Analysis of piezometric trends in the Medina del Campo Ground-water Body to understand the status and drivers of changes of groundwater-related ecosystem services. NAIAD EU Project

Resumo

The area covered by the Medina del Campo Groundwater Body (MCGB, Duero River Basin, Spain) is an important agricultural production region. Groundwater is the main provisioning source for irrigation, to supply many small towns and also to support surface groundwater-related ecosystems (SGRE). The area is prone to climatic and geomorphological hazards such as floods and droughts. The aquifers is formed by a tick (100 to > 500 m) accumulation of Tertiary fine-sized alluvial, eolian and lacustrine sediments. Groundwater levels have declined up to 20 m in some areas in the last 40 years. In the framework of the NAIAD H2O20 project, we are analysing the role of groundwaterrelated ecosystem services for drought hazard mitigation and to support SGRE, in a context of increasing climatic variability and testing different management strategies. The objective of this work is to understand the evolution of some provisioning and regulating ecoservices and its causes, based on the analysis of temporal piezometric trends. The Mann-Kendall test has been used to analyse the temporal trends of piezometric and precipitation time series in the MCGB for the period 1985-2018. The results have been studied on a regional scale with the support of GIS. The study was based on data from 137 piezometers and 10 meteorological stations. The analysis was performed for twotime intervals based in the different lengths of the piezometric series available: 1985-2001 and 2002-2018. A clear and generalized decreasing piezometric trend has been identified for the interval 1985-2001. For the interval 2002-2018, many piezometers show a clear increasing trend while others do not show any tendency. Some punctual (both spatial and temporal) correlations have been observed between decreasing piezometric levels and decreasing precipitation but given the characteristics of the aquifer and the piezometers, this is attributed to augmented pumping to complement the soil water deficit on dry years. The observed general piezometric trends are attributed mostly to the effect of groundwater management actions after the entry into force of the Water Framework Directive. The study is still under development.