Conjunctive Use of Surface and Groundwater in a Problem of Environmental Protection: A Case in Salento Peninsula in Southern Italy

Abstract

The Ionic area of Apulia, in Southern Italy, has a very peculiar surface hydrology. The average annual rainfall is merely 500 mm, which gives rise to very little runoff. Groundwater resources are extensive and are favoured by natural recharge through the fractured soil. The groundwater system consists of a lens-shaped freshwater layer floating on top of intruded sea water. A multifaceted economic development plan has been formulated for this area by local and national authorities. However, the problems of environmental protection are related to the construction and operation of urban and industrial wastewater treatment plants. Extracted groundwater is mixed with brackish water from a coastal spring that has a flow of about 2 m3/s and with diversion of 2.4 m3/s from a large aqueduct system, starting from a reservoir more than 200 km away. This quantity of water is requested for irrigating an area on the order of 20,500 hectares. For this system an ‘incident’ is any situation in which a discharge of contaminated water, either onto the topsoil or below ground, is characterized by quality parameters that exceed acceptable limits. A secondary set of incidents can be defined if there is not enough water available to meet the demand for the most common uses. The situation in which the farmers have no water for irrigation is particularly serious, especially when the level of the water table is lowered or the piezometric surface of the saline water has risen.