ANALYSIS OF RIVER CONTROL MEASURES IN GRAVEL BED STREAM M - A CASE STUDY

Abstract

The fluvial characteristics of gravel-bed rivers quite significantly differ from that of sand-bed rivers in many aspects such as sediment size, sediment transport, unpredictable geological features that may be encountered under river bed and sides, variedly changing flow etc. Hence, prediction of river behavior of such river is very difficult. An attempt has been made here to analyze the design aspects of river control measures in such rivers with the present day state of knowledge. Gravel-bed streams are generally found in mountainous region and they are encountered with flashy floods and move with high velocity, which carries heavy bed load containing gravels, cobbles and boulders. In such rivers most of the sediments move along its bed as bed load while suspended load is quite negligible. Moreover, the sediment transport in such river is episodic. The problem in the gravel-bed river is generally associated with bank erosion and sometimes, overtopping of banks. There are occasions when important towns, installations, human lives and properties situated along the bank of such rivers are threatened by such problems. These problems arise mainly due to insufficient flow area to pass the flow discharges. Obviously, the approach for managing such problems in gravel-bed river calls for different treatment. With the rising cost of conventional methods of river control measures, coupled with decreasing availability of boulders, the need has been felt for prescribing cost effective and appropriate protection measures in such streams