This refers to bottom land of the river holding water column. This may be made of sand, soil or finally rock. Type of river bed and type of rock will help in two ways.
- This rock can be used in construction of nanodam itself. Removal of rock implies more water storage
- If the rock/gravel is of construction grade, to some extent quarrying can be allowed, which removes further rock and hence increasing additional water storage. Querried rock may be used for other construction activities.
- Sand deposition is seen many rivers in south India which is as building material. Removal of sand can further increase storage capacity of nanodams.
Flat river bed helps in accumulation of sand/river soil which can be removed once every 3 to 5 years by emptying the water during hot summer season. This soil can be studied for use as top soil for non agricultural lands.
Width of the river
Refers to width of the river line. More the width, more the water storage capacity; however increases cost of construction.
Depth of the river
This refers height of adjacent land from the surface of the river bed. More the depth of river, more will be the storage.
Length of the river
Refers to length of the river.
Zone of influence
Zone of influence for a given nanodam is defined as area surrounding the nano dam to a length where water storage is influenced by presence of this nanodam
Water flow velocity
Maximum speed of flow of water observed during monsoon seasons India. Peak water flow velocity is needed to ascertain the height of the nanodam. Waterflow velocity depends on various factors like geographic area, height, gradient, river bed formations, width gradient (river becomes smaller or larger over a given length), canals, water inflows etc.