The Climate Hazards Group Infrared Precipitation with Station data (CHIRPS) dataset, first released in 2014, is a high‐resolution blended rainfall product with quasi‐global coverage that has not previously been evaluated over Iran. Here, we assess the performance of the CHIRPS rainfall estimates against ground‐based rainfall observations across Iran over the time period 2005–2014 inclusive. Results show that performance of CHIRPS is best over areas and during months of predominantly convective precipitation, with the highest correlations in the southern coastal lowlands, which are characterized by heavy rains of convective origin. Correlations are stronger with variables such as altitude, particularly alongside coastal regions in the north and south, where surface water produces more moisture in the atmosphere. Results of pairwise comparison statistics and categorical skill scores reveal the influence of altitude and precipitation amount, while categorical skill metrics vary more with changes in precipitation amount than with latitudinal or longitudinal changes.

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Lake Trasimeno is a closed lake in Central Italy and in historically its water level has been affected by wide fluctuations mostly depending on the climate. The lake has suffered many water crises due to water scarcity and in recent decades, droughts have also severely affected the economic and environmental situation. The aim of this study was to analyze the possibility of limiting these severe level fluctuations by evaluating of feasible water resource management policies that could also reduce the environmental stress of this area. Therefore, a specific decision support system (DSS) has been developed in order to simulate different scenarios for the entire water system of the Trasimeno area. In particular, the hydrological model implemented in the DSS allowed for the simulation and validation of different management policy hypotheses for the water resource in order to mitigate environmental and water crises for the Lake Trasimeno. Results indicated that it is possible to transfer a certain amount of water from nearby reservoirs without affecting the availability of the resource for specific users. In this way, Lake Trasimeno can benefit both from an increase in water levels in the lake, so a possible better situation in quantitatively and qualitatively.

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The Water Exploitation Index (WEI), or withdrawal ratio, is an indicator of water scarcity, which has been updated into its WEI+ form by the Committee of Experts of the European Commission. In calculating the total abstraction of fresh water, this indicator also includes the possible return flow and management rules. The demand for freshwater and long-term freshwater resources are both necessary to calculate the WEI+. These values are not easy to assess at basin or sub-basin level and, for this reason, WEI values are generally calculated at the country level. This paper introduces a new approach to calculate the WEI+, with the purpose of extending its use to basin and sub-basin levels. The methodology is based on flow duration curve estimation, which evaluates freshwater resources, and a Web-GIS system that evaluates water abstractions distribution. This approach allows for the assessment of locally stressed areas in the hydrographic network and could provide a fundamental step toward more comprehensive regional water resources management plans. The new methodology is tested in some sub-basins of the Upper Tiber River Basin (Italy). These results contribute to the analysis of water withdrawals sustainability, based on the policy of the European Environment Agency, which is aimed toward the development of a proactive approach for reducing water stress.