Wereldwaterdag The answeris in nature Tom De Bie

Transcription

1 Wereldwaterdag The answeris in nature Tom De Bie

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11 IntegratedWater Management 1. the River Basin District (Scheldt and Meuse) > River basin management plans 2. theflemishregion(river basins Scheldt, Meuse, IJzer, Polders of Bruges) 3. the sub-basins(11) > River catchment management plans Coordination Committee on Integrated Water Policy 11

12 Senne subbasin Water management Flanders Brussels Wallonia 12

13 Senne subbasin Flanders Brussels Water management Flanders Vlaamse Waterweg Wallonia 13

14 Senne subbasin Flanders Brussels Water management Flanders Vlaamse Waterweg Flanders Environment Agency Wallonia 14

15 Senne subbasin Flanders Brussels Water management Flanders Vlaamse Waterweg Flanders Environment Agency Province Wallonia 15

16 Senne subbasin Flanders Brussels Water management Flanders Vlaamse Waterweg Flanders Environment Agency Province Municipalities Wallonia 16

17 Senne subbasin Flanders Brussels Water management Flanders Vlaamse Waterweg Flanders Environment Agency Province Municipalities Adjoining landowners Wallonia 17

18 Senne subbasin Flanders Wallonia Brussels Water management Flanders Vlaamse Waterweg Flanders Environment Agency Province Municipalities Adjoining landowners Brussels Port of Brussels Brussels Environment Municipalities Wallonia SPW DGO2 SPW DCNN Province Municipalities Adjoining landowners 18

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20 Floodrisk Protection against flooding in Dijlevalley south of Leuven Technical solution: construction of dikes and retention basins Ecological solution: natural flooding area ( = current situation) Comparison of ecosystem services: Carbon sequestration in soil <> vegetation Denitrification Capturing fine dust Regulation of sedimentation Infiltration Recreation (Smaller investment cost) 20

21 Floodrisk Maximized flow rate through city Leuven Slow down flow rate upstreamleuven and optimize the use of the natural flooding area during flooding events Extensive management upstream Leuven Help from beaver: hotspot 21

22 Floodrisk Maximized flow rate through city Leuven Slow down flow rate and optimizethe use of the natural flooding area during flooding event Extensive management upstream part Help from beaver: hotspot 22

23 A man-made marsh in the Scheldt estuary, protects densely populated areas from storm surge flooding. The sluice allows daily tidal flooding of the marsh (from Temmerman et al., 2013, Nature; Vildaphoto) 23/03/

24 cost-efficient and ecologically sound alternative to conventional coastal engineering (sea walls) 23/03/

25 Selfpurificationcapacity Waste water treatment: necessary Restoring the natural dynamics and processes of rivers > increase selfpurification capacity + increase resilience Cost-efficient + biodiversity Riparian zone 5m width -1 km length with nitrogen load 10 mg/l surface water > Removal of 88 kg N /year (~ yearly discharge 25 people) 25

26 1 ha tidal area removal153 kg N/yrfromthe surface water 26

27 Zwarte beek(lummen) Increase self-purification capacity: creating wetlands, more room for the river,remeandering(increased residence time of water) ) 27

28 Zuunbeek(Sint-Pieters-Leeuw) Decreased flood risk Increased self-purification capacity Increased flow diversity (macrophytes, macroinvertebrates) Improved recreation Removal of fish migration barriers 28

29 Demer Reconnect 30 cutoff meanders 29

30 Natural wastewater treatment: floodingarea Sint-Truiden Water quality(nitrogen, suspended solids, phosphorus, ) of river Melsterbeek improved significantly after passing through the wetland 30

31 Vaalbeek Oud-Heverlee Dijle - Heverlee Molenbeek - Kampenhout IJse - Hoeilaart Leibeek-Kampenhout 31

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33 But Pond complex Zonhoven, hotspot of biodiversity

34 Pollutedhighway runoff Stormwaterrunofffromroadways: PAH s(polyaromatichydrocarbons) Heavy metals Gasoline constituents Road salts 34

35 Pollutedhighway runoff Technical solution (Switzerland) 35

36 Pollutedhighway runoff Semi-technical solution (Belgium, Bertem) Sludge collection Reed bed Influent Effluent > river 36

37 Pollutedhighway runoff 37

38 Water in thecities Rivers can reduceurbanheatislandeffect(1 à 2 C) Improved health, reduced stress level, faster recovery Increased value of houses 38

39 Water in thecities 39

40 Water in thecities 40

41 The answer is in nature? Context-dependent, case by case assessment Nature based solutions often costefficient (maintenance, sustainability) Technical solutions > single service Natural solutions > bundles of ecosystem services Biodiversity benefits But we need a lot of space (not always available in Flanders) 41