Integrated Assessment of Water Reservoir Systems Performance with the Implementation of Ecological Flows under Varying Climatic Conditions

Abstract

Projections of future climate relying on the use of climate models are still uncertain but decision makers are compelled to analyse the potential impacts of climate variability. The methodology presented in this paper can be widely used with a very large set of climate projections that are available today to the scientific community to generate input data at the watershed scale for the simulation and evaluation of water reservoir systems operation considering the implementation of ecological flows. The conceptual framework was applied to the analysis of Odeleite-Beliche multi-reservoir system in southern Portugal. In the selected case study, climate projections of monthly precipitation and temperature for the period 2021–2050 were obtained from the EURO-CORDEX initiative database; adjustment of climate projections was made with the quantile mapping method; natural inflows to the reservoirs were estimated with the Temez hydrological model; AQUATOOL was used in water system simulation; and reliability, resilience, vulnerability and dimensionless maximum deficit were used as performance criteria indicators. Two management perspectives were considered by prioritizing the water supply or the ecological flows. The results showed greater variation in the impacts on the water supply due to differences in the natural inflows generated from diverse climate projections compared to the results obtained with a different prioritization scheme. Failures in meeting current maximum withdrawals on Odeleite-Beliche multi-reservoir system with the implementation of ecological flows were registered only with climate projections that anticipate reductions of the natural inflows higher than 10% compared to natural inflows estimated by hydrological modelling using historical meteorological data.