Indian Journal of Science and Technology

Abstract

India is blessed with great Himalayas as well as hilly areas in peninsular and central areas providing opportunity for hydro power at all scale including Small Hydropower (SHP) development. Water is diverted from the streams for hydro power generation using suitable diversion structures. Conventional types of raised-crest weirs are not well suited for hill streams having steep slopes and boulder movement during floods. Inflatable dam or also known as rubber dam is one type of diversion structure to control and regulate the water for power generation.The experience of inflatable dams in India is very limited even though worldwide over 4,000 installations exist and more than 10 manufacturers offer this type of weir. There are only three installations so far used for irrigation or municipal purposes and not a single rubber dam for hydropower projects in India. For selecting a suitable diversion structure, economic and technical aspects are to be carefully considered. Different types of diversion weirs including rubber dam used for diverting water for Small Hydropower (SHP) projects are studied and presented. The design of diversion weir depends on the quantity of water withdrawal and width of stream. This study is an attempt to study the rubber dam technology for Small Hydropower in India. Five different sites were selected for the present study. Rubber dam was also compared with conventional raised gravity weir, trench weir (Tyrolean), bush and boulder weir and “mathu bund” (a local name). The life cycle of these different types of weirs for same hydraulic conditions and for different discharge were computed and compared with that of imported rubber dam as well as Indian rubber dam. The cost of rubber dam was estimated based on personal communications with the experts of manufacturers and practitioners of the subject area, as well as case studies of already constructed rubber dams in India installed for purposes other than hydropower. Operation and maintenance cost and different losses on account of head, water loss and repair were taken into account for different types of weirs for calculating life cycle cost. Possible damage that may be caused by major flood for different types of weir was also calculated monetarily in terms of power loss. The ease of inflation and deflation reduces the flood damage cost, O & M cost, sediment removal cost and repair work cost. With the comparative analysis, it is found that average life cycle cost of raised gravity weir, bush and boulder, mathu bund and trench weir (Tyrolean), is 2,3, 5 and 6 times respectively more than imported rubber dam. Life cycle cost of Indian rubber dam and average life cycle cost of imported rubber dam is about three times more than Indian rubber dam. It is recommended to use inflated weir in Small Hydropower projects being cost effective and energy efficient.
Keywords: Cost Effective, Inflatable Dams, Life Cycle Cost, SHP, Weir