Reservoir

Reservoir The term 'reservoir' is variously used for manmade containers for storing surface water; aquifers reserving groundwater; and rocks possessing specific properties for accumulating hydrocarbon (oil and gas).

It could be a receptacle, constructed (of earthwork, concrete dam) to contain and store a large supply of water. This stored water may be used for generation of hydro-electricity and irrigation (eg kaptai lake), or other purposes. Also a place or area in which water naturally collects in large quantities, like bagakain lake and Rinkhyongkine Lake of chittagong hill tracts.

List of the major reservoirs and their uses in Bangladesh:

Lakes	Characteristics	Use
Rinkhyongkine Lake, Bandarban	1,609 km long and 0.25 km wide, watershed of the Rinkhyong river	River navigation, fishing and important water source for the nearby elephant habitat
Bogakine Lake, Chittagong	Small and parallelogram shaped	Navigation, household use and irrigation
Kaptai Lake, Chittagong	567 sq km	Hydroelectricity generation, navigation, fishing and irrigation
Foys [Foyej] Lake, Chittagong	136 ha	Water supply for railway area and important recreational site
Ahshula Rwadh [Hrad], Eastern Barind	Steep bank, deep lake, northwest to southeast alignment, a block fault	Use for household and important irrigation supply source

The term may also refer to subsurface water reservoir commonly known as aquifer. The subsurface water reservoirs are mainly of Dupi Tila sandstone all over the country, which is porous and permeable.

Again, reservoir is also referred as a porous rock body accumulating large hydrocarbon (oil or gas) deposit in subsurface. Sandstone of Boka Bil Formation of the Upper Surma Group acts as major reservoir for natural gas in the large producing gas fields of Bangladesh (e.g. Chhatak, Kailastila, Bakhrabad). [Mohd Shamsul Alam]