title: Impacts of climate change on precipitation and discharge extremes through the use of statistical downscaling approaches in a Mediterranean basin.
abstract: Mediterranean region is characterized by high precipitation variability often enhanced by orography, with strong seasonality and large inter-annual fluctuations, and by high heterogeneity of terrain and land surface properties. As a consequence, catchments in this area are often prone to the occurrence of hydrometeorological extremes, including storms, floods and flash-floods. A number of climate studies focused in the Mediterranean region predict that extreme events will occur with higher intensity and frequency, thus requiring further analyses to assess their effect at the land surface, particularly in small- and medium-sized watersheds. In this study, climate and hydrologic simulations produced within the Climate Induced Changes on the Hydrology of Mediterranean Basins (CLIMB) EU FP7 research project were used to analyze how precipitation extremes propagate into discharge extremes in the Rio Mannu basin (472.5km(2)), located in Sardinia, Italy. The basin hydrologic response to climate forcings in a reference (1971-2000) and a future (2041-2070) period was simulated through the combined use of a set of global and regional climate models, statistical downscaling techniques, and a process based distributed hydrologic model. We analyzed and compared the distribution of annual maxima extracted from hourly and daily precipitation and peak discharge time series, simulated by the hydrologic model under climate forcing. For this aim, yearly maxima were fit by the Generalized Extreme Value (GEV) distribution using a regional approach. Next, we discussed commonality and contrasting behaviors of precipitation and discharge maxima distributions to better understand how hydrological transformations impact propagation of extremes. Finally, we show how rainfall statistical downscaling algorithms produce more reliable forcings for hydrological models than coarse climate model outputs.
authors.affiliation: Dipartimento di Ingegneria Civile, Ambientale ed Architettura, Università degli Studi di Cagliari, Cagliari, Italy; Consorzio Interuniversitario Nazionale per la Fisica dell'Atmosfere e dell'Idrosfere, Tolentino, Italy. Electronic address: monicapiras@unica.it.
authors.forename: Monica
authors.initials: M
authors.lastname: Piras
authors.affiliation: Julie Ann Wrigley Global Institute of Sustainability, Arizona State University, Tempe, AZ, United States.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mascaro
authors.affiliation: Dipartimento di Ingegneria Civile, Ambientale ed Architettura, Università degli Studi di Cagliari, Cagliari, Italy; Consorzio Interuniversitario Nazionale per la Fisica dell'Atmosfere e dell'Idrosfere, Tolentino, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Deidda
authors.affiliation: School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, United States; School of Earth and Space Exploration, Arizona State University, Tempe, AZ, United States.
authors.forename: Enrique R
authors.initials: ER
authors.lastname: Vivoni
keywords: Climate change; Distributed hydrologic model; Extreme events; Mediterranean region; Statistical downscaling