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Many recent studies indicate climate change as a phenomenon that can potentially alter the water cycle, also implying new challenges in drought risk management. Impacts of drought are difficult to study, as this phenomenon is usually characterized by multiannual evolution scales, meaning that few occurrences may take place in a climatologic period of 30-years. Hence, it is of key importance to assess the quality of Regional climate models (RCMs), which are commonly used for assessing future impacts of climate change on hydrological events. To this end, a common approach consists in evaluating models' capability to simulate historic climate by comparing models' simulations to observational gridded datasets, available at global or continental spatial scales. Regardless of the specific methods used to assess the differences between simulated and observed data, a main limitation in this approach is that the considered spatial resolution is too coarse for reliable climate change impact studies at hydrologically relevant scales, especially in areas of complex topography. From this point of view, large scale observational gridded datasets are of poor applicability, since they are built upon low-density hydro-meteorological networks.The Coordinated Regional Climate Downscaling Experiment (CORDEX) initiative provides climate data simulated by RCMs developed by several research centers all over the world. In the present study we use climate data for the Euro-Mediterranean area, known as EURO-CORDEX (www.euro-cordex.net). In particular, simulations for an historic reference period (baseline) and for future projections up to 2100, with a 12.5 km grid resolution, are available for four different greenhouse gas concentration trajectories (Representative Concentration Pathways). We propose a statistical methodological framework to assess the quality of the EURO-CORDEX RCMs with respect to their ability to simulate historic climate by a comparison with high-density and high-quality ground-based observational datasets. In particular, the focus of this study is on observed thermometric and pluviometric regimes in Southern Italy at time scales from monthly to annual, which are particularly useful for drought analyses. To this aim, performances indicators relevant for assessing the accuracy of assessments are also considered. The proposed methodology is applied to Sicily and Calabria regions, where long historical precipitation and temperature series have been recorded by the ground-based networks operated by the formerly Regional Hydrographic Offices, whose density is considerably greater than observational gridded datasets available at European level, such as E-OBS. Results show that the proposed methodology is capable to highlight clearly skills and weaknesses of different RCMs and can help to properly select the models for climate projections in the investigated areas, with respect to the examined hydrologic processes. [ABSTRACT FROM AUTHOR]

While future climate simulations with Regional Climate models are becoming increasingly common, there is increased interest about the effects of climate change on the hydrological cycle at small spatial scales.We present a new hydrological RCP8.5 scenario simulation over Italy using the high resolution CHyM model, driven by the RegCM Regional Climate Model at 12km. The simulation spans the period 1976-2100, with a resolution ranging from 300 to 900m (depending on the region). Future changes both in terms of mean and extreme discharges under the RCP8.5 climate scenario are presented and discussed.Average discharges show a shift towards increased fall and winter flows by the end of the century, especially for the northern regions fed by the Alpine mountain range. The patterns follow changes in the average precipitation provided by the driving RCM.Several flood proxy metrics are analysed, including mean annual peak discharge, peak over threshold events and 100-year return period projected flow (Q100).In particular, the Q100 metric shows a strong increase in future extreme discharge, on average doubling the intensity of such events by the end of the century. Extreme flow changes are uniform across most of the Italian territory, but are particularly marked over the eastern coast of central Italy, where Q100 change values can exceed +200%. [ABSTRACT FROM AUTHOR]

The Mediterranean region has been identified as one of the main climate change hotspots: its sensitivity to global change is high and its evolution remains uncertain. The region experiences many interactions and feedbacks at the oceanic, atmospheric, and hydrological levels, while facing high anthropogenic activities. Analysing the water cycle over the Mediterranean region is of major importance to environmental and socio-economic aspects. The satellite monitoring of the Mediterranean water cycle represents one of the key challenges for the hydrological community.The presentation will show recent results on using satellite soil moisture and precipitation products for hydrometeorological prediction in the Mediterranean region, and particularly for the prediction of floods and landslides. Specifically, we will show the comparison of multiple satellite precipitation products for predicting flood in 100+ basins over the Mediterranean Basin by also using different hydrological models. Moreover, the assessment of satellite precipitation products for predicting the occurrence of landslides in Italy is carried out. Among the investigated satellite products, we have firstly considered state-of-the-art products such as TMPA (TRMM Multisatellite Precipitation Analysis), GPM (Global Precipitation Measurement), and H SAF (EUMETSAT Satellite Application Facility on Support to Operational Hydrology and Water Management). Secondly, we have tested the innovative products using the SM2RAIN algorithm for rainfall retrieval from multiple satellite soil moisture products including ASCAT (Advanced SCATterometer), SMOS (Soil Moisture and Ocean Salinity mission) and SMAP (Soil Moisture Active and Passive mission). [ABSTRACT FROM AUTHOR]