The most common way that man-made lakes are created is by damming a running body of water. It could be an area with small streams running through it or even a large river. An area that is in a low-lying spot or even a small area with a waterfall may be chosen. Those that make the decision of how large to make the lake by deciding how large the dam should be built.
The dam is built upward and outward in order to hold back the water to the size of the pond or lake desired. The overflow of the lake is directed to a specific location over or through the dam so that once the lake or pond has reached its desired size, the overflow will go over a spillway supplying the other side of the dam to have back its original amount of water flow.
Around the world, man made lakes, or reservoirs, serve as water sources. A man-made lake is usually constructed by diverting water from a river into a reservoir by using a dam.
The reservoir is filled with water runoff and precipitation during seasonal changes, which prevents evaporation. Additionally, dykes can be formed by excavating land or by surrounding water with dykes.
Man-made lakes come in many different sizes and are used for a variety of purposes, including irrigation, stormwater management, energy, and resource conservation. The creation of man-made lakes has a number of advantages and disadvantages.
Advantages of Man Made Lakes:
- water as a resource
- drinking water
- flood protection
- agricultural irrigation
- hydropower (energy production)
- water storage
- increased fishery
- ecological impacts
- human pollution
- displacement of local populations
- expensive construction and maintenance
Lakes can range in size from small ponds to larger bodies of water. A valley reservoir is built by building a dam perpendicular to the flow of a river. In off-river storage reservoirs, water is supplied by gravity or a pump and is enclosed parallel to the river.
A bounded or embankment reservoir has controlled outflows and inflows to or from one or more rivers. Water is moved from one drainage to another through tunnels, canals, and reservoirs in a cascade reservoir along a single river.
Because large reservoirs are built with heavy machinery and materials and require more maintenance and quality control than smaller reservoirs, they can be expensive.