Topographic and Seismic Constraints on the Vulnerability of Himalayan Hydropower

Abstract

We compiled damages to hydropower projects (HPPs) in the wake of Nepal's 2015 Gorkha earthquake and its main aftershock. Based on 41 records of HPP losses, we identify the main mechanisms determining the degree of loss. We show that, among these mechanisms, earthquake-triggered landslides had the largest share. Landslides clustered where peak ground acceleration and river steepness Mχ, a metric frequently used in tectonic geomorphology, attain high values. A Bayesian logistic regression reveals that both metrics are credible predictors for HPP damage states. Our study underscores the vulnerability of Himalayan hydropower to landsliding. We estimate that ~25% of existing, currently constructed, and planned HPPs and >10% of potential HPP sites along Himalayan rivers have high probabilities of moderate to severe damage during future earthquake. Our study highlights that HPP hazard assessments need to consider both seismic and the geomorphic setting of HPP sites conjunctively.