Economics of Climate Resilience: Flood Management

Submitted by Michael Rastall | published 27th Mar 2013 | last updated 15th May 2013

Executive summary

In combination with sea level rise (and coastal erosion), changing rainfall patterns, including events of higher rainfall intensity, could contribute to an increased risk of flood events in the future (Lowe et al., 2009). Furthermore, areas not currently considered at risk could experience pluvial or fluvial flooding.

Several options exist to address flood risk, including hard engineering solutions (e.g. flood barriers) and Natural Flood Management (NFM) measures. The focus of this particular analysis is the latter.

In response to the projected increase in flood risk and the request for more evidence by policy officials, this report addresses the question set by Defra:

“What is the case for further intervention to encourage the use of soft engineering/habitat management for flood risk management?”

NFM measures can either reduce runoff (e.g. farm management to increase filtration) and/or attenuate flow (e.g. riparian tree planting, flood plain reconnection). They are more effective at reducing the frequency of flooding for high probability fluvial events (e.g. less than a one in twenty year return period) compared to extreme events (e.g. one in 200 year return period). NFM measures can either be considered alone or as part of a package alongside other soft or hard engineering measures.

NFM measures can also provide important wider benefits including improving water quality, carbon sequestration or habitat restoration, among others. They are only likely to be pursued effectively if these benefits are incorporated within the overall assessment of their costs and benefits.