Climate changes and water resource planning: WIZ, an operational tool

The institutional activity of the Arno River Basin Authority is focused on two strategical planning processes: the River Basin Management Plan, according to 2000/60/CE European Direcitve, and the Flood Management Plan, according to 2007/60/CE European Directive. Both plans contain most of the contents of Arno River Basin Plan, developed after the italian law L. 183/89, and are tackling with a global approach the management of extreme flood events and water budget problems. In this context, the evaluation of climate change impact on the water cycle is extremely relevant. Therefore the Arno River Basin Authority is engaged to analyze the impact of climate changes on water status, regarding as main reference the IPCC AR4 report e their connected forecasting scenarios. The involvement in a LIFE+ project (WIZ – WaterIZe Spatial Planning) is the framework for a sample of preliminary evaluations, with the aim to include in the next updated edition of River Basin Management Plan new adapting measures (more than mitigation actions), in order to fight the negative impact of climate change on the possibility to achieve the Water Framework Directive’s quality objectives. Focusing the attention on the Lower Arno valley (Valdarno Inferiore) and taking into account as simplifying hypothesis a linear correlation between groundwater recharge and total rainfall fluctuations, the effects of actual and projected climate changes are evaluated. For each water abstraction area, the potential variation of available groundwater for antropic use (in cubic meter per year) is estimated, showing a decreasing trend ranging, with a high spatial variability, in a 5-10% interval. Due the increase of water demand and the distribution network losses, even such a percentage of decreasing potential recharge should be carefully evaluated; without water savings measures and investments on the renovation of distribution networks, an increase of the typical summer water scarcity crisis is high probable.