Dredging alone will not contain flood risk new study finds

Published by David Hayden on

February 3, 2017

A new report written by ecologist Anja Murray for Friends of the Earth, Ireland recommends that Ireland adopt natural flood management techniques. The report delivers a salient message to Irish policy makers. Global warming will increase the incidence and severity of flooding and engineering strategies such as dredging riverbeds and building walls will not be effective. Instead, the ecology of land-use needs to be managed so as to retain water and slow the flow during times of heavy rainfall.

[x_blockquote cite=”Anja Murray” type=”left”]Natural flood management is an approach that is virtually unknown in Ireland and has not been widely discussed in any relevant spheres here, despite the growing problem of widespread flood damage in recent years and forecasts of worse to come.[/x_blockquote]

Land-use changes in recent decades have had a negative impact on flooding. Expansion and intensification of agriculture as well as urban development, which has often taken place on historic floodplains, resulted in loss of capacity. Dredging has continued in many Irish river channels which causes flooding downstream. Paving in urban areas has reduced the permeability of soils, this in combination with drainage and infilling of wetlands puts Ireland at risk for floods.

The report highlights the incidence of ‘extreme rainfall events’ and links them to climate change. This reality in combination with the decline in floodplains and soil permeability are creating an extremely high risk profile for many areas in Ireland.  Natural flood measures recommended by the report include peat bog restoration, woodland creation, wetland protection, incentivised agricultural land-use changes, floodplain restoration and managed coastal realignment. The report looks at several case studies of successful implementation of natural flood management including the North Yorkshire ‘Slowing the Flow’ project and the Dutch ‘Room for the River’ project as well as restoration projects which have taken place in Belgium and England.

The report concludes with a brief case study of Corcagh Park where flood risk has been successfully managed by the construction of wetlands. Five off-line lakes, controlled by weirs, were constructed on the floodplain. These lowered areas serve as a holding area to retain flood waters and allow them to be slowly released back into the river as the flood subsides.

The report is particularly encouraging for environmentalists who are not only offering a practicable solution to flooding but also proving that the environmental sector can act as the solution not just as the whistle-blower. Ecological initiatives such as peatland restoration and woodland creation are the solution to flooding and more. The measures also further ecological goals such as biodiversity and carbon capture. In order to protect ourselves from flood risk we need to protect our natural ecosystems. The study demonstrates clearly that natural processes are most effective. The lesson for lawmakers is that going green prevents flooding, let’s hope government takes heed of this wisdom.

The report was funded through the Irish Environmental Network by the environment fund.

[x_button shape=”square” size=”regular” float=”none” href=”http://www.foe.ie/download/pdf/natural_flood_management_a_study_for_friends_of_the_earth_february_2017.pdf” info=”none” info_place=”top” info_trigger=”hover”] Click here to read the report in full[/x_button]

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David Hayden

David is a contributor to the Green News. He has a Bachelor's Degree in International Business and French from UCD as well as a Master's Degrees in French literature and New Media from the University of California at San Diego and the Johns Hopkins University.