Impact of climate change on the water balance of the Apuo-Versilia plain acquifer (Tuscany, Italy)

The authors drafted the water balance of the multi-layer aquifer of the Apuo-Versilia Plain, (Provinces of Lucca and Massa- Carrara) extending for about 152 km2. The water budget, relating to the average year of the period 2010-2012, includes both natural and anthropic terms. Availability of data allowed to calculate with a good approximation some terms (rain water infiltration, groundwater pumping, losses of aqueduct pipelines and sewers) while others (infiltration from water courses, draining of land reclamation systems) have been calculated with methods designed ad hoc but with poor validation. The budget closes with a positive balance of 56 million m3/year, which correspond to the outflow from the aquifer to the sea minus the marine intrusion: there is no data to calculate this term, which we have taken as the unknown term of the balance equation. Therefore, the budget is rough, but it allowed us to estimate the effects of climate change for two decades in the near future (2030-2040 and 2050-2060) according to two emission scenarios, RCP4.5 and RCP8.5: the recharge would be reduced 11% in 2036 and 15% in 2056. In these budgets, we have not considered the variations in anthropic terms because we have no elements to predict them. Climate change, which also will bring about an increasing of marine intrusion, will probably cause a greater use of groundwater. This could alter the balance of the hydrogeological system, which has so far shown a substantial stability, as demonstrated by the monitoring of piezometric levels in the Plain.