Analysis of the Relationship between Meteorological and Hydrological Droughts in the Guadalquivir River Basin

One of the consequences of climate change is the increased number of droughts in arid regions. Additionally, droughts are expected to be more severe, as a consequence of the decrease in precipitations and river flow. The southern part of the Iberian Peninsula will be affected by this trend, so it is important to understand how meteorological and hydrological droughts are related in this area. In this study, the relationship between hydrological and meteorological droughts in the Guadalquivir river basin is studied. The analysis of droughts is performed using observational data from reservoirs, belonging to Confederacion Hidrografica del Guadalquivir, and two datasets from Centro Superior de Investigaciones Cientificas: SPETo for reference evapotranspiration, and SPREAD for precipitation. These data allow for the calculation of two drought indices: the Standardized Precipitation Evapotranspiration Index (SPEI), describing meteorological drought; and the Standardized Streamflow Index (SSI), describing hydrological drought. By studying the correlation between these indices, the connection between the two mentioned drought types can be better understood. Results show that orography and soil have a major impact on how both drought types behave, meaning that the river basin can be divided in small areas with similar behavior. Moreover, the studied relationship changes through the hydrological year because of drastic differences in precipitation and streamflow. These factors, together with the strong river regulation of this basin, conform an interesting study area that is analyzed in order to understand how future changes in climate variables will affect the development of droughts.