International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 07 | July-2017
p-ISSN: 2395-0072
www.irjet.net
Dam Break Analysis of Idukki Dam using HEC RAS Abhijith R1, Amrutha G2, Gopika Vijayaraj3, Rijisha T V4 Asst. Professor, Department of Civil Engineering, Viswajyothi College of Engineering and Technology, Vazhakulam, Kerala, India 2,3,4 UG Scholar, Department of Civil Engineering, Viswajyothi College of Engineering and Technology, Vazhakulam, Kerala, India ---------------------------------------------------------------------***--------------------------------------------------------------------1
developments, contingency evacuation planning and real time flood forecasting. For assessing the flood damage due to dam breach it is necessary to predict not only the possibility and mode of a dam failure, but also the flood hydrograph of discharge from the dam breach and the propagation of the flood waves. The studies are to map or delineate areas of potential flood inundation resulting from a dam breach, flood depth, flow velocity and travel time of the flood waves etc. Knowledge of the flood wave and flood-inundation area caused by a dam breach can potentially mitigate loss of life and property damage. The significance of the study is to develop the river hydraulics model, simulate a dam failure and map the resulting flood wave. The proper modelling of the hazards associated with dam break will assist in land use planning and developing emergency response plan to help mitigate catastrophic loss to human life and property that might be inflicted by floods.
Abstract - Idukki reservoir, with an active capacity of
1459000000 m3 is a part of the Idukki Hydroelectric Project and comprises of Idukki Arch Dam, Kulamavu Dam and Cheruthoni dam. During the monsoon period when the dams are full at its Maximum Reservoir Level (MRL) or in an adverse event of dam break, the maximum discharge gets released from these dams. This results into floods on downstream and may cause disaster in cities or towns settled on the banks of the reservoir. This paper presents a case study of dam break analysis of Idukki Arch Dam using HEC-RAS software which involves prediction of dam break parameters, flood hydrograph, time of arrival of flood wave, peak flow. The resulting flood wave is routed along downstream using unsteady flow equations. In order to correctly draw the flood risk maps, the HEC-RAS method has been used together with the HEC-GeoRAS extension as an extension to the ongoing study.
Following are the objectives of the study
Key Words: Idukki dam, Dam break analysis, Flood modelling, HEC-RAS
• To conduct dam breach analysis of Idukki Arch Dam using HEC-RAS 5.0
1. INTRODUCTION
Dam-breach flood-inundation maps indicate areas that would be flooded as a result of a dam failure. The inundated areas depicted on flood-inundation maps are approximate, and accuracy of such maps is a function of the accuracy of the topographic data, the hydraulic models on which the maps are based, the assumptions made about the dam failure mode, and the initial flood wave.
Dam is a barrier that impounds water that plays a vital role in the economy of the country. The water retained is generally used for irrigation, aquaculture, industrial use, human consumption, etc. However, in the unlikely and rare event of their failure, these may cause catastrophic flooding in the downstream area which may result in huge loss and damage to human life and property. In this study the dam break analysis and flood modelling of Idukki reservoir is done with the help of HEC-RAS. Hydrologic Engineering Center’s River Analysis System (HEC-RAS) modelling software developed by the U.S. Army Corps of Engineers, a standard for dam-breach flood-inundation models, is used to perform steady-flow simulations to model the dynamic nature of the flood wave produced by a dam-breach scenario. The reservoir consists of three dams. They are Idukki dam, Cheruthoni dam and Kulamavu dam.
3. METHODOLOGY Dam break analysis can be done using the flood routing techniques proposed by St. Venant’s equations for unsteady flow. His approach solves both the continuity and momentum equations for a differential volume of onedimensional flow, where the forces on the control volume are limited to the effect of gravity, pressure variation, and friction or roughness of the channel walls. Mass is conserved in the solution and the effect of acceleration within the control volume and momentum fluxacross the upstream and downstream faces are considered. It consists of two independent variables Q and t. Solution of this equation depends on the number of cross-sections. Because of the complexity in solving the entire equation simultaneously software HEC-RAS has
2. SCOPE AND OBJECTIVE The prediction of the dam break flood is very important for the purposes of planning and decision making concerning to dam safety, controlling downstream
© 2017, IRJET
|
Impact Factor value: 5.181
|
ISO 9001:2008 Certified Journal
|
Page 3410