An Index-Based Method to Assess Impacts of Global Change on Seawater Intrusion Problems

Abstract

Global change (GC) might produce important changes in the components of the water balance in coastal aquifers modifying the dynamic of the seawater intrusion (SWI). An assessment of these impacts on freshwater-seawater interaction requires an integrated analysis of quantity and quality issues. In this paper we propose a method to assess and summarise impacts of GC on SWI at different spatial scale. It requires generating consistent plausible future scenarios taking into account climate change, Land Use and Land Cover (LULC) change and Sea Level Rise (SLR) in coastal aquifers. We propose an integrated analysis of the hydrological impacts of potential future scenarios based on a sequential coupling of mathematical models: rainfall-recharge models, agronomic water requirements and irrigation returns models, and fluid density-dependent flow models. We intend to use these models’ results (hydraulic head and chloride concentration maps) to apply an indices-based method to assess and summarize SWI problems (status and vulnerability) at different spatial scale, moving from maps to 2D conceptual cross sections and lumped indices. It can help to identify coastal groundwater bodies in risk of not achieving a good status in accordance with the Water Framework Directive and to identify possible management strategies to reduce existing impacts. The temporal evolution of the indices can be used to assess resilience and trends respect to SWI problems in the historical period and future potential scenarios. In this work we show the results obtained for the Plana de Oropesa-Torrablanca aquifer but different groundwater (GW) bodies and temporal periods can be compared.