Please use this identifier to cite or link to this item: http://localhost:8081/xmlui/handle/123456789/3603
Authors: Akhtar, Md. Perwej
Issue Date: 2009
Abstract: River morphology is one of the most complex phenomena, not only because the flow and flow patterns vary in time and space, but also because the coupling to the river valley and channel, in which the flow is contained, varies. Alluvial rivers carry the sediment with the flow. The hydraulic parameter of the channel decides the sediment transport capacity. When the sediment quantity becomes more or less than the transport capacity, deposition or scour occurs causing morphological changes in the course affecting the structure made across or along the river channel as well as flow pattern of the river. The morphological changes of river is also interrelated with the hydraulic parameters of the channel changes such as bed deformation and bank erosion because of mutual relationship between water flow and sediment transport. Study of morphological changes is very important to manage the river to achieve the minimum water depth for navigation, in low flow as well as predicting the water surface elevation during floods in estimating flood related damaged. The study of morphology and its management of such a large alluvial river like Ganga and Koshi with great deal of channel instability and intricacies, warrant an all embracing approach to evolve cost effective solutions focused not only on the navigation channel development and flood protection, but also to effectively tackle closely interlinked channel process of bank erosion, channel widening and river bed aggradations or degradations on a fairly durable basis. Reliable and quantitative estimate of the bed aggradations or degradation are very important in alluvial river for developing durable fairway to get sufficient water depth in low flow as well as accurately predicting the water surface elevations during floods in estimating flood to protect the bank from erosion. Thus, engineers are greatly interested in accurately predicting the behaviour of river under various flows and sediment loads so that better information can be obtained for the planning and design of river control structures, development of navigation channel, flood protection measures and other water diversion structures. The present study in the above background comprises the study on morphological changes in two rivers one is Ganga and other is Koshi River. The study on Ganga River is first to investigate suitable sediment predictor models with the validation of thalweg of iv year 2006 with year 2007 at two sites Nakhwa and Debchandpur. It has been found that Yang Predictor model with Nash-Sutcliff efficiency (E), R and RMSE value 0.793, 0.938 and 0.226 at Nakhwa site and 0.741, 0.931 and 0.231 at Debchandpur site respectively is best suitable. On the basis of this finding Yang sediment predictor model is used to study •the bed changes with the changes in geometry of cross-section at selected locations by running the sediment analysis model HEC-RAS at all the six selected sites Nakhwa, Debchandpur, Arjunpur, Digha, Punarak and Bateshwarasthan. Than after it has been also studied with the application of Steady flow simulation model HEC-RAS, rises in water depth with the consequent effect of bed changes in low flow at all the aforesaid sites.The Hydrological data of Varanasi, Ghazipur, Buxar, Patna and Hathidah are used in present studies. The application of low cost river training structures like bamboo submerged vanes, polymer rope Gabion submerged vanes and R.C.0 Kellner Jack Jetty were also done for field trial experiment to achieve the required purpose at two sites Nakhwa and Debchandpur. The approximate cost for both sites comes to Rs. 30.20 Lakhs and Rs.39.27 Lakhs. In Koshi River threat analysis of existing spurs in Eastern afflux Bundh in the upstream of the Bhimnagar Barrage has been conducted. The Methodology adopted for threat analysis of spurs along Eastern afflux Bundh is analytical method one is arc/chord ratio method and another is Delft Hydraulic Lab Method. The average arc/chord ratio comes to 1.401. With the three options it has been also suggested remedial measures. This analysis indicates that it may be advisable to provide small length of spurs at less spacing as compared to long length spurs at more spacing which would be vulnerable to strong hydrodynamic action of the river causing possible failure. Shorter length spurs are relatively less exposed to stronger river action and thereby stand better chances of remaining intact so as to afford desired bank protection.
Other Identifiers: M.Tech
Research Supervisor/ Guide: Garg, Rahul Dev
Sharma, Nayan
metadata.dc.type: M.Tech Dessertation
Appears in Collections:MASTERS' DISSERTATIONS (WRDM)

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