Assessment of Environmental Flow Requirements for Hydropower Projects in India

Increasing water withdrawals from many rivers of the world is leading to severe degradation in river ecosystems. Water is allocated for environmental needs so that a river can perform its natural functions. Environmental flows (EF) try to strike a balance between the use of water of a river for economic development, societal needs and delivering ecosystem services. This article describes a framework to assess environmental flows for a hydropower project in India in a situation where limited hydrological and very limited ecosystem data are available. It recommends that in such a situation, an acceptable EF regime can be arrived at by analysing hydrological data, supplemented by whatever ecosystem data are available and creating various scenarios of EFs. Benefits and impacts of different EF scenarios can then form the basis to determine an appropriate EF regime. Application of the framework is demonstrated in a case study in India. Adaptive management, where feedbacks are used to update and improve the decisions is helpful in such situations.