Impact of Climate Change on Extreme Rainfall in France Throughout Trend Detections in Average Climatic Characteristics
Abstract
The great interest on climate change during these last years has led to a quasi unanimous conclusion for scientists: the Earth climate changes. An increase of precipitation in the middle and high latitude area of north hemisphere was detected. In order to prevent hydrological risks, it's interesting to know if these global changes lead to an increase of extreme events. Indeed in the hydrologic context, the estimation of return period is primary for hydraulic building dimensioning. When considering problem of fire, urbanisation, hydrological installations, the study of water runoff alone can be misleading. So we must do a preliminary work on rainfall. However climate models have difficulties to represent efficiently extreme events. Moreover classical statistical methods seem to be limited because of the lack of very long series which can lead to a bad estimation of distribution tails. An original approach is applied to estimate impacts of climate change on extreme events in using an hourly rainfall stochastic generator which can be coupled with a rainfall-runoff model. The climate evolution is detected by the generator parameters. These parameters are estimated by an average, and not by extreme values, of climatic characteristics. From daily information of 139 rain gauge stations, evolution of generator parameters has been studied in the metropolitan France between 1960 and 2003. We applied the Poisson-Pareto-Peak-Over-Threshold model and linear trend has been tested by the Maximum Likelihood Ratio test. Parameter evolution has been evaluated from a regional approach in clustering several stations. Changes on average rainfall characteristics are amplified on extremes. The observed trends occur mainly between December and May. Taking into account the climate change doesn't lead to a big change in the quantiles estimation compared to their estimation under a hypothesis of climate stationary. But if observed trends are confirmed in the future, extreme event occurrence probabilities will increase notably in the North- West, East and mountain landscape of France in the next years. Finally, we compared trends observed on data to scenarios proposed by the climatic model used for the IMFREX project. Indeed it proposes evolution scenarios of some average variables which are well correlated with the rainfall generator parameters.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2008
- Bibcode:
- 2008AGUFM.H21A0806C
- Keywords:
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- 1630 Impacts of global change (1225);
- 1817 Extreme events;
- 3245 Probabilistic forecasting (3238);
- 3305 Climate change and variability (1616;
- 1635;
- 3309;
- 4215;
- 4513)