Modelling the Effects of Groundwater-Based Urban Supply in Low-Permeability Aquifers: Application to the Madrid Aquifer, Spain

The European Union Water Framework Directive establishes the obligation to all Member States to develop and implement catchment-scale management plans. These aim at reaching a good status of all water bodies in Member States by 2015 or, at the latest, by 2027. Numerical models provide a suitable approach to evaluate the possibilities of achieving this goal by enabling users to deal with complex hydrological interrelations in a dynamic manner. This paper presents a modelling-based approach to examine the past and future effects of groundwater-based urban supply in Metropolitan Madrid, Spain. Monthly scale model calibration is based on 32 years of water table observations. Care is taken to address the effect of intensive pumping on groundwater levels and streamflows, as well as the role of groundwater resources in meeting urban demands during dry spells. The paper concludes by reflecting on the implications and probabilities of meeting the aforementioned deadlines, as well as on the sustainability of past and future pumping trends. Policy considerations aside, modelling results suggest that groundwater extractions could be augmented considerably without causing a significant decrease in streamflows.