International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 12 Issue: 08 | Aug 2025
p-ISSN: 2395-0072
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Hydraulic Structure Impact on Flood Inundation Mapping: A Comprehensive Approach Neman Sharif M.M1, Dr. Inayathulla M2 1Research Scholar, DCE, University of Visvesvaraya College of Engineering, Bengaluru
2Professor, DCE, University of Visvesvaraya College of Engineering, Bengaluru, Karnataka, India
---------------------------------------------------------------------***--------------------------------------------------------------------inundation. The extent and severity of flood inundation Abstract - Accurate flood inundation mapping is
are influenced by various factors, including terrain slope, elevation, rainfall intensity, drainage density, land use patterns, and soil characteristics.
fundamental for effective flood risk management, urban planning, and emergency preparedness. While advances in hydrologic and hydraulic modeling have significantly improved the precision of these maps, the nuanced influence of hydraulic structures such as dams is often simplified or overlooked. This study presents a comprehensive approach to assess the impact of Krishna Raja Sagara (KRS) dam on flood inundation patterns. KRS dam is a type of Gravity dam constructed with stone masonry along with surki mortar having a length of 2621 m and has a maximum height of 44.66 m and the bottom width of the dam is 33.88 m covering a catchment area of 10961 km2. The Gross storage capacity of the dam is 1400 MCum. The design flood discharge is estimated to be 9911 cumecs. A total number of 152 gates have been installed to dispose off the surplus as well as water stored in the KRS dam which are situated at different levels of the dam having varying capacities. Utilizing integrated 1D/2D hydrodynamic modeling data, we simulate flood events under diverse scenarios, comparing inundation extents and depths with and without detailed representation of structure. The methodology incorporates detailed structural geometry, operational rules, and their interaction with upstream and downstream flow dynamics. Preliminary findings demonstrate that hydraulic structures can significantly alter flood wave propagation, water surface elevations, and flow velocities, leading to considerable differences in predicted inundation areas and depths. The maximum inundation area observed in the maps generated was 288.407sq.km respectively in 2D modeling. The maximum water surface elevation observed is 755.139 (m) with overtopping failure with Dam break scenario.
Dams are engineered hydraulic structures constructed across rivers to form reservoirs, serving a range of purposes including flood control, hydropower generation, irrigation, water supply for domestic and industrial use, and recreational activities [1]. However, dam failures pose significant risks to public safety and the environment. Historical disasters, such as the 1975 Banqiao and Shimantan Dam collapses in China (85,000 fatalities), the 2018 Patel Dam failure in Kenya (41 deaths), and the 1994 Merriespruit tailings dam disaster in South Africa (17 fatalities), highlight the catastrophic consequences of dam breaches ( [2]; [3]; [4]). Other notable failures include the St. Francis Dam (1928), Buffalo Creek Dam (1972), and Teton Dam (1976), which caused extensive property damage and loss of life ( [5]; [6]). Globally, over 800,000 dams have been constructed [7], but their failure—often due to overtopping (34% of cases), foundation defects, or extreme weather—can lead to devastating downstream flooding [8]. The 1975 Banqiao Dam disaster, triggered by extreme rainfall, resulted in widespread fatalities, displacement, and disease outbreaks [9]. Since the 1970s, dam safety concerns have grown, prompting studies on breach mechanisms, flood modeling, and risk mitigation [10]. Traditional approaches relied on over engineered structures, but modern strategies emphasize flood forecasting, emergency action plans, and downstream evacuation [11]. Advanced modeling tools, such as HECRAS, HEC-HMS, and DAMBRK, simulate breach scenarios, predict flood extents, and support emergency planning ( [12]. [13]). Parametric and analytical models estimate breach dimensions and outflow hydrographs, while GISbased tools like HEC-GeoRAS enhance inundation mapping ( [14]; [15]).
Key Words: Flood Inundation Mapping, hydrologic, hydraulic modelling, Dam breach analysis, HEC-RAS · HEC-HMS.
1.INTRODUCTION :
1.1 Significance of Dam Break Study
A flood is defined as the overflow of water onto land that is normally dry, typically caused by excessive rainfall leading to high flows in rivers, streams, or drainage channels, or by water ponding near the point of precipitation. When a river's carrying capacity is exceeded, the excess water spills over its banks, resulting in
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Impact Factor value: 8.315
The present study on dam break analysis helps in many ways and has got much significance as listed below:
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Helps in assessing the potential extent of damage in downstream areas of the dam.
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