Natural Hazards and Earth System Science www.nat-hazards-earth-syst-sci.net 1561-8633 1684-9981 10 1 2010 10.5194/nhess-10-61-2010 http://www.nat-hazards-earth-syst-sci.net/10/61/2010/ http://www.nat-hazards-earth-syst-sci.net/10/61/2010/nhess-10-61-2010.html http://www.nat-hazards-earth-syst-sci.net/10/61/2010/nhess-10-61-2010.pdf 61 72 2010-01-14 Vulnerability assessment of Central-East Sardinia (Italy) to extreme rainfall events A. Bodini antonella.bodini@mi.imati.cnr.it Q. A. Cossu Institute of Applied Mathematics and Information Technology, Milan, Italy Sardinian Environmental Protection Agency, Sassari, Italy In Sardinia (Italy), the highest frequency of extreme events is recorded in the Central-East area (3–4 events per year). The presence of high and steep mountains near the sea on the central and south-eastern coast, causes an East-West precipitation gradient in autumn especially, due to hot and moist currents coming from Africa. Soil structure and utilization make this area highly vulnerable to flash flooding and landslides. The specific purpose of this work is to provide a description of the heavy rainfall phenomenon on a statistical basis. The analysis mainly focuses on i) the existence of trends in heavy rainfall and ii) the characterization of the distribution of extreme events. First, to study possible trends in extreme events a few indices have been analyzed by the linear regression test. The analysis has been carried out at annual and seasonal scales. Then, extreme values analysis has been carried out by fitting a Generalized Pareto Distribution (GPD) to the data. As far as trends are concerned, different results are obtained at the two temporal scales: significant trends are obtained at the seasonal scale which are masked at the annual scale. By combining trend analysis and GPD analysis, the vulnerability of the study area to the occurrence of heavy rainfall has been characterized. Therefore, this work might support the improvement of land use planning and the application of suitable prevention systems. Future work will consider the extension of the analysis to all Sardinia and the application of statistical methods taking into account the spatial correlation of extreme events. Alpert, P., Ben-Gai, T., Baharad, A., Benjamini, Y., Yekutieli, D., Colacino, M., Diodato, L., Ramis, C., Homar, V., Romero, R., Michaelides, S., and Manes, A.: The paradoxical increase of Mediterranean extreme daily rainfall in spite of decrease in total values, Geophys. Res. Lett., 29, 1536, doi:10.1029/2001GL013554, 2002. Antonioli, F., Silenzi, S., Gabellini, M,. and Mucedda, M.: High resolution climate trend over the last 1000 years from a stalagmite in Sardinia (Italy), Quaternaria Nova, 7, 54–69, 2003. Betrò, B., Bodini, A., and Cossu, Q. A.: Using a hidden Markov model to analyze extreme rainfall events in Central-East Sardinia, Environmetrics, 19, 702–713, 2008. Bodini, A. and Cossu, Q. A.: Analisi della piovosità in Ogliastra (Sardegna, Italia) nel periodo 1951–1999, Milan, CNR-IMATI Technical Report, 08-04, available at: http://www.mi.imati.cnr.it/iami/abstracts/08-04.html, 2008 (in Italian). Brunetti, M., Colacino, M., Maugeri, M., and Nanni, T.: Trends in the daily intensity of precipitation in Italy from 1951 to 1996, Int. J. Climatol., 21, 299–316, 2001. Brunetti, M., Maugeri, M., Monti, F., and Nanni, T.: Changes in daily precipitation frequency and distribution in Italy over the last 120 years, J. Geophys. Res., 109, D05102, doi:10.1029/2003JD004296, 2004. Chessa, P. A., Cesari, D., and Delitala, A. M. S.: Mesoscale regimes of precipitation and temperature over Sardinia (Italy) and the related synoptic-scale circulations, Theor. Appl. Climatol., 63, 195–221, 1999. Cislaghi, M., De Michele, C., Ghezzi, A., and Rosso, R.: Statistical assessment of trends and oscillations in rainfall dynamics: analysis of long daily Italian series, Atmos. Res., 77, 188–202, 2005. Coles, S. G.: Regional modelling of extreme storms via max-stable processes, J. Roy. Stat. Soc B Met., 55, 797–816, 1993. Coles, S.: An Introduction to Statistical Modelling of Extreme Values, Springer Verlag, London, 2001. Cossu, Q. A., De Waele, J., and Di Gregorio, F.: Coastal Karst geomorphosites at risk? A case study: the floods of 6–11 December 2004 in central-east Sardinia, in: Natural and Anthropogenic Hazards in Karst Areas: Recognition, Analysis and Mitigation. Geological Society, edited by: Parise, M. and Gunn, J., London, Special Publications, 279, 85–95, doi:10.1144/SP279.8~0305-8719/07/, 