The upwelling groundwater flux has been investigated by deep piezometers in a spring area characterized by alluvial deposits covering a karst substratum in Southern Italy. The piezometers are of varying depth located in a flat area. They have been monitored for a long period (about 40 years), and when measured, a good relationship between spring discharge and hydraulic head was observed. The local upwelling groundwater flux has been deducted by the increasing of the hydraulic head in depth, which allows the estimation of ascendant hydraulic gradient and groundwater velocity during the dry and wet seasons. A specific analytical solution has been used to estimate the zone involved by the ascendant flow, and could also be used in other spring areas. Some physical and chemical characteristics of spring water have been collected, including the radon (222 Rn) activity, to support the phenomenon of the ascendant flux. The man geological and hydrogeological features leading to ascendant flux in karst environments is also discussed for some areas of Southern Italy, where many springs are affected.

The hydraulic phenomenon of upwelling groundwater flow affecting the karst area of the Grassano-Telese springs (southern Italy) has been investigated through piezometric measurements, discharge, and chemical–physical monitoring of springs, radon activity included. Locally, both large karst springs and sulfurous thermal springs are closely located, and raise several questions on their origin. In this study, the phenomenon of the upwelling flow is supported by different types of evidences: Amazing density of sinkholes connected to hypogenic speleogenesis processes, constancy of temperature, and hydraulic conductivity of spring water, change of radon activity during the hydrological year, increasing of the hydraulic head with depth. Numerical code provides an estimation of the upwelling phenomenon in an unconfined aquifer feeding the karst springs, using MODFLOW tools. Based on the results reached, the phenomenon of the upwelling flow is able to explain the hydrological processes observed in the Telese karst area.

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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.

The hydraulic phenomenon of upwelling, affecting several karst springs of Apennines, has been investigated through piezometric data at different depth and chemical-physical data of springs water. Three different springs in Campania region were analyzed (Serino, Grassano and Caposele springs), characterized by three different groundwater schemes, but with the same upwelling phenomena at the springs. Some data (spring discharge and piezometric levels) have been acquired from the municipal waterwork,. Other data (physical-chemical parameters and Radon values (222Rn)) have been collected ad hoc in spring waters, included the spring discharges of Grassano springs. All the data pointed out that karst springs considered are fed by groundwater flux that locally is vertical. This features, common to others springs of Apennines, can be relevant in the realization of the tapping work, in their maintenance and for the definition of the protection area of the springs.