Reservoirs – Types | Purpose | Impact | Advantages | Disadvantages | Difference Between Dams and Reservoirs

Reservoirs are large open storage structure which is used to collect and store water so that it can be drawn and used later for different purposes. It is created by constructing a dam across a river. It is a major component of any water resource project. The reservoir can be used to regulate the natural streamflow and can make the outflow in desired patterns.

Types of Reservoirs

Based on the Purpose of construction of the reservoir, it is classified into four types

1. Storage reservoir

• Since these are used to conserve water they are also called conservation reservoirs
• Storage reservoirs store water in the rainy season and release them when the river flow is low
• In India, these are constructed mainly for irrigation purposes
• Also called single purpose conservation reservoirs

2. Flood Control reservoir

• Mostly called flood-mitigation reservoir
• These are mainly used to store a portion of flood flows to protect the downstream places
• The excess water is stored in the reservoir when the flood discharge exceeds the safe capacity
• The water stored in the reservoir is released when the inflow to the reservoir is decreased
• Designed mostly to moderate the flood and not to conserve water for a long time
• This reservoir has a relatively large, sluice-way capacity for permitting rapid drawdown before or after the occurrence of flood
• There are two types of flood control reservoirs namely Detention reservoirs and Retarding reservoirs.

3. Distribution reservoir

• A reservoir that is constructed within a city water supply system is called a distribution reservoir
• A small storage reservoir to meet the peak demand of water for municipal water supply or irrigation
• Water is pumped at a uniform rate throughout the day for 24 hours but the demand varies from time to time
• It stores water during the lean demand and supplies during the high demand
• Rarely used for the supply of water for irrigation, mainly used for municipal water supply.

4. Multipurpose reservoirs

• Constructed to serve for more than one purpose
• For example – Irrigation, Hydroelectric power, water supply, navigation, flood control, recreation, and wildlife conservation
• The projects having reservoirs that are designed and operated to serve two or more purposes should be termed multipurpose.

Purpose of reservoirs

The main purposes of reservoirs are

• Used to meet the water requirements of cities during dry weather flow in rivers
• For hydroelectric power generation during the months of discharge in the ring to maintain a minimum water level
• For the protection of low lying areas against flooding
• For growing fishes and other aquatic life
• For recreation purposes such as swimming etc.
• To meet the irrigation water requirements of the area when discharge in a river is lower than the demand
• To protect the hydroelectric equipment and pumping machinery from silt and debris present in the water.

Advantages of reservoirs

• Controlled and sustained supply of water for irrigation encourages to use of additional areas for cropping
• After proper treatment water can be used for drinking purposes
• The water stored can be used to generate electricity
• Can be used for flood control
• Upstream water ponds can be used for fish farming
• Control the debris from the water.

Disadvantages of reservoirs

• A large area of land will be submerged and will be turned into a reservoir by the rise of water
• Many people should have to be relocated
• Life cycles of the aquatic animals will get affected
• On the downstream side, there will be a decrease in the nutrients
• Overall there will be a reduction in diversity around the reservoir.

Difference between dams and reservoirs

Impact of reservoirs on environment

• The construction of reservoirs mainly affects aquatic life and also disrupts the life cycles of fish
• It causes the dislocation of the people living near that place
• The quality of life may get affected due to the storage of water.

How does nature maintain groundwater reservoirs?

The groundwater reservoir is maintained by the water that percolates into the rock layer of the ground from natural discharges, the discharge will be mainly from the precipitation. The water from precipitation seeps into the ground and leads to underground reservoirs.

List of reservoirs in India

There is a total of 44 reservoirs, please check the list with the river name.

Also Read: Sardar Sarovar dam and List of Dams in India

Question and Answers