http://localhost:8081/jspui/handle/123456789/18821 2026-05-07T20:40:46Z 2026-05-07T20:40:46Z Sharma, Vasundhara http://localhost:8081/jspui/handle/123456789/20533 2026-04-27T06:18:34Z 2023-06-01T00:00:00Z

Title: Reservoir sedimentation analysis using empirical methods and HEC-RAS: Panchet Dam, Jharkhand Authors: Sharma, Vasundhara Abstract: Dams have played a vital role in the development of the economy of the country. Currently, India stands third in the number of dams worldwide, with 5745 large dams, including 411 dams under construction (NLRD, 2019). These dams should be managed to sustain the benefits for humankind and the environment. Sedimentation in reservoirs is one of the significant deterrents for dams. Further, the sedimentation rates have increased due to extreme events. The process of sedimentation not only reduces the reservoir's storage capacity but also affects its proper operation. Traditional management strategies adopted by the dam authorities are check dam, sluicing, flushing, density current venting, sediment replenishment, hydraulic dredging, dry excavation, etc. However, for the practical applicability of these management strategies, reservoir modelling and sediment distribution analysis is vital. Empirical methods and Numerical modelling using HEC-RAS are used to predict the sediment deposition pattern in the reservoir. Initially, a study is carried out on the Bhima reservoir in the Krishna basin, having a gross storage capacity of 3320 MCM, to understand the change in the sedimentation pattern of the reservoir from 1977 to 2011. CWC published Compendium 2020 on Reservoir Sedimentation which showed a cumulative percentage loss of 12.77% in overall reservoir capacity across India with an average rate of sedimentation of 0.815 Th. cum/sq. km/yr. Only empirical methods such as Empirical Area Reduction method and Area Increment method is used. Due to the unavailability of inflow discharge data at the Bhima dam, the study area is changed to the Panchet dam. Further study is conducted for the Panchet reservoir in the Damodar basin using both the empirical methods and HEC-RAS simulation. For the numerical simulation in HEC-RAS, inflow series data, sediment load data, bed gradation are required. The reservoir has data related to past capacity surveys (seven numbers) and inflow data series from 1961 to 2021. For the Bhima reservoir, Empirical Area Reduction method gives the revised capacity as 2896.30 MCM whereas the observed revised capacity is 2896.96MCM. The shape of the reservoir is Type 2 Floodplain foothill type in 1977 which changed to Type 1 Lake type reservoir in 2011. For the Panchet reservoir, EAR method and AI methods are applied for the year 1962,1964,1975,1985,1996 and 2020. For 2020, EAR method shows a correlation of 0.996 and AI method shows a correlation of 0.98. Further, for the prediction of new zero elevation for 2030,2040,2050 Moody’s method is used and EAR method is used for the sediment distribution. For 1D quasi unsteady simulation in HEC-RAS, initially the model is run with taking Larsen (Copeland) as the transport function. After the simulation of model, rating curve analysis is done 5 taking seven different transport functions and comparison is done between the predicted and the observed rating curve. Acker-White gives better result as compared to other transport functions. Also, the sediment deposition of 31.19 MCM is predicted for simulation from 2020-2030. However, the reservoir volume loss for different methods comes out to be different. It is concluded that, using both the empirical methods and the numerical method HEC-RAS, 50 percent of the sediment is deposited in the upper 30-35 percent of depth resulting in the deposition in head reaches, thus observing a longitudinal deposition pattern of delta in the dam. Further, this study emphasizes the importance of sedimentation modelling for proper planning of reservoirs.

2023-06-01T00:00:00Z P. R., Rahul http://localhost:8081/jspui/handle/123456789/20532 2026-04-27T06:15:00Z 2023-06-01T00:00:00Z

Title: Sediment transport modelling of rivers Bharathapuzha & Periyar using HEC- RAS Authors: P. R., Rahul Abstract: Sediment transport has great importance in flood monitoring as flood control schemes mainly depend upon the peak flood levels. The flood levels may be changed in the same discharge and sometimes the pattern of the flow of natural channels changes due to the siltation and the flood pattern of the region can be changed. The 244 Km long river Periyar is also known as the lifeline of the Indian State Kerala. The Bharathapuzha and the Periyar are the major rivers in Kerala much prone to morphological changes. The river Bharathapuzha also known as the Nila is the second-longest river in Kerala and originated from the Anamalai hills. The major share of the industries in Kerala is situated along the banks of these rivers and human settlement is more along these river banks. It is observed that the morphology of these rivers was greatly affected by the 2018 Kerala flood and the flood pattern of the region along the banks has been changed. Also, the flow-carrying capacity of the river Periyar has been greatly affected by the changes in the morphological alterations. River Bharathapuzha is an interstate river between the states of Kerala and Tamilnadu. Due to the sedimentation and erosion, the morphology of the river Bharathapuzha has changed a lot in recent times and it affected the flow-carrying capacity of the river. During the lean season, it has been observed that the flow in the river is intermittent and dry at a lot of stretches. Hence it is decided to conduct sediment modelling using HEC RAS 6 for studying the changes in the morphology of the river Periyar and Bharathapuzha. The data has been collected from the GDSQ sites of the Central Water Commission at Neeleeswaram (River Periyar) and Mankara (River Bharathapuzha). At both of these stations, the gauge, discharge, sediment, water quality and meteorological observations are conducted throughout the year daily and the site Neeleeswaram is a full climatic station. The flow and sediment data have been collected from 1971 to 2021. Initially, 1-D sediment modelling has been conducted on the rivers Periyar & Bharathapuzha at the stretches near the sites Neeleeswaram & Mankara. The geometry has been created using the actual - observed cross-sections that have been received from the CWC. Quasi-unsteady flow approach has been used for the modelling. The flow series created from the discharge data received from the CWC has been used as the U/S boundary condition and the friction slope calculated from the actual observation at the CWC site was used as the downstream boundary condition of normal depth. The initial conditions for the sediment data were provided from the bed gradation samples from the CWC sites and the boundary condition for the sediment data was given as the sediment time series data collected from the CWC site Neeleeswaram & Mankara. After the successful running of the model, the output of the sediment simulation has been analysed and significant erosion and sedimentation have been observed in the different sections of the river stretch at Periyar. While comparing the results of the River Bharathpuzha model, It is identified as the river was not much proned to the bed erosion.

