Hydraulic Structures and Irrigation design & drawing
have a narrow opening in the valley so that the length of the dam is small. The cost of the dam is
often a controlling factor in the selection of a site for the reservoir.
3. Watertightness of the reservoir The geological conditions of the reservoir site should be such
that the reservoir basin is watertight. The reservoir sites having pervious rocks are not suitable.
The reservoir basins having shales, slates, schists, gneiss, granite, etc. are generally suitable.
4. Good hydrological conditions The hydrological conditions of the river at the reservoir site
should be such that adequate runoff is available for storage. The catchment area of the river
should give high yield. There should not be heavy losses in the catchment due to evaporation,
transpiration and percolation.
5. Deep reservoir The site should be such that a deep reservoir is formed after the construction
of the dam. A deep reservoir is preferred to a shallow reservoir because in the former the
evaporation losses are small, the cost of land acquisition is low and the weed growth is less.
6. Small submerged area The site should be such that the submerged area is a minimum. It
should not submerge costly land and property. It should not affect the ecology of the region.
Monuments of historical and architectural importance should not be submerged.
7. low silt inflow The life of the reservoir is short if the river water at the site has a large quantity
of sediments. The reservoir site should be selected such that it avoids or excludes the water from
those tributaries which carry a high percentage of silt.
8. No objectionable minerals The soil and rock mass at the reservoir site should not contain any
objectionable soluble minerals which may contaminate the water. The stored water should be
suitable for the purpose for which the water is required.
9. Low cost of real estate The cost of real estate for the reservoir site, dam,dwellings, roads.
railways, etc. should be low.
2. Explain the zones of storage in a reservoir?
A large number of terms are commonly used for reservoir planning. These terms are defined
below. It may be noted that various terms are sometimes used to indicate the same quantity.
1. Full reservoir level (FRL) The full reservoir level (FRL) is the highest water level to
which the water surface will rise during normal operating conditions. The effective
storage of the reservoir is computed upto the full reservoir level. The FRI is the highest
level at which water is intended to be held for various uses without any passage of water
Dept of Civil Engg, SJBIT