The Use of Wetlands for Flood Attenuation FINAL REPORT - An Taisce

Recommendations

Info

The Use of Wetlands for Flood Attenuation Aquatic Services Unit, UCC BEFORE AFTER Fig. 8: Floodplain storage and restoration of meanders on the Inde River, upstream of, Eschweiler, Germany (images from the JAF website 24 ) 6.4.5 Coastal Realignment: Hesketh Out Marshes, UK. The site is located on the south bank of the Ribble Estuary, Lancashire. The marshes had been reclaimed for 30 years by the time managed coastal realignment began. The dual driving forces behind the project, undertaken by the UK Environment Agency (EA), were to (1) increase flood storage potential and defence standard, and (2) restore salt marsh habitat for wildlife. Breaching was completed for the first part of the project in 2009. 15km of creeks were excavated (widths ranging from 17 to 2m), essentially reinstating historic creek system (most of which had been destroyed due to arable works); 11 saline lagoons were created and field boundary ditches were infilled. Partnership between agencies (including the Environment Agency, Natural England and RSPB) made the scheme possible. Funding sources included the EA’s flood risk management budget, and a contribution by Lancaster City Council – the latter to compensate for damage to another SPA in the region caused by defence works. Land purchase costs were higher than originally expected which was a problem on the scheme. Also, whilst the public were generally supportive of the project, concerns were raised about land drainage which the EA responded to by undertaking additional work to the land drainage system (a series of constructed upstream pools) (ABPmer web database 25 ). Tides first inundated the entire site in March/April 2009 and, beneficially, the observed tidal inundation exceeded modelling predictions. It covers a total of 180ha comprised of 40ha mudflat, c.110ha saltmarsh, 7ha saline lagoons and 23ha transitional and floodbank habitat. Figure 9 illustrates the scheme. 24 http://www.jaf.nu/nieuw/eng/home/index.html 25 http://www.abpmer.net/omreg/easycontrols/database/details1.asp?ID=93&lstType=Managed%20breach FINAL REPORT, February, 2012 50
The Use of Wetlands for Flood Attenuation Aquatic Services Unit, UCC N River Ribble Fig. 9: Aerial map of the Ribble Estuary with a plan of the nature reserve created at Hesketh Out Marshes through managed realignment. Further fields to the east are planned for restoration (lower image from the RSPB Liverpool 26 ) 6.4.6 Washland creation: Long Eau, Lincolnshire, UK The Long Eau, typical of many rivers with engineered flood defence banks for agricultural improvement, had little connection between river and floodplain. In the mid 1990s embankments were set-back along a section of the Long Eau at Manby (Lincolnshire) at a cost of £60,000 (in 1995), opening up the area for seasonal flooding to help alleviate downstream flooding. The National Rivers Authority (lead agency at the time) funded the setback out of an environmental conservation budget designed to 26 http://www.rspbliverpool.org.uk/RSPB%20Hesketh%20Out%20Marsh.htm Seawall breaches FINAL REPORT, February, 2012 51
Page 1 and 2: The Use of Wetlands for Flood Atten
Page 49: The Use of Wetlands for Flood Atten
Page 101 and 102:
The Use of Wetlands for Flood Atten
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
show all

The Use of Wetlands for Flood Attenuation FINAL REPORT - An Taisce

Create successful ePaper yourself

Delete template?

Save as template?