Dam Break Analysis and Risk Assessment [A Case Study of Tendaho Dam]
No Thumbnail Available
Date
2015-12
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa
Abstract
This thesis analyzes the probable failure of a dam under a set of pre-defined
scenarios, within the framework of a case study, the case subject being the
Tendaho dam located at Afar Region of Ethiopia. The failure of the dam is not
analyzed neither structural nor hydraulic wise but, is assumed to be triggered
when certain critical WSELs are exceeded. Hence, the analyses focused on the
aftermath of the failure and strive to anticipate the level of inundation at
downstream of the dam itself. Break parameters prediction, peak outflow
prediction were shown as the essential for the dam break analysis and
eventually determined the loss of the life. Tendaho dam break was further
modeled and analyzed using USACE Hydrologic Engineering Center’s River
Analysis System (HEC-RAS Version 4.1) model based on available technical
and geometric data. Water surface elevations and discharges occurring at
downstream of the Tendaho dam were predicted spatially and temporally under
the defined set of eleven scenarios. Eight of the scenarios were analyzed for
overtopping failure of the dam. Two of the scenarios were analyzed for piping
failure and the last scenario was analyzed to investigate the sensitivity of
Manning roughness. Overtopping failure yielded more severe flow conditions
at downstream. The worst case scenario was found to be scenario W4 (when all
the three spillway gates are completely closed). Hence, indicative inundation
map and settlements under risk were identified. Total numbers of fatalities for
precise and vague understanding of warnings were found 1,012 and 2,972
respectively. The thesis study further addressed some available pre-event
measures that may be taken in advance.
Keywords: Tendaho Dam, HEC-RAS, HEC-GeoRAS, Breach, Dam Failure,
Dam Break Analysis
Description
Keywords
Tendaho Dam, HEC-RAS, HEC-GeoRAS, Breach, Dam Failure, Dam Break Analysis