The rapid socio-economic growth which has occurred in the past decades has continued to stress conditions in the Apulian hydrogeological system in Southern Italy, thereby leading to different hazardous conditions. Groundwater for domestic, irrigation and industrial use has been withdrawn in large quantities over the years so that the aquifers are increasingly becoming the ultimate "receptacle" for domestic and industrial wastewater. Apulia is affected by two major types of human-related pollution_ salt contamination which is spreading over large portions of land thus reducing the availability of good quality water; and chemico-physical and biological pollution which is mainly confined to urban areas. Recently, urban contamination has aroused great interest following the continuous and senseless use of the subsoil for wastewater collection. This is especially relevant to the health, environmental and economic emergency that hit the area in 1994 (cholera epidemic). In Apulia there are four hydrogeological units. Apart from Puglia Tableland (Tavoliere), the remaining hydrogeological units share some common features. They consist of large and deep Mesozoic carbonate aquifers, the predominant rock material of which is either limestone or limestone-dolomite. Aquifers are affected by karst and fracturing phenomena well below the sea level whereas intruded seawater underlies fresh groundwater owing to a difference in density. In both the Gargano Promontory (Gargano) and the low Murge Plateau (Murgia) aquifers are under pressure except on a restricted coastline strip. In the Salentine Peninsula (Salento), subsurface water flow under phreatic conditions is prevailing. The Salentine hydrogeological unit is the only unit, which is lapped by the sea on both sides. Puglia Tableland hydrogeological unit consists of a large porous aquifer less than some ten meters deep with a clayey impermeable bottom. Only in the vicinity of the coast the aquifer is deep enough to allow seawater intrusion. The Tableland unit is the only unit where surface water resources are found flowing into quite large water streams. Salt contamination of the Apulian groundwater - which flows within Mesozoic limestones and overlies intruded seawater - is a well long known and thoroughly investigated phenomenon (Cotecchia 1977). Nowadays, a strong connection between the increase in salt contamination and the lowering of piezometric levels, which can be ascribed to groundwater overdraft and/or a natural decrease in groundwater recharge, has been recognised in coastal aquifers. The evolution of salt-induced pollution and the gradual shortage of fresh groundwater are largely the result of subsurface water mismanagement. Despite the massive import of water, the Apulian groundwater supply hardly meets 20% of the local demand for drinking water. Furthermore, groundwater is often the only resource available for diffuse water-demanding production processes in the area. The special severity of the situation calls for a rigorous approach based on available scientific knowledge and supplemented by up-to-date investigations of the evolution of groundwater quality. Hence, continuous and systematic monitoring is of paramount importance to ensure a sustainable use of this resource. The collection of chronological and geo-information data, gathered by a monitoring network, will allow the investigation of the phenomena in progress and the safe management of this natural resource. This is the reason why awareness of the behaviour of subsurface water bodies should be fostered. In order to characterize the evolutionary features of increasing saline and human-related pollution, data was gathered by a regionally based continuously operating hydrogeological surveying network. It uses more than 100 wells, some of which are hundreds of meters deep, equipped with multiparameter sensors, connected to a geo-information system. Periodical water samples are taken from the wells, the samples are analysed by chemical, physical and bacteriological parameters with the aim of detecting any farming and industrial pollutants. The effects of human activity on groundwater pollution and depletion are described in this paper, together with indirect effects connected with continental seawater intrusion.

The study area is located in Southern Italy, southeast of Naples (Figure 1). The phenomena of slope instability and floods have long been a constant feature in this portion of the Apennines, with earthquakes and meteoric events accounting for the main triggering factors. Landslides have often resulted in dreadful economic and human losses. A magnitude-6.8 earthquake that triggered many large landslides hit the study area on November 23, 1980. A number of geological, geomorphological, hydrological and geotechnical features of the study area are examined in detail in the final technical report of an EEC research project (EEC 1996). This paper examines the space distribution of rainfall and temperature accounting for the distribution of landslides before the earthquake on 23 November 1980 and the changes occurred afterwards. The major climatic elements, namely monthly precipitation and temperature, are analysed with geostatistic methods and discussed. The space variability is compared to the landslide proneness distribution within the area.