A conceptual and numerical model for groundwater management: a case study on a coastal aquifer in southern Tuscany, ItalyUn modèle conceptuel et numérique pour la gestion de l’eau souterraine: une étude de cas sur un aquifère côtier en Italie méridionale, ItalieUn modelo conceptual y numérico para la gestión de aguas subterráneas: un caso de estudio en el acuífero costero del sur de Toscana, Italia地下水管理概念模型与数值模型——以意大利托斯卡纳南部沿海含水层为例Um modelo conceptual e numérico para a gestão de águas subterrâneas: caso de estudo de um aquífero costeiro no sul de Toscana, Itália

Ongoing hydrogeological research aims to develop a correct management model for the Plio-Pleistocene multi-aquifer system of the Albegna River coastal plain (southern Tuscany, Italy); overexploitation of this aquifer for irrigation and tourism has caused seawater intrusion. The conceptual model is based on field and laboratory data collected during the 1995–2003 period. Meteoric infiltration and flows from the adjoining carbonate aquifer recharge the aquifer. Natural outflow occurs through a diffuse flow into the sea and river; artificial outflow occurs through intensive extraction of groundwater from wells. Water exchanges in the aquifer occur naturally (leakage, closing of aquitard) and artificially (multiscreened wells). The aquifer was represented by a three-dimensional finite element model using the FEFLOW numerical code. The model was calibrated for steady-state and transient conditions by matching computed and measured piezometric levels (February 1995–February 1996). The model helped establish that seawater intrusion is essentially due to withdrawals near the coast during the irrigation season and that it occurs above all in the Osa-Albegna sector, as well as along the river that at times feeds the aquifer. The effects of hypothetical aquifer exploitation were assessed in terms of water budget and hydraulic head evolution.