Multi-criteria decision-making (MCDM) for the sustainable management of water withdrawals in Alpine watercourses

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Comparing Multi-Criteria Decision-Making Methods for the Assessment of Flow Release Scenarios From Small Hydropower Plants in the Alpine Area

Growing energy demand and targets for reducing greenhouse gas emissions are driving a significant hydropower (HP) generation expansion in the Alpine area. However, despite its advantages, HP implementation causes several impacts on the ecological status of river systems and the preservation of characteristic landscapes. The use of decision-making tools, like multi-criteria decision-making (MCDM) methods, can provide helpful support to achieve more sustainable solutions for complex water management problems. In Aosta Valley (NW Italy), an MCDM experimental approach is being applied to define the optimal environmental flow scenario to be released by HP plants, in an attempt to balance energy production needs, economic profitability and environmental safeguard. Four criteria are considered (energy, environment and fishing, landscape, economy) and key stakeholders are involved in the entire decision-making process. However, there is a need to test also other MCDM methodologies in order to understand if an alternative approach could be more suitable for future, more complex, HP management decisions. Therefore, in this paper, seven different MCDM methods are applied to an existing small run-of-the-river HP plant for the selection of the optimal flow release scenario, i.e., SAW, WPM, AHP, TOPSIS, VIKOR, ELECTRE III, and the initially adopted method, SHARE MCA. The results obtained with the application of the different MCDM methods are investigated and statistically compared. The strengths and weaknesses of the different methodological approaches are also discussed. Based on the comparative results and the consequent evaluations, SHARE MCA, WPM, and VIKOR appear to have the most interesting characteristics in terms of overall feasibility

Definition of an indicator assessing the impact of a dam on the downstream river landscape

Abstract The increasing number of water withdrawals in Alpine regions represents a significant threat to aquatic ecosystems and river landscape (riverscape). To assess their sustainability, the impacts on river ecological status and landscape features need to be quantified with appropriate indicators. However, assessment of landscape attributes is a complex challenge, due to the lack of standardized methods. Moreover, few metrics quantifying the impacts of water withdrawal on downstream riverscape perception are available in the scientific literature. In this paper, a new indicator, named Landscape Protection Level (LPL), aimed at assessing the effects of water withdrawals on the river landscape, is presented. The indicator has been developed in Aosta Valley (NW Italian Alps), where the river network is heavily exploited by hundreds of withdrawals for hydropower production and irrigation, and it has been included in a multi-criteria analysis (MCA) procedure to assess the sustainability of water withdrawal licenses in relation to different flow release scenarios. The LPL indicator is based on three parameters, Constraint Factor, Release Factor, and Visual Elements Factor, quantifying the presence of landscape protection constraints, the ratio of flow released downstream of the dam to the available river discharge, and the impact on the visual perception of the bypassed stretch, respectively. Its application in four real case studies of existing hydropower plants is presented and discussed in the paper, demonstrating the indicator applicability to assess both specific release values and flow release scenarios varying over the year. Results are analyzed by highlighting the main strengths and weaknesses of the indicator and proposing some suggestions for future improvements. In particular, the reactiveness of the indicator, the representativeness of the stakeholders' interests, the transparency of the indicator calculation procedure, and the time required for data collection and processing are discussed. Finally, future activities aimed at further improving the indicator applicability and transferability to different river contexts are proposed

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