Trends in channel capacity DO modify flood hazards

2015-02-09

New methods that could help better understand why flood hazard is increasing or decreasing have been published in Geophysical Research Letters. The research, led by Dr Louise Slater, a lecturer at Queen Mary University of London, examined trends in both streamflow and channel capacity in rivers across the USA.

By developing new methods to assess flood frequency, the authors demonstrated that accurately quantifying changes requires the separate accounting of both streamflow and channel capacity. The researchers say that the development can contribute to flood management systems and help estimate insurance costs more accurately.

Until now, alterations in the frequency of floods have been thought to be influenced primarily by climatic changes in the volumes of streamflow flowing in rivers and over floodplains. Dr Slater said,

“In assessing flood risk, river channel capacity is generally assumed to remain relatively constant over set periods of time. However, we now know that trends in flood hazard are not just about hydrology. We compared the contributions of channel capacity and flow frequency to historical flood hazard in 401 rivers across the USA, and found that significant trends in channel capacity were far more widespread that trends in hydrology. Our findings are especially relevant to the UK, given the recent controversy surrounding the causes of flooding in the Somerset Levels.”

Dr Slater was supported in her research by co-authors Dr Michael Singer of the Department of Earth & Environmental Sciences at the University of St Andrews, and Professor James Kirchner of the Department of Environmental Sciences, ETH Zurich.

The article is available here.