Conceptual Hydrogeological Model and Groundwater Resource Estimation in a Complex Hydrothermal Area: The Case of the Viterbo Geothermal Area (Central Italy)

Antonella Baiocchi, Francesca Lotti, Vincenzo Piscopo

Dipartimento di Scienze Ecologiche e Biologiche (DEB), Università degli Studi della Tuscia, Viterbo, Italy.

DOI: 10.4236/jwarp.2012.44026                

Abstract

The conceptual hydrogeological model of the Viterbo thermal area in central Italy and the yield of the groundwater sys- tem have been examined. This area is of great geothermal interest. Through new investigations, three overlapping aquifers have been found. This study examines in detail the two shallower aquifers, characterized by different hydraulic and chemical characteristics. The first aquifer is related to the regional groundwater flow of the Cimino-Vico volcanic system and is generally characterized by cold, fresh waters used for irrigation and drinking water supply. The second aquifer, i.e. the thermal aquifer, supply thermal spas and public pools; it is present where the local hydrostratigraphic, structural and geothermal conditions permit a relatively active flow of higher salinity thermal waters (40?C - 62?C). These two aquifers interact vertically and laterally, giving rise to mixed waters circulating in the first aquifer. The first aquifer is recharged by direct infiltration and inflow from regional groundwater, as well as inflow from the second aquifer. The yield of the thermal aquifer is at least 170 L/s, discharging into thermal springs and wells, besides feeding the shallow aquifer vertically and laterally. Even if a future development of the second aquifer is potentially achievable on a global scale, the exploitation of the thermal waters is strictly dependent on the specific local hydrogeological equilibrium between the overlapping aquifers, different from place to place. The case study highlights that, in the volcanic hydrogeological environment, one of the most stringent constraints in determining the correct usage of a resource is the variable level of interaction of groundwater with different qualities.

Keywords

Volcanic Aquifer; Thermal Waters; Overlapping Aquifers Interaction; Viterbo; Italy

Conflicts of Interest

The authors declare no conflicts of interest.