2023-06-01T00:00:00Z Kumar, Prem http://localhost:8081/jspui/handle/123456789/20531 2026-04-27T06:14:23Z 2023-06-01T00:00:00Z

Title: Reservoir Sedimentation Assessment using Remote Sensing for Maithon reservoir Authors: Kumar, Prem Abstract: An eroded sediment particle originating from the catchment enters the reservoir by propagating along with the river inflow. At the location where the river meets the reservoir, the cross-sectional area of the river suddenly increases and hence flow velocity decreases. The coarse particles settle at the mouth of the reservoir, whereas the fine particles settle further down in the reservoir. Thus, reservoir storage capacity reduces significantly due to sedimentation, so its assessment is of prime importance for water resources development projects. The sedimentation assessment of the Maithon reservoir has been carried out using Landsat-8 and sentinel-1A dataset by using NDWI, Density slicing and Ostu’s Algrothim remote sensing techniques. The analysis results are compared with the bathymetric survey of Maithon Reservoir of the year 2019, and the variation in the results has been calculated. The results obtained using the Otsu histogram thresholding technique, carried in ArcGIS software, had a deviation of 4.65%. The density slicing method carried out in ERDAS Imagine software had a deviation of 5.01 %. The variation of 5.01% indicates that density slicing provides reliable results in estimating the live storage of the reservoir. Furthermore, the density slicing method allows for a more refined delineation of water bodies but may require manual selection of pixel values. The results obtained using the NDWI technique had a deviation of 3.22 %, which is relatively low compared to those obtained using Ostu and density slicing techniques.

2023-06-01T00:00:00Z Nongbet, Amrita http://localhost:8081/jspui/handle/123456789/19057 2026-02-16T11:02:49Z 2023-06-01T00:00:00Z

Title: DAM BREACH ANALYSIS OF UMIAM EARTHEN DAM USING HEC-RAS Authors: Nongbet, Amrita Abstract: The Analysis of dam breaches using the Hydraulic Engineering Center's River Analysis System (HEC-RAS) is crucial in assessing the safety of dams and developing effective emergency response strategies. This study explores the utilization of HEC-RAS, a widely employed water flow modelling program, to understand the potential outcomes of a dam breach and its subsequent consequences. Through the simulation of dam breach scenarios and the estimation of flood wave characteristics, HEC-RAS assists in assessing the severity of a dam breach, studying the downstream propagation of floods, and devising effective measures to prevent their occurrence. Providing an overview of the significance of HEC-RAS in enhancing dam safety and safeguarding lives, properties, and ecosystems during dam breach incidents, this abstract emphasizes the importance of preparing an emergency action plan (EAP). Consequently, conducting a dam breach analysis becomes imperative to identify the critical discharge threshold that could potentially lead to the dam's failure in such an event. In this study, the dam breach analysis of the Umiam Earthen Dam in Meghalaya's Ri-Bhoi district utilises a two-dimensional (2D) hydraulic model known as the HEC-RA to improve the accuracy and reliability of hydraulic models when simulating a dam breach scenario and creating flood potential inundation maps., the study incorporates a digital elevation model (DEM) extracted with 30 m resolution from the Shuttle Radar Topography Mission (SRTM) for generating the geometry data and a Geographic Information System (GIS). The probable maximum flood (PMF) uses as reservoir inflow; the reservoir routing using modified Pul’s method was carried out in the Hydraulic Engineering Center's Hydrologic Modeling System (HEC-HMS) model to determine the outflow; the results show the comparison of the inflow and outflow hydrographs. The HEC-RAS model simulates dam breach parameters such as breach width, breach formation failure time, and breach side slope determined from distinct empirical methods. The outflow characteristics, such as maximum water surface elevation, maximum velocity, maximum depth, and minimum travel time, are predicted using the HEC-RAS two-dimensional (2D) model obtained from four distinct empirical methods. A comparison makes between the obtained results. The flood inundation maps prepare using Froehlich’s equation for piping failure for the downstream affected villages using the maximum water levels generated by the dam breach model. As a result of piping failure, the downstream area directly below the dam encounters a peak flow of 3471.36 m3/s, leading to an inundation area of 110 km2 before reaching the Assam border.

2023-06-01T00:00:00Z