their nominated objectives. 8 Default water allocation limits for selected catchments in the Canterbury Region

9 1 Introduction 1.1 Background The National Policy Statement for Freshwater Management (MfE 2011) requires that Regional Councils define environmental flow limits that include both minimum flows and total allocation limits. Environment Canterbury (ECan) is currently developing a new Land and Water Plan that, among other things, will establish limits for the allocation of water across the Canterbury region. In some catchments in the Canterbury region where demand for abstraction is high, these limits are already/will be set using catchment specific information such as ecological, physical habitat and hydrological studies for that catchment. In the remaining catchments, where demand for water abstraction is lower, default or interim limits are required. The objective of these limits is to provide a specific level of environmental protection, while enabling out-of-channel water use at specified levels of availability and reliability. To achieve this, limits need to include at least minimum flows (the flow below which no water can be abstracted) and total allocation (the total quantity of water that can be abstracted upstream of any location). One method for setting default limits is to use rules of thumb that are based on hydrological indices such as the mean annual low flow (MALF). This is the approach that is taken by the proposed National Environmental Standard for Ecological Flows and Water Levels (proposed NES; MfE 2008). The proposed interim limits are based on a proportion of MALF, which varies for two river size classes. Small and large rivers are those with mean flows less than and greater than 5 m 3 s -1 respectively, and minimum flows are set at 90% and 80% of MALF respectively. The proposed NES sets total allocation for small and large rivers at 30% and 50% of MALF respectively (MfE 2008). Rules of thumb based on MALF are easily applied to set minimum flows and total allocation, but there are two disadvantages. First, the consequences of retaining any specific proportion of MALF are not clearly articulated, making justification of the rules difficult. Second, the consequences of uniform limits to define minimum flows and total allocation are spatially variable, because flow regimes and the relationship between environmental protection and flow are variable in space (e.g., Snelder et al. 2011). Simulation modelling of potential water allocation limits will enable ECan to evaluate and choose among options for minimum flows and total allocations by assessing the consequences for environmental protection, and the availability and reliability of water for out-of-stream use, across the catchments of interest in the Canterbury region. 1.2 Scope The scope of this project involved the use of the Environmental Flows Strategic Allocation Platform (EFSAP) to simulate the consequences of various scenarios for water allocation for all river and stream reaches in a specified subset of water management units in the Canterbury region (Figure 4). EFSAP is a software programme developed by NIWA using Ministry of Science and Innovation funding to enable assessment of different environmental flows and total allocations on reliability of supply and instream habitat. There are two key steps in undertaking this work: a) testing and improvement of hydrological estimates; and b) Default water allocation limits for selected catchments in the Canterbury Region 9

10 simulating the consequences of various environmental flow and allocation scenarios. The details involved in these steps are discussed below Hydrological estimates The EFSAP program requires estimates of hydrological characteristics for all locations of interest. The first step in the project was to obtain the best available estimates for these hydrological characteristics for the Canterbury region, as well as estimates of their uncertainties. A separate report (Booker & Woods 2012) details the findings of that part of the study and includes a comparison of methods for calculating hydrological indices, from purely empirical methods (i.e., statistical modelling) to those applying more physically-based approaches Simulation analyses The aim of this project was to undertake a series of simulation analyses of different water allocation scenarios using EFSAP. The output from these analyses describes the retention of physical habitat for target species, the availability of water for out-of-channel uses (i.e., the estimated total allocation as a flow in m 3 s -1 ), and the reliability of that water supply (proportion of the time abstractions are fully or partially restricted). Because these outputs are spatially variable, the results were to be presented as maps and also summarized statistically (e.g., histograms showing the distribution of values or catchment averages of the output values). Initially, the consequences of the proposed NES minimum flow and total allocation rules on reliability of supply and instream habitat for target species were simulated for all rivers and streams in the catchments of interest. The target species on which to base the analysis of physical habitat were to be defined in consultation with ECan staff based on observed data and values identified in local planning documents. The consequences for more than one target species were to be simulated. A range of alternative scenarios, ranging from more environmentally conservative limits than the proposed NES to limits more permissive of resource use than the proposed NES, were also to be simulated. It was anticipated that rules would need to vary spatially in order to account for differences in hydrological regimes and physical habitat-flow relationships. Ideally, rules would be identified for a small number of easily defined sub-regions or river classes (e.g., based on stream order or dominant catchment geology), that would define specific management units such that the consequences were reasonably uniform within and between such management units. 10 Default water allocation limits for selected catchments in the Canterbury Region

11 2 Limits for Water Allocation Limits to water resource use are typically applied for two reasons. First, limits are imposed to constrain human-induced alteration of river flows to levels that are judged to be sufficient to sustain environmental values (Acreman et al. 2008, Poff et al. 2010, Richter et al. 2006). Second, economic considerations require that limits on water resource use are specified so that the total availability of water resources and their reliability is quantified and understood. In situations where water resource development is intense (e.g., involving storage and diversions), many aspects of a river s flow regime may be altered, including high flows and the seasonal distribution of flows. In these situations, complex limits commensurate with the environmental impact and scale of the development are required to manage the effects. However, the more common situation is multiple small run-of-river or groundwater abstractions that are spread throughout a catchment with little, if any, facility for water storage. Environmental effects in this situation arise primarily due to the cumulative aggregation of abstractions, which can result in increased frequency and duration of low flows, but usually have a negligible impact on higher flows (Nilsson & Renöfält 2008). In these situations, the impact of abstraction can be controlled by defining two types of limit; minimum flows (the flow at which abstractions must be restricted to protect river ecosystem characteristics and functions) and total allocation (the total volume or rate that water can be abstracted). The minimum flow and total allocation interact with each other and the flow regime to determine the consequences for environmental protection (i.e., the magnitude and duration of low flows) and out-of-channel uses (i.e., the proportion of the time abstractions are partially and fully restricted). Because of these interactions, limits are only effective, and the consequences of those limits for instream values and out-of-channel use can only be established, if both minimum flow and total allocation are defined. An example of how the minimum flow and total allocation interact with the flow regime to determine consequences for instream and out-of-channel use at a site is illustrated with reference to the proposed NES rules. The top panel of the diagram shown in Figure 1 shows how a measure of environmental state, the availability of instream habitat for adult brown trout (Salmo trutta), varies with flow at a site. The mean flow at the site is 11.7 m 3 s -1 and the MALF is 2.6 m 3 s -1 (Point A, Figure 1). The availability of suitable physical habitat for brown trout declines with both increasing and decreasing flow from an optimum at 6.2 m 3 s -1 (Point B, Figure 1). The lower panel shows a flow duration curve (FDC) for the natural flow regime (i.e., the FDC that would have occurred if no abstractions were occurring). Under the proposed NES, the minimum flow at the site would be 80% of MALF or 2.1 m 3 s -1, (Point C, Figure 1), which equates to retention of 87% of the physical habitat available for adult brown trout at the MALF (Point D, Figure 1) (i.e., a decline of 13% relative to the amount of habitat available under average natural low flow conditions). The minimum flow and the natural FDC (i.e., the FDC that would have occurred with no abstractions) can be used to define the proportion of time that complete restriction (cessation of abstractions) occurs. Complete restriction occurs for the proportion of time that the natural flow is at or below the minimum flow, equating to 2.4% of the time in this case (Point E, Figure 1). The management flow is defined by adding the total allocation to the minimum flow, and describes the flow below which partial restriction of abstractions would be required to Default water allocation limits for selected catchments in the Canterbury Region 11

12 maintain the river at the minimum flow. Under the proposed NES, total allocation at the example site would be 50% of MALF or 1.3 m 3 s -1, resulting in a management flow of 3.4 m 3 s -1 (Point F, Figure 1). Thus, when natural flows are below 3.4 m 3 s -1 (i.e., 10.0% of the time, point G, Figure 1), the allowable abstraction is restricted to the natural flow minus the minimum flow. A consequence of this restriction is that residual flows (natural flows minus abstractions) are constant at the minimum flow (i.e., flat-lining ) for the proportion of time that natural flows are between the management and minimum flows (i.e., between points G and E, Figure 1). Thus, in this example the river would be flat-lined 7.6% of the time. Time Time flow flow is is less less (%) (%) Habitat Habitat (% (% WUA WUA at at MALF) D G E Minimum flow MALF A Total Allocation Management flow C F Flow Flow (m(m3/s) 3 s -1 ) B Figure 1: Schematic diagram of aspects of limit setting based on flow duration curve and flow-habitat relationships. The two plots are for a river with a mean flow of 11.7 m 3 s -1 and a MALF of 2.6 m 3 s -1. The top plot shows the flow-habitat relationship for adult brown trout estimated using generalised instream habitat models (Jowett et al. 2008) using the method described by (Snelder et al. 2011). The lower plot shows the flow duration curve that was estimated using methods described by (Snelder et al. 2011). The lower plot shows the nominated minimum flow, management flow and proportion of the time that abstractions would be restricted (partially and completely). Letters indicate key values that are referred to in the text. 12 Default water allocation limits for selected catchments in the Canterbury Region

13 This example demonstrates that the choice of limits involves a trade-off between values. Choosing a lower minimum flow would reduce protection of environmental values, but increase reliability for out-of-channel use, whilst choosing a higher allocation limit would increase the availability of water for out-of-channel uses, but with lower reliability and reduced protection for environmental values. It also illustrates that when arbitrary rules, such as the proposed NES, are used to define limits, this trade-off is pre-determined. Ideally, limits should not be prescribed by arbitrary rules, but instead be based on environmental and water resource use objectives. If the objectives are clear (i.e., defined levels of protection for environmental values and availability and reliability of water for out-ofchannel users), decision-making is more transparent. The role of scientific tools is to provide defensible criteria that will meet these objectives. A significant scientific challenge to this process is the integration of tools in a way that accounts for how minimum flows, total allocation and the flow regime interact, to define a relevant range of options for objectives and associated limits. When setting water resource use limits over broad geographical areas, a further challenge is spatial variation in environmental characteristics. Spatial variation means that relevant objectives are likely to vary within and between catchments and that the consequences of any set of limits are likely to be variable. This means that objectives and associated limits often need to be spatially specific (i.e., applying to the particular set of circumstances in a geographically defined location; (Snelder & Hughey 2005, Snelder et al. 2004). Default water allocation limits for selected catchments in the Canterbury Region 13

14 3 Methods 3.1 EFSAP model description EFSAP is a tool to enable planners and water allocation decision-makers to simulate and compare spatially explicit water management scenarios at catchment, regional and national scales. It is able to simulate the spatially explicit consequences of multiple takes on both outof-stream and in-stream values, demonstrate the trade-off between environmental state and resource use, and allow comparison of different water allocation management scenarios. It is based on the application of generalized models across all locations in a spatial framework. Further details of the model structure are described below Spatial framework The spatial framework for EFSAP is the River Environment Classification (REC; Snelder & Biggs 2002), which comprises a digital representation of the New Zealand river network and a classification system that are contained within a Geographic Information System (GIS). The river network representing the Canterbury region comprises 94,350 segments with a mean length of c. 800 m. Each segment is associated with several attributes including the total catchment area, stream order, and the climatic topographic, geological, and land-cover characteristics of the upstream catchment. The REC classifies all river and stream segments into classes at several levels of detail (Snelder & Biggs 2002). The first and second levels of the REC assign individual segments of the river network into classes that discriminate variation in the climate and topography of the catchment. ECan has used the second level of the REC to define management units in its Natural Resources Regional Plan (Environment Canterbury 2011) Hydrological data EFSAP requires estimates of several hydrological characteristics including: MALF, mean flow (Qbar), and the shape of the FDC. FDCs are a hydrological tool that is used to represent the percentage of time flows are equalled or exceeded for a particular river location (Vogel & Fennessey 1995) (Figure 2). This project required both annual (i.e., calculated across the entire year) and monthly (i.e., calculated for individual months) FDCs so that the consequences for availability and reliability of water supply for out-of-channel uses could be reported for the whole year and the most restrictive (summer) months. Approaches for estimating these hydrological characteristics are described by Booker and Woods (2012). The methods with the lowest uncertainties have been used with EFSAP to undertake the simulation analyses for this project. 14 Default water allocation limits for selected catchments in the Canterbury Region

15 Figure 2: An example of annual and monthly FDCs for a network segment. Minimum flow is indicated by the vertical dashed line. Reliability for any given month is indicated by the point at which the FDC meets the dashed line. For example, the black square indicates reliability based on the annual FDC (c. 95%), the orange square indicates reliability based on the February FDC (c. 85%) Generalized habitat v. flow relationships EFSAP utilizes coupled generalized models of mean wetted width versus flow and habitat versus reach-averaged specific discharge (width/flow) to describe the relationship between habitat availability and flow at a site. Estimating hydraulic geometry National estimates of at-station hydraulic geometry parameters are provided by Booker (2010). Booker (2010) defines a power-law relationship between discharge, Q (m 3 s -1 ), and mean wetted width, W (m), for each river reach: log d d d ( W ) = d ( ) ( ( )) d1 log Q + d2 log Q = a0 a1 log( A) b0 b1 log( A) c c log( A) 0 + = (b) 1 + = (c) (1) (a) Default water allocation limits for selected catchments in the Canterbury Region 15

16 where A is catchment area (km 2 ) and a, b, and c take values dependent on REC classes. These models are used in EFSAP to estimate the mean wetted width and subsequently to compute width-flow relationships for all REC network segments. Estimating instream physical habitat Conventional instream physical habitat models link hydraulic model predictions with microhabitat-suitability criteria to predict the availability of suitable habitat at various discharge rates (e.g., RHYHABSIM; Clausen et al. 2004, Jowett 1996, Jowett & Biggs 2006). The availability of suitable physical habitat is commonly expressed as Weighted Usable Area (WUA) in m 2 per 0m of river channel (Figure 3). WUA is an aggregate measure of physical habitat quality and quantity, and will be specific to a particular discharge and taxa/life stage. Instream physical habitat models can be used to assess WUA over a range of flows and therefore to make predictions of how habitat changes with changes in flow. Figure 3: WUA versus flow curves for adult brown trout and brown trout fry for a network segment (mean flow = 20 m 3 s -1 ). These curves were defined by combining equations 1 and 2. MALF for the segment (3.3 m 3 s -1 ) is shown by the black square on the curve. WUA at the proposed NES minimum flow of 80% MALF are shown by the dashed lines. Note that WUA decreases between MALF and the minimum flow for adult brown trout, but increases for brown trout fry. 16 Default water allocation limits for selected catchments in the Canterbury Region

