INTRODUCTION

• Dams and weirs are some of the barriers which when construct across the rivers and streams, cause accumulation of water behind them.
• The water thus accumulat in form of an artificial lake is know reservoir.
• In broad sense, any collected water in form of a pool or lake, may be termed as reservoir.
• Dams and reservoirs are the most important elements of any multipurpose river basin development.
• River water may be used for generation of hydroelectric power, irrigation, and water supply source for some town or city.
• All these uses require a constant or almost constant supply of water.
• But we know that discharge in rivers and streams remains fluctuating.
• During rains, the water in the river may be more than the requirements and during dry period the discharge in the river may become less than the minimum requirements.
• Thus to store the excess water, flowing during floods, dams are constructed across the rivers.
• This stored water is use to augment the supplies of the river during dry weather.
• By this arrangement it is possible to generate hydroelectric power, provide irrigation facilities and make available drinking water for whole of the year.
• Actually dams and reservoirs are complementary to each other.
• Reservoir can be develop only by constructing dam, conversely when dam is construct reservoir is bound to develop.
• Both dams and reservoirs, being very important elements of any multipurpose irrigation project, have to be very carefully planned, designed and operated.
• This involves proper selection of site, for dam.