Evaluation of the relationship between meteorological and hydrological droughts in the southern Iberian Peninsula

Society is facing a challenge due to climate change. Particularly, there are several areas where droughts will impact economic activities and landscapes, and decisions must be made in order to alleviate these effects. River flow regulation plays a major role in this regard, since it reduces the existing correlation between meteorological and hydrological droughts.
The aim of this work is to investigate the response of hydrological drought to meteorological drought under the influence of reservoir. To this effect, the Guadalquivir River Basin, in the southern Iberian Peninsula, has been studied. The aridity of this basin is expected to increase in the future, with longer and more severe meteorological droughts. Moreover, the Guadalquivir presents a strong regulation along its course. Therefore, streamflow and precipitation data have been analysed. With these data, meteorological and hydrological drought indices, such as the Standardized Precipitation Index (SPI), the Standardized Precipitation-Evapotranspiration Index (SPEI), and the Standardized Streamflow Index (SSI), have been calculated, focusing on how they correlate based on time scale and spatial distribution. The meteorological drought indices have been calculated in varying time scales, showing that the hydrological response is different depending on characteristics such as orography and river section. The correlation between the indices is generally strong in the study area, but the results show that its importance decreases as the streamflow becomes more regulated.
The results of this study could be added to the current tools for decision making in the economic fields that are most affected by droughts. Since droughts are a major effect of climate change in the area, this study could also act as a first step for the study of future droughts through climate and hydrological models.
Keywords: Drought indices, river regulation, hydrological response.
ACKNOWLEDGEMENTS: This work was funded by the FEDER / Junta de Andalucía - Ministry of Economy and Knowledge / Project [B-RNM-336-UGR18], and by the Spanish Ministry of Economy, Industry and Competitiveness, with additional support from the European Community Funds (FEDER) [CGL2017-89836-R].