17 Criticisms of instream physical habitat models include lack of biological realism (Orth 1987) and failure of microhabitat-suitability criteria to reflect the detailed mechanisms that lead to density environment associations (Booker et al. 2004, Lancaster & Downes 2010, Mathur et al. 1985). However, many microhabitat suitability models have a high degree of transferability between rivers and are therefore useful bases for the physical management of stream catchments (Lamouroux et al. 2010). The models have been applied throughout New Zealand (Lamouroux & Jowett 2005) and the world (Dunbar & Acreman 2001), primarily to assess impacts of abstraction. PHABSIM in particular has become a legal requirement for many impact studies in the USA (Reiser et al. 1989) and a standard tool employed to define minimum flows in New Zealand. Generalised instream habitat models (Lamouroux & Jowett 2005) have been developed from the results of many individual habitat studies conducted throughout New Zealand. These models generalise the relationship between flow and habitat in natural stream reaches based on simple reach-average hydraulic characteristics (Lamouroux & Jowett 2005). Therefore, when linked with hydraulic geometry models, generalized habitat models make it possible to simulate the relationship between flow and habitat over whole river networks (see examples in (Jowett 1998, Lamouroux 2008, Lamouroux & Capra 2002, Snelder et al. 2011). We used the generalized instream habitat models provided by (Jowett et al. 2008) to estimate WUA as a function of reach-averaged specific discharge (width/flow). The flow-habitat relationships describe a unimodal shape that depends on two coefficients, j and k that are specific to a taxa and i, which is specific to a reach: WUA Q i W j j e k Q W = 1 (2) The ratio of WUA at two discharge rates depends only on discharge rates and the widthdischarge relationship, but not on the reach coefficient i. Consequently, the width-flow relationship (Equation 1) can be combined with Equation 2 to estimate change in habitat with changes in flow over a whole river network (Lamouroux & Souchon 2002) Analysis options EFSAP is based on the analysis and simulation of four key variables: Flow changes (c.f. total allocation) ( Q) Minimum flow (Q_Min) Reliability (R) Habitat change ( H) When undertaking a simulation, any two of these variables may be specified and the other two will be calculated at all locations on the river network. For example, to simulate the consequences of the proposed NES minimum flow and total allocation limits for small rivers (<5 m 3 s -1 ), flow change ( Q) would be set as 30% MALF and minimum flow (Q_min) as 90% MALF, and reliability of supply (R) and habitat change ( H) for the target species would be calculated by the model for all locations. Default water allocation limits for selected catchments in the Canterbury Region 17

18 EFSAP can be run in two modes: global and local. Global simulations are used to evaluate the spatial consequences of uniform rules or objectives across the river network. In this mode, all reaches are treated as independent and thus the spatial distribution of takes upstream of a site is not taken into consideration, and effects are not accumulated down the river network. The global mode was used for this project. The local mode allows simulation of the cumulative effects of site specific takes. In this mode, the location, take volume ( Q) and minimum flow (Q_min) of every abstraction is specified and the effects are accumulated down the river network. This approach is more suitable for catchment specific investigations where good data are available on the location of takes. 3.2 Applying EFSAP in Canterbury Assumptions This project takes a regional approach to simulating the consequences of different water allocation limits. The models upon which EFSAP is based are not calibrated for every location on the river network, but instead provide a generalised estimate that, when considered collectively, help to understand regional scale patterns. Results should therefore be evaluated and interpreted at a regional scale, and should not be used for assessments at specific locations on the river network. Booker and Woods (2012) showed that characteristics of the FDC can vary between months and monthly FDCs are different to the annual FDC. This means that for a given minimum flow and allocation limit, reliability of supply for out-of-channel uses will vary between months, with the lowest reliability occurring in the month with the greatest frequency of low flows. To allow for this variability, EFSAP simulations for Canterbury have been run using the annual FDC and the FDC for February only. The February FDC was chosen for analysis because, on average, the greatest frequency of low flows occurs in this month and therefore it is the most resource limiting month. Estimates of reliability of supply were based on the position of various proportions of the 7- day MALF on the flow duration curves. For this calculation, we had a choice of three different estimates of MALF to locate on the flow duration curve at each location. These were: a) MALF from HUC (Hydrology of Ungauged Catchments projects); b) specific MALF estimated from a random forest regression model and then multiplied by catchment area; and c) the flow on each estimated flow duration curve that corresponded to the estimated position of MALF (as predicted by a random forest model of the proportion of time for which MALF is exceeded) on that flow duration curve. Given that there may be errors associated with both estimated MALF and estimated FDCs, we chose to apply the last of these three options, as it was the most likely to produce accurate estimates of reliability of supply. Comparisons of reliability of supply at % of MALF (results not shown) showed that there was little difference between our second and third methods of estimating MALF, but that the HUC method produced higher estimates of reliability of supply. When simulating consequences for environmental state and reliability for out-of-channel uses, it is assumed that the full quantity of allocated water available is taken all of the time. This represents the worst case scenario. In reality this is rarely the case, but greatest demand for out-of-channel uses typically occurs when the resource is most limited (i.e., dry 18 Default water allocation limits for selected catchments in the Canterbury Region

19 summers) and therefore it is important that water resource use limits are designed to provide sufficient protection of environmental values and reliability of supply at full capacity. EFSAP uses instream physical habitat as its measure of environmental state. The use of physical habitat is based on the assumption that habitat availability, rather than other factors such as water quality or migration barriers, is the primary limiting factor on the target species. Physical habitat is used as a surrogate for the suitability of a site to support the target species, but the availability of suitable habitat does not mean that a species will be present, and the quantity of suitable habitat does not necessarily correlate with species abundance Target catchments The locations of interest comprised all stream segments in the forty eight catchments defined by ECan and shown in Figure 4. Default water allocation limits for selected catchments in the Canterbury Region 19

20 Figure 4: Location of ECan catchments of interest for determination of default water allocation limits. 20 Default water allocation limits for selected catchments in the Canterbury Region

21 3.2.3 Indicator species Generalised habitat models are currently only available for a restricted number of species and life stages in New Zealand (Appendix A; Table 5). The values for the model coefficients were derived by Jowett et al. (2008) from a dataset of 99 stream reaches in New Zealand. The flow demand (in terms of optimal discharge per unit width; Table 5) for some species is logical based on our understanding of the traits of the individual species, e.g., torrentfish (which prefer fast flowing riffle habitats) having the highest demand of the native fish species. However, the optimal discharge defined by the Jowett et al. (2008) models are less intuitively logical for others, e.g., common bully (which have very plastic habitat requirements, but relatively high flow demand). It is possible that this is symptomatic of a sampling bias in the data used to derive the models towards daytime habitats in wadeable gravel rivers. Further work is required to validate the use of these models, and particularly their transferability across different river types. This research would help to reduce uncertainty in the models and their output. It would also be beneficial to expand the range of species and life stages included to provide more flexibility in selecting relevant target species. The indicator species used for this assessment were determined with reference to both known (New Zealand Freshwater Fish Database; NZFFD) and predicted fish distributions (Leathwick et al. 2008), and values identified in local planning documents for the Canterbury region (Table 1). Table 1: Indicator species used for EFSAP simulations in Canterbury. Indicator species Assessment area Justification Brown trout adult Clarence River catchment Fishery value Food producing habitat All catchments Food availability for drift feeding fish Bluegill bully All catchments Relatively broad distribution and high flow demand Scenarios Uniform rules can be defined as standardised, unvarying limits that apply equally to all sites in a class. The proposed NES default minimum flow and allocation limits are uniform rules, divided into two classes based on river size (small < mean flow 5 m 3 s -1 large). Uniform rules are easy to apply and manage, but can result in spatially varying consequences for both instream and out-of-channel water uses and consequent equity problems for stakeholders. We first simulated the consequences of the proposed NES default minimum flow and allocation limits for large rivers (Q_min 80% MALF, Q 50% MALF). We then simulated a range of scenarios encompassing both more environmentally conservative and more resource use enabling limits than the proposed NES defaults. All scenarios were based on proportions of MALF (Q_min 10-% MALF; Q % MALF in 5% increments) and were applied to all locations in the catchments of interest Analyses Reliability of supply was determined for both the proportion of time that abstractions are partially restricted (Point G, Figure 1) and the proportion of time that no abstraction is possible because natural flows are at or below the minimum flow (Point E, Figure 1). These Default water allocation limits for selected catchments in the Canterbury Region 21

22 two points were termed reliability at the management flow and reliability at the minimum flow respectively. The availability of physical habitat was described in terms of the weighted usable area (WUA). For every segment of the river network, we calculated WUA at MALF and at the scenario minimum flow for each species. To allow comparison of all network segments we expressed the WUA at the minimum flow as a percentage of the WUA at MALF (Point D, Figure 1). We analysed the spatial patterns of the consequences for reliability and habitat under the proposed NES scenarios. Results were initially mapped and a visual inspection used to identify likely drivers of any spatial differentiation in consequences. We then used REC reach attribute data, e.g., stream order or catchment geology, to try and distinguish spatial differences and subsequently define spatial classes or potential management units with relatively uniform consequences for reliability and habitat. If significant spatial differences could be identified and defined, results were split into spatial classes for further analysis, with the consequences for the full range of uniform rule scenarios summarised statistically and presented as a decision space. This allows visual comparison of the range of potential outcomes for habitat and reliability resulting from different combinations of minimum flow and allocation limit. 22 Default water allocation limits for selected catchments in the Canterbury Region

23 4 Results 4.1 Proposed NES rules The proposed NES allocation rules for large rivers (minimum flow 80% of MALF and total allocation 50% of MALF) were applied to all reaches in the catchments of interest and used to evaluate the spatial patterns and variability in consequences for resource reliability and instream habitat for the target species. Scenarios were run using both the annual and February flow duration curves to compare the consequences under average and low flow conditions. Based on the annual FDC, reliability at management flow is generally higher in the northern catchments and Banks Peninsula, and lower in the southern catchments (Figure 5). However, despite the spatial variability between the catchments of interest, the vast majority of locations have a reliability of supply between 70 and 90% (Figure 10). Under low flow conditions in February, the reliability of supply at the management flow improves in some areas, but declines in others (Figure 5). This shift is dependent on the shape and position of the February FDC, relative to the annual FDC. The result is much greater spatial variation in the consequences, with the majority of sites now having a reliability of supply between 40 and % (Figure 10). Of particular note is the significant decline in reliability that appears to occur in the Clarence catchment in February. The reliability of supply at minimum flow, which represents the proportion of time that at least some water is available for allocation, follows a similar spatial pattern to reliability at the management flow, with generally higher reliability in the northern catchments and poorer reliability in the larger southern catchments (Figure 6). For the annual FDC, reliability at minimum flow ranged between 85% and %, and for the February FDC, the range increased to between 70% and %, but the overall median shifted towards higher reliability (Figure 10). The Clarence catchment was again spatially differentiated from the other catchments of interest. The spatial patterns of consequences for instream habitat appeared to be similar across all three indicators and also similar between the annual and February FDC scenarios (Figure 7, Figure 8 & Figure 9 for adult brown trout, drift food producing habitat and bluegill bullies respectively). More detailed analysis of the variability in responses (Figure 11) indicated that at some sites, habitat availability increased relative to that available at MALF under the proposed NES large river rules. The majority of sites, however, displayed a loss of habitat, which was typically greater under the annual FDC than the February FDC (Figure 11). The high spatial variation in the response of the habitat variables was subsequently identified as a key driver to identifying and defining spatially discrete management units for setting default water limits. Default water allocation limits for selected catchments in the Canterbury Region 23

24 Reliability at management flow (Annual FDC - NES large river rules) Reliability at management flow (February FDC - NES large river rules) Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) Figure 5: Maps showing the reliability at management flow in the catchments of interest under the proposed NES large river rules. Left: Annual flow duration curve; Right: February flow duration curve. 24 Default water allocation limits for selected catchments in the Canterbury Region

25 Reliability at minimum flow (Annual FDC - NES large river rules) Reliability at minimum flow (February FDC - NES large river rules) Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) <= < Reliability (%) Figure 6: Maps showing the reliability at minimum flow in the catchments of interest under the proposed NES large river rules. Left: Annual flow duration curve; Right: February flow duration curve. Default water allocation limits for selected catchments in the Canterbury Region 25

26 Brown trout adult (Annual FDC - NES large river rules) Brown trout habitat (February FDC - NES large river rules) % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF Figure 7: Maps showing the change in habitat for adult brown trout in the catchments of interest under the proposed NES large river rules. Left: Annual flow duration curve; Right: February flow duration curve. 26 Default water allocation limits for selected catchments in the Canterbury Region

27 Food producing habitat (Annual FDC - NES large river rules) Food producing habitat (February FDC - NES large river rules) % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF Figure 8: Maps showing the change in food producing habitat in the catchments of interest under the proposed NES large river rules. Left: Annual flow duration curve; Right: February flow duration curve. Default water allocation limits for selected catchments in the Canterbury Region 27

28 Bluegill bully habitat (Annual FDC - NES large river rules) Bluegill bully habitat (February FDC - NES large river rules) % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <=.9.9 < % of habitat at MALF <=.4.4 < % of habitat at MALF <=.1.1 < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF % of habitat at MALF <= < % of habitat at MALF <=.6.6 < % of habitat at MALF <=.3.3 < % of habitat at MALF <=.1.1 < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF <= < % of habitat at MALF Figure 9: Maps showing the change in habitat for bluegill bullies in the catchments of interest under the proposed NES large river rules. Left: Annual flow duration curve; Right: February flow duration curve. 28 Default water allocation limits for selected catchments in the Canterbury Region

