Author(s): S. B. Kulkarni; V. M Wakalkar
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Keywords: No Keywords
Abstract: Comprehensive river management programmes such as construction of storage reservoirs, diversion structures like weirs, barrages, bridge crossings, navigation locks, river training works for bank protection by providing groynes or embankments need estimation of river parameters like width, depth as well as sediment discharge. Lacey's relationships for determining above parameters are largely utilised for alluvial rivers. Similarly, Blench, Leopold, Maddock and Chitale have evolved parametric relationships utilising data of unlined canals and alluvial rivers of braided and meandering type. H. H. Chang has developed nomograms considering variables such as river slope, width and sediment load based on minimum energy principle. However, these formulations are mainly from the river data with large sediment load. Alluvial rivers carry large amount of sediment load causing erosion of bed, formation of shoals and change in river course. The shape of the cross-section of a river channel at any location is a function of the flow, quantity and character of the sediment in movement through the section and the composition of the materials making up the bed and banks of the channel. Parametric relations based on these data are not directly applicable to other rivers i. e., non-alluvial or bouldery rivers. Because of geologic and climatic conditions, two different characteristics of rivers are seen in India, one originating in the Himalayas and flowing through Indo-Gangetic plains considered as alluvial rivers; while the other one is Southern Indian rivers originating from hard rock areas of Sahyadri, Satpura and Vindhya mountains carrying less sediment load and are formed as incised rivers. The banks of the Southern Indian rivers are generally firm and bed material is different from bank material. To study the characteristics of such rivers, Narmada has been selected and the data of this river have been analysed for different gauge sites and compared with regime relationships of the other investigators. Fig. 1 shows the river basin of Narmada and the Table-1 shows comparison of the various parameters obtained from the analysis of data. It brings out clearly that application of Lacey's relationships for such rivers is likely to under-estimate the depth while over-estimate the width and the relationships proposed in the paper (9 and 10 of table enclosed) are more suitable for the particular case.
Year: 1993