Impact of rising piezometric levels on Greater Buenos Aires due to partial changing of water services infrastructure

The intensive exploitation, since the beginning of the century, of a semiconfined aquifer in Buenos Aires City (Argentina) and its surrounding areas has caused large drawdown cones by the coalescence of smaller ones.The population of the area is about 11 million inhabitants.The climate is subhumid-humid with a mean annual rainfall of 1050 mm/year and a surplus of 270 mm/year. Some of the effects caused by the intensive exploitation have been saline intrusion and leakage from the phreatic aquifer through the aquitard, which caused a fall of the water table. As a consequence of the demand increase and closing of production wells due to salinization and nitrate content, treated water from the la Plata River began to be imported. The recovery of piezometric levels has caused the phreatic level to rise, with a serious impact on the urban infrastructure, established some decades ago. Based on successive flow - nets, on the system parameters T,S;K, K',T' and on the value of imported yields, a monitoring system with forecast capacity is proposed, as well as an operative model for phenomena control, using alternative pumping on both aquifers. Se analiza el origen y efectos de la recuperación de niveles freáticos, como consecuencia del ascenso de los niveles piezométricos en sectores del Gran Buenos Aires y La Plata. Se proponen alternativas de corrección y la implementación de un modelo matemático del fenómeno con capacidad de pronóstico. Facultad de Ciencias Naturales y Museo