29 Reliability at management flow (Annual FDC - NES large river rules) Reliability at minimum flow (Annual FDC - NES large river rules) Density Density Reliability (%) Reliability (%) Reliability at management flow (February FDC - NES large river rules) Reliability at minimum flow (February FDC - NES large river rules) Density Density Reliability (%) Reliability (%) Figure 10: Variation in reliability at management and minimum flows across all locations of interest. Top: Annual flow duration curve; Bottom: February flow duration curve. Default water allocation limits for selected catchments in the Canterbury Region 29

30 Brown trout habitat (Annual FDC - NES large river rules) Food producing habitat (Annual FDC - NES large river rules) Bluegill bully habitat (Annual FDC - NES large river rules) Density Density Density % of habitat at MALF % of habitat at MALF % of habitat at MALF Brown trout habitat (February FDC - NES large river rules) Food producing habitat (February FDC - NES large river rules) Bluegill bully habitat (February FDC - NES large river rules) Density 0.10 Density 0.10 Density % of habitat at MALF 0 20 % of habitat at MALF % of habitat at MALF Figure 11: Variation in habitat response across all locations of interest for the three indicators. Top: Annual flow duration curve; Bottom: February flow duration curve. 30 Default water allocation limits for selected catchments in the Canterbury Region

31 4.2 Spatial patterns In order to reduce the variability in consequences, and thus improve equitability for stakeholders, we attempted to define spatially discrete management units with relatively uniform outcomes for each of the values. Exploratory data analysis was carried out using REC classes to differentiate spatial groupings. In most cases, little differentiation was observed between the REC classes, indicating that this was not a suitable method for defining spatial management units. However, during these analyses it became clear that the response of the Clarence catchment, and particularly the main stem of the Clarence River, differed significantly enough from the rest of the locations to signify that definition of the Clarence as a separate spatial management unit was appropriate. This was further supported by the fact that the Clarence River was the only significant trout fishery within the catchments of interest, and therefore would be managed against different values. Consequently, two spatial management units were defined, being the Clarence catchment, and all other catchments (Table 2). Further investigation of the consequences within the Clarence catchment identified that, particularly for instream habitat, there was a significant difference in the response between the larger main stem and its tributaries. We therefore separated the Clarence management unit into two sub-units defined by mean discharge (Table 2; Figure 12; Figure 13). The flow threshold for differentiating small and large streams was defined at a mean discharge of 5 m 3 s -1, with flows greater than this defined as the Clarence large river management unit and flows smaller than this defined as the Clarence small river management unit. This threshold was based on the different consequences for instream habitat for all three indicators (brown trout, food producing and bluegill bullies). There may be some argument for further refining the Clarence large river management unit into large and very large rivers based again on the response of instream habitat, with increases in habitat observed for the largest rivers (Figure 13). However, as the Clarence is currently a relatively undeveloped catchment, it may not be necessary to increase the number of management units at this stage. It is recognised that currently there is a relatively broad range of variability in consequences for reliability within the other catchments management unit (Figure 12). More detailed analysis of this class may help to distinguish more spatially uniform management sub-units, but is beyond the scope of this project. This variability will have implications for defining appropriate rules to meet objectives in all locations and for equitability between stakeholders. However, because the aim of this project is to support definition of regional scale default allocation limits, rather than catchment and site specific rules, we consider that this level of variability is acceptable. Table 2: Definition of spatial management units for default allocation limits in Canterbury. Management unit Spatial definition Clarence large river Clarence catchment and mean flow 5 m 3 s -1 Clarence small river Clarence catchment and mean flow <5 m 3 s -1 Other catchments All catchments that aren t the Clarence. No size differential because majority of reaches are <5 m 3 s -1 Default water allocation limits for selected catchments in the Canterbury Region 31

32 Reliability at management flow (Annual FDC - NES large river rules) Clarence large river Clarence small river Other catchments Reliability at minimum flow (Annual FDC - NES large river rules) Clarence large river Clarence small river Other catchments Density 0.10 Density Reliability (%) Reliability (%) Reliability at management flow (February FDC - NES large river rules) Clarence large river Clarence small river Other catchments Reliability at minimum flow (February FDC - NES large river rules) Clarence large river Clarence small river Other catchments Density Density Reliability (%) Reliability (%) Figure 12: Density plots showing variation in reliability within and between the three management units. Top: Annual flow duration curve; Bottom: February flow duration curve. 32 Default water allocation limits for selected catchments in the Canterbury Region

33 Brown trout habitat (Annual FDC - NES large river rules) Food producing habitat (Annual FDC - NES large river rules) Clarence large river Clarence small river Other catchments Density % of habitat at MALF Clarence large river Clarence small river Other catchments 0.15 Density Density % of habitat at MALF Bluegill bully habitat (February FDC - NES large river rules) Clarence large river Clarence small river Other catchments % of habitat at MALF Food producing habitat (February FDC - NES large river rules) Clarence large river Clarence small river Other catchments 0 % of habitat at MALF Brown trout habitat (February FDC - NES large river rules) Density Bluegill bully habitat (Annual FDC - NES large river rules) Clarence large river Clarence small river Other catchments Density Density Clarence large river Clarence small river Other catchments % of habitat at MALF % of habitat at MALF Figure 13: Density plots showing the variation in consequences for instream habitat within and between management units. Left: Brown trout; Middle: Food producing habitat; Right: Bluegill bully habitat; Top: Annual flow duration curve; Bottom: February duration curve. Default water allocation limits for selected catchments in the Canterbury Region 33

34 4.3 Decision space diagrams A range of allocation scenarios were simulated using EFSAP for each management unit, for both the annual and February FDCs. For each management unit, the consequences for each value for the full range of simulated scenarios were then summarised in a decision space diagram. Here we have presented decision space diagrams that encompass minimum flows ranging from 10% to % of MALF and total allocation limits that range from 10% to 150% of MALF, each in 10% increments. The full range of scenarios presented may not be considered acceptable in all circumstances and this should be considered as part of the limit selection process. ECan have defined objectives for reliability of supply and retention of physical habitat: 4. median annual reliability at management flow of at least 95% 5. median annual reliability at minimum flow of at least 95%, and 6. median annual reduction in physical habitat of no greater than 25% of the habitat available at MALF. The combinations of limits that satisfy these objectives are surrounded by a thick black line on the respective decision space diagrams. Table 3 summarises where the decision space diagrams for each value and each management unit can be found. Guidance on how these diagrams can be used to inform the limit setting process can be found in the discussion (Section 5.2). Table 3: Summary of decision space diagrams presented. Diagrams are shown for both the annual and February FDCs. Management unit Reliability at management flow Reliability at minimum flow Brown trout adult Food producing habitat Bluegill bully habitat Clarence large river Figure 14 Figure 15 Figure 16 Figure 17 Figure 18 Clarence small river Figure 19 Figure 20 Figure 21 Figure 22 Figure 23 Other catchments Figure 24 Figure 25 NA Figure 27 Figure Default water allocation limits for selected catchments in the Canterbury Region

35 4.3.1 Clarence large river mangement unit Reliabilty at Management Flow (Annual FDC) Reliabilty at Management Flow (February FDC) -10 (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) -10 (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) 76.4 (73.5;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) 90.1 (89.2;90.1) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) 76.4 (73.5;) 70.5 (67.2;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) 90.1 (89.2;90.1) (86.3;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) 76.4 (73.5;) 70.5 (67.2;) 63.9 (63.9;70.5) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) 90.1 (89.2;90.1) (86.3;) (;86.3) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) 76.4 (73.5;) 70.5 (67.2;) 63.9 (63.9;70.5) 58.6 (58.6;63.9) (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) 90.1 (89.2;90.1) (86.3;) (;86.3) 81.7 (;) -50 (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) 76.4 (73.5;) 70.5 (67.2;) 63.9 (63.9;70.5) 58.6 (58.6;63.9) 55 (53.1;58.6) Total allocation (%MALF) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) 90.1 (89.2;90.1) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 91.7 (91.7;) 90.1 (89.2;90.1) (86.3;) 93.8 (93.1;94.4) 91.7 (91.7;) 90.1 (89.2;90.1) (86.3;) (;86.3) 91.7 (91.7;) 90.1 (89.2;90.1) (86.3;) (;86.3) 81.7 (;) 90.1 (89.2;90.1) (86.3;) (;86.3) 81.7 (;) 79.2 (;) (86.3;) (;86.3) 81.7 (;) 79.2 (;) 76.4 (73.8;) (;86.3) 81.7 (;) 79.2 (;) 76.4 (73.8;) 73.5 (70.8;76.4) 81.7 (;) 79.2 (;) 76.4 (73.8;) 73.5 (70.8;76.4) 70.5 (67.6;73.5) 79.2 (;) 76.4 (73.8;) 73.5 (70.8;76.4) 70.5 (67.6;73.5) 67.2 (64.2;70.5) Total allocation (%MALF) (90.9;) (;98.4) (;95.5) (;90.9) 76.4 (73.5;) (;98.4) (;95.5) (;90.9) 76.4 (73.5;) 70.5 (67.2;) (;95.5) (;90.9) 76.4 (73.5;) 70.5 (67.2;) 63.9 (63.9;70.5) (;90.9) 76.4 (73.5;) 70.5 (67.2;) 63.9 (63.9;70.5) 58.6 (58.6;63.9) 76.4 (73.5;) 70.5 (67.2;) 63.9 (63.9;70.5) 58.6 (58.6;63.9) 55 (53.1;58.6) 70.5 (67.2;) 63.9 (63.9;70.5) 58.6 (58.6;63.9) 55 (53.1;58.6) 51.3 (47.5;53.1) 63.9 (63.9;70.5) 58.6 (58.6;63.9) 55 (53.1;58.6) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 58.6 (58.6;63.9) 55 (53.1;58.6) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 55 (53.1;58.6) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 40 (36.2;41.9) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 40 (36.2;41.9) 36.2 (32.5;38.1) (89.2;90.1) (86.3;) (;86.3) 81.7 (;) 79.2 (;) 76.4 (73.8;) 73.5 (70.8;76.4) 70.5 (67.6;73.5) 67.2 (64.2;70.5) (62.1;67.2) (67.2;) 63.9 (63.9;70.5) 58.6 (58.6;63.9) 55 (53.1;58.6) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 40 (36.2;41.9) 36.2 (32.5;38.1) 34.4 (30.7;36.2) -120 (86.3;) (;86.3) 81.7 (;) 79.2 (;) 76.4 (73.8;) 73.5 (70.8;76.4) 70.5 (67.6;73.5) 67.2 (64.2;70.5) (62.1;67.2) 62.1 (58.6;) (63.9;70.5) 58.6 (58.6;63.9) 55 (53.1;58.6) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 40 (36.2;41.9) 36.2 (32.5;38.1) 34.4 (30.7;36.2) 30.7 (27.1;32.5) -130 (;86.3) 81.7 (;) 79.2 (;) 76.4 (73.8;) 73.5 (70.8;76.4) 70.5 (67.6;73.5) 67.2 (64.2;70.5) (62.1;67.2) 62.1 (58.6;) 58.6 (55.3;62.1) (58.6;63.9) 55 (53.1;58.6) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 40 (36.2;41.9) 36.2 (32.5;38.1) 34.4 (30.7;36.2) 30.7 (27.1;32.5) 28.9 (25.4;30.7) (;) 79.2 (;) 76.4 (73.8;) 73.5 (70.8;76.4) 70.5 (67.6;73.5) 67.2 (64.2;70.5) (62.1;67.2) 62.1 (58.6;) 58.6 (55.3;62.1) 56.8 (53.1;60.4) (53.1;58.6) 51.3 (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 40 (36.2;41.9) 36.2 (32.5;38.1) 34.4 (30.7;36.2) 30.7 (27.1;32.5) 28.9 (25.4;30.7) 27.1 (23.7;28.9) (;) 76.4 (73.8;) 73.5 (70.8;76.4) 70.5 (67.6;73.5) 67.2 (64.2;70.5) (62.1;67.2) 62.1 (58.6;) 58.6 (55.3;62.1) 56.8 (53.1;60.4) 55 (49.8;58.6) (47.5;53.1) 47.5 (43.8;49.4) 43.8 (40;45.6) 40 (36.2;41.9) 36.2 (32.5;38.1) 34.4 (30.7;36.2) 30.7 (27.1;32.5) 28.9 (25.4;30.7) 27.1 (23.7;28.9) 25.4 (22;25.4) Minimum flow (%MALF) Minimum flow (%MALF) Figure 14: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for reliability at management flow. The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. Default water allocation limits for selected catchments in the Canterbury Region 35

36 Reliabilty at Minimum Flow (Annual FDC) Reliabilty at Minimum Flow (February FDC) -10 (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) -10 (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) -50 (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) -50 (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) Total allocation (%MALF) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (99.7;) (99.7;) (99.7;) (99.7;) (99.7;) (;) (;) (;) (;) (;) 99.2 (99;99.7) 99.2 (99;99.7) 99.2 (99;99.7) 99.2 (99;99.7) 99.2 (99;99.7) 98.6 (98.4;99.3) 98.6 (98.4;99.3) 98.6 (98.4;99.3) 98.6 (98.4;99.3) 98.6 (98.4;99.3) (97.5;98.6) (97.5;98.6) (97.5;98.6) (97.5;98.6) (97.5;98.6) (96.4;97.5) (96.4;97.5) (96.4;97.5) (96.4;97.5) (96.4;97.5) 95.5 (94.9;96.3) 95.5 (94.9;96.3) 95.5 (94.9;96.3) 95.5 (94.9;96.3) 95.5 (94.9;96.3) 93.8 (93.1;94.4) 93.8 (93.1;94.4) 93.8 (93.1;94.4) 93.8 (93.1;94.4) 93.8 (93.1;94.4) Total allocation (%MALF) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (98.6;) (98.6;) (98.6;) (98.6;) (98.6;) (;) (;) (;) (;) (;) (94.4;) (94.4;) (94.4;) (94.4;) (94.4;) (90.9;) (90.9;) (90.9;) (90.9;) (90.9;) (;98.4) (;98.4) (;98.4) (;98.4) (;98.4) (;95.5) (;95.5) (;95.5) (;95.5) (;95.5) (;90.9) (;90.9) (;90.9) (;90.9) (;90.9) -110 (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) -110 (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) -120 (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) -120 (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) -130 (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) -130 (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) -140 (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) -140 (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) -150 (;) (;) (99.7;) (;) 99.2 (99;99.7) 98.6 (98.4;99.3) (97.5;98.6) (96.4;97.5) 95.5 (94.9;96.3) 93.8 (93.1;94.4) -150 (;) (;) (;) (98.6;) (;) (94.4;) (90.9;) (;98.4) (;95.5) (;90.9) Minimum flow (%MALF) Minimum flow (%MALF) Figure 15: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for reliability at minimum flow. The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. 36 Default water allocation limits for selected catchments in the Canterbury Region

