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Maity, Swapan Kumar
- Local Scour at and Around Vertical Hydraulic Structure - A Case Study Around the Piers of Bridges on Rupnarayan River, WB
Authors
1 Dept. of Geography and Environment Management, Vidyasagar University, Midnapur-721102, West Bengal, IN
Source
Indian Science Cruiser, Vol 26, No 6 (2012), Pagination: 38-46Abstract
Local scouring is the lowering of the riverbed level by water erosion due to separation of flow and development of vortices around hydraulic structures. Excavating and carrying away materials from the bed and banks of streams and from around the hydraulic structures cause failure of riverine structures throughout the world especially during the river floods. The present study incorporates the review of the existing literature on scour with emphasis on the understanding of the mechanism of scouring, prediction of scour depth, correlation of local scour and sediment transport capacity and reduction techniques of local scour around vertical piers. Actual scour depth data have been collected from the piers of bridges near Kolaghat region on Rupnarayan River. The expected scour depth is calculated based on different scour controlling parameters for the same. Dou (1997) established the relationship between local scouring and effective sediment transport capacity (STC). Many researchers have employed different techniques to predict the maximum depth and diameter of scour hole. In a few studies, procedures to reduce the scour depth have been used by making use of splitter plates and collars on the piles. Helical wires or cables wrapped spirally around the pile resembling a threaded pile have also been used to reduce the scour. With the use of different special techniques, the scour depth has been reported to reduce by modifying the flow field near the bridge elements. The Lacey-Inglis method (1992, 1944) is used in India for estimation of the design scour depth around hydraulic structures. Prediction of scour depth and protecting it is very difficult due to many uncertainties associated with it and sometimes become very costly. More studies and investigations are still required to predict the scour depth effectively and also to find cost-effective ways to protect the scour.
Keywords
Local Scouring, Hydraulic Structures, Sediment Transport Capacity, Scour Depth, Splitter Plates, Collars, Threaded Piles.
- Shear Stress for Sediment Entrainment in connection with Grain Size at Lower Reach of the Rupnarayan River, West Bengal, India
Authors
1 Head of Department of Geography and Environment Management, Vidyasagar University, Midnapur-721102, West Bengal, IN
Source
Indian Science Cruiser, Vol 28, No 1 (2014), Pagination: 16-26Abstract
The lower reach of the Rupnarayan Rjver has experierced a net shoaling of 26.57 million with 42.04 million m3 deposition and 15.47 million m3 scouring during the last 20 years. Attempts have been made to calculate the available shear stress and critical shear stress in connection with the grain size of sediments.
Keywords
Shoaling and Scouring, Shear Stress, Sediment Texture, Skewness, Suspension.- History of Evolution of the Rupnarayan River, West Bengal, India
Authors
1 Dept. of Geography, Nayagram P.R.M. Govt. College, Jhargram-721125, West Bengal, IN
Source
Indian Science Cruiser, Vol 37, No 1 (2023), Pagination: 28-32Abstract
River Silabati joins with river Dwarakeswar at Bandar, near Ghatal and gives the birth of the Rupnarayan river. Earlier maps reveal that river Rupnarayan has changed its course significantly within historic times. In Gastaldi map (1561) the river was named as Ganga and in Van Den Broucke’s map (1660) it was named as Patragatta River. Finally, the river was named as Rupnarayan in Rennell’s map (1764-1776). Gastaldi’s map (1561) shows that, the river Rupnarayan is discharging its water through its two bifurcated channels bordering an island at the mouth. But in the map of 1703, the south-easterly channel has disappeared. Presently, a large amount of water and sediment of Rupnarayan river and its tributaries are being discharged to the Hoogly river (near Geonkhali) through out the year.Keywords
Rupnarayan, Change of river course, Earlier maps, Discharge of water and sediment.References
- L S S O’Malley, Physical Aspects, Bengal District Gazetteers, Midnapore, West Bengal District Gazetteers, page 1-141, 1995.
- S C Mukhopadhyay and A Dasgupta, River Dynamics of West Bengal, Physical Aspects, Prayas Publishers and Book Sellers, Vol.I, page 1-220, 2010.
- G Sinha and A N Basu, A Study of the Tidal Propagation through the Rupnarayan River with the Help of “Mathematical Model”, B.B.I. & P. Publication No 110, Proc.41st Annual Research Session, Vol. IB (Hydraulics), 1960.