Hydrogeology of the Karst Area of the Grassano and Telese Springs

Abstract

This work deals with the hydraulic phenomenon of the ascendant groundwater flow affecting the karst area of the Grassano and Telese springs (Campania, Southern Italy). It has been investigated through piezometric measurements, discharge and chemical-physical monitoring of springs and measurements of the radon 222Rn activity. The presence of ascendant flows is supported by numerous and different types of evidences in the area: location and topographical position of the springs; amazing density of sinkholes connected to geomorphic processes that develop below the topographic surface and involve the rising of CO2 and H2S rich waters; constancy of the temperature and the electrical conductivity of the spring waters over the time; fluctuation of the radon activity during the hydrological year; increasing of the hydraulic head with depth; presence of artesian conditions in the alluvial plain. Numerical simulations of the groundwater flow also support the general phenomenon of the ascendant flow in the discharge area and represent a useful background to interpret hydrological phenomena in the study area. The results of the simulations are suitable with all the hydrogeological processes observed in the area of the Grassano and Telese springs; this last is thought to belong to the regional groundwater flow system of the Matese massif and represents its discharge zone.

Keywords

• karst springs; ascendant groundwater flow, sinkholes; H2S and CO2; groundwater modelling