2007. Cossu, Q. A., Bodini, A., and Canu, S.: Vulnerabilità della regione Sardegna agli eventi estremi di precipitazione, in: Atti del "12mo Convegno nazionale di Agrometeorologia", Sassari, 15–17 June 2009a (in Italian). Cossu, Q. A., De Waele, J., Bodini, A., Sanna, L., and Cabras, S.: Peak discharge evaluation off ive exceptional flash floods of 2004–2008 in Central-East Sardinia karst areas and their geomorfological effectiveness (Italy), EGU General Assembly, Vienna, Austria, EGU2009-4066, 19–24 April 2009b. De Waele, J.: Interaction between a dam site and karst springs: The case of Supramonte (Central-East Sardinia, Italy), Eng. Geol., 99, 128–137 doi:10.1016/j.enggeo.2007.11.010, 2008. Delitala, A. M. S., Cesari, D., Chessa, P. A., and Ward, M. N.: Precipitation over Sardinia (Italy) during the 1946-1993 rainy seasons and associated large-scale climate variations, Int. J. Climatol., 20, 519–541, 2000. Duce, P., Cesaraccio, C., Canu, S., Motroni, A., Dettori, M., Cocco, T., Antolini, G., and Zinoni, F.: Individuazione delle aree agricole e delle colture a forte rischio per variazioni climatiche, in: Risultati Conclusivi del Progetto finalizzato di ricerca "Climagri – Cambiamenti climatici e agricoltura", Collana Climagri n 51, CRA-UCEA, Roma, 79–91, ottobre 2006 (in Italian). Frich, P., Alexander, L. V., Della-Marta, P., Gleason, B., Haylock, M., Klein Tank, A., and Peterson, T.: Global changes in climatic extremes during the 2nd half of the 20th century, Clim. Res., 19, 193–212, 2002. Gilleland, E. and Katz, R. W.: Tutorial for The Extremes Toolkit: Weather and Climate: Applications of Extreme Value Statistics, available at: http://www.assessment.ucar.edu/toolkit/(last access: 29 September 2009), 2005. Haylock, M. and Nicholls, N.: Trends in extreme rainfall indices for an updated high quality data set for Australia, 1910–1998, Int. J. Climatol., 20, 1533–1541, 2000. Klein Tank, A. M. G. and Können, G. P.: Trends in indices of daily temperature and precipitation extremes in Europe, 1946–99, J. Climate, 16, 3665–3680, 2003. Kostopoulou, E. and Jones, P. D.: Assessment of climate extremes in the eastern Mediterranean, Meteorol. Atmos. Phys., 89, 69–85, 2005. Koutsoyiannis, D.: Statistics of extremes and estimation of extreme rainfall, 1, Theoretical investigation, Hydrolog. Sci. J., 49, 575–590, 2004a. Koutsoyiannis, D.: Statistics of extremes and estimation of extreme rainfall, 2, Empirical investigation of long rainfall records, Hydrolog. Sci. J., 49, 591–610, 2004b. Leadbetter, M. R.: On extreme values in stationary sequences, Z. Wahrscheinlichkei., 28, 289–303, 1974. Ludi, E.: Climate change, water and food security. Overseas Development Institute Background Note, ODI, London, March 2009 Miller, K. and Yates, D.: Climate Change and Water Resources: A Primer for Municipal Water Providers, AWWA Research Foundation, Denver, 2005. Montagna, P., McCulloch, M., Mazzoli, C., and Silenzi, S.: B/Ca, Sr/Ca,U/Ca and Mg/Ca ratios of a non-tropical coral (Cladocora caespitosa) from the Northern Adriatic Sea (Mediterranean Sea) and their relationship to sea surface temperature, 10th International Coral Reef Symposium, Okinawa, Japan, Abstract book, 269~pp., 28~June–2~July 2004. Motroni, A. and Canu, S.: Climate indicators for assessing sensitive areas to drought and desertification in Sardinia (Italy), Proceedings of WMO/FAO/Cost Action Workshop on "Climatic analysis and mapping for agriculture", 2005. Norrant, C. and Douguédroit, A.: Monthly and daily precipitation trends in the Mediterranean (1950–2000), Theor. Appl. Climatol., 83, 89–106, 2006. Osborn, T. J. and Hulme, M.: Evidence for trends in heavy rainfall events over the UK, Philos. T. R. Soc A, 360, 1313–1325, 2002. Padoan, S., Ribatet, M., and Sisson, S. A.: Likelihood-based inference for max-stable processes, JASA, Theory and Methods, in press, 2010. Peterson, T. C., Folland, C., Gruza, G., Hogg, W., Mokssit, A., and Plummer, N.: Report on the activities pf the Working Group on Climate Change Detection and Related Rapporteurs 1998–2001, World Meteorological Organization, Geneva, Switzerland, Report WCDMP-47, WMO-TD 1071, 2001. Vörösmarty, C. J., Green, P., Salisbury, J., and Lammers, R. B.: Global Water Resources: Vulnerability from Climate Change and Population Growth, Science, 289(5477), 284–288, 2000. Walther, G. R., Post, E., Convey, P., Menzel, A., Parmesan, C., Beebee, T. J. C., Fromentin, J. M., Hoegh-Guldberg, O., and Bairlein, F.: Ecological responses to recent climate change, Nature, 416, 389–395, 2002.