Hydrogeological and geochemical characterisation of the Rock of Orvieto

The town of Orvieto, located on the Rock of the same name, is an example of ''vulnerable town''; problems of slope instability connected with the lithological and morphological characteristics of the Rock have been thor- oughly examined and discussed during previous research studies. Hydrogeochemical data about groundwater recharging the springs present in the area were never taken into account. Pollution of the springs is well known but still occurs for unclear reasons. The aim of this work is there- fore to present the results of a hydrogeological and geo- chemical investigation of all the springs along the slopes of Orvieto hill and at the foot of the tuffaceous Rock, to characterize the groundwater flow paths and to suggest a possible source of contamination. The research study was carried out during three hydrogeochemical surveys in the years 1998-1999, 2003-2004, and 2007-2008.