International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 06 | June 2025
p-ISSN: 2395-0072
www.irjet.net
DAM BREAK ANALYSIS AND FLOOD INUNDATION MAPPING USING HEC-RAS Sandesha K M1, Neman Sharief M.M2, Dr.M.Inayathulla3 1PG Student(WRE), Department of Civil Engineering, University of Visvesvaraya College of Engineering, Bengaluru, 2Research Scholar, Department of Civil Engineering, University of Visvesvaraya College of Engineering, Bengaluru, 3Professor, Department of Civil Engineering, University of Visvesvaraya College of Engineering, Bengaluru,
Karnataka, India ---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Dams are multi-functional structures widely used
impacts and are instrumental in preparing mitigation strategies. This study incorporates both hydrological and hydraulic modelling components, offering a holistic approach toward dam safety evaluation.
for storing water, generating electricity, and managing floods. However, their failure, especially during extreme rainfall events, can lead to catastrophic flooding in downstream areas. This study presents a comprehensive dam break analysis and flood inundation mapping for the Harangi Dam, located in Karnataka, India. Using HEC-RAS 2D and ArcGIS tools, simulations were carried out to model potential overtopping and piping failure scenarios. The resulting flood hydrographs and inundation extents were compared for different breach conditions. The peak flood discharges obtained were 21,451.66 cumec for overtopping and 15,585.31 cumec for piping failure. The maximum inundation area for overtopping was found to be 120.857 square kilometers, significantly higher than the areas affected by piping failure and large controlled release scenario. About 157 downstream villages were found to be at risk due to overtopping failure. The study highlights the importance of hydraulic modeling and floodplain mapping in identifying vulnerable zones, supporting disaster preparedness, and formulating mitigation strategies for dam safety management.
1.1 Objectives
Dams are critical infrastructure that play a vital role in water resource management. However, their failure can result in significant loss of life and property. With increasing concerns over climate-induced extreme rainfall and structural vulnerabilities, dam break studies have become essential. This paper focuses on the Harangi Dam in Karnataka, assessing flood risks arising from both overtopping and piping failure scenarios. Flood Inundation Mapping (FIM) is used to identify at-risk areas downstream of the dam using HEC-RAS two-dimensional modeling and GIS tools. In recent years, with the rising unpredictability of weather patterns and climate extremes, the relevance of dam break modeling has increased significantly. Comprehensive risk assessments help in evaluating possible downstream
Impact Factor value: 8.315
To prepare flood inundation and flood wave arrival time maps for the downstream region under dam break conditions, and a flood inundation map for the downstream region under without dam break condition.
To estimate the number of villages affected or inundated due to overtopping failure.
The Harangi Dam is an essential water infrastructure project built across the Harangi River, a tributary of the Cauvery, located in Kodagu district of Karnataka. Positioned at around 12° 29′ 30″ N latitude and 75° 54′ 20″E longitude. It began impounding water in 1982, and since then, it has played a significant role in supporting regional agriculture and ensuring water security for nearby districts, especially during dry spells. The dam is a composite structure with masonry and earthen materials, the Harangi Dam spans 845.82 meters in length. In addition to its practical utility, the Harangi Dam has also become a peaceful tourist destination, with wellmaintained gardens, tranquil waters, and scenic views of the Western Ghats, especially captivating during the monsoon season. It has become a spot where infrastructure meets nature. In all, the Harangi Dam is a symbol of sustainable water management, agricultural support, and eco-tourism, quietly enriching the lives and landscapes of southern Karnataka.
1. INTRODUCTION
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To determine the peak flood discharge resulting from a dam failure due to both overtopping and piping failure.
2. STUDY AREA
Key Words: Flood inundation mapping, Harangi Dam, ArcGIS, Overtopping failure, Piping failure, Emergency planning
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