References

[1]	R. Cataldi, M. Mongelli, P. Squarci, L. Taffi, G. Zito and C. Calore, “Geothermal Ranking of Italian Territory,” Geo- thermics, Vol. 24, No. 1, 1995, pp. 115-129. doi:10.1016/0375-6505(94)00026-9
[2]	G. Bertrand, H. Celle-Jeanton, F. Huneau, S. Loock and C. Renac, “Identification of Different Groundwater Flow- paths within Volcanic Aquifers Using Natural Tracers for the Evaluation of the Influence of Lava Flows Morphol- ogy (Arghat Basin, Cha?ne des Puys, France),” Journal of Hydrology, Vol. 391, No. 3-4, 2010, pp. 223-234. doi:10.1016/j.jhydrol.2010.07.021
[3]	J. V. Cruz and M. O. Silva, “Hydrogeologic Framework of the Pico Island (Azores, Portugal),” Hydrogeology Jour- nal, Vol. 9, No. 2, 2001, pp. 177-189. doi:10.1007/s100400000106
[4]	E. Custodio, “Groundwater Characteristics and Problems in Volcanic Rock Terrains,” In: IAEA, Isotope Tech- niques on the Study of the Hydrology of Fractured and Fissured Rocks, STI/PUB 790, Vienna, 1989, pp. 87-137.
[5]	E. Custodio, “Groundwater in Volcanic Rocks,” In: Krasny, J. and J. M. Sharp, Eds., Groundwater in Fractured Rocks, Taylor and Francis Group, London, 2007
[6]	V. Piscopo, V. Allocca and F. Formica, “Sustainable Ma- nagement of Groundwater in Neapolitan Volcanic Areas, Italy,” In: O. Sililo, et al., Eds., Groundwater: Past Achieve- ments and Future Challenge, Balkema, Rotterdam, 2000.
[7]	V. Piscopo, A. Baiocchi, S. Bicorgna and F. Lotti, “Hy- drogeological Support for Estimation of the Sustainable Well Yield in Volcanic Rocks: Some Examples from Cen- tral and Southern Italy,” Proceedings of 36th IAH Con- gress on Integrating Groundwater Science and Human Well-Ceing, Toyama, 26 October-1 November 2008, pp. 1652-1666.
[8]	P. Ambrosetti, M. G. Carboni, M. A. Conti, A. Costantini, U. Esu Nicosia, G. Parisi and F. Sandrelli, “Evoluzione Paleogeografica e Tettonica dei BAcini Tosco-Umbro Laziali nel Pliocene e Nel Pleistocene Inferiore,” Memo- rie della Società Geologica Italiana, Vol. 19, 1978, pp. 573-580.
[9]	P. Baldi, F. A. Decandia, A. Lazzarotto and A. Calamai, “Studio Geologico del Substrato della Copertura Vulca- nica Laziale Nella Zona dei Laghi di Bolsena, Vico e Bracciano,” Memorie Società Geologica Italiana, Vol. 13, No. 4, 1974, pp. 575-606.
[10]	F. Barberi, G. Buonasorte, R. Cioni, A. Fiordelisi, L. For- esi, S. Iaccarino, M. A. Laurenzi, A. Sbrana, L. Vernia and I. M. Villa, “Plio-Pleistocene Geological Evolution of the Geothermal Area of Tuscany and Latium,” Memorie Descrittive della Carta Geologica d’Italia, Vol. 49, 1994, pp. 77-134.
[11]	G. Marinelli, F. Barberi and R. Cioni, “Sollevamenti Neo- genici e intrusioni acide della Toscana e del Lazio setten- trionale,” Memorie della Società Geologica Italiana, Vol. 49, No. , 1993, pp. 279-288.
[12]	L. Beccaluva, P. Di Girolamo and G. Serri, “Petrogenesis and Tectonic Setting of the Roman Volcanic Province, It- aly,” Lithos, Vol. 26, No. 3-4, 1991, pp. 191-221. doi:10.1016/0024-4937(91)90029-K
[13]	S. Conticelli and A. Peccerillo, “Petrology and Geochem- istry of Potassic and Ultrapotassic Volcanism in Central Italy: Petrogenesis and Inferences on the Evolution of the Mantle Sources,” Lithos, Vol. 28, No. 3-6, 1992, pp. 221- 240. doi:10.1016/0024-4937(92)90008-M
[14]	G. Marinelli, “Magma Evolution in Italy,” In: C. H. Squ- yres, Ed., Geology of Italy, The Earth Science Society of the Lybian Arab Republic, Tripoli, 1975, pp. 165-219.
[15]	A. Peccerillo and P. Manetti, “The Potassium Alkaline Volcanism of Central-Southern Italy: A Review of the Data Relevant to Petrogenesis and Geodynamic Signifi- cance,” Transactions of the Geological Society of South Africa, Vol. 88, No. 2, 1985, pp. 379-384.
