Environmental flow requirements of river Sone: impacts of low discharge on fisheries

Environmental flow of the river Sone at Indrapuri barrage was estimated using 36 years discharge data and the Global Environmental Flow Calculator Software. To maintain the river in moderate condition and to keep basic ecosystem functions intact, at least 18.9% of mean annual runoff (MAR) has been estimated, while the actual discharge of the river was merely 5.16% of MAR. The river presently holds 89 fish species, but 20 species reported in an earlier study were not observed, while 14 new fish species were encountered. Sediments, water and macro-benthic biota of the river were also studied to know the effect of low discharge.