Areal exploitation of groundwater in coastal dunes, Buenos Aires, Argentina

CARRETERO SILVINA; KRUSE EDUARDO

Global Groundwater Resources and Management

Scientific Publishers (India)

Lugar: Jodhpur, India; Año: 2010; p. 385 - 398

In the study area, the groundwater of low salinity is restricted to thefringe of coastal dunes. This is the only drinking water source for a permanent populationthat is greater than 10,000 inhabitants. In summer, the region presents a tourist highwhich multiplies the population by 5. In this paper the current groundwater exploitationin an area with limited reserves of fresh water, where the demand of water is increasing isdescribed.The coastal dunes have a morphological expression between 0.5 to 3.5 m.a.s.l. The freshwater lens is limited by sea water and brackish continental water. To avoid the salt waterintrusion an areal exploitation is carried out. There is a pumping field located outside theurbanized area, composed of 7 horizontal wells, Ranney type, and of 21 well point systems,each one connected to 10 wells. The extraction depth varies between 4m and 6m.The system recharge only takes place from the precipitations (1000 mm/y), while thenatural discharge is by the evapotranspiration (640 mm/y), with water surplus of 360mm/y. In the current situation, a direct relationship between the precipitations and thevariations of the phreatic level is observed. The extracted flows are in the range of theregulating reserves and therefore there is not a substantial modification of the naturalwater cycle. It is necessary to increase the drinking water supply to cover the needs of abigger number of inhabitants. The management pattern should include the selection ofnew exploitation areas including a detailed water input and output quantification to thehydrological system. An areal exploitation to scarce depth is also recommended, beingfundamental that the use areas should be declared reservation areas to conserve therecharge areas and to avoid all possible contamination of the groundwater.