Comment on 'A stratigraphic and geophysical approach to studying the deep-circulating groundwater and thermal springs, and their recharge areas, in Cimini Mountains-Viterbo area, central Italy': paper published in Hydrogeology Journal (2010) 18:1319-1341, by Ugo Chiocchini, Fabio Castaldi, Maurizio Barbieri, Valeria Eulilli

In this article, the author comments on the study by Ugo Chiocchini and colleagues on hydrogeological model of the hydrothermal in Viterbo, Italy. The author says that the findings were concerned on the recharge and the negative trend in the discharge of the thermal waters. He mentions the reasons why the authors' conclusion are questionable, such as the hydrochemical difference of the thermal waters from the River Nera springs and the River Nera springs' lower elevation than the thermal springs. Analyses of hydrogen and oxygen isotopes and isotopic ratios are also discussed.