[16]	C. Cimarelli and D. de Rita, “Structural Evolution of the Pleistocene Cimini Trachytic Volcanic Complex (Central Italy),” Bulletin of Volcanology, Vol. 68, No. 6, 2006, pp. 538-548. doi:10.1007/s00445-005-0028-3
[17]	D. Lardini and G. Nappi, “I Cicli Eruttivi del Complesso Vulcanico Cimino,” Rendiconti della Società Italiana di Mineralogia e Petrologia, Vol. 42, 1987, pp. 141-153.
[18]	F. Sollevanti, “Geologic, Volcanologic and Tectonic Set- ting of the Vico-Cimino Area, Italy,” Journal of Volca- nology and Geothermal Research, Vol. 17, No. 1-4, 1983, pp. 203-217. doi:10.1016/0377-0273(83)90068-9
[19]	A. Bertagnini and A. Sbrana, “Il Vulcano di Vico: Strati- grafia del Complesso Vulcanico e Sequenze Eruttive Delle Formazioni Piroclastiche,” Memorie della Società Geolologica Italiana, Vol. 35, No. 2, 1986, pp. 699-713.
[20]	G. Nappi, L. Valentini and M. Mattioli, “Ignimbritic De- posits in Central Italy: Pyroclastic Products of the Quaternary Age and Etruscan Footpaths. Field Trip Guide Book—P09,” Proceedings 32nd International Geological Congress, Florence, 20-28 August 2004, p. 32.
[21]	G. Perini, S. Conticelli and L. Francalanci, “Inferences of the Volcanic History of the Vico Volcano, Roman Mag- matic Province, Central Italy: Stratigraphic, Petrographic and Geochemical Data,” Mineralogica et Petrographica Acta, Vol. 15, 1997, pp. 67-93.
[22]	G. Buonasorte, M. G. Carboni and M. A. Conti, “Il Sub- strato Plio-Pleistocenico Delle Vulcaniti Sabatine: Con- siderazioni Stratigrafiche e Paleoambientali,” Bollettino della Società Geologica Italiana, Vol. 110, No. 1, 1991, pp. 35-40.
[23]	R. Funiciello, E. Locardi, G. Lombardi and M. Parotto, “The Main Volcanic Groups of Latium. Relations be- tween Structural Evolution and Petrogenesis,” Geologica Romana, Vol. 15, 1976, pp. 279-300.
[24]	P. La Torre, R. Nannini and F. Sollevanti, “Geothermal Exploration in Central Italy: Geophysical Survey in Cimi- ni Range Area,” European Association of Exploration Geo- physicists: 43th Meeting, Venezia, 26-29 May 1981.
[25]	G. Buonasorte, A. Fiordelisi, E. Pandeli, U. Rossi and F. Sollevanti, “Stratigraphic Correlations and Structural Set- ting of the Pre-Neoautochtonous Sedimentary Sequences of Northern Latium,” Periodico di Mineralogia, Vol. 56, 1987, pp. 111-122.
[26]	A. Calamai, R. Cataldi, E. Locardi and A. Praturlon, “Distribuzione Delle Anomalie Geotermiche Nella Fascia Preappenninica Tosco-Laziale (Italia),” Symposium Inter- national Sobre Energia Geotérmica en America Latina, Ciudad de Guatemala, 16-23 October 1976, pp. 189-229.
[27]	B. Della Vedova, G. Pellis, J. P. Foucher and J. P Rehault, “Geothermal Structure of Tyrrhenian Sea,” Marine Geol- ogy, Vol. 55, No. 3-4, 1984, pp. 271-289. doi:10.1016/0025-3227(84)90072-0
[28]	F. Mongelli, G. Zito, N. Ciaranfi and P. Pieri, “Interpreta- tion of Heat Flow Density of the Apennine Chain, Italy,” Tectonophysics, Vol. 164, No. 2-4, 1989, pp. 267-280. doi:10.1016/0040-1951(89)90020-6
[29]	G. Chiodini, F. Frondini and L. Marini, “Theoretical Geo- thermometers and PCO2 Indicators for Aqueous Solutions Coming from Hydrothermal Systems of Medium-Low Temperature Hosted in Carbonate-Evaporite Rocks. Ap- plication to the Thermal Springs of the Etruscan Swell, Italy,” Applied Geochemistry, Vol. 10, No. 3, 1995, pp. 337-346. doi:10.1016/0883-2927(95)00006-6
[30]	G. Chiodini, F. Frondini and F. Ponziani, “Deep Struc- tures and Carbon Dioxide Degassing in Central Italy,” Geothermics, Vol. 24, No. 1, 1995, pp. 81-94. doi:10.1016/0375-6505(94)00023-6
[31]	V. Duchi and A. Minissale, “Distribuzione Delle Mani- festazioni Gassose Nel Settore Peritirrenico Tosco-Laziale e Loro Interazione con gli Acquiferi Superficiali,” Bollet- tino della Società Geologica Italiana, Vol. 114, No. 2, 1995, pp. 337-351.