37 (-5.81;7.11) 9.92 (-12.4;13.4) 12.8 (-19.8;18.2) 5.47 (-5.81;7.11) 9.92 (-12.4;13.4) 12.8 (-19.8;18.2) 5.47 (-5.81;7.11) 9.92 (-12.4;13.4) 12.8 (-19.8;18.2) Brown trout adult habitat (Annual FDC) 5.47 (-5.81;7.11) 9.92 (-12.4;13.4) 12.8 (-19.8;18.2) 5.47 (-5.81;7.11) 9.92 (-12.4;13.4) 12.8 (-19.8;18.2) 5.47 (-5.81;7.11) 9.92 (-12.4;13.4) 12.8 (-19.8;18.2) 5.47 (-5.81;7.11) 9.92 (-12.4;13.4) 12.8 (-19.8;18.2) 5.47 (-5.81;7.11) 9.92 (-12.4;13.4) 10.8 (-13.6;14.9) 5.47 (-5.81;7.11) 6.63 (-6.89;8.89) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) 0.72 (-1.46;2.03) 0.72 (-1.46;2.03) (-5.93;6.94) 9.46 (-12.6;12.9) 12 (.1;17.4) 5.27 (-5.93;6.94) 9.46 (-12.6;12.9) 12 (.1;17.4) 5.27 (-5.93;6.94) 9.46 (-12.6;12.9) 12 (.1;17.4) Brown trout adult habitat (February FDC) 5.27 (-5.93;6.94) 9.46 (-12.6;12.9) 12 (.1;17.4) 5.27 (-5.93;6.94) 9.46 (-12.6;12.9) 12 (.1;17.4) 5.27 (-5.93;6.94) 9.46 (-12.6;12.9) 12 (.1;17.4) 5.27 (-5.93;6.94) 9.46 (-12.6;12.9) 12 (.1;17.4) 5.27 (-5.93;6.94) 9.46 (-12.6;12.9) 9.65 (-12.9;14.1) 5.27 (-5.93;6.94) 5.72 (-6.15;8.29) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) 0.45 (-0.515;1.44) 0.45 (-0.515;1.44) 13.6 (-28;20.8) 13.6 (-28;20.8) 13.6 (-28;20.8) 13.6 (-28;20.8) 13.6 (-28;20.8) 13.6 (-28;20.8) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) 12.3 (-28.5;19.7) 12.3 (-28.5;19.7) 12.3 (-28.5;19.7) 12.3 (-28.5;19.7) 12.3 (-28.5;19.7) 12.3 (-28.5;19.7) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) (-37.2;20.2) 11.3 (-37.2;20.2) 11.3 (-37.2;20.2) 11.3 (-37.2;20.2) 11.3 (-37.2;20.2) 13.4 (-29.4;21) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) (-37.9;18.8) 9.47 (-37.9;18.8) 9.47 (-37.9;18.8) 9.47 (-37.9;18.8) 9.47 (-37.9;18.8) 12.2 (-28.9;19.8) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) Total allocation (%MALF) (-47.3;15.3) (-58.4;4.37) 5.07 (-47.3;15.3) (-58.4;4.37) 5.07 (-47.3;15.3) (-58.4;4.37) (-70.6;-14.7) (-70.6;-14.7) (-60.4;-0.013) (-83.8;-44.6) (-72.9;-21.7) (-60.4;-0.013) (-86.3;-54.7) (-72.9;-21.7) (-60.4;-0.013) 5.07 (-47.3;15.3) 2.82 (-49;13) 2.82 (-49;13) 2.82 (-49;13) 2.82 (-49;13) 10.2 (-38.7;19.4) 10.2 (-38.7;19.4) 10.2 (-38.7;19.4) 10.2 (-38.7;19.4) 10.2 (-38.7;19.4) 13.4 (-29.4;21) 13.4 (-29.4;21) 13.4 (-29.4;21) 13.4 (-29.4;21) 13.4 (-29.4;21) 13.2 (-21.1;19.1) 13.2 (-21.1;19.1) 13.2 (-21.1;19.1) 13.2 (-21.1;19.1) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 10.8 (-13.6;14.9) 10.8 (-13.6;14.9) 10.8 (-13.6;14.9) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 6.63 (-6.89;8.89) 6.63 (-6.89;8.89) 6.63 (-6.89;8.89) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) 0.72 (-1.46;2.03) 0.72 (-1.46;2.03) 0.72 (-1.46;2.03) 0.72 (-1.46;2.03) Total allocation (%MALF) (-48.2;13.5) (-59.7;2.27) 2.39 (-48.2;13.5) (-59.7;2.27) 2.39 (-48.2;13.5) (-59.7;2.27) (-72.1;-17.3) (-72.1;-17.3) (-60.1;-1.05) (-85.2;-47.4) (-72.6;-22.5) (-60.1;-1.05) (-86.2;-55.2) (-72.6;-22.5) (-60.1;-1.05) 2.39 (-48.2;13.5) 1.79 (-48.6;11.8) 1.79 (-48.6;11.8) 1.79 (-48.6;11.8) 1.79 (-48.6;11.8) 9.15 (-38.2;18.1) 9.15 (-38.2;18.1) 9.15 (-38.2;18.1) 9.15 (-38.2;18.1) 9.15 (-38.2;18.1) 12.2 (-28.9;19.8) 12.2 (-28.9;19.8) 12.2 (-28.9;19.8) 12.2 (-28.9;19.8) 12.2 (-28.9;19.8) 12.1 (.5;18.1) 12.1 (.5;18.1) 12.1 (.5;18.1) 12.1 (.5;18.1) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 9.65 (-12.9;14.1) 9.65 (-12.9;14.1) 9.65 (-12.9;14.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 5.72 (-6.15;8.29) 5.72 (-6.15;8.29) 5.72 (-6.15;8.29) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) 0.45 (-0.515;1.44) 0.45 (-0.515;1.44) 0.45 (-0.515;1.44) 0.45 (-0.515;1.44) (-86.3;-54.7) (-72.9;-21.7) (-60.4;-0.013) 2.82 (-49;13) 10.2 (-38.7;19.4) 13.4 (-29.4;21) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) (-86.2;-55.2) (-72.6;-22.5) (-60.1;-1.05) 1.79 (-48.6;11.8) 9.15 (-38.2;18.1) 12.2 (-28.9;19.8) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) (-86.3;-54.7) (-72.9;-21.7) (-60.4;-0.013) 2.82 (-49;13) 10.2 (-38.7;19.4) 13.4 (-29.4;21) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) (-86.2;-55.2) (-72.6;-22.5) (-60.1;-1.05) 1.79 (-48.6;11.8) 9.15 (-38.2;18.1) 12.2 (-28.9;19.8) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) (-86.3;-54.7) (-72.9;-21.7) (-60.4;-0.013) 2.82 (-49;13) 10.2 (-38.7;19.4) 13.4 (-29.4;21) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) (-86.2;-55.2) (-72.6;-22.5) (-60.1;-1.05) 1.79 (-48.6;11.8) 9.15 (-38.2;18.1) 12.2 (-28.9;19.8) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) (-86.3;-54.7) (-72.9;-21.7) (-60.4;-0.013) 2.82 (-49;13) 10.2 (-38.7;19.4) 13.4 (-29.4;21) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) (-86.2;-55.2) (-72.6;-22.5) (-60.1;-1.05) 1.79 (-48.6;11.8) 9.15 (-38.2;18.1) 12.2 (-28.9;19.8) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) (-86.3;-54.7) (-72.9;-21.7) (-60.4;-0.013) 2.82 (-49;13) 10.2 (-38.7;19.4) 13.4 (-29.4;21) 13.2 (-21.1;19.1) 10.8 (-13.6;14.9) 6.63 (-6.89;8.89) 0.72 (-1.46;2.03) (-86.2;-55.2) (-72.6;-22.5) (-60.1;-1.05) 1.79 (-48.6;11.8) 9.15 (-38.2;18.1) 12.2 (-28.9;19.8) 12.1 (.5;18.1) 9.65 (-12.9;14.1) 5.72 (-6.15;8.29) 0.45 (-0.515;1.44) Minimum flow (%MALF) Minimum flow (%MALF) Figure 16: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for change in adult brown trout habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. Default water allocation limits for selected catchments in the Canterbury Region 37

38 (-6.08;6.46) 4.88 (-6.08;6.46) 4.88 (-6.08;6.46) Food producing habitat (Annual FDC) 4.88 (-6.08;6.46) 4.88 (-6.08;6.46) 4.88 (-6.08;6.46) 4.88 (-6.08;6.46) 4.88 (-6.08;6.46) 4.88 (-6.08;6.46) 0.66 (-1.53;1.86) (-6.2;6.29) 4.67 (-6.2;6.29) 4.67 (-6.2;6.29) Food producing habitat (February FDC) 4.67 (-6.2;6.29) 4.67 (-6.2;6.29) 4.67 (-6.2;6.29) 4.67 (-6.2;6.29) 4.67 (-6.2;6.29) (-6.2;6.29) (-0.549;1.32) 8.65 (-12.9;12) 8.65 (-12.9;12) 8.65 (-12.9;12) 8.65 (-12.9;12) 8.65 (-12.9;12) 8.65 (-12.9;12) 8.65 (-12.9;12) 8.65 (-12.9;12) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) 8.19 (-13.1;11.6) 8.19 (-13.1;11.6) 8.19 (-13.1;11.6) 8.19 (-13.1;11.6) 8.19 (-13.1;11.6) 8.19 (-13.1;11.6) 8.19 (-13.1;11.6) 8.19 (-13.1;11.6) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) 10.9 (.5;16) 10.9 (.5;16) 10.9 (.5;16) 10.9 (.5;16) 10.9 (.5;16) 10.9 (.5;16) 10.9 (.5;16) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) 10 (.9;15.3) 10 (.9;15.3) 10 (.9;15.3) 10 (.9;15.3) 10 (.9;15.3) 10 (.9;15.3) 10 (.9;15.3) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) 10.9 (-28.9;17.7) 10.9 (-28.9;17.7) 10.9 (-28.9;17.7) 10.9 (-28.9;17.7) 10.9 (-28.9;17.7) 10.9 (-28.9;17.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) 9.61 (-29.5;16.7) 9.61 (-29.5;16.7) 9.61 (-29.5;16.7) 9.61 (-29.5;16.7) 9.61 (-29.5;16.7) 9.61 (-29.5;16.7) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) (-38.2;16.3) 7.92 (-38.2;16.3) 7.92 (-38.2;16.3) 7.92 (-38.2;16.3) 7.92 (-38.2;16.3) 10.5 (.4;17.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) (-38.9;15) 6.07 (-38.9;15) 6.07 (-38.9;15) 6.07 (-38.9;15) 6.07 (-38.9;15) 9.47 (-29.8;16.6) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) Total allocation (%MALF) (-59.5;-0.695) (-59.5;-0.695) (-59.5;-0.695) (-50.2;8.21) (-48.4;10.7) 1.07 (-48.4;10.7) 1.07 (-48.4;10.7) (-71.6;-19.8) (-71.6;-19.8) (-61.5;-5.14) (-84.5;-48.5) (-73.8;-26.5) (-61.5;-5.14) (-86.9;-58.1) (-73.8;-26.5) (-61.5;-5.14) 1.07 (-48.4;10.7) (-50.2;8.21) (-50.2;8.21) (-50.2;8.21) 6.67 (-39.8;15.3) 6.67 (-39.8;15.3) 6.67 (-39.8;15.3) 6.67 (-39.8;15.3) 6.67 (-39.8;15.3) 10.5 (.4;17.7) 10.5 (.4;17.7) 10.5 (.4;17.7) 10.5 (.4;17.7) 10.5 (.4;17.7) 11.1 (-21.8;16.7) 11.1 (-21.8;16.7) 11.1 (-21.8;16.7) 11.1 (-21.8;16.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 9.35 (-14.1;13.3) 9.35 (-14.1;13.3) 9.35 (-14.1;13.3) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 5.9 (-7.2;8.06) 5.9 (-7.2;8.06) 5.9 (-7.2;8.06) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) 0.66 (-1.53;1.86) 0.66 (-1.53;1.86) 0.66 (-1.53;1.86) 0.66 (-1.53;1.86) Total allocation (%MALF) (-49.4;8.99) (-60.7;-2.68) (-60.7;-2.68) (-60.7;-2.68) (-73;-22.1) (-49.4;8.99) (-73;-22.1) (-49.4;8.99) (-61.2;-6.03) (-85.9;-51.2) (-73.6;-27.2) (-61.2;-6.03) (-86.8;-58.5) (-73.6;-27.2) (-61.2;-6.03) (-49.4;8.99) (-49.8;7.15) (-49.8;7.15) (-49.8;7.15) (-49.8;7.15) 5.71 (-39.3;14.2) 5.71 (-39.3;14.2) 5.71 (-39.3;14.2) 5.71 (-39.3;14.2) 5.71 (-39.3;14.2) 9.47 (-29.8;16.6) 9.47 (-29.8;16.6) 9.47 (-29.8;16.6) 9.47 (-29.8;16.6) 9.47 (-29.8;16.6) 10.1 (-21.3;15.8) 10.1 (-21.3;15.8) 10.1 (-21.3;15.8) 10.1 (-21.3;15.8) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 8.35 (-13.4;12.5) 8.35 (-13.4;12.5) 8.35 (-13.4;12.5) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 5.01 (-6.43;7.52) 5.01 (-6.43;7.52) 5.01 (-6.43;7.52) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) 0.4 (-0.549;1.32) 0.4 (-0.549;1.32) 0.4 (-0.549;1.32) 0.4 (-0.549;1.32) (-86.9;-58.1) (-73.8;-26.5) (-61.5;-5.14) (-50.2;8.21) 6.67 (-39.8;15.3) 10.5 (.4;17.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) (-86.8;-58.5) (-73.6;-27.2) (-61.2;-6.03) (-49.8;7.15) 5.71 (-39.3;14.2) 9.47 (-29.8;16.6) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) (-86.9;-58.1) (-73.8;-26.5) (-61.5;-5.14) (-50.2;8.21) 6.67 (-39.8;15.3) 10.5 (.4;17.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) (-86.8;-58.5) (-73.6;-27.2) (-61.2;-6.03) (-49.8;7.15) 5.71 (-39.3;14.2) 9.47 (-29.8;16.6) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) (-86.9;-58.1) (-73.8;-26.5) (-61.5;-5.14) (-50.2;8.21) 6.67 (-39.8;15.3) 10.5 (.4;17.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) (-86.8;-58.5) (-73.6;-27.2) (-61.2;-6.03) (-49.8;7.15) 5.71 (-39.3;14.2) 9.47 (-29.8;16.6) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) (-86.9;-58.1) (-73.8;-26.5) (-61.5;-5.14) (-50.2;8.21) 6.67 (-39.8;15.3) 10.5 (.4;17.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) (-86.8;-58.5) (-73.6;-27.2) (-61.2;-6.03) (-49.8;7.15) 5.71 (-39.3;14.2) 9.47 (-29.8;16.6) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) (-86.9;-58.1) (-73.8;-26.5) (-61.5;-5.14) (-50.2;8.21) 6.67 (-39.8;15.3) 10.5 (.4;17.7) 11.1 (-21.8;16.7) 9.35 (-14.1;13.3) 5.9 (-7.2;8.06) 0.66 (-1.53;1.86) (-86.8;-58.5) (-73.6;-27.2) (-61.2;-6.03) (-49.8;7.15) 5.71 (-39.3;14.2) 9.47 (-29.8;16.6) 10.1 (-21.3;15.8) 8.35 (-13.4;12.5) 5.01 (-6.43;7.52) 0.4 (-0.549;1.32) Minimum flow (%MALF) Minimum flow (%MALF) Figure 17: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for change in food producing habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. 38 Default water allocation limits for selected catchments in the Canterbury Region

