The appropriate implementation of the concept of Water-related Ecosystem Services (WES) in water resources planning can support the development of productive activities and, at the same time, sustain local ecosystems. However, such implementation it is only possible when both WES supply and demand are evaluated, eventually with a spatially explicit method, for gaining insights into the ecohydrological behavior of a basin and the anthropogenic pressures on the available water resources. Based on the integration of hydrological modelling and Water Footprint (WF) analysis, this study aims at developing a methodology to analyze both the supply and demand of WES, evaluating a Water Ecosystem Services Footprint (WESF) associated with the agricultural sector. The proposed methodology is based on a 3-tiered approach: 1) evaluating the WES demand determined by the agricultural sector using the WF Assessment methodology; 2) quantifying the WES supply by applying the Soil Water Assessment Tool (SWAT); 3) estimating the green, blue, and gray WESF through dedicated indicators in order to identify the main hotspots. The methodology is applied to a specific case study in the upstream part of the Arno river basin (Central Italy). By means of subnational WF statistics the green, blue, and gray WF of the agricultural sector is calculated, determining the spatial distribution of WES demand in the catchment. SWAT results quantify the available water resources, pointing out the blue/green surface water partitioning, where precipitation is divided into 25% runoff and 46% evapotranspiration, and the associated WES supply. Merging the results, the WESF spatial pattern is evaluated, properly identifying the most critical areas in the catchment. WESF represents an operative tool to look at agricultural water management from an ecosystem-based perspective, supporting the identification of the strategies to explore the sustainable coupling of biosphere and anthroposphere.
Keywords: Arno river; Ecosystem services; Integrated water resources management; SWAT; Water Footprint.
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