Advances in Geosciences www.adv-geosci.net 1680-7340 1680-7359 10 Observation, Prediction and Verification of Precipitation (EGU Session 2006) 2007 10.5194/adgeo-10-51-2007 http://www.adv-geosci.net/10/51/2007/ http://www.adv-geosci.net/10/51/2007/adgeo-10-51-2007.html http://www.adv-geosci.net/10/51/2007/adgeo-10-51-2007.pdf 51 57 2007-04-26 Mapping monthly rainfall data in Galicia (NW Spain) using inverse distances and geostatistical methods J. M. Mirás-Avalos jmirasa@udc.es A. Paz-González E. Vidal-Vázquez P. Sande-Fouz Faculty of Sciences, University of Coruña, 15071 Coruña, Spain EPS Lugo, University of Santiago de Compostela, 27002 Lugo, Spain In this paper, results from three different interpolation techniques based on Geostatistics (ordinary kriging, kriging with external drift and conditional simulation) and one deterministic method (inverse distances) for mapping total monthly rainfall are compared. The study data set comprised total monthly rainfall from 1998 till 2001 corresponding to a maximum of 121 meteorological stations irregularly distributed in the region of Galicia (NW Spain). Furthermore, a raster Geographic Information System (GIS) was used for spatial interpolation with a 500×500 m grid digital elevation model. Inverse distance technique was appropriate for a rapid estimation of the rainfall at the studied scale. In order to apply geostatistical interpolation techniques, a spatial dependence analysis was performed; rainfall spatial dependence was observed in 33 out of 48 months analysed, the rest of the rainfall data sets presented a random behaviour. Different values of the semivariogram parameters caused the smoothing in the maps obtained by ordinary kriging. Kriging with external drift results were according to former studies which showed the influence of topography. 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