Protocols and tools for mapping and ground-truthingwetlands in South Africa. Namhla Mbona : Freshwater Planner SANBI

Transcription

1 Protocols and tools for mapping and ground-truthingwetlands in South Africa Namhla Mbona : Freshwater Planner SANBI

2 Wetland Inventory per catchment Wetland extent Wetland type Regional type Hydro-geomorphic (HGM) type Wetland condition Other information Assessment Awareness Wetland assessments, monitoring NJ2 Communications and wise use management guidelines Conservation Prioritisation, rehabilitation, biodiversity stewardship, formal protection NJ1 Legislation Policy and legislation

3 Slide 2 NJ1 NJ2 Changed "Biodiversity stewardship" to lower case "biodiversity stewardship" Nancy, 2015/03/12 Changed "assessment" and "conservation" and associated boxes Nancy, 2015/03/12

4 Structure of the manual PART A : outlines what is necessary to consider and prepare before you start a wetland mapping project. This includes the correct choice of scale and aspects of project design. PART B : covers the practical preparation that must be undertaken before leaving the office. This often involves preparation of GIS data, desktop digitisation and desktop modelling of wetlands. PART C: covers the approach and methods for conducting wetland mapping in the field. Field-based ground-truthing, which improves confidence levels of wetland data, is necessary for the intermediate and detailed mapping. PART D: outlines the follow-up desktop requirements for cleaning and integrating the data and conducting quality control assessments.

5 PART A. BEFORE YOU START DESIGNING A WETLAND MAPPING PROJECT Components of wetland inventory data Choosing the appropriate level of data detail Choose what data attributes to record Field or desktop? A combined approach is ideal.. Generic Terms of Reference Human time is expensive, computer time is cheap* Algorithms do not get bored or tired* Automated processes do not replace people* *Aaron Smith, Minnesota Inventory, USA Wetlands mapped in the field = greater accuracy (if done correctly), but may only map a handful of wetlands in a catchment (may miss a unique wetland type, or the only remaining pristine wetlands). Time consumed by visiting wetlands individually places severe restrictions on the extent of the area covered. Modelling has a risk of image misinterpretation and non-natural shapes (fragments, squares)

6 PART B. DESKTOP PREPARATION BEFORE YOU LEAVE FOR THE FIELD Catchment approach Wetland data attributes 1 GIS layers and layer sources Approaches to desktop wetland mapping Desktop mapping of wetland extent Wetland type* Regional setting Landscape unit Hydro-geomorphic (HGM) unit Wetland condition modelling image interpretation/digitising *Ollis, D.J., Snaddon, K., Job, N. & Mbona, N. (2013) Classification system for wetlands and other aquatic ecosystems in South Africa. User Manual: inland systems. SANBI Biodiversity Series 22. South African National Biodiversity Institute, Pretoria. 2 3 PART C. IN THE FIELD In-field wetland extent determination* Hydrology Wetland plants Wetland soils Tools to support in-field mapping (datasheets, photo herbarium, tablet etc) In-field assessment of wetland condition HGM and regional wetland ecosystem type 2 levels of detail (catchment approach) *DWAF (2005) A practical field procedure for identification and delineation of wetland and riparian areas. Department of Water Affairs and Forestry, Pretoria.

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8 Rapid assessment datasheet

9 GIS ATTRIBUTES

10 PART D. DESKTOP FOLLOW-UP / BACK IN THE OFFICE Data integration and cleaning Final review Quality control and data management Review GIS topology Review wetland boundary and attribute with team and local experts Assign attributes to any remaining wetlands in the catchment, based on understanding gained from detailed and rapid field work