Drought propagation under combined influences of reservoir regulation and irrigation over a Mediterranean catchment

Drought is a natural phenomenon that is controlled by different factors such as natural climate, catchment controls, and in many worldwide regions it is now driven by human activities (i.e. reservoirs, irrigation, groundwater abstractions). Reservoirs initially ensure water availability and cope with drought, especially in semi-arid regions; however, this human modification to the environment may lead both positive and negative effects over the hydrological cycle. This involves a better understanding of hydrological processes and incorporating human interactions to improve drought management within coupled human-natural systems

This study is focused on a strongly irrigated area located in the northeast of the Iberian Peninsula, the northern part of the Aragón and Cataluña district supplied by the Barasona reservoir. We implemented a simple water management model to simulate the reservoir operation (human-influenced scenario) and examine the contribution of human activities, associated with irrigation, on the water budget and drought propagation. For this purpose, we use simulation performed by the SASER model which provided a natural scenario (without human influence) to contrast with the human-influenced scenario.

Here, we explore the linkages between agricultural drought, associated with evapotranspiration, and hydrological drought, thus we applied standardized indices to identify droughts, then we compare them to each other and assess changes induced by human activities. The first results demonstrated satisfactory performance to simulate reservoir storage and outflows against observed data, KGE values of 0.4 and 0.82, respectively. The human modifications modulate the hydrological response of the catchment, and alter the intensity of hydrological drought, while human activities reduced the intensity of agricultural droughts.