Are cities ready for extreme rainfall?

Climate change may cause extreme weather phenomena such as torrential rainfall in the summer months. Are our urban water drainage systems up to the task during these periods of peak load? Researchers from TU Delft, the Royal Netherlands Meteorological Institute and Deltares are working on the robustness of urban water systems. A number of highly interesting preliminary results have been published in the international journal Climatic Change under open access terms.

In 2006, the Royal Netherlands Meteorological Institute (KNMI) published four climate scenarios for the Netherlands that reflected various climatological expectations for the country. These scenarios also include expected precipitation amounts. These expectations reflect precipitation in a given 24-hour period. Urban water managers, however, are much more interested in forecasts that cover a much shorter span of time: an hour or less. They want to know if their urban water systems will be able to handle more intense peak loads in the future during periods of potentially torrential rainfall. Recalling the intense rainfall in the Netherlands in August 2010, they are specifically interested in the effects of short, yet intense rain showers in combination with rapid roof and road-surface drainage.

TU Delft and KNMI researchers have established a relation between maximum daytime temperature, wind speed and direction, daily precipitation and the expected peak precipitation load in the course of one hour.

This relationship can serve as a basis for developing a model that urban water managers can use to calculate the effectiveness of their drainage systems. The model will help address the question of whether extra measures will be needed to deal with peak loads of greater intensity. The most important result is that the intensity of brief rain showers will increase along with rising summer temperatures as forecast by the KNMI. Urban water drainage systems will be put to the test more often in the future. It is likely that we will see situations like the one in August 2010 more often.

Further details

 Professor N.C. van de Giesen
[email protected]
+31 (0) 15 278 71 80
 TU Delft Science Information Officer Roy Meijer
[email protected]
+31 (0) 15 278 17 51



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