Hydrogeological numerical modeling of the southeastern portion of the Lucca Plain (Tuscany, Italy), stressed by groundwater exploitation

In the hydrogeological field, the numerical modeling is well known as a powerful tool to set up a management strategy that can prevent groundwater mining. To overcome its somehow “exoteric fame”, it needs as many as possible of local field tests in order to become real world common practice in groundwater management. The Lucca Plain aquifer shows a severe piezometric drop associated to an unregulated competition between agriculture, industry, public and private drinking water wells. It was chosen to test a finite difference numerical model capability as a crisis analysis and forecasting tool and as a regulatory action technical support benchmark. The southern Lucca Plain geological and hydrogeological conceptual model was translated into a MODFLOW grid. Public and private pumping wells were monthly surveyed from January 2007 to October 2008. Calibration allowed the numerical model to achieve a good statistical correspondence with reality. The resulting virtual reality highlighted the heavy hydrogeological stress affecting the area, where pumping rate significantly exceeds the recharge in the studied period. The sensibility analysis highlighted rainfall recharge and pumping rate as the more sensitive values among the input data. Since the calibration process implied a remarkable increase of the officially declared pumping rate, numerical modeling, when a lot of calibration data are available, showed promising capability of back-analysis to estimate the real pumping rate for a given area