39 (-2.34;17.2) 14.7 (-2.34;17.2) 14.7 (-2.34;17.2) Bluegill bully habitat (Annual FDC) 14.7 (-2.34;17.2) 14.7 (-2.34;17.2) 14.7 (-2.34;17.2) 14.7 (-2.34;17.2) 14.7 (-2.34;17.2) 14.7 (-2.34;17.2) 1.83 (-0.351;4.62) (-2.48;17.1) 14.5 (-2.48;17.1) 14.5 (-2.48;17.1) Bluegill bully habitat (February FDC) 14.5 (-2.48;17.1) 14.5 (-2.48;17.1) 14.5 (-2.48;17.1) 14.5 (-2.48;17.1) 14.5 (-2.48;17.1) 14.5 (-2.48;17.1) 1.22 (-0.109;3.28) 30.3 (-5.62;36) 30.3 (-5.62;36) 30.3 (-5.62;36) 30.3 (-5.62;36) 30.3 (-5.62;36) 30.3 (-5.62;36) 30.3 (-5.62;36) 30.3 (-5.62;36) 17.5 (-2.84;22.2) 1.83 (-0.351;4.62) 29.8 (-5.91;35.6) 29.8 (-5.91;35.6) 29.8 (-5.91;35.6) 29.8 (-5.91;35.6) 29.8 (-5.91;35.6) 29.8 (-5.91;35.6) 29.8 (-5.91;35.6) 29.8 (-5.91;35.6) 16.6 (-2.57;20.8) 1.22 (-0.109;3.28) 46.1 (-9.99;55.9) 61.2 (-15.7;75.7) 46.1 (-9.99;55.9) 61.2 (-15.7;75.7) 46.1 (-9.99;55.9) 61.2 (-15.7;75.7) 46.1 (-9.99;55.9) 61.2 (-15.7;75.7) 46.1 (-9.99;55.9) 61.2 (-15.7;75.7) 46.1 (-9.99;55.9) 61.2 (-15.7;75.7) 46.1 (-9.99;55.9) 49.9 (-10.9;61.5) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) 45.2 (-10.5;55.1) 59.7 (-16.3;74.4) 45.2 (-10.5;55.1) 59.7 (-16.3;74.4) 45.2 (-10.5;55.1) 59.7 (-16.3;74.4) 45.2 (-10.5;55.1) 59.7 (-16.3;74.4) 45.2 (-10.5;55.1) 59.7 (-16.3;74.4) 45.2 (-10.5;55.1) 59.7 (-16.3;74.4) 45.2 (-10.5;55.1) 46.1 (-10.6;59.1) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) (-23;93.9) 73.9 (-23;93.9) 73.9 (-23;93.9) 73.9 (-23;93.9) 73.9 (-23;93.9) 64.6 (-16.8;81) 49.9 (-10.9;61.5) 34.1 (-6.3;41.4) 17.5 (-2.84;22.2) 1.83 (-0.351;4.62) (-23.7;91.6) 71.5 (-23.7;91.6) 71.5 (-23.7;91.6) 71.5 (-23.7;91.6) 71.5 (-23.7;91.6) 60.5 (-16.6;78) 46.1 (-10.6;59.1) 31.1 (-6.04;39.6) 16.6 (-2.57;20.8) 1.22 (-0.109;3.28) Total allocation (%MALF) (-32.1;107) 80.6 (-43.2;110) 64.2 (-56.9;96.3) 21.7 (-73.8;50.3) 6.1 (-77.2;29.5) 81.8 (-32.1;107) 80.6 (-43.2;110) 64.2 (-56.9;96.3) 57 (-59.5;87.6) 57 (-59.5;87.6) 81.8 (-32.1;107) 80.6 (-43.2;110) 78.4 (-45.2;109) 78.4 (-45.2;109) 78.4 (-45.2;109) 81.8 (-32.1;107) 82.5 (-33.6;109) 82.5 (-33.6;109) 82.5 (-33.6;109) 82.5 (-33.6;109) 76.4 (-24.3;98) 76.4 (-24.3;98) 76.4 (-24.3;98) 76.4 (-24.3;98) 76.4 (-24.3;98) 64.6 (-16.8;81) 64.6 (-16.8;81) 64.6 (-16.8;81) 64.6 (-16.8;81) 64.6 (-16.8;81) 49.9 (-10.9;61.5) 49.9 (-10.9;61.5) 49.9 (-10.9;61.5) 49.9 (-10.9;61.5) 49.9 (-10.9;61.5) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) Total allocation (%MALF) (-33;103) 74.8 (-44.5;106) 78 (-33;103) 74.8 (-44.5;106) (-58.8;90.3) (-58.8;90.3) (-76.2;42.9) (-59.3;83.3) (-77.2;26.5) (-59.3;83.3) 78 (-33;103) 74.8 (-44.5;106) 74.1 (-45;104) 74.1 (-45;104) 74.1 (-45;104) 78 (-33;103) 78.1 (-33.4;105) 78.1 (-33.4;105) 78.1 (-33.4;105) 78.1 (-33.4;105) 72.1 (-24.1;94.4) 72.1 (-24.1;94.4) 72.1 (-24.1;94.4) 72.1 (-24.1;94.4) 72.1 (-24.1;94.4) 60.5 (-16.6;78) 60.5 (-16.6;78) 60.5 (-16.6;78) 60.5 (-16.6;78) 60.5 (-16.6;78) 46.1 (-10.6;59.1) 46.1 (-10.6;59.1) 46.1 (-10.6;59.1) 46.1 (-10.6;59.1) 46.1 (-10.6;59.1) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) (-77.2;29.5) 6.1 (-77.2;29.5) 6.1 (-77.2;29.5) 6.1 (-77.2;29.5) 57 (-59.5;87.6) 57 (-59.5;87.6) 57 (-59.5;87.6) 57 (-59.5;87.6) 78.4 (-45.2;109) 78.4 (-45.2;109) 78.4 (-45.2;109) 78.4 (-45.2;109) 82.5 (-33.6;109) 82.5 (-33.6;109) 82.5 (-33.6;109) 82.5 (-33.6;109) 76.4 (-24.3;98) 76.4 (-24.3;98) 76.4 (-24.3;98) 76.4 (-24.3;98) 64.6 (-16.8;81) 64.6 (-16.8;81) 64.6 (-16.8;81) 64.6 (-16.8;81) 49.9 (-10.9;61.5) 49.9 (-10.9;61.5) 49.9 (-10.9;61.5) 49.9 (-10.9;61.5) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 34.1 (-6.3;41.4) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 17.5 (-2.84;22.2) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) 1.83 (-0.351;4.62) (-77.2;26.5) (-59.3;83.3) (-77.2;26.5) (-59.3;83.3) (-77.2;26.5) (-59.3;83.3) (-77.2;26.5) (-59.3;83.3) 74.1 (-45;104) 74.1 (-45;104) 74.1 (-45;104) 74.1 (-45;104) 78.1 (-33.4;105) 78.1 (-33.4;105) 78.1 (-33.4;105) 78.1 (-33.4;105) 72.1 (-24.1;94.4) 72.1 (-24.1;94.4) 72.1 (-24.1;94.4) 72.1 (-24.1;94.4) 60.5 (-16.6;78) 60.5 (-16.6;78) 60.5 (-16.6;78) 60.5 (-16.6;78) 46.1 (-10.6;59.1) 46.1 (-10.6;59.1) 46.1 (-10.6;59.1) 46.1 (-10.6;59.1) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 31.1 (-6.04;39.6) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 16.6 (-2.57;20.8) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) 1.22 (-0.109;3.28) (-77.2;29.5) 57 (-59.5;87.6) 78.4 (-45.2;109) 82.5 (-33.6;109) 76.4 (-24.3;98) 64.6 (-16.8;81) Minimum flow (%MALF) 49.9 (-10.9;61.5) 34.1 (-6.3;41.4) 17.5 (-2.84;22.2) 1.83 (-0.351;4.62) (-77.2;26.5) (-59.3;83.3) 74.1 (-45;104) 78.1 (-33.4;105) 72.1 (-24.1;94.4) 60.5 (-16.6;78) Minimum flow (%MALF) 46.1 (-10.6;59.1) 31.1 (-6.04;39.6) 16.6 (-2.57;20.8) 1.22 (-0.109;3.28) Figure 18: Clarence catchment (mean flow 5 m 3 s -1 ) decision space diagrams for change in bluegill bully habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. Default water allocation limits for selected catchments in the Canterbury Region 39

40 4.3.2 Clarence small river management unit Reliabilty at Management Flow (Annual FDC) Reliabilty at Management Flow (February FDC) -10 (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) -10 (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) (72;93.8) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) (85.2;89.2) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) (72;93.8) (;90.1) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) (85.2;89.2) (81.7;86.3) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) (72;93.8) (;90.1) 72 (60.4;86.3) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) (85.2;89.2) (81.7;86.3) (;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) (72;93.8) (;90.1) 72 (60.4;86.3) 67.2 (55;81.7) (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) (85.2;89.2) (81.7;86.3) (;) (75;) (;) (93.1;) (;) (;98.8) (;) (72;93.8) (;90.1) 72 (60.4;86.3) 67.2 (55;81.7) 60.4 (49.4;) Total allocation (%MALF) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) (85.2;89.2) 94.9 (93.8;) (91.7;93.8) 90.1 (;91.7) (85.2;89.2) (81.7;86.3) (91.7;93.8) 90.1 (;91.7) (85.2;89.2) (81.7;86.3) (;) 90.1 (;91.7) (85.2;89.2) (81.7;86.3) (;) (75;) (85.2;89.2) (81.7;86.3) (;) (75;) 73.5 (70.5;) (81.7;86.3) (;) (75;) 73.5 (70.5;) 70.5 (67.2;75) (;) (75;) 73.5 (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (75;) 73.5 (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (60.4;70.5) 73.5 (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (60.4;70.5) 62.1 (56.8;67.2) Total allocation (%MALF) (93.1;) (;) (;98.8) (;) (72;93.8) (;) (;98.8) (;) (72;93.8) (;90.1) (;98.8) (;) (72;93.8) (;90.1) 72 (60.4;86.3) (;) (72;93.8) (;90.1) 72 (60.4;86.3) 67.2 (55;81.7) (72;93.8) (;90.1) 72 (60.4;86.3) 67.2 (55;81.7) 60.4 (49.4;) (;90.1) 72 (60.4;86.3) 67.2 (55;81.7) 60.4 (49.4;) 56.8 (45.6;73.5) 72 (60.4;86.3) 67.2 (55;81.7) 60.4 (49.4;) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 67.2 (55;81.7) 60.4 (49.4;) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 60.4 (49.4;) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 43.8 (36.2;62.1) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 43.8 (36.2;62.1) 41.9 (32.5;58.6) -110 (85.2;89.2) (81.7;86.3) (;) (75;) 73.5 (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (60.4;70.5) 62.1 (56.8;67.2) 58.6 (55;) -110 (;90.1) 72 (60.4;86.3) 67.2 (55;81.7) 60.4 (49.4;) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 43.8 (36.2;62.1) 41.9 (32.5;58.6) 38.1 (30.7;55) -120 (81.7;86.3) (;) (75;) 73.5 (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (60.4;70.5) 62.1 (56.8;67.2) 58.6 (55;) 56.8 (51.3;62.1) (60.4;86.3) 67.2 (55;81.7) 60.4 (49.4;) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 43.8 (36.2;62.1) 41.9 (32.5;58.6) 38.1 (30.7;55) 36.2 (27.1;53.1) -130 (;) (75;) 73.5 (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (60.4;70.5) 62.1 (56.8;67.2) 58.6 (55;) 56.8 (51.3;62.1) 53.1 (49.4;60.4) (55;81.7) 60.4 (49.4;) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 43.8 (36.2;62.1) 41.9 (32.5;58.6) 38.1 (30.7;55) 36.2 (27.1;53.1) 32.5 (25.4;49.4) -140 (75;) 73.5 (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (60.4;70.5) 62.1 (56.8;67.2) 58.6 (55;) 56.8 (51.3;62.1) 53.1 (49.4;60.4) 51.3 (45.6;58.6) (49.4;) 56.8 (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 43.8 (36.2;62.1) 41.9 (32.5;58.6) 38.1 (30.7;55) 36.2 (27.1;53.1) 32.5 (25.4;49.4) 30.7 (23.7;45.6) (70.5;) 70.5 (67.2;75) 67.2 (63.9;72) (60.4;70.5) 62.1 (56.8;67.2) 58.6 (55;) 56.8 (51.3;62.1) 53.1 (49.4;60.4) 51.3 (45.6;58.6) 49.4 (43.8;55) (45.6;73.5) 51.3 (41.9;70.5) 47.5 (38.1;) 43.8 (36.2;62.1) 41.9 (32.5;58.6) 38.1 (30.7;55) 36.2 (27.1;53.1) 32.5 (25.4;49.4) 30.7 (23.7;45.6) 28.9 (22;43.8) Minimum flow (%MALF) Minimum flow (%MALF) Figure 19: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for reliability at management flow. The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. 40 Default water allocation limits for selected catchments in the Canterbury Region

