SILT CONTROL IN RESERVOIRS USING DIVERSION TUNNEL & BLANK PANELS

Abstract

Silting of a reservoir is a natural process which starts once the river channel is dammed and ends when the reservoir is practically filled with sediments. It is an unavoidable process, that cannot be interrupted or stopped, but it can be controlled to some degree by means of certain . . practices, measures and works. These practices and measures include a) Catchment area t'reatmeirt, b) Various engineering measures such as sediment trapping reservoirs, river regulation works, slope and bank protection works, bypassing structures, off stream storage reservoirs and c) Reservoir operation such as sediment sluicing. In case of hydroelectric projects the main emphasis is given to minimize the entry of coarse and medium part of sediment into the power intake. The size and quantum of silt has a major impact on the operation of hydropower projects in terms of siltation of reservoirs and serious damage to the equipments. It underlines the desirability of silt consciousness during various stages of the project such as investigation, design, operation and maintenance. Damages to turbine and under water parts due to abrasive action of silt carried by rivers, especially the steep sloping Himalayan rivers, result in frequent shutdowns of power stations with consequent loss in power generation and this has • been causing a serious concern. The prevention of medium and coarse fraction of suspended sediment entering into the power intake of run-of-river hydroelectric projects is thus of paramount importance. Hence, various measures to deal with such sediment problems in run-ofriver schemes have to be employed at investigation and design stage for new upcoming projects and also for existing projects at operation and maintenance stage. This dissertation work intends to study the various existing methods and recent developments for elimination / reduction of silt content from the reservoirs and also the mitigation of suspended sediment in front of intakes of hydroelectric projects of the run-of—river schemes.