DAM BREACH FLOOD MODELING USING HEC-RAS 2D: APPLICATION TO ATTABAD LANDSLIDE DAM

Abstract

The objective of this research is to model the dam failure scenario of the Landslide DAM Attabad Lake located in Gilgit Baltistan, Pakistan, and to assess its effects on downstream regions. It's critical to assess the potential for breaches in embankment dams to devise emergency response strategies. The flood wave's physical and hydrodynamic characteristics arising from the dam's collapse are linked to various factors of breach such as its width, slope, and the time it takes to form. In January 2010, a massive rockslide, with an estimated volume of approximately 55 million cubic meters, blocked the Hunza River, leading to the creation of Attabad Lake as a result of rockslide damming. The cause of the dam's overtopping was mainly the swift increase in lake water levels, spurred by intense rainfall and the melting of snow. Initially, the dam-maintained stability; however, the escalating water level eventually caused it to overtop. This resulted in the erosion of the dam's crest and the creation of a breach channel, which progressively expanded and deepened, culminating in the dam's total collapse and the subsequent downstream surge of a large volume of water and debris. Insights from this incident stress the necessity of enhanced surveillance and early alert systems, consistent maintenance and examination of existing structures, and the formulation of emergency plans to reduce the detrimental effects of dam collapses on communities and ecosystems downstream. This study underscores the significance of acknowledging the risks posed by natural disasters in the planning, construction, and management of infrastructures in susceptible regions.