Rapid climate risk assessment methodologies for hydropower projects: concepts and theory

Due to substantial uncertainties in the presently available climate change projections, a Climate Risk Assessment (CRA) of hydropower projects must aim at assessing the potential hydro-meteorological impacts of a wide range of possible future climate conditions on inter alia water resources availability, hydro-energy generation potential and environmental flows, as well as its potential impacts on the economic and environmental performance of hydropower infrastructure. State-of-the-art assessments of climate risks follow bottom-up methodologies - as advocated in IHA's Hydropower Sector Climate Resilience Guide (2019) - for incorporating climate risks in project analyses. These methodologies are generally designed to employ extensive hydrological, climate and water resources system modeling. However, practical time and financial constraints do often not permit time consuming in-depth analyses, nor may they be warranted in view of the inherent large uncertainties at various levels of the analyses. Therefore, this chapter will present rapid climate risk assessment methodologies for estimating the potential impacts of climate change in probabilistic terms of hydrological impacts, the related changes in water resources availability and the potential changes in project performance indicators, including economic indicators. Essentially, the methodology is based on the concept of climate elasticities of catchment runoff, translated into climate elasticities of water resources system performance and of the economic performance of water resources projects, through the use of readily available ensembles of climate change projections. Applications of these methodologies are illustrated in Chapter 12 through selected case studies.