A Proposed Method to Estimate Climate Change Impacts on Dam's Spillway Design Flood

Abstract

Overtopping of a dam, which can be due to inadequate spillway design, is often a precursor to dam failure. Generally, dam spillways are designed using historical hydro-meteorological records. However, the hydrological regime of rivers and floods' intensity may change in the future due to climate change. Although climate change impacts should be considered in spillway design, their consideration remains a challenge. Spillway flow is affected by many factors, each of which can change due to climate change. This paper aims to propose a method for assessing the impacts of climate change on spillway design floods, which considers a wide range of these changes. The method incorporates a robust weather generator, a daily hydrological model, and a reservoir model. The results indicated that the conjunction of the models can acceptably simulate extreme spillway flows. The proposed method was used to assess climate change's impact on the annual maximum spillway flows of a potential large dam in Iran under three Representative Concentration Pathway (RCP) scenarios of the Hadley Centre Global Environment Model version 2-Earth System (HadGEM2-ES) model. The findings indicate that while mean monthly spillway flow decreases under all scenarios, extreme spillway flows significantly increase under the RCP 8.5 scenario.