Integrating meso-scale habitat modelling in the multicriteria analysis (MCA) process for the assessment of hydropower sustainability.

The increasing number of water abstractions and water-use conflicts in alpine regions represents a significant threat for these fragile aquatic ecosystems. The use of tools, like multicriteria analysis (MCA), can support related decision-making processes towards sustainable solutions. In this paper, an innovative approach to assess water withdrawals sustainability by integrating the MesoHABSIM (Mesohabitat Simulation Model) into an MCA framework is presented and discussed. The methodology was implemented by replacing, within the MCA assessment, Water Framework Directive biological indicators with the MesoHABSIM based river Habitat Integrity Index, related to watercourse discharge and morphology, which allows quantifying the impacts of withdrawals on river ecosystems and fish communities. The resulting MCA procedure considers four criteria (energy, environment and fishing, landscape, economy) and requires only the use of measurable indicators based on watercourse discharge and its continuous monitoring. It was tested in Aosta Valley region (NW Italy) to both ex ante and ex post scenarios, for different types of water withdrawals and, currently, 20 experimentations, involving 58 hydropower plants and 12 farmer consortia, are ongoing. The proposed MCA process demonstrated its applicability with an increased decision-making quality and involved stakeholders’ satisfaction and is being officially endorsed in the regional River Strategic Plan