The International Information Center for Geotechnical Engineers

Wednesday, 28 January 2015 08:43

New parameter in flood risk assessment recent study reveals

New parameter in flood risk assessment recent study reveals Credits: http://www.townofbraintreegov.org/

With half a million dollars spent to adress direct flooding costs in the U.S. in 2012, flood risk evaluation is still hard to perform, since not all contributing factors are recognized, frequently leading to questionable river basin management decisions. A new study by UC Santa Barbara focuses on the basic principles of flood hazard analysis, indicating that not accounting for channel capacity may result into misleading estimates of the flood susceptibility levels also affecting flood insurance premiums calculation. 

The study was conducted by Associate Professor Michael Singer and his colleagues from UC Santa Barbara and was recently published in the journal Geophysical Research Letters. Scientists indicated that in addition to the correlation of flood hazard to the frequency of high water flow, one should also consider the channel's capacity to accommodate it. Based on digitized USGS data, PhD student at the University of St. Andrews in Scotland, Louise Slater, focused on a set of 401 stations, providing the team with data over a time span of 40 to 60 years, to develop a novel methodology for separating the effects of hydrology (associated with water flow) and geomorphology (associated with channel capacity) on flood hazard.

According to Prof. Singer, "If there's more water coming from the watershed but the channel gets enlarged somehow, that would offset the increased water flow. Hence, these two potentially interacting factors could have no change or they could increase the amount of change in one direction or another." Based on 10-year trends in channel capacity, results indicate that channel capacity does affect long-term flooding frequency, changing considerably flood hazard levels in most of the sites that were studied. For example, channels clogged with sediment or vegetation end up impeding water flow, significantly increasing flood hazard levels. In such areas flood hazard is underestimated by the conventional methods, not accounting for changes in channel morphology. The opposite trend is also observed, in areas where capacity of river channels is increased. 

Singer concluded that "in order to develop appropriate management strategies or to set flood insurance premiums for any location, you need to consider both the flow frequency and channel capacity effects of flood hazard".

To learn more on the study, please click here

 

Source: www.sciencedaily.com

Read 1870 times Last modified on Wednesday, 28 January 2015 10:47

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