Screening tool central to flood risk assessment
Posted: Thursday 12th March 2009
The increasing frequency of potentially catastrophic flooding events has focused the attention of utility companies on flood risk assessment for those installations vital in maintaining customer supplies. Working with a major electricity distribution company and drawing upon a diverse range of scientific and technical skills, ADAS has developed a screening tool which allows for early assessment of flood risk on the utility company’s infrastructure.
Realising that a number of its key sites fall within Environment Agency (EA) designated flood risk areas, a major electricity distribution company recently commissioned ADAS to firstly determine if the classification was correct, and if so what protection might be required against fluvial flooding caused by river or coastal floods. The second strand of the project was the development of a cost effective risk assessment screening tool to allow the company to conduct early risk assessment from pluvial flooding on essential parts of the utility company’s infrastructure.
“Pluvial flooding results from overflow caused by prolonged and heavy rainfall, but can be intensified by issues such as blocked sewers and storm drains,” says ADAS scientist Jodie Whitehead. “The risk to a site from pluvial flooding is dependent upon many factors including topography, drainage capacity within the upstream catchment area, and the extent of any impermeable surfaces in the locality.”
Using its scientific understanding of catchment hydrology, the ADAS team has produced a methodology with the following assets:
· Applicable to both urban and rural sites· Applicable at a scale resolution of less than 100m
· Sensitive to differing catchment characteristics such as land cover
· Able to account for spatial variability in rainfall
· Simple and easy to reproduce
· Low cost implementation
“By integrating a wide range of data sets we have been able to use a combination of GIS based screening, targeted field visits and historic records of pluvial flooding in the area to produce this simple and effective tool. This should enable the company to better target flood mitigation measures and hence reduce the risk of interruption to electricity supplies for its customers,” she says.
The screening tool is very flexible and can be applied to any company. With catastrophic flooding becoming an increasingly frequent occurrence, utility companies are advised to carry out flood risk assessments sooner rather than later to ensure that suitable alleviation measures are in place.
