Development of a site selection methodology for run-of-river hydroelectric power plants within the water-energy-ecosystem nexus

Even though water-energy systems and ecosystems have complex relationships, regional energy policies seldom con-sider this connection. The current regional energy policies are developed primarily based on technical and socio-economical aspects and lack ecological considerations that may deteriorate the ecosystems and sustainability of these policies. Hence, considering the water-energy-ecosystem nexus in the development stage of the energy policies can aid decision-makers in initiating successful multi-dimensional energy policies. This study proposes a novel ap-proach to develop an environmental index to support the regional energy policies that rely on Run-of-river (RoR) hy-droelectric power plants (HEPPs) with a nexus approach. First, significant environmental impacts of RoR HEPPs are identified as environmental flows, impacts on ecologically valuable areas such as heritage sites, wetlands, national parks, river water quality degradation, modification of habitat, and impact on ecosystems and biodiversity loss. Then these impacts are represented through indicators and are aggregated into an overall environmental performance index through a fuzzy multi-criteria decision-making approach. The proposed approach allows the integration of eco-logical dimensions into the evaluation of RoR HEPPs through easy-to-measure indicators, among which environmental flow is a critical component.