Actionable human-water system modelling under uncertainty

Abstract

[EN]This paper develops an actionable interdisci-plinary model that quantifies and assesses uncertainties in water resource allocation under climate change. To achieve this objective, we develop an innovative socio-ecological grand ensemble that combines climate, hydrological, and mi-croeconomic ensemble experiments with a widely used deci-sion support system for water resource planning and manage-ment. Each system is populated with multiple models (multi-model), which we use to evaluate the impacts of multiple cli-mate scenarios and policies (multi-scenario, multi-forcing) across systems so as to identify plausible futures where wa-ter management policies meet or miss their objectives and to explore potential tipping points. The application of the meth-ods is exemplified by a study conducted in the Douro River basin (DRB), an agricultural basin located in central Spain. Our results show how marginal climate changes can trigger non-linear water allocation changes in the decision support systems (DSSs) and/or non-linear adaptive responses of ir-rigators to water shortages. For example, while some irriga-tors barely experience economic losses (average profit and employment fall by < 0.5 %) under mild water allocation re-ductions of 5 % or lower, profit and employment fall by up to 12 % (∼ 24 ×) when water allocation is reduced by 10 %or less (∼ 2×). This substantiates the relevance of informing the potential natural and socio-economic impacts of adapta-tion strategies and related uncertainties for identifying robust decisions.