Delimiting Freedom Space for Rivers Using GIS and Remote Sensing:

Transcription

1 Delimiting Freedom Space for Rivers Using GIS and Remote Sensing: Updating existing tools to manage functional and resilient river systems Joanna Eyquem and Fabien Hugue (AECOM) Pascale Biron (University of Concordia) 6 th International Conference on Natural Channel Systems May 24, 2018

2 2 Early Experiences in Ontario Protocols are just a guide Don t just turn the handle If you have a better idea, let s hear it!

3 a) How is the Freedom Space approach different from current Ontario protocols? b) How can we make better use of GIS and Remote Sensing data? 6 th International Conference on Natural Channel Systems May 24, 2018

4 4 Climate Change Driver for Sustainable Management

5 5 Flood Risk Mapping not Erosion Risk Mapping

6 6 River Management Around the World Flooding risk based room Netherlands UK And more recently erosion Fluvial territory France Spain Vermont

7 7 Approach and Protocols in Ontario

8 8 Freedom Space (Espace de liberté) in Quebec Flood Risk + Erosion Risk + Wetlands e/guides_milieux_aquatiques/leau_lb_77.pdf

9 9 Freedom Space cf. Natural Hazards in Ontario Identifies different levels of flood and erosion risk within the overall «Freedom Space» Involves hydrogeomorphological assessment of flood and erosion mechanisms using LiDAR data Specifically incorporates wetlands as part of the minimal corridor Requires field reconnaissance to predict different levels of flood and erosion risk

10 10 Different Degrees of Freedom!

11 11 Different Degrees of Freedom! L min (Minimal Level): Frequent flooding AND/OR short-term erosion AND/OR Riparian wetlands L func (Functional Level): Moderately frequent flooding AND/OR long-term erosion risk (similar to meander belt width) L rare (Rare Level): Rare floods with minor erosion risk

12 12 Flooding space + Mobility space = Freedom space F high F med F low M 50 M floodplain L min L func L rare Matane River, Gaspesie peninsula, Qc, Canada

13 13 Need for Field Reconnaissance Different levels of flood and erosion risk are delineated by combining hydrogeomorphology and hydraulic modeling. Typically field work is required: o indicators of flooding (alluvial deposits on floodplain, scouring from extreme floods, bank erosion, ice scars) o indicators of non-flooding (non-alluvial deposits, extensive pedogenesis indicating long term stability)

14 a) How is the Freedom Space approach different from current Ontario tools? b) How can we make better use of GIS and Remote Sensing data? 6 th International Conference on Natural Channel Systems May 24, 2018

15 15 Remote Sensing - all about Resolutions Spatial (what extent and how detailed / pixel size) Spectral (what colors / how many bands / band widths) Temporal (time of day ; season ; year / time-lapse between two images / change detection) Radiometric (color (bit) depth)

16 16 LiDAR Coverage in Quebec

17 17 Research and Development Dr Fabien Hugue Remote sensing of fluvial environments: Automating the freedom space delineation to support sustainable river management at large scale Joanna Eyquem Dr Pascale Biron

18 18 Use of LiDAR for Hydromorphological Analysis Flooding mechanisms Fluvial geomorphological processes / channel evolution Identification of erosional (Er) and depositional (Sed) zones of the Matane River using LiDAR (from Demers et al. 2014).

19 19 Case Study: River Mastigouche, Quebec Additional complexity due to presence of abandoned channels and fluvial terraces Terraces formed due to the lowering of base level Use of LiDAR to identify terrace features and understand flooding mechanisms Combined with hydraulic modeling to identify areas of disconnected floodplain

20 20 Case Study: River Mastigouche, Quebec A Section transversal A B Elevation (m) B Distance (m) Wetlands Main channel Cross-section of the Mastigouche River, Qc, using LiDAR data, showing abandoned channel and formation of fluvial terraces

21 21 Automating the Freedom Space Approach Remote sensing techniques can help to: Detect the river course at different dates (avoid hand digitizing of channel evolution) Objectively identify homogenous reaches (avoid hand digitizing / subjectivity) Provide estimations of water depth for flood modelling (to determine flood damages) Standardize mapping techniques to export the methodology in other rivers and watershed contexts Avoid cost / time required for field work (particularly in remote locations)

22 22 Automating the Freedom Space Approach Computing mobility space from historical air photo digitization

23 23 Automating the Freedom Space Approach Compute mobility spaces from historical air photo digitization Erosion & accretion rates calculation

24 24 Automating the Freedom Space Approach Compute mobility spaces from historical air photo digitization Mobility space delineation

25 25 Remote Sensing Products: Resolution & Costs (2011) UAVs

26 a) How is the Freedom Space approach different from current Ontario tools? b) How can we make better use of GIS and Remote Sensing data? 6 th International Conference on Natural Channel Systems May 24, 2018