Alicante Province, with an area of 5,817 km2, is located in the SE of Spain. It ranks as the 4th most populous province of the fifty into which Spain is divided. From the middle of the last century, it has experienced an important economic development due to the transformation from rainfed to irrigated agriculture, as well as to the increase of tourism and industry. The scarcity of superficial resources in the region has made groundwater to have been a basic resource to supply water for these activities.
Regarding hydrogeological features in the province most of the aquifers are carbonated. There are mainly Cretaceous limestones and dolomites, but also Tertiary calcarenites, sandstones and limestones and Jurassic limestones and dolomites. There are also some detritic aquifers but not only their extension is smaller but also have worse hydraulic characteristics and in some cases poor quality water. Broadly speaking, the North-East and the South-West areas of the province are two differentiated domains. The first one has larger carbonatic aquifer systems under more humid climatic conditions, with average annual rainfall ranging between 500 and 900 mm. Thus aquifers have significant recharge rates and greater resources. On the other hand, in the South-West, where the carbonate aquifers are smaller due to the high tectonic compartmentalization and with rainfall annual averages ranging between 250 and 400 mm, recharge rates and so resources are scarce. Therefore, these areas concentrate the main overexploitation problems, specifically the basin of river Vinalopó.
In general, the quality of groundwater for current uses vary from good to excellent, with a predominance of bicarbonated calcium-magnesium facies related to the numerous carbonate aquifers. However, in the southern half of the province and in some aquifers in connection with the sea the quality is insufficient for practically all use, due to mineralization problems.
Provincial total input is currently estimated to be about 445 hm3year-1, with a difference between inputs and outputs of 28.5 hm3year-1 in average. This latter figure is considered the overall groundwater overexploitation in the province, which is nearly half than ten years ago. This reduction is the result of a series of factors such as the arrival of external flows, the improvement of the efficiency of irrigation and supply networks, as well as infradotation to irrigation, or even abandonment, of some uses due to insufficient supply in quantity or quality. However, the natural scarcity exposed causes that the moderate to small recharge rates are incapable of balancing the intensive extractions that have taken place for decades.