Discovering future vulnerabilities of the Jucar River Basin under climate change

Today the management of water systems requires robust policies capable of withstanding deviations from the conditions for which they were originally designed due to the large degree of uncertainty about future inflows and water demands. Under evolving and deeply uncertain hydroclimatic inputs, the performance of these systems may degrade to a point where they become unable to meet the primary objectives for which they were built, potentially causing declines in water resource system performance or even complete system failure.

Here we present a Multi-Objective, Robust Decision Making analysis applied to the case study of Jucar river basin in Spain, where the balance between water demand and available resources is already precarious. As in most Mediterranean basins, climate change is expected to further reduce water availability, increasing the intensity of drought episodes, and challenging the long-term sustainability of water use. Using a hydroeconomic model of the basin, we assessed the performance of the current system’s operations in terms of agricultural and hydropower benefits, along with ecosystem services under different CMIP6 scenarios over the time horizon 1980-2100. These climate projections are then synthetically perturbed to generate a larger ensemble of future scenarios, which is used to complement the robustness analysis and identify via scenario discovery the most critical drivers under which the system is expected to fail.

Preliminary results using the nominal IPCC scenarios indicate substantial system vulnerabilities emerging over the next decades, especially under the pessimistic SSP5-8.5 projection. These findings suggest the need of identifying candidate adaptation options to be triggered according to the future evolution of the system in order to ensure a timely adaptation of water management strategies to future changes.