Connecticut Water Trails Association
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Connecticut Water Trails Association |
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Connecticut Water Trails Program Dams
Classification Of Dams
According to their functions, dams serve three main purposes: storage, diversion, or detention.
Storage Dams
They are constructed to impound water in periods of surplus supply for use in periods of deficiency. Many small dams impound the spring runoff for later use in dry summers. Storage dams may also provide a water supply, or improved habitat for fish and wildlife. They may store water for hydroelectric power generation, irrigation or for a flood control project
The specific purpose of a storage dam influences its design and determines the amount of reservoir needed. Where multiple purposes are involved e.g. both power and irrigation, reservoir allocation is usually made for each separate use. The volume of storage establishes the height and width of the dam.
Diversion Dams
They provide sufficient pressure for pushing water into ditches, canals, or other conveyance systems. Such shorter dams are used for irrigation, and for diversion from a stream to a distant storage reservoir.
Detention Dams
They minimize the effect of sudden floods and trap sediment.
Overflow Dams
They carry water discharge over their crests, and are made of materials that will not be eroded by such discharges. Non-overflow dams are designed not to be overtopped, and may include earth and rock in their structure. Often the two types are combined to form a composite structure.
To prevent a dam from being overtopped, spillway structures carry off excess water. In earth fill dams, essential spillways are built as separate structures, often a shaft or tunnel adjacent to the dam. With concrete gravity dams, the downstream side of the structure acts as the spillway.
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