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Spatial rainfall quantification in the Sahel rural area (Ferlo, Senegal) and in a European urban area (Greater Lyon, France). Evaluation of spatial interpolation methods Volume 20, issue 3, juillet-août-septembre 2009

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Laboratoire climatologie risques environnement, CNRS UMR 5600 Université Jean Moulin Lyon 3 18, rue Chevreul 69007, Lyon France, Département de géographie Faculté des sciences humaines et arts Université de Poitiers 97, avenue du Recteur Pineau 86000 Poitiers France, Département de géographie Faculté des sciences humaines Université Cheikh Anta Diop BP5005 Dakar-Fann Sénégal

In countries suffering from very low annual rainfall, such as the Sahel, or equally in urban centres that are at risk of flooding, it is vital to have in-depth knowledge of the spatio-temporal distribution of rainfall. Data relating to the study of rainfall is obtained via a network of rain gauges. Improved understanding of the rainfall event is achieved by interpolating punctual data. However, spatial interpolation methods are numerous and the choice of which to use depends on a variety of factors including accuracy, computation and time consumption. Therefore, five interpolation methods have been evaluated by a cross validation technique over two study areas: the rural Ferlo catchment in Senegal, and the greater Lyon urban area in France. This study concludes that no technique offers any advantage over the others, and calculations, level of complexity and velocity have to be taken into account to choose an appropriate method.