Monitoraggio e misure di velocità in un acquifero carsico costiero (Bari, Italia meridionale)

The study area is located in the Murgia plateau which constitutes a large and deep coastal karstic aquifer (of Mesozoic age); the predominant rock material of which is either limestone or limestonedolomite. The aquifer is affected by karst and fracturing phenomena, also well below the sea level, whereas intruded seawater underlies fresh groundwater owing to a difference in density. The groundwater flow is confined except on a restricted coastline strip. 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 the coastal area. The fluctuations of the transition zone, in the absence of human influences, are closely related to alternating periods of recharge and depletion of the aquifer, though a certain unbalance is likely to occur between recharge due to rainfall infiltration and the discharge due tapping by wells. To contribute to the study of these phenomena on the basis of affordable and long-lasting data, a surveying station was realised in a well bored for this purpose in the urban area of Bari. The monitoring started in 2004; collecting data on piezometric level, water temperature. Multi-parameter logs are executed every six month along the well, using probes equipped with sensors of temperature, specific electrical conductivity, pH, dissolved oxygen and Eh. The detailed characterisation of vertical flow variability has been realised with tracer tests realised in the well. The sampling of groundwater and the analysis of laboratory complete the carried out activity. The time series and whole data are anyalised highlighting the peculiarities of the selected karstic aquifer.