Testing the eartH2Observe Datasets to Compute the SPI and SPEI Over the Magdalena-Cauca Macrobasin in Colombia

Drought indices are used to quantify and evaluate the characteristics of a drought event. However, the low availability of meteorological information on a regional scale may affect its applicability. In this paper the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) are calculated over the vast region of the Magdalena-Cauca Macrobasin (MCMB), to test the accuracy of the meteorological reanalysis (WFDEI and MSWEP) and large scale global hydrological models (HTESSEL, ORCHIDEE, WaterGAP3 and PCR-GLOBWB) applied within the international research project EartH2Observe, and to study regional droughts in Colombia. Through the comparisons of the results of the SPI, the MSWEP was chosen as the best precipitation product in the MCMB, and from the outputs of the hydrological models with MSWEP as input, results showed that the WaterGAP3 model performed best for potential evapotranspiration. On the other hand, correlation with the Multivariate ENSO Index (MEI) was found to be strongest for the 6-month SPEI index of the WaterGAP3 model. Therefore, this drought index and model are recommended to be used in further research on droughts and ENSO in the MCMB.