Use of historical data to assess the occurrence of floods in small watersheds in the French Mediterranean area

摘要

The results of an investigation on historical floods in four watersheds ofthe Aude region in France are presented herein. Using both, archive documentsand field investigations, the discharges of the main historical floods couldbe estimated for a period ranging from one to two centuries. The use of thisdata, in addition to systematic discharge measurements (continuous series ofabout 30 years in each case) shows that the calibration of Gumbel and EVIIdistributions is highly modified by using historical data, despite of thepoor accuracy of discharge estimations for historical floods. In some cases,it is also possible, with a simple test using historical data, to exclude astatistical distribution (Gumbel in the presented case) which is not adaptedto represent both historical and systematic data samples. Lastly, thehistorical data gathered highlights important differences in floodintensities among the four studied watersheds, differences that have now tobe explained.