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]