Abstract:
Environmental flows assessment is a process which
determines the allocated water for maintaining
aquatic habitats and ecological processes in a
environment. The river system attains zero flow in
low flow period due to construction of hydropower
generating structures, water retaining structure and
withdrawal of water by water users, which possesses
a tremendous threat to the environment, ecology &
aquatic life. Therefore a need arises to regulate the
reservoirs for releasing the adequate water in the
river throughout the year as well as a flushing flow
once in a year. Thus environmental flows assessment
is done in Lower Mahanadi sub-basin and
recommended to provide the EFRs on average 33%
of MAF with a range of Low flow 110% of mean low
flow & High flow 23% of mean high flow to be
ensured at any circumstances to avoid any
degradation of river ecosystem. In the present study
the assessment of the environmental flows on the
basis of Tennant method, Tessman method, VMF
method, Q90_Q50 method, Smakhtin method, low
flow index (7Q10) method and FDC (EMC shifting
technique) method using Global Environmental
Flow Calculator (GEFC) software have been made.
