Aquifer recharge in Moura region (South Portugal)

Dissertação de mest., Recursos Hídricos, Faculdade de Ciências e Tecnologia, Univ. do Algarve, 2011

According to the International Panel for Climatic Changes (IPCC), decreases in mean annual precipitation and changes in its annual distribution associated with increases in temperature, can lead to significant decrease in recharge of aquifers in southern Europe, which can turn into a major problem at a large regional scale. Moura-Ficalho aquifer (MF) is a karstic-fissured aquifer made of Paleozoic carbonate rocks (dolomitic rocks and marbles) in the Alentejo region, located in south of Portugal. Beside this predicted decrease in recharge, in this aquifer the situation was increased by soil erosion and clogging of sink holes and other karstic recharge structures, so in MF decrease in recharge has been detected and, for this reason more research and measures to reverse this desertification evolution are required. The unbalanced condition of this aquifer was first detected after the implementation of a monitoring piezometric network (Costa, in ERHSA, 2001) and the calibration of a groundwater flow model using data collected from October 2000 until December 2005 (Costa, 2008). According to the transient model developed on a monthly base, by A. Costa, water recharge was not enough to compensate the water losses by the aquifer. The simulation period included one wet year (2000/01), three mean years (from 2001 to 2004) and a very dry year (2004/05). However, mean annual precipitation in these five years was 530 mm, which equals the mean annual precipitation estimated by considering long time series. Furthermore, according to predicted climate changes, the climate trends towards drier weather and so, this problem will tend to become increased, probably not only in MF but also in other karstic aquifer in southern part of Portugal. This work intends to investigate the relationship between groundwater and surface water, and to detect areas where the natural recharge is taking place and where it should be increased in order to mitigate this environmental problem. To reach this aim, several scenarios of the former groundwater modeling outputs were worked out with the help of Geographic Information System (Arc GIS). Also the subject about artificial recharge of aquifers was developed and applied to this region.