Services Rendered:


Topographic Data Processing

FEMA dam failure methodology

Inundation Mapping


Theun Hinboun Power Company Vientiane, Lao PDR


Robert Allen Jnr

General Manager

Dates of Performance:

June 2011 – May 2012

Status of Project:

Current phase completed

DSI performed a hydraulic analysis for failure on the Nam Gnouang (NG) Dam in Bolikhamxai Province, Lao PDR as part of the Theun-Hinboun Expansion Project (THXP) of the Theun-Hinboun Power Company (THPC). The dam is located on the Nam Gnouang River, a tributary to the Nam Theun River, approximately 9 km upstream of the confluence. NG Dam failure analysis was conducted in support of preparation of the Emergency Response Plan (ERP). The ERP helps facilitate the management of floods that are caused or exacerbated by the dam due to either dam operations or dam failure, and to reduce the risk to lives and property from the consequences of dam failure.

Phase 1 of the study was a preliminary assessment for NG Dam failure scenarios based on a HEC-RAS model of the TH Reservoir. Based on the results of Phase 1, additional works were recommended for Phase 2 of the study including further data collection and an extension of the HEC-RAS model to avoid the downstream boundary effect and properly represent the floodplain. Following the recommendations from Phase 1, the HEC-RAS model was revised and used for the analysis of the NG Dam failure scenarios. Based on the analysis results, a series of flooding maps were prepared for ERP. As inundation levels and areal extents are needed to support this assessment, following FEMA dam failure guidance for the analysis, DSI conducted hydraulic analysis and developed inundation maps for a range of scenarios.