Different interpolation methods comparative study for rainfall maps elaboration in La Gomera (Canary Islands): Assessment of the altitude incorporation

Groundwater is the main water resource in La Gomera (Canary Islands) where it represents almost 70% of the consumption. Since the elaboration of the preliminary works of the Insular Hydrological Plan in 1996 there has not been other estimation of the island’s rainfall. For an accurate estimation of the future hydrogeological resources of the island it is necessary to know and assess carefully the recharge estimates. It is for this reason that the choice of the rainfall interpolation method is so important. In this study two different interpolation methods have been used to compare their results with the real data of the gauges and to obtain doing that the best precipitation estimate in the area. Results show the kriging with external drift to be the best interpolation method in the study area and that the use of the relationship between elevation and precipitation increase the accuracy of the mode