Southern Italy

D. DUCCI1 & G. TRANFAGLIA2

1 Department of Geotechnical Engineering - "Federico II" University, Piazzale Tecchio, 80-80125 Naples, Italy (e-mail: [email protected])

2Department of Inland and Marine Waters Protection - National Agency for Environmental Protection - APAT, Via Curtatone, 3-00185 Rome, Italy

Abstract: In order to estimate the influence of global climate change upon the hydrological regime, variations in the water budget prompted by precipitation and temperature changes were evaluated in the region of Campania (southern Italy). In many parts of the region, precipitation distribution in the last 20 years shows a marked reduction. During the same period, Campania also experienced a regional temperature increase of about 0.3°C. Water budgets, calculated in a geographical information system environment for the region's hydrogeological structures, show a mean decrease of 30% of average infiltration within the present climate scenario. The structures most affected are carbonate aquifers, with the flow of springs being significantly reduced (about 70 m3/s). The most severely affected zones are the mountainous areas in the southern and northern parts of Campania.

Direct human-induced effects on the use of groundwater resources consist in the depletion of the groundwater table and the reduction in spring discharge, while indirect effects lie in contamination and in the reduction of surface water flow. A further effect on aquifer recharge and hence water levels in aquifers and springs is brought about by climate change. Indeed, climate change impacts on groundwater have been identified as a critical problem for groundwater managers. All in all, groundwater resource management in western Europe has to cope with increasing human pressure, hence increasing water demand, and, in almost all regions, a decrease in groundwater resources due to climate change.

In 2004 groundwater resources accounted for 86.4% of Italy's drinking water requirements and as much as 99.7% of such requirements in Campania. Groundwater management thus has to take due account of groundwater budgets and their possible changes so as to achieve a sustainable equilibrium between annual recharge and extraction.

At present, academics are widely involved in the task of ensuring the sustainable use of ground-water resources. For example the 2004 UNESCOGRAPHIC project (Groundwater Resources Assessment under the Pressures of Humanity and Climate Change) deals with groundwater resources assessment and forecasting under the various pressures of human activities and climate changes.

Evaluation of the changes in groundwater recharge rates requires determination of a ground-water budget to establish the role of each climatic variable (P and T) in groundwater recharge. In fact, the basic groundwater balance equation -applicable when there are no interactions with other aquifers or surface waters (rivers, lakes, seas, etc.) and in the absence of exploitation and artificial recharge - generally defines groundwater recharge as the difference between precipitation and the sum of evapotranspiration and surface runoff. If the climate gauge network is dense, it is possible, working in a geographical information system (GIS) environment, to evaluate the effect of each climatic variable on recharge in space. Moreover, if the climate data series are long, the influence of each climatic variable on the recharge in time may be estimated. Both such evaluations have been performed in this paper to estimate in a simple fashion the role in recharge of decreased precipitation and of increased evapotranspiration due to warmer temperatures, and to highlight the negative balance between recharge and discharge in Campania, as testified by the recorded decrease in groundwater levels and spring discharge.

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