41 Reliabilty at Minimum Flow (Annual FDC) Reliabilty at Minimum Flow (February FDC) -10 (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) -10 (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) -50 (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) -50 (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) Total allocation (%MALF) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (99.2;) (99.2;) (99.2;) (99.2;) (99.2;) 99 (98.4;) 99 (98.4;) 99 (98.4;) 99 (98.4;) 99 (98.4;) (97.2;98.6) (97.2;98.6) (97.2;98.6) (97.2;98.6) (97.2;98.6) (95.5;97.5) (95.5;97.5) (95.5;97.5) (95.5;97.5) (95.5;97.5) 94.9 (93.8;) 94.9 (93.8;) 94.9 (93.8;) 94.9 (93.8;) 94.9 (93.8;) (91.7;93.8) (91.7;93.8) (91.7;93.8) (91.7;93.8) (91.7;93.8) Total allocation (%MALF) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (99.7;) (99.7;) (99.7;) (99.7;) (99.7;) (98.8;) (98.8;) (98.8;) (98.8;) (98.8;) 99.3 (;) 99.3 (;) 99.3 (;) 99.3 (;) 99.3 (;) (93.1;) (93.1;) (93.1;) (93.1;) (93.1;) (;) (;) (;) (;) (;) (;98.8) (;98.8) (;98.8) (;98.8) (;98.8) (;) (;) (;) (;) (;) -110 (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) -110 (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) -120 (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) -120 (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) -130 (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) -130 (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) -140 (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) -140 (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) -150 (;) (;) (;) (;) (99.2;) 99 (98.4;) (97.2;98.6) (95.5;97.5) 94.9 (93.8;) (91.7;93.8) -150 (;) (;) (;) (99.7;) (98.8;) 99.3 (;) (93.1;) (;) (;98.8) (;) Minimum flow (%MALF) Minimum flow (%MALF) Figure 20: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for reliability at minimum flow. The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. Default water allocation limits for selected catchments in the Canterbury Region 41

42 Brown trout adult habitat (Annual FDC) Brown trout adult habitat (February FDC) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-2.85;-0.278) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-11.2;-10.1) (-2.22;-0.208) (-22.2;.1) (-22.2;.1) (-22.2;.1) (-22.2;.1) (-22.2;.1) (-22.2;.1) (-22.2;.1) (-22.2;.1) (-13.7;-11.1) (-2.85;-0.278) (-22.2;.2) (-22.2;.2) (-22.2;.2) (-22.2;.2) (-22.2;.2) (-22.2;.2) (-22.2;.2) (-22.2;.2) (-13.1;-10.9) (-2.22;-0.208) (-33;.2) (-33;.2) (-33;.2) (-33;.2) (-33;.2) (-33;.2) (-33;.2) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-33.1;.3) (-33.1;.3) (-33.1;.3) (-33.1;.3) (-33.1;.3) (-33.1;.3) (-33.1;.3) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-43.6;.4) (-43.6;.4) (-43.6;.4) (-43.6;.4) (-43.6;.4) (-43.6;.4) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-43.7;.5) (-43.7;.5) (-43.7;.5) (-43.7;.5) (-43.7;.5) (-43.7;.5) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-54;-50.5) (-54;-50.5) (-54;-50.5) (-54;-50.5) (-54;-50.5) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-54.2;-50.6) (-54.2;-50.6) (-54.2;-50.6) (-54.2;-50.6) (-54.2;-50.6) -44 (-45;-41.6) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) Total allocation (%MALF) (-64.2;-60.6) (-64.2;-60.6) (-64.2;-60.6) (-64.2;-60.6) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-74;-70.5) (-74;-70.5) (-74;-70.5) (-83.4;-80.4) (-83.4;-80.4) (-75.1;-72.1) (-92.3;-89.8) (-84.3;-81.9) (-75.1;-72.1) (-92.9;-91.5) (-84.3;-81.9) (-75.1;-72.1) (-65.5;-62) (-65.5;-62) (-65.5;-62) (-65.5;-62) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) Total allocation (%MALF) (-64.3;-60.8) (-64.3;-60.8) (-64.3;-60.8) (-64.3;-60.8) (-55.3;-51.7) (-74.2;-70.8) (-74.2;-70.8) (-74.2;-70.8) (-65.3;-61.9) (-55.3;-51.7) (-83.6;-80.7) (-83.6;-80.7) (-92.3;-90.2) (-84.2;-81.8) (-92.9;-91.4) (-84.2;-81.8) (-75;-71.9) (-75;-72) (-75;-72) (-65.3;-61.9) (-55.3;-51.7) (-65.3;-61.9) (-55.3;-51.7) (-65.3;-61.9) (-55.3;-51.7) (-45;-41.6) (-45;-41.6) (-45;-41.6) (-45;-41.6) (-45;-41.6) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-92.9;-91.5) (-84.3;-81.9) (-75.1;-72.1) (-65.5;-62) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-92.9;-91.4) (-84.2;-81.8) (-75;-72) (-65.3;-61.9) (-55.3;-51.7) (-45;-41.6) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-92.9;-91.5) (-84.3;-81.9) (-75.1;-72.1) (-65.5;-62) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-92.9;-91.4) (-84.2;-81.8) (-75;-72) (-65.3;-61.9) (-55.3;-51.7) (-45;-41.6) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-92.9;-91.5) (-84.3;-81.9) (-75.1;-72.1) (-65.5;-62) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-92.9;-91.4) (-84.2;-81.8) (-75;-72) (-65.3;-61.9) (-55.3;-51.7) (-45;-41.6) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-92.9;-91.5) (-84.3;-81.9) (-75.1;-72.1) (-65.5;-62) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-92.9;-91.4) (-84.2;-81.8) (-75;-72) (-65.3;-61.9) (-55.3;-51.7) (-45;-41.6) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) (-92.9;-91.5) (-84.3;-81.9) (-75.1;-72.1) (-65.5;-62) (-55.6;-51.9) (-45.4;-41.8) (-34.9;-31.6) (-24.4;-21.4) (-13.7;-11.1) (-2.85;-0.278) (-92.9;-91.4) (-84.2;-81.8) (-75;-72) (-65.3;-61.9) (-55.3;-51.7) (-45;-41.6) (-34.5;-31.4) (-23.9;-21.2) (-13.1;-10.9) (-2.22;-0.208) Minimum flow (%MALF) Minimum flow (%MALF) Figure 21: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for change in adult brown trout habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. 42 Default water allocation limits for selected catchments in the Canterbury Region

43 Food producing habitat (Annual FDC) Food producing habitat (February FDC) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-2.89;-0.282) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-11.3;-10.2) (-2.25;-0.211) (-22.5;.4) (-22.5;.4) (-22.5;.4) (-22.5;.4) (-22.5;.4) (-22.5;.4) (-22.5;.4) (-22.5;.4) (-13.8;-11.3) (-2.89;-0.282) (-22.5;.5) (-22.5;.5) (-22.5;.5) (-22.5;.5) (-22.5;.5) (-22.5;.5) (-22.5;.5) (-22.5;.5) (-13.3;-11) -1.1 (-2.25;-0.211) (-33.4;.6) (-33.4;.6) (-33.4;.6) (-33.4;.6) (-33.4;.6) (-33.4;.6) (-33.4;.6) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-33.5;.7) (-33.5;.7) (-33.5;.7) (-33.5;.7) (-33.5;.7) (-33.5;.7) (-33.5;.7) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) (-44.1;.8) (-44.1;.8) (-44.1;.8) (-44.1;.8) (-44.1;.8) (-44.1;.8) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-44.2;.9) (-44.2;.9) (-44.2;.9) (-44.2;.9) (-44.2;.9) (-44.2;.9) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) (-54.6;-50.9) (-54.6;-50.9) (-54.6;-50.9) (-54.6;-50.9) (-54.6;-50.9) (-45.8;-42.2) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-54.7;-51.1) (-54.7;-51.1) (-54.7;-51.1) (-54.7;-51.1) (-54.7;-51.1) (-45.5;-42) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) Total allocation (%MALF) (-64.7;-61.1) (-64.7;-61.1) (-64.7;-61.1) (-64.7;-61.1) (-56.1;-52.4) (-45.8;-42.2) (-74.5;-71) (-74.5;-71) (-74.5;-71) (-83.8;-80.8) (-83.8;-80.8) (-75.6;-72.6) (-92.5;-90.1) (-84.7;-82.4) (-75.6;-72.6) (-93.2;-91.8) (-84.7;-82.4) (-75.6;-72.6) (-66;-62.6) (-66;-62.6) (-66;-62.6) (-66;-62.6) (-56.1;-52.4) (-45.8;-42.2) (-56.1;-52.4) (-45.8;-42.2) (-56.1;-52.4) (-45.8;-42.2) (-56.1;-52.4) (-45.8;-42.2) (-35.4;-32) (-35.4;-32) (-35.4;-32) (-35.4;-32) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) Total allocation (%MALF) (-64.9;-61.3) (-64.9;-61.3) (-64.9;-61.3) (-64.9;-61.3) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-74.7;-71.3) (-74.7;-71.3) (-74.7;-71.3) (-65.8;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-84;-81.1) (-84;-81.1) (-75.5;-72.4) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-92.6;-90.5) (-84.7;-82.2) (-75.5;-72.5) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-93.1;-91.7) (-84.7;-82.3) (-75.5;-72.5) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) (-13.3;-11) (-13.3;-11) (-13.3;-11) (-13.3;-11) -1.1 (-2.25;-0.211) -1.1 (-2.25;-0.211) -1.1 (-2.25;-0.211) -1.1 (-2.25;-0.211) -1.1 (-2.25;-0.211) (-93.2;-91.8) (-84.7;-82.4) (-75.6;-72.6) (-66;-62.6) (-56.1;-52.4) (-45.8;-42.2) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-93.1;-91.7) (-84.7;-82.3) (-75.5;-72.5) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) (-93.2;-91.8) (-84.7;-82.4) (-75.6;-72.6) (-66;-62.6) (-56.1;-52.4) (-45.8;-42.2) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-93.1;-91.7) (-84.7;-82.3) (-75.5;-72.5) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) (-93.2;-91.8) (-84.7;-82.4) (-75.6;-72.6) (-66;-62.6) (-56.1;-52.4) (-45.8;-42.2) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-93.1;-91.7) (-84.7;-82.3) (-75.5;-72.5) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) (-93.2;-91.8) (-84.7;-82.4) (-75.6;-72.6) (-66;-62.6) (-56.1;-52.4) (-45.8;-42.2) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-93.1;-91.7) (-84.7;-82.3) (-75.5;-72.5) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) (-93.2;-91.8) (-84.7;-82.4) (-75.6;-72.6) (-66;-62.6) (-56.1;-52.4) (-45.8;-42.2) (-35.4;-32) (-24.7;-21.7) (-13.8;-11.3) (-2.89;-0.282) (-93.1;-91.7) (-84.7;-82.3) (-75.5;-72.5) (-65.9;-62.4) (-55.8;-52.3) (-45.5;-42.1) (-34.9;-31.8) (-24.2;-21.5) (-13.3;-11) -1.1 (-2.25;-0.211) Minimum flow (%MALF) Minimum flow (%MALF) Figure 22: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for change in food producing habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. Default water allocation limits for selected catchments in the Canterbury Region 43

