Articles | Volume 18, issue 12
Hydrol. Earth Syst. Sci., 18, 5201–5217, 2014
https://doi.org/10.5194/hess-18-5201-2014
Hydrol. Earth Syst. Sci., 18, 5201–5217, 2014
https://doi.org/10.5194/hess-18-5201-2014

Research article 15 Dec 2014

Research article | 15 Dec 2014

Quantification of hydrologic impacts of climate change in a Mediterranean basin in Sardinia, Italy, through high-resolution simulations

M. Piras1,2, G. Mascaro1,2,3, R. Deidda1,2, and E. R. Vivoni3,4 M. Piras et al.
  • 1Dipartimento di Ingegneria Civile, Ambientale ed Architettura, Università degli Studi di Cagliari, Cagliari, Italy
  • 2Consorzio Interuniversitario Nazionale per la Fisica dell'Atmosfere e dell'Idrosfere, Tolentino, Italy
  • 3School of Sustainable Engineering and the Built Environment, Arizona State University, Tempe, AZ, USA
  • 4School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA

Abstract. Future climate projections robustly indicate that the Mediterranean region will experience a significant decrease of mean annual precipitation and an increase in temperature. These changes are expected to seriously affect the hydrologic regime, with a limitation of water availability and an intensification of hydrologic extremes, and to negatively impact local economies. In this study, we quantify the hydrologic impacts of climate change in the Rio Mannu basin (RMB), an agricultural watershed of 472.5 km2 in Sardinia, Italy. To simulate the wide range of runoff generation mechanisms typical of Mediterranean basins, we adopted a physically based, distributed hydrologic model. The high-resolution forcings in reference and future conditions (30-year records for each period) were provided by four combinations of global and regional climate models, bias-corrected and downscaled in space and time (from ~25 km, 24 h to 5 km, 1 h) through statistical tools. The analysis of the hydrologic model outputs indicates that the RMB is expected to be severely impacted by future climate change. The range of simulations consistently predict (i) a significant diminution of mean annual runoff at the basin outlet, mainly due to a decreasing contribution of the runoff generation mechanisms depending on water available in the soil; (ii) modest variations in mean annual runoff and intensification of mean annual discharge maxima in flatter sub-basins with clay and loamy soils, likely due to a higher occurrence of infiltration excess runoff; (iii) reduction of soil water content and actual evapotranspiration in most areas of the basin; and (iv) a drop in the groundwater table. Results of this study are useful to support the adoption of adaptive strategies for management and planning of agricultural activities and water resources in the region.

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Short summary
We quantified the hydrologic impacts of climate change in the Rio Mannu basin (472.5 km2), Sardinia, Italy. We created high-resolution climate forcings for a physically based distributed hydrologic model by combining four climate models with two statistical downscaling tools of precipitation and potential evapotranspiration. A significant diminution of mean annual runoff at the basin outlet (mean of -32%), and a reduction of soil water content and actual evapotranspiration are expected.