Assessment of dams’ efficiency under the effect of climate change and urban expansion: Um Hablian Dam, Jeddah, Saudi Arabia (Case Study)

Abstract

This paper analyzes the effect of climate change and urbanization on the efficiency of dams that have been built to protect Jeddah city in Saudi Arabia from severe floods. Um Hablian dam is considered a case study. Several data have been collected to address the objectives. Among these data are the historical rainfall, digital elevation models, a base map of Jeddah city, and its future expansion up to 2050. Hydrological analyses have been performed using common software: HEC-HMS, GIS, and WMS software to estimate the floods under the normal (design) conditions, the effect of climate change, and urbanization. It has been shown that under the normal condition (NC) scenario, the Um Hablian dam capacity can accommodate the floods for up to 200 years return period. The effect of the climate change scenario (CC) is more significant than the effect of the urbanization scenario (U). The effect of urbanization scenario (U) leads to shortening the time to peak of the flood. In the combined scenarios (CC+U), the runoff volume exceeded the dam capacity by about 102% and the dam is expected to get overtopped by 40% from the current dam height. The dam lake is expected to inundate 53% more area than the current condition.