Draining the Tangjiashan Barrier Lake

Abstract

This paper documents the emergency breaching of an approximately 110-m-high landslide dam that was created at Tangjiashan during the 2008 Wenchuan earthquake of China’s Southwest Sichuan Province. As an emergency measure, a 13-m-deep channel was excavated to reduce the volume and head of the released water during the dam breaching and to create a controlled flood that was intended to prevent catastrophic consequence for 1.2 million people downstream. From detailed monitoring and survey works carried out during and after the dam break it was found that (1) the breaching initiated at a pool water level of 742.1 m with an estimated flow velocity of 2.4 m/s, and virtually terminated at a pool water level of 720.3 m with an estimated velocity of 2.5 m/s, which can be regarded as the incipient velocity that initiated erosions for the soils at this particular site; (2) a controlled flood released