[32]	A. Minissale and V. Duchi, “Geothermometry on Fluids Circulating in a Carbonate Reservoir in North-Central It- aly,” Journal of Volcanology and Geothermal Research, Vol. 35, No. 3, 1988, pp. 237-252. doi:10.1016/0377-0273(88)90020-0
[33]	A. Minissale, D. M. Kerrick, G. Magro, M. T. Murell, M. Paladini, S. Rihs, N. C. Sturchio, F. Tassi and O. Vaselli, “Geochemistry of Quaternary Travertines in the Region North of Rome (Italy): Structural, Hydrologic and Paleo- climatic Implications,” Earth and Planetary Science Let- ters, Vol. 203, No. 2, 2002, pp. 709-728. doi:10.1016/S0012-821X(02)00875-0
[34]	A. Baiocchi, W. Dragoni, F. Lotti, G. Luzzi and V. Pis- copo, “Outline of Theology of the Cimino and Vico Area and of the Interaction between Groundwater and Lake Vico (Lazio Region, Central Italy),” Bollettino della So- cietà Geologica Italiana, Vol. 125, No. 2, 2006, pp. 187- 202.
[35]	C. Boni, P. Bono and G. Capelli, “Schema Idrogeologico Dell’Italia Centrale,” Memorie della Società Geologica Italiana, Vol. 35, No. 2, 1986, pp. 991-1012.
[36]	G. Capelli, R. Mazza and C. Gazzetti, “Strumenti e Stra- tegie per la Tutela e l’uso Compatibile Della Risorsa Idri- ca del Lazio: Gli Acquiferi Vulcanici,” Pitagora, Bologna, 2005.
[37]	V. Piscopo, M. Barbieri, V. Monetti, G. Pagano, S. Pis- toni, E. Ruggi and D. Stanzione, “Hydrogeology of Ther- mal Waters In Viterbo Area, Central Italy,” Hydrogeol- ogy Journal, Vol. 14, No. 8, 2006, pp. 1508-1521. doi:10.1007/s10040-006-0090-8
[38]	U. Chiocchini, F. Castaldi, M. Barbieri and V. Eulilli, “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,” Hydrogeology Journal, Vol. 18, No. 6, 2010, pp. 1319-1341. doi:10.1007/s10040-010-0601-5
[39]	P. Baldi, G. C. Ferrara, L. Masselli and G. Pieretti, “Hy- drogeochemistry of the Region between Monte Amiata and Rome,” Geothermics, Vol. 2, No. 3-4, 1973, pp. 124- 141. doi:10.1016/0375-6505(73)90020-5
[40]	M. Angelone, C. Cremisini, V. Piscopo, M. Proposito and F. Spaziani, “Influence of Hydrostratigraphy and Struc- tural Setting on the Arsenic Occurrence in Groundwater of the Cimino-Vico Volcanic Area (Central Italy),” Hy- drogeology Journal, Vol. 17, No. 4, 2009, pp. 901-914. doi:10.1007/s10040-008-0401-3
[41]	G. Capasso and S. Inguaggiato, “A Simple Method for the Determination of Dissolved Gases in Natural Waters. An Application to Thermal Waters from Volcano Island,” Applied Geochemistry, Vol. 13, No. 5, 1998, pp. 631-642. doi:10.1016/S0883-2927(97)00109-1
[42]	S. Epstein and T. Mayeda, “Variation of 18O Content of Water from Natural Sources,” Geochimica et Cosmochi- mica Acta, Vol. 4, No. 5, 1953, pp. 213-224. doi:10.1016/0016-7037(53)90051-9
[43]	F. Yanagisawa and H. Sakai, “Preparation of SO2 for Sulfur Isotope Ratio Measurements by the Thermal De- composition of BaSO4-V2O5-SiO2 Mixtures,” Analytical Chemistry, Vol. 55, No. 6, 1983, pp. 985-987. doi:10.1021/ac00257a046
[44]	M. P. Neary, “Tritium Enrichment—To Enrich or Not to Enrich?” Radioactivity and Radiochemistry, Vol. 8, 1997, pp. 23-35.
[45]	SIMN, “Annali Idrologici,” Servizio Idrografico e Mareo- grafico Nazionale, Ministero dei Lavori Pubblici, Roma, 1951-1999.
[46]	Regione Lazio, “Annali Idrologici,” Ufficio Idrografico e Mereografico Regione Lazio, Roma, 2000-2010.
[47]	G. Allen, S. Pereira, D. Raes and M. Smith, “Crop Evapo- transpiration—Guidelines for Computing Crop Water Re- quirements,” Natural Resources Management and Environment Department, FAO, Rome, 1998.
[48]	C. T. Haan, “Statistical Methods in Hydrology,” The Iowa State University Press, Ames, 1977.
[49]	S. Carnicelli, D. Sagri, U. Chiocchini and S. Madonna, “Geopedologia,” In: U. Chiocchini, Ed., La Geologia Del- la Città di Viterbo, Cangemi Editore, Roma, 2004.
