Dr Stephen Holness & Andrew Skowno - Ecosol Brent Corcoran, WWF-South Africa

Transcription

1 Dr Stephen Holness & Andrew Skowno - Ecosol Brent Corcoran, WWF-South Africa

2 Mapping Ecological Infrastructure for the greater umngeni Catchment Project concept EI introduction Logic we used to define and identify EI Specific methods used Outputs What can be learnt from it?

3 Introduction Support targeted investment in the maintenance and rehabilitation of Ecological Infrastructure (EI) Ecosol was appointed by WWF to map the key areas of EI Focus on EI supporting the water supply to Umgeni Water Supplies ethekwini, Pietermaritzburg and others.

4 WHAT IS ECOLOGICAL INFRASTRUCTURE? Functioning ecosystems that deliver valuable services to people e.g fresh water, climate regulation, soil formation and disaster risk reduction. Ecological infrastructure includes healthy mountain catchments, rivers, wetlands, coastal dunes, nodes & corridors of natural habitat, which form a network of interconnected structural elements in the landscape. What does this mean in practice? Can we map it (specifically) with current data and at a scale useful for planning?

5 Functioning ecosystems that deliver valuable services to people Spring Grove Dam R1.67 billion Demand led umkhomazi Smithfield and Impendle Dams $$$$$$

6 Functioning ecosystems that deliver valuable services to people Focus on water supply NB: Not a full definition of all EI Water production and stream flow augmentation e.g. natural areas with high water yield and portions of the landscape required to support flow during the dry season Erosion control e.g. erosion prone areas which need to be kept intact or rehabilitated Enhancement of water quality including sediment trapping, phosphates, nitrates and toxicants Flood attenuation e.g. the particular types of wetland which are important for delaying flood peaks and reducing flood intensity

7 Build a bottom-up set of EI Not all of intact nature Need to make the case linking an area to a specific valuable service But no scope for new data collection so needed to apply new concept to largely existing data KZN landcover 1: and FEPA river and national wetland dataset (but not FEPA analysis) ProEcoServ helpful Wetland services evaluation (Kotze)

8 Overall approach Features Condition Key ecological infrastructure i.e. the most important stuff for delivering water related services Additional ecological infrastructure i.e. other important bits. Intact i.e. avert loss or protect Degraded i.e. c/should be restored Transformed i.e. lost but may need to manage to deal with negative impacts

9 Functioning ecosystems that deliver valuable services to people 3 categories i.t.o. condition Ecological Infrastructure: Intact areas for protection i.e. Areas that are in good condition Potential Ecological Infrastructure: EI Areas for rehabilitation i.e. Areas that are in poor condition Mitigate impacts i.e. Areas where value has been lost, but there may be opportunities to reduce negative impacts EI

10 Excellent KZN landcover Re-classified grid

11 But what is important???

12 Water production & stream flow augmentation Built on the logic of ProEcoServ refine to a local scale Strategic Water Source Areas

13 Water production & stream flow augmentation Proecoserv 1 runoff grid smoothed out. Values above 220mm/yr runoff were then designated as high water yield areas.

14 Water production & stream flow augmentation Ecological Infrastructure Potential EI: Areas for rehabilitation Mitigate impacts Water production & stream flow augmentation In high yield areas Rivers (over 220mm runoff) Terrestrial areas Wetlands Riparian buffers (100m minimum; 500m larger rivers) All natural habitat types (as per landcover) Degraded areas (as per landcover) Transformed areas (as per landcover) All natural wetlands In lower yield areas (under 220mm runoff) Rivers Wetlands Riparian buffers (32m minimum; 100m larger rivers) All natural wetlands All areas Wetlands specifically important for water production & stream flow augmentation Unchannelled valley-bottom wetland with 50m buffer Valleyhead seep with 50m buffer Values: 2 = Key ecological infrastructure 1 = Additional Ecological Infrastructure

15 Water production & stream flow augmentation

16 Flood attenuation 84 & 87

17 Flood attenuation Ecological Infrastructure Potential EI: Areas for rehabilitation Mitigate impacts Flood attenuation Rivers Wetlands Rivers Wetlands specifically important for flood attenuation Riparian buffers (250m on larger rivers, 100m on smaller but perennial rivers) Channelled valley-bottom wetland with 50m buffer Floodplain wetland with 100m buffer Pans (Depression & flat) with 50m buffer Seep with 50m buffer Unchannelled valley-bottom wetland with 50m buffer Valleyhead seep with 50m buffer Values: 2 = Key ecological infrastructure 1 = Other Ecological Infrastructure

18 Flood attenuation

19 Erosion control Specific wetland types which reduce erosion risk Mapped areas of gully erosion Areas with high sediment yields Gullies Mararakanye N, Le Roux JJ (2012) Gully location mapping at a national scale for South Africa. South African Geographical Journal 94: doi: / Erosion (sediment yield) Le Roux JJ, Morgenthal TL, Malherbe J, Pretorius DJ, Sumner PD (2008) Water erosion prediction at a national scale for South Africa. Water SA 34: Gully dataset was used directly. Areas with actual sediment yields above 25t/ha/yr were classified as high sediment yield

20 Erosion control Ecological Infrastructure Potential EI: Areas for rehabilitation Mitigate impacts Erosion control Wetlands Erosion prone areas which need to be kept intact or rehabilitated Values: 2 = Key ecological infrastructure 1 = Other Ecological Infrastructure Wetlands specifically important for erosion control Terrestrial areas Channelled valley-bottom wetland with 100m buffer Floodplain wetland with 100m buffer Seep with 100m buffer Unchannelled valley-bottom wetland with 100m buffer Valleyhead seep with 100m buffer Areas with high sediment yield Areas with gully erosion 2 1

21 Erosion control

22 Enhancement of water quality Ecological Infrastructure Potential EI: Areas for rehabilitation Mitigate impacts Enhancement of water quality (including sediment trapping, phosphates, nitrates and toxicants) Channelled valley-bottom wetland with 50m buffer Floodplain wetland with 100m buffer Wetlands Wetlands specifically important for water quality enhancement Pans (Depression & flat) with 50m buffer Seep with 100m buffer Unchannelled valley-bottom wetland with 100m buffer Valleyhead seep with 100m buffer Rivers Rivers Riparian buffers (32m minimum; 100m larger rivers) Riparian buffers (250m on larger rivers, 100m on smaller but perennial rivers) Values: 2 = Key ecological infrastructure 1 = Other Ecological Infrastructure

23 Enhancement of water quality

24 Put it all together

25 Zoom in...

26 Lessons Yes it is possible to map EI specifically, with current data, and at a scale useful for planning Can be used for making the case and planning Other observations: EI is not necessarily equal to CBA but will overlap in many instances Hooray for good landcover Ditto for other building block data (e.g. wetlands)

27 Way forward Detailed prioritization Finer scale implementation planning Specific demand led issues at a local scale sholness@nmmu.ac.za