Evaluation of Ecological Flow Requirement in Downstream of Hydropower Project Through Hydrological Modelling and GIS Approach A Case Study of Beas River Basin in Himachal Pradesh India

Abstract

The Environment Impact Assessment is a decision-making tool and formal study process used to predict the ecological consequences of any development project and its environmental management. The main source of power production in Himachal Pradesh is hydroelectricity. The Beas River with a length of 470kms flows from Rohtang in Manali to meet the Sutlej River in Punjab has an identified hydropower potential of 6000MW. To tap this potential, the Himachal Government has already constructed many projects in the Beas River basin. This implies that the river bed could be dry during the summer period or lean period. Hence there may arise a situation in which the ecosystem can t be able to sustain the riverbed ecology and riparian environment due to its case. The inability to maintain minimal flows may prompt the weakening of the subordinate ecosystem s water condition. The general term used to depict the flow that is necessary to maintain the river ecosystem s feature is minimum flow. Therefore, there has been a greater need to evaluate the requirements of the Environmental (Protection) Act, 1986; 15% of the minimum observed the flow of the stream has to be released, to the downstream of the diversion structure for the protection of flora, fauna, and aquatic life between intake and confluence point of tailrace and the stream as per the NGT order. newlineThe aim of the research work has three folds. Firstly, to evaluate the sufficiency of 15% minimal flow in the downstream by hydrological modeling and using Environmental flow methods for the selected hydropower projects. Secondly, assess the changes in the environment due to the operation and construction of the selected Hydropower project and validate the Environmental flow requirements using the GIS application. For the validation purpose, the impact assessment in the study area using the questionnaire survey in the downstream side of the hydropower projects focused particularly on the farmers and downstream habitats has been carried out. newline