Natural Flood Management in the Tweed Catchment

Transcription

1 Natural Flood Management in the Tweed Catchment

2 Drivers Statutory duty under the Flood Risk Management (Scotland) Act 2009 to promote sustainable flood risk management Consequential interest in taking forward research into NFM techniques and measures Development of Flood Protection Schemes with NFM considered as part of the solution. Solution to sediment management problems Response to extreme flood events in a rural area Climate change and need for increased resilience Obvious synergies between WFD delivery, improvement of designated site, LBAP etc. Potential Multiple Benefits improvement to water quality, fisheries, tourism, landscape, soil conservation, carbon sequestration etc.

3 Natural Flood Management projects in the Tweed catchment

4 The Bowmont Water Project

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11 Responses to Sept 2012 flood : Bar 2 Mean elevation change: m Sediment volume change: m 3 Aug 2012 Oct Structure Net change: m 3

12 Eddleston Water Project

13 Background - Why Eddleston? Scale 70 km2 Variety of land use types Good source-pathwayreceptor model Substantial modification over time bad status Flooding issues in Eddleston and Peebles

14 Core aims investigate the potential of reducing the risk of flooding to the communities of Eddleston and Peebles by restoring natural features within the catchment. improve the river habitat for wildlife and fisheries; work with landowners and communities in the Eddleston valley to maximise the benefits they would gain from such work, while maintaining farm business productivity/profitability.

15 Ancillary aims, objectives and opportunities Act as test bed for a raft of different policy areas including: - Improvement of a water body under the RBMP and WFD - Practicalities of delivering NFM under the Flood Risk Management Act - Improvement of an SAC/SSSI - Improvement of a world class fishery and mainstay of the local economy - Understanding the contribution of groundwater flows to flooding - Climate proofing - increasing farm/community resilience to more extreme climatic events - Woodland expansion in a working landscape - Carbon sequestration and payment for ecosystem services - Understanding and overcoming barriers in engaging land managers - Land Use Strategy planning using ecosystem services approach

16 A partnership approach The project is coordinated by Tweed Forum and involves the following organisations in terms of management, research, advice and funding. Scottish Government SEPA Scottish Borders Council Dundee University British Geological Survey Forestry Commission SNH NFU Scotland The Tweed Foundation Forest Carbon The Woodland Trust CEMEX Ltd The Environment Agency Scottish Power And many land owners and farmers.

17 Achievements to date Scoping Phase

18 Monitoring network establishing the baseline and measuring impact Surface water Groundwater Ecology - fish, invertebrates, macrophytes Ecosytem services Economic

19 Achievements to date practical works Works on the main stem (pathway section) Historic planform Roy Military Survey circa 1750 Toll road map 1792

20 Today s planform

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24 Re-meandering

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26 Source areas planting

27 Ruddenleys. 17ha tree planting, 3 large ponds, 12 log jams

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30 z Wester Deans 2500m of transverse hedges and 3 flood retention ponds

31 Flow restrictors/debris dams Middle Burn 10 log jams

32 Craigburn root wads

33 Craigburn. Re-profiling 300m and 34 log jams over 800m

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35 Summary of practical outputs and outcomes 66 hectares of riparian woodland created 16,000 metres of fencing erected 1.8km of river re-meandered 56 flow restrictors installed 19 leaky ponds created (7000 square metres) Over 70,000 trees planted 23,000 tonnes of carbon sequestered (over 100 year period) Waterbody status under WFD has gone from Bad status to Moderate.

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37 Funding...for work on the ground Interventions on 17 different farms amounting to some 600k Public sector Scottish Government, Water Environment Fund, SRDP, Scottish Borders Council. Private (and charitable) sector Forest Carbon, CEMEX, Woodland Trust, Scottish Power and land owner contributions. Considerable added value and leverage for individual funders

38 Role of Tweed Forum Trusted intermediary and facilitator Overcoming barriers to participation engaging land managers Ensuring the right measures, happen in the right place. Achieving critical mass involving multiple land owners to achieve impact at the catchment scale Securing funding package and overseeing all works Promoting and communicating multiple benefits

39 Critical mass and multiple benefits

40 Achieving multiple benefits

41 Monitoring network 11 stream gauging stations (Dundee)+ 2 (Forest Research) +2 SEPA 4 x Tipping Bucket Rainfall Groundwater and hillslope monitoring (BGS Darnhall Mains)

42 Main stem rated streamflow record (Eddleston Village) Baseline period Interventions Flow (cumec) /03/11 02/04/11 01/05/11 31/05/11 29/06/11 29/07/11 27/08/11 26/09/11 25/10/11 24/11/11 23/12/11 22/01/12 20/02/12 20/03/12 19/04/12 18/05/12 17/06/12 16/07/12 15/08/12 13/09/12 13/10/12 11/11/12 11/12/12 09/01/13 08/02/13 09/03/13 08/04/13 07/05/13 06/06/13 05/07/13 04/08/13 02/09/13 02/10/13 31/10/13 30/11/13 29/12/13 27/01/14 26/02/14 27/03/14 26/04/14 25/05/14 24/06/14 23/07/14 22/08/14 20/09/14 20/10/14

43 m 3 s -1 Flow generation analysis high flow events Andrew Black High flow event captured in rating Gauges (ADCP) Areas responsible for rapid flow Response identified + insights into routing 22 nd June 2012 highest event on record excellent test of catchment response BGS

44 Tributaries - debris flow deflector studies Wood deflectors installed May 2013 (Forest Enterprise) Hydraulically modelled Predict effects of high flow event, e.g. 1 in 25 year Small peak attenuation, delay of ~1hr in peak wave T Ball cumec :00 04:48 09:36 14:24 1/25 yr Geom2_Scenario1 simulated_real Geom2_Scenario2

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