44 Bluegill bully habitat (Annual FDC) Bluegill bully habitat (February FDC) (-9.89;-8.67) (-9.89;-8.67) (-9.89;-8.67) (-9.89;-8.67) (-9.89;-8.67) (-9.89;-8.67) (-9.89;-8.67) (-9.89;-8.67) (-9.89;-8.67) (-2.5;-0.241) (-9.92;-8.66) (-9.92;-8.66) (-9.92;-8.66) (-9.92;-8.66) (-9.92;-8.66) (-9.92;-8.66) (-9.92;-8.66) (-9.92;-8.66) (-9.92;-8.66) (-1.94;-0.182) (-19.8;-17.6) (-19.8;-17.6) (-19.8;-17.6) (-19.8;-17.6) (-19.8;-17.6) (-19.8;-17.6) (-19.8;-17.6) (-19.8;-17.6) (-12.1;-9.66) (-2.5;-0.241) (-19.8;-17.5) (-19.8;-17.5) (-19.8;-17.5) (-19.8;-17.5) (-19.8;-17.5) (-19.8;-17.5) (-19.8;-17.5) (-19.8;-17.5) (-11.6;-9.5) (-1.94;-0.182) (-29.7;-26.7) (-29.7;-26.7) (-29.7;-26.7) (-29.7;-26.7) (-29.7;-26.7) (-29.7;-26.7) (-29.7;-26.7) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-29.8;-26.7) (-29.8;-26.7) (-29.8;-26.7) (-29.8;-26.7) (-29.8;-26.7) (-29.8;-26.7) (-29.8;-26.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-39.7;-36) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-49.6;-45.6) (-49.6;-45.6) (-49.6;-45.6) (-49.6;-45.6) (-49.6;-45.6) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-49.7;-45.7) (-49.7;-45.7) (-49.7;-45.7) (-49.7;-45.7) (-49.7;-45.7).1 (-41;-37.2) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) Total allocation (%MALF) (-59.6;-55.5) (-59.6;-55.5) (-59.6;-55.5) (-59.6;-55.5) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-69.6;-65.7) (-69.6;-65.7) (-69.6;-65.7) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-79.6;-76.1) (-79.6;-76.1) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-89.6;-86.7) (-;-77.7) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-90.3;-88.7) (-;-77.7) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) Total allocation (%MALF) (-59.7;-55.6) (-59.7;-55.6) (-59.7;-55.6) (-59.7;-55.6) (-50.8;-46.8) (-69.7;-65.7) (-69.7;-65.7) (-69.7;-65.7) (-60.7;-56.8) (-50.8;-46.9) (-79.7;-76.3) (-79.7;-76.3) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9) (-89.7;-87.1) (-80.4;-77.7) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9) (-90.2;-88.6) (-80.4;-77.7) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9).1 (-41;-37.2).1 (-41;-37.2).1 (-41;-37.2).1 (-41;-37.2).1 (-41;-37.2) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-90.3;-88.7) (-;-77.7) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-90.2;-88.6) (-80.4;-77.7) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9).1 (-41;-37.2) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-90.3;-88.7) (-;-77.7) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-90.2;-88.6) (-80.4;-77.7) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9).1 (-41;-37.2) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-90.3;-88.7) (-;-77.7) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-90.2;-88.6) (-80.4;-77.7) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9).1 (-41;-37.2) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-90.3;-88.7) (-;-77.7) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-90.2;-88.6) (-80.4;-77.7) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9).1 (-41;-37.2) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) (-90.3;-88.7) (-;-77.7) (-70.7;-67.2) (-60.9;-56.9) (-51.1;-46.9) (-41.3;-37.3) (-31.6;-27.9) (-21.8;-18.7) (-12.1;-9.66) (-2.5;-0.241) (-90.2;-88.6) (-80.4;-77.7) (-70.5;-67.1) (-60.7;-56.8) (-50.8;-46.9).1 (-41;-37.2) (-31.2;-27.7) (-21.4;-18.5) (-11.6;-9.5) (-1.94;-0.182) Minimum flow (%MALF) Minimum flow (%MALF) Figure 23: Clarence catchment (mean flow < 5 m 3 s -1 ) decision space diagrams for change in bluegill bully habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. 44 Default water allocation limits for selected catchments in the Canterbury Region

45 4.3.3 Other catchments management unit Reliabilty at Management Flow (Annual FDC) Reliabilty at Management Flow (February FDC) -10 (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) -10 (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (68.9;91.7) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) (79.2;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (68.9;91.7) 73.5 (60.4;86.3) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) (79.2;) (75;86.3) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (68.9;91.7) 73.5 (60.4;86.3) (53.1;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) (79.2;) (75;86.3) (68.9;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (68.9;91.7) 73.5 (60.4;86.3) (53.1;) 60.4 (45.6;76.4) -50 (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) (79.2;) (75;86.3) (68.9;) 75 (63.9;81.7) -50 (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (68.9;91.7) 73.5 (60.4;86.3) (53.1;) 60.4 (45.6;76.4) 53.1 (38.1;72) Total allocation (%MALF) (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) 94.4 (;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) (79.2;) (90.1;93.8) 89.2 (;91.7) 86.3 (;90.1) (79.2;) (75;86.3) 89.2 (;91.7) 86.3 (;90.1) (79.2;) (75;86.3) (68.9;) 86.3 (;90.1) (79.2;) (75;86.3) (68.9;) 75 (63.9;81.7) (79.2;) (75;86.3) (68.9;) 75 (63.9;81.7) 72 (60.4;) (75;86.3) (68.9;) 75 (63.9;81.7) 72 (60.4;) 68.9 (55;) (68.9;) 75 (63.9;81.7) 72 (60.4;) 68.9 (55;) (51.3;76.4) 75 (63.9;81.7) 72 (60.4;) 68.9 (55;) (51.3;76.4) 63.9 (47.5;75) 72 (60.4;) 68.9 (55;) (51.3;76.4) 63.9 (47.5;75) 60.4 (43.8;73.5) Total allocation (%MALF) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (68.9;91.7) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (68.9;91.7) 73.5 (60.4;86.3) 93.1 (85.2;99) (;96.4) (68.9;91.7) 73.5 (60.4;86.3) (53.1;) (;96.4) (68.9;91.7) 73.5 (60.4;86.3) (53.1;) 60.4 (45.6;76.4) (68.9;91.7) 73.5 (60.4;86.3) (53.1;) 60.4 (45.6;76.4) 53.1 (38.1;72) 73.5 (60.4;86.3) (53.1;) 60.4 (45.6;76.4) 53.1 (38.1;72) 47.5 (34.4;67.2) (53.1;) 60.4 (45.6;76.4) 53.1 (38.1;72) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 60.4 (45.6;76.4) 53.1 (38.1;72) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 53.1 (38.1;72) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 36.2 (22;56.8) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 36.2 (22;56.8) 32.5 (18.8;53.1) -110 (79.2;) (75;86.3) (68.9;) 75 (63.9;81.7) 72 (60.4;) 68.9 (55;) (51.3;76.4) 63.9 (47.5;75) 60.4 (43.8;73.5) 58.6 (41.9;72) (60.4;86.3) (53.1;) 60.4 (45.6;76.4) 53.1 (38.1;72) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 36.2 (22;56.8) 32.5 (18.8;53.1) 28.9 (17.3;49.4) -120 (75;86.3) (68.9;) 75 (63.9;81.7) 72 (60.4;) 68.9 (55;) (51.3;76.4) 63.9 (47.5;75) 60.4 (43.8;73.5) 58.6 (41.9;72) 55 (38.1;68.9) -120 (53.1;) 60.4 (45.6;76.4) 53.1 (38.1;72) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 36.2 (22;56.8) 32.5 (18.8;53.1) 28.9 (17.3;49.4) 27.1 (14.3;47.5) -130 (68.9;) 75 (63.9;81.7) 72 (60.4;) 68.9 (55;) (51.3;76.4) 63.9 (47.5;75) 60.4 (43.8;73.5) 58.6 (41.9;72) 55 (38.1;68.9) 53.1 (36.2;67.2) (45.6;76.4) 53.1 (38.1;72) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 36.2 (22;56.8) 32.5 (18.8;53.1) 28.9 (17.3;49.4) 27.1 (14.3;47.5) 25.4 (12.9;45.6) (63.9;81.7) 72 (60.4;) 68.9 (55;) (51.3;76.4) 63.9 (47.5;75) 60.4 (43.8;73.5) 58.6 (41.9;72) 55 (38.1;68.9) 53.1 (36.2;67.2) 51.3 (32.5;) (38.1;72) 47.5 (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 36.2 (22;56.8) 32.5 (18.8;53.1) 28.9 (17.3;49.4) 27.1 (14.3;47.5) 25.4 (12.9;45.6) 23.7 (11.6;41.9) (60.4;) 68.9 (55;) (51.3;76.4) 63.9 (47.5;75) 60.4 (43.8;73.5) 58.6 (41.9;72) 55 (38.1;68.9) 53.1 (36.2;67.2) 51.3 (32.5;) 49.4 (30.7;63.9) (34.4;67.2) 43.8 (28.9;63.9) 40 (25.4;60.4) 36.2 (22;56.8) 32.5 (18.8;53.1) 28.9 (17.3;49.4) 27.1 (14.3;47.5) 25.4 (12.9;45.6) 23.7 (11.6;41.9) 22 (10.4;40) Minimum flow (%MALF) Minimum flow (%MALF) Figure 24: All catchments other than the Clarence decision space diagrams for reliability at management flow. The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. Default water allocation limits for selected catchments in the Canterbury Region 45

46 Reliabilty at Minimum Flow (Annual FDC) Reliabilty at Minimum Flow (February FDC) -10 (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) -10 (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) -50 (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) -50 (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) Total allocation (%MALF) (;) (;) (;) (;) (;) (99.2;) (99.2;) (99.2;) (99.2;) (99.2;) (98.6;) (98.6;) (98.6;) (98.6;) (98.6;) (;) (;) (;) (;) (;) 98.8 (;) 98.8 (;) 98.8 (;) 98.8 (;) 98.8 (;) (;99.3) (;99.3) (;99.3) (;99.3) (;99.3) 96.4 (94.4;) 96.4 (94.4;) 96.4 (94.4;) 96.4 (94.4;) 96.4 (94.4;) 94.4 (;) 94.4 (;) 94.4 (;) 94.4 (;) 94.4 (;) (90.1;93.8) (90.1;93.8) (90.1;93.8) (90.1;93.8) (90.1;93.8) 89.2 (;91.7) 89.2 (;91.7) 89.2 (;91.7) 89.2 (;91.7) 89.2 (;91.7) Total allocation (%MALF) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (;) (94.9;) (94.9;) (94.9;) (94.9;) (94.9;) 97.5 (90.9;) 97.5 (90.9;) 97.5 (90.9;) 97.5 (90.9;) 97.5 (90.9;) 93.1 (85.2;99) 93.1 (85.2;99) 93.1 (85.2;99) 93.1 (85.2;99) 93.1 (85.2;99) (;96.4) (;96.4) (;96.4) (;96.4) (;96.4) -110 (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) -110 (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) -120 (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) -120 (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) -130 (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) -130 (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) -140 (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) -140 (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) -150 (;) (99.2;) (98.6;) (;) 98.8 (;) (;99.3) 96.4 (94.4;) 94.4 (;) (90.1;93.8) 89.2 (;91.7) -150 (;) (;) (;) (;) (;) (;) (94.9;) 97.5 (90.9;) 93.1 (85.2;99) (;96.4) Minimum flow (%MALF) Minimum flow (%MALF) Figure 25: All catchments other than the Clarence decision space diagrams for reliability at minimum flow. The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. 46 Default water allocation limits for selected catchments in the Canterbury Region

47 Bluegill bully habitat (Annual FDC) Bluegill bully habitat (February FDC) (-9.95;-9.2) (-9.95;-9.2) (-9.95;-9.2) (-9.95;-9.2) (-9.95;-9.2) (-9.95;-9.2) (-9.95;-9.2) (-9.95;-9.2) (-9.95;-9.2) (-3.26;-0.296) (-9.99;-9.24) (-9.99;-9.24) (-9.99;-9.24) (-9.99;-9.24) (-9.99;-9.24) (-9.99;-9.24) (-9.99;-9.24) (-9.99;-9.24) (-9.99;-9.24) (-1.63;-0.155) (-19.9;-18.5) (-19.9;-18.5) (-19.9;-18.5) (-19.9;-18.5) (-19.9;-18.5) (-19.9;-18.5) (-19.9;-18.5) (-19.9;-18.5) (-12.8;-10) (-3.26;-0.296) (;-18.6) (;-18.6) (;-18.6) (;-18.6) (;-18.6) (;-18.6) (;-18.6) (;-18.6) (-11.4;-9.87) (-1.63;-0.155) (-29.9;-27.9) (-29.9;-27.9) (-29.9;-27.9) (-29.9;-27.9) (-29.9;-27.9) (-29.9;-27.9) (-29.9;-27.9) (-22.5;-19.7) (-12.8;-10) (-3.26;-0.296) (;-28.1) (;-28.1) (;-28.1) (;-28.1) (;-28.1) (;-28.1) (;-28.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-39.8;-37.4) (-39.8;-37.4) (-39.8;-37.4) (-39.8;-37.4) (-39.8;-37.4) (-39.8;-37.4) (-32.2;-29.4) (-22.5;-19.7) (-12.8;-10) (-3.26;-0.296) (;-37.7) (;-37.7) (;-37.7) (;-37.7) (;-37.7) (;-37.7).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-49.8;-47.1) (-49.8;-47.1) (-49.8;-47.1) (-49.8;-47.1) (-49.8;-47.1) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-12.8;-10) (-3.26;-0.296) (-49.9;-47.5) (-49.9;-47.5) (-49.9;-47.5) (-49.9;-47.5) (-49.9;-47.5) (.9;-38.8).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) Total allocation (%MALF) (-59.7;-56.8) (-59.7;-56.8) (-59.7;-56.8) (-59.7;-56.8) (-69.7;-66.7) (-69.7;-66.7) (-69.7;-66.7) (-61.3;-58.9) (-79.7;-76.6) (-79.7;-76.6) (-89.7;-86.7) (-80.7;-79.1) (-90.4;-89.5) (-80.7;-79.1) (-71;-69) (-71;-69) (-71;-69) (-61.3;-58.9) (-61.3;-58.9) (-61.3;-58.9) (-51.6;-49) (-51.6;-49) (-51.6;-49) (-51.6;-49) (-51.6;-49) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-12.8;-10) (-12.8;-10) (-12.8;-10) (-12.8;-10) (-12.8;-10) (-3.26;-0.296) (-3.26;-0.296) (-3.26;-0.296) (-3.26;-0.296) (-3.26;-0.296) Total allocation (%MALF) (-59.9;-57.4) (-59.9;-57.4) (-59.9;-57.4) (-59.9;-57.4) (-50.8;-48.6) (.9;-38.8) (-69.9;-67.4) (-69.9;-67.4) (-69.9;-67.4) (-60.6;-58.5) (-50.8;-48.7) (.9;-38.8) (-79.9;-77.6) (-79.9;-77.6) (-70.5;-68.6) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8) (-89.9;-87.9) (-80.4;-78.9) (-70.5;-68.7) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8) (-90.2;-89.3) (-80.4;-78.9) (-70.6;-68.7) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8).3 (-31;-29.1).3 (-31;-29.1).3 (-31;-29.1).3 (-31;-29.1).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-90.4;-89.5) (-80.7;-79.1) (-71;-69) (-61.3;-58.9) (-51.6;-49) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-12.8;-10) (-3.26;-0.296) (-90.3;-89.4) (-80.4;-79) (-70.6;-68.7) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-90.4;-89.5) (-80.7;-79.1) (-71;-69) (-61.3;-58.9) (-51.6;-49) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-12.8;-10) (-3.26;-0.296) (-90.3;-89.4) (-80.4;-79) (-70.6;-68.7) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-90.4;-89.5) (-80.7;-79.1) (-71;-69) (-61.3;-58.9) (-51.6;-49) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-12.8;-10) (-3.26;-0.296) (-90.3;-89.4) (-80.4;-79) (-70.6;-68.7) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-90.4;-89.5) (-80.7;-79.1) (-71;-69) (-61.3;-58.9) (-51.6;-49) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) (-12.8;-10) (-3.26;-0.296) (-90.3;-89.4) (-80.4;-79) (-70.6;-68.7) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) (-90.4;-89.5) (-80.7;-79.1) (-71;-69) (-61.3;-58.9) (-51.6;-49) (-41.9;-39.2) (-32.2;-29.4) (-22.5;-19.7) Minimum flow (%MALF) (-12.8;-10) (-3.26;-0.296) (-90.3;-89.4) (-80.4;-79) (-70.6;-68.7) (-60.7;-58.6) (-50.8;-48.7) (.9;-38.8) Minimum flow (%MALF).3 (-31;-29.1) (-21.2;-19.5) (-11.4;-9.87) (-1.63;-0.155) Figure 26: All catchments other than the Clarence decision space diagrams for change in bluegill bully habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. Default water allocation limits for selected catchments in the Canterbury Region 47