[50]	P. Lorenzoni, M. Raglione, P. Quantin, D. Bidini and L. Lulli, “Studio Dell’Apparato Vulcanico di Vico (Lazio). IV. I Suoli Delle Colate Piroclastiche,” Annali Istituto Sperimentale di Studio e Difesa Suolo Firenze, Vol. 16, 1985, pp. 199-226.
[51]	L. Lulli, C. Blasi, G. Abate, D. Bidini, S. Fascetti, P. Lor- enzoni and M. Marchetti, “Studio Pedologico Dell’Apparato Vulcanico di Vico (Lazio). VIII. L’effetto Della Ve- getazione Sulla Genesi dei Suoli,” Annali Istituto Speri- mentale di Studio e Difesa Suolo Firenze, Vol. 17, 1986, pp. 159-172.
[52]	Regione Lazio, “Carta di Uso del Suolo,” Direzione Re- gionale Territorio e Urbanistica, Regione Lazio, Roma, 2003.
[53]	B. Conforto, “Risultati Della Prima Fase di Ricerche di Forze Endogene nel Viterbese,” L’Ingegnere, Vol. 27, 1954, pp. 345-350.
[54]	B. Conforto, “Risultati Della Prima Fase di Ricerche di Forze Endogene nel Viterbese,” L’Ingegnere, Vol. 27, 1954, pp. 521-530.
[55]	P. P. Mattias and V. Ventriglia, “La Regione Vulcanica dei Monti Cimini e Sabatini,” Memorie della Società Geolologica Italiana, Vol. 9, No. 3, 1970, pp. 331-384.
[56]	B. Toro, “Anomalie Residue di Gravità e Strutture Profonde Nelle Aree Vulcaniche del Lazio Settentrionale,” Geologica Romana, Vol. 17, 1978, pp. 35-44.
[57]	B. Camponeschi and F. Nolasco, “Le Risorse Naturali Della Regione Lazio. 2 Monti Cimini e Tuscia Romana,” Regione Lazio, Roma, 1984.
[58]	G. Buonasorte, R. Cataldi, A. Ceccarelli, A. Costantini, S. D’Offizi, A. Lazzarotto, A., Ridolfi, P. Baldi, A. Borelli, G. Bertini, R. Bertrami, A. Calamai, G. Cameli, R. Corsi, C. D’Acquino, A. Fiordelisi, A. Grezzo and F. Lovari, “Ricerca ed Esplorazione Nell’Area Geotermica di Torre Alfina (Lazio—Umbria),” Bollettino della Società Geologica Italiana, Vol. 107, No. 2, 1988, pp. 265-337.
[59]	G. Buonasorte, E. Pandeli and A. Fiordelisi, “The Alfina 15 Well: Deep Geological Data from Northern Latium (Torre Alfina Geothermal Area),” Bollettino della Società Geologica Italiana, Vol. 110, No. 3-4, 1991, pp. 823-831.
[60]	R. Cataldi and M. Rendina, “Recent Discovery of a New Geothermal Field: Alfina,” Geothermics, Vol. 2, No. 3-4, 1973, pp. 106-116. doi:10.1016/0375-6505(73)90016-3
[61]	G. Cavarretta, G. Giannelli, G. Scandiffio and F. Tecce, “Evolution of the Latera Geothermal System II: Meta- morphic Hydrothermal Mineral Assemblages and Fluid Chemistry,” Journal of Volcanology and Geothermal Re- search, Vol. 26, No. 3-4, 1985, pp. 337-364. doi:10.1016/0377-0273(85)90063-0
[62]	V. Duchi, L. Matassoni, F. Tassi and B. Nisi, “Studio Geochimico dei Fluidi (Acque e Gas) Circolanti Nella Regione Vulcanica dei M.ti Vulsini (Italia Centrale),” Bollettino della Società Geologica Italiana, Vol. 122, No. 1, 2003, pp. 47-61.
[63]	G. Giannelli and G. Scandiffio, “The Latera Geothermal System (Italy): Chemical Composition of the Geothermal Fluid and Hypotheses on Its Origin,” Geothermics, Vol. 18, No. 3, 1989, pp. 447-463. doi:10.1016/0375-6505(89)90068-0
[64]	G. F. Pinder and J. F. Jones, “Determination of the Ground- water Component of Peak Discharge from Chemistry of Total Runoff,” Water Resources Research, Vol. 5, No. 2, 1969, pp. 438-445. doi:10.1029/WR005i002p00438
[65]	H. Craig, “Isotopic Variations in Meteoric Water,” Sci- ence, Vol. 133, No. 3465, 1961, pp. 1702-1703. doi:10.1126/science.133.3465.1702
[66]	A. Longinelli and E. Selmo, “Isotopic Composition of Precipitation in Italy: A First Overall Map,” Journal of Hydrology, Vol. 270, No. 1-2, 2003, pp. 75-88.
[67]	I. D. Clark and P. Fritz, “Environmental Isotopes in Hy- drogeology,” Lewis Publishers, New York, 1997.
[68]	C. W. Thornthwaite, “An Approach toward a Rational Classification of Climate,” Geographical Review, Vol. 38, No. 1, 1948, pp. 55-94. doi:10.2307/210739
[69]	C. W. Thornthwaite and J. R. Mather, “The Water Bal- ance,” Publication in Climatology, Vol. 8, No. 1, 1955.