Influence of reservoir management on Guadiana streamflow regime

Abstract Study region Guadiana international catchment, located in the Iberian Peninsula. Study focus The Guadiana River catchment has registered an intense and speed up modification of its natural regime over the last few decades to cope with water scarcity. Such modifications pose a serious challenge to the development of improved management tools as information on available water resources is often not detailed enough. This study aimed to simulate the flow regime of the Guadiana River using the MOHID-Land model during a 30 years period. Two scenarios were defined by considering (or not) inputs from reservoirs. Model performance was assessed by comparing simulated and measured monthly streamflow at 24 hydrometric stations influenced (9 stations) or not (15 stations) by reservoir management. New hydrological insights for the region Streamflow simulations produced quite acceptable estimates for most of the hydrometric stations not influenced by reservoirs. However, results also showed the importance of non-simulated processes (e.g., groundwater abstractions) to the accurate prediction of the Guadiana flow regime. For the stations influenced by reservoir management, model simulations generally overestimated streamflow measurements. Information related to reservoir management needs thus to be made clearer for achieving better results, which can only be accomplished when national water agencies improve their cooperation protocols. Further model limitations were also addressed as well as the necessary developments for improving streamflow estimates in future modeling applications.