48 Food producing habitat (Annual FDC) Food producing habitat (February FDC) (-11.4;-10.5) (-11.4;-10.5) (-11.4;-10.5) (-11.4;-10.5) (-11.4;-10.5) (-11.4;-10.5) (-11.4;-10.5) (-11.4;-10.5) (-11.4;-10.5) (-3.72;-0.341) (-11.4;-10.6) (-11.4;-10.6) (-11.4;-10.6) (-11.4;-10.6) (-11.4;-10.6) (-11.4;-10.6) (-11.4;-10.6) (-11.4;-10.6) (-11.4;-10.6) (-1.88;-0.179) (-22.5;.9) (-22.5;.9) (-22.5;.9) (-22.5;.9) (-22.5;.9) (-22.5;.9) (-22.5;.9) (-22.5;.9) (-14.5;-11.5) (-3.72;-0.341) (-22.6;-21.1) (-22.6;-21.1) (-22.6;-21.1) (-22.6;-21.1) (-22.6;-21.1) (-22.6;-21.1) (-22.6;-21.1) (-22.6;-21.1) (-12.9;-11.3) (-1.88;-0.179) (-33.5;-31.3) (-33.5;-31.3) (-33.5;-31.3) (-33.5;-31.3) (-33.5;-31.3) (-33.5;-31.3) (-33.5;-31.3) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-33.6;-31.5) (-33.6;-31.5) (-33.6;-31.5) (-33.6;-31.5) (-33.6;-31.5) (-33.6;-31.5) (-33.6;-31.5) -23 (-23.9;-22) (-12.9;-11.3) (-1.88;-0.179) (-44.2;-41.5) (-44.2;-41.5) (-44.2;-41.5) (-44.2;-41.5) (-44.2;-41.5) (-44.2;-41.5) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-44.4;-41.9) (-44.4;-41.9) (-44.4;-41.9) (-44.4;-41.9) (-44.4;-41.9) (-44.4;-41.9) (-34.7;-32.6) -23 (-23.9;-22) (-12.9;-11.3) (-1.88;-0.179) (-54.7;-51.7) (-54.7;-51.7) (-54.7;-51.7) (-54.7;-51.7) (-54.7;-51.7) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-54.9;-52.2) (-54.9;-52.2) (-54.9;-52.2) (-54.9;-52.2) (-54.9;-52.2) (-45.3;-43) (-34.8;-32.6) -23 (-23.9;-22) (-12.9;-11.3) (-1.88;-0.179) Total allocation (%MALF) (-64.8;-61.6) (-64.8;-61.6) (-64.8;-61.6) (-64.8;-61.6) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-74.6;-71.4) (-74.6;-71.4) (-74.6;-71.4) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-83.9;-80.9) (-83.9;-80.9) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-92.6;-89.8) (-84.9;-83.1) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-93.3;-92.2) (-84.9;-83.1) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) Total allocation (%MALF) (-65.1;-62.3) (-65.1;-62.3) (-65.1;-62.3) (-65.1;-62.3) (-55.7;-53.3) (-45.4;-43.1) (-34.8;-32.6) (-74.9;-72.2) (-74.9;-72.2) (-74.9;-72.2) (-65.8;-63.4) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) (-84.2;-81.8) (-84.2;-81.8) (-75.5;-73.3) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) (-92.8;-90.9) (-84.7;-) (-75.5;-73.4) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) (-93.2;-92.1) (-84.7;-83) (-75.5;-73.4) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) -23 (-23.9;-22) -23 (-23.9;-22) -23 (-23.9;-22) -23 (-23.9;-22) -23 (-23.9;-22) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) (-93.3;-92.2) (-84.9;-83.1) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-93.3;-92.2) (-84.9;-83.1) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-93.3;-92.2) (-84.9;-83.1) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-93.3;-92.2) (-84.9;-83.1) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) (-93.3;-92.2) (-84.9;-83.1) (-75.9;-73.6) (-66.4;-63.7) (-56.5;-53.6) (-46.3;-43.3) (-35.9;-32.9) (-25.3;-22.3) (-14.5;-11.5) (-3.72;-0.341) Minimum flow (%MALF) (-93.2;-92.1) (-93.2;-92.1) (-93.2;-92.1) (-93.2;-92.1) (-93.2;-92.1) (-84.7;-83) (-84.7;-83) (-84.7;-83) (-84.7;-83) (-84.7;-83) (-75.5;-73.4) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) (-75.5;-73.4) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) (-75.5;-73.4) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) (-75.5;-73.4) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) (-75.5;-73.4) (-65.8;-63.5) (-55.8;-53.4) (-45.4;-43.1) (-34.8;-32.6) Minimum flow (%MALF) -23 (-23.9;-22) -23 (-23.9;-22) -23 (-23.9;-22) -23 (-23.9;-22) -23 (-23.9;-22) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) (-12.9;-11.3) (-1.88;-0.179) Figure 27: All catchments other than the Clarence decision space diagrams for change in food producing habitat (% of habitat available at MALF). The median value for all locations in the management unit is presented, with the 10th and 90th percentiles included in brackets. Left: Annual flow duration curves; Right: February flow duration curves. Black line on the annual FDC decision space indicates the combinations of limits that satisfy ECan s objectives. 48 Default water allocation limits for selected catchments in the Canterbury Region

49 5 Discussion 5.1 Consequences of proposed NES default limits The consequences of applying the proposed NES default allocation limits to each of the management units are presented in Table 4 and have been taken directly from the decision space diagrams for each value for each management unit. The proposed NES large river rules (minimum flow of 80% of MALF and total allocation of 50% of MALF) were used for the Clarence large river management unit, while the proposed NES small river rules (minimum flow of 90% of MALF and total allocation of 30% of MALF) were used for the other two management units. These results demonstrate the variability in consequences for each of the values between the management units, but also over different time periods. Median reliability at management flow is the same (%) for the annual FDC in both the Clarence large and small river management units. However, for the February FDC, median reliability is much lower in the Clarence large river management unit (63.9%) than in the Clarence small river management unit (%). The response in brown trout habitat is also significantly different between the two Clarence management units, with the median change in habitat in the Clarence large river management unit (10.8%) being positive (i.e., an increase in habitat), and there being a negative median change in habitat in the Clarence small river management unit (-12.3%). This pattern is also evident for the drift food producing habitat and bluegill bullies. The other catchments management unit displays a similar response to the Clarence small river management unit, but median reliability at the management flow is lower for both the annual and February FDCs in the other catchments management unit. Table 4: Summary of the consequences of applying the proposed NES default limits to each of the three management units. The proposed NES large river rules were applied to the Clarence large river management unit, and the proposed NES small river rules were applied to the Clarence small river and Other catchments management units. The median and the 10 th and 90 th percentile values (in parentheses) are shown for each consequence for all locations in each management unit. Negative values indicate a decrease in habitat from that available at MALF. Management unit Reliability at management flow Reliability at minimum flow Brown trout adult Food producing habitat Bluegill bully habitat Clarence large river Annual FDC February FDC (86.3; ) 63.9 (63.9; 70.5) (96.4; 97.5) (; 98.4) 10.8 (-13.6;14.9) 9.65 (-12.9; 14.1) 9.35 (-14.4; 13.3) 8.35 (-13.4; 12.5) 34.1 (-6.3; 41.4) 31.1 (-6.04; 39.6) Clarence small river Annual FDC February FDC (85.2; 89.2) (; 90.1) 94.9 (93.8; ) (; 98.8) (-13.7; -11.1) (-13.1; -10.9) (-13.8; -11.3) (-13.3; -11) (-12.1; -9.66) (-11.6; -9.5) Other catchments Annual FDC February FDC (79.2; ) 73.5 (60.4; 86.3) (90.1; 93.8) 93.1 (85.2; 99) NA (-14.5; -11.5) NA (-12.9; -11.3) (-12.8; -10) (-11.4; Default water allocation limits for selected catchments in the Canterbury Region 49

50 The proposed NES default limits are only one of a range of options available to planners for managing water resource use. The challenge for water resource managers is to evaluate the relative advantages and disadvantages of different allocation scenarios so that an informed decision can be made on the most appropriate limit combinations. The EFSAP decision space diagrams can facilitate this process by summarising the regional scale consequences of particular water resource use limit combinations. The following section describes how the EFSAP decision space diagrams can be used to support the decision making process. 5.2 Use of decision space figures for limit setting Definition of water resource use limits involves a trade-off between different instream and out-of-channel uses of water. EFSAP is used to evaluate the consequences of a range of scenarios for water allocation limits, thereby enabling water resource managers to make a more informed and transparent choice. The following guidance is provided to explain how to use the EFSAP modelling outputs presented in this report for choosing limits from amongst the different scenarios. The scenarios assessed using EFSAP, and their associated consequences for reliability and instream habitat, are presented as decision space diagrams. The decision space summarises the consequences for each scenario (i.e., combination of minimum flow and allocation limit). For each scenario, the median, 10 th and 90 th percentiles of the consequences for the values (i.e., the reliability or change in habitat) are presented (Figure 28). These percentiles summarise the consequences of that combination of limits for all locations in a management unit. The median is used to represent the average consequence for that value across all locations in a management unit. In some locations the consequence will be worse, and in some locations better. The difference between the 10 th and 90 th percentiles gives an indication of how variable the consequences for a value are across all locations within the management unit. The greater the difference between these figures, the larger the variation in consequences between locations, the smaller the difference between the figures, the more uniform and thus equitable the consequences are between locations in the management unit. Ninety percent of locations in the management unit will have a consequence which is at least as good as the 10 th percentile. Figure 28: Interpreting the decision space diagram summary statistics. 50 Default water allocation limits for selected catchments in the Canterbury Region

51 The first task in determining appropriate water resource use limits should be the determination of objectives for each value. Ideally objectives should be clear (i.e., defined levels of protection for environmental values and availability and reliability of water for out-ofchannel uses), transparent (i.e., stakeholders can understand why they have been selected as objectives) and measureable (i.e., it is possible to measure whether the objectives are being met). Once objectives have been set, the decision space diagrams can be used to determine which combination of limits satisfies the objectives. ECan have defined objectives of an annual median reliability at management flow of 95%, median reliability at minimum flow of 95% and a median loss of habitat 25%. These thresholds were used to identify on the decision space diagrams the combinations of minimum flow and total allocation which satisfy the relevant objective for each value (areas enclosed by thick black lines in Figure 14 to Figure 27). For this application, the black lines are defined by whether the median value in each square meets the objective threshold, but potentially other percentiles could be used. Once the subset of limits that satisfy the objectives for each individual value have been defined, they are combined to find the set of limits which meet all objectives. For each of the three ECan management units, the intersection of the objectives is shown in Figure 29 by the grey shaded areas. These represent the combinations of minimum flow and total allocation that satisfy the objectives for all values assessed in that management unit. It is noted that the proposed NES default limits do not satisfy all objectives for any of the management units (i.e., they fall outside of the grey shaded area). In this case, the defined objectives for all values result in a combination of limit options that overlap (Figure 29). Water resource managers therefore have the choice of defining limits that satisfy all objectives. However, there still remains a range of limit combinations that satisfy all the objectives and therefore resource managers are still required to make value judgements to define the final choice of limits. Options could include, for example, maximising environmental protection, maximising reliability or maximising total allocation. The decision will vary based on the relative importance of the different values assessed, and may vary between management units. This decision making process should also take into consideration additional values, e.g., natural character or cultural values, which are not evaluated by EFSAP. For example, a minimum flow of 10% of MALF (which satisfies all objectives in all three management units considered here), combined with a modest allocation (e.g., 20% MALF) may not be considered acceptable due to the excessive departure from the natural range of variability that may typify natural character. If further stakeholder consultation were to result in changes to the objective thresholds, it is possible that a situation may arise whereby no combination of limits would satisfy all objectives concurrently. In this situation, a compromise has to be found between the different values until an acceptable combination of limits can be agreed upon. The decision space diagrams can assist in this trade-off process by illustrating the relative consequences of alternative management decisions. This makes the process of limit setting more transparent and accountable. Default water allocation limits for selected catchments in the Canterbury Region 51

52 Figure 29: Illustration of evaluating objectives for multiple values and determining range of limits that satisfy all objectives. Top: Clarence large river management unit; Middle: Clarence small river management unit; Bottom: Other catchments management unit. 52 Default water allocation limits for selected catchments in the Canterbury Region