Participatory Modeling of Small Agricultural Reservoirs in the Orcia Watershed, Italy

Climate change in the Mediterranean causes altered precipitation patterns and increasing temperatures, especially in summer, with negative impacts on agricultural systems. Italian Val d’Orcia hosts thousands of small agricultural ponds or reservoirs (SmARs), several of which are abandoned. Recently, interest in restoring them is growing given the concerns about impelling irrigation water shortages. Indeed, typical rainfed crops such as vineyards and olive groves now need to be irrigated to obtain satisfactory productions. Within the AG-WaMED PRIMA project (Advancing non conventional water management for innovative climate-resilient water governance in the Mediterranean Area), we analyse the current situation of SmARs considering economic, hydrological and governance aspects. Stakeholders’ involvement is crucial to understand the challenges and to co-produce possible solutions. The outputs of two workshops carried out in the Orcia watershed, together with desktop analyses, showed that more than 1000 SmARs exist (average surface: 0.14 ha). Nowadays, most of them are not used due to various problems like siltation, abandonment of rural areas and lower production incentives. Representing this high number of SmARs in a semi-distributed hydrological model such as the Soil and Water Assessment Tool + (SWAT+) agro-hydrological model is fundamental but also challenging. To do this, we prepared a set of criteria which was discussed during the workshops to establish whether a SmAR should be included or not. In future research, the prepared SWAT+ model will be used to estimate the impact of SmARs on streamflow and sedimentation dynamics, with the overall aim to feed the other studies carried out within the AG-WaMED project. Additional rounds of stakeholders’ feedback are envisioned to further improve the model's representativeness and to select the alternative scenarios to be simulated.