Estimating Water System Performance Under Climate Change: Influence of the Management Strategy Modeling

Water resource management models, used to anticipate global change impact on water system performance, are classically a crude representation of real water systems. This paper analyzes how the representation of the management model may influence estimates of changes in performance for a multiobjective water reservoir in the French Alps. We consider three management strategy representations named as clear-, short- and far-sighted management. They are based on different forecastability degrees of seasonal inflows into the reservoir. The strategies are optimized using a Dynamic Programming algorithm (deterministic for clear-sighted and implicit stochastic for short- and far-sighted). Changes in system performance are estimated for a multimodel multimember ensemble of hydroclimatic simulations under the SRES-A1B emission scenario. They are much more influenced by changes in hydro-meteorological variables than by the strategy representation. The simple clear-sighted management representation has a quite similar effect as the far-sighted one supposedly closer to real world. The short-sighted representation misestimates the system performance, especially when inter-annual inflow variability is high.