A MULTIFACET APPROACH FOR SUSTAINING RIVERINE FISHERIES THROUGH ENVIRONMENTAL FLOWS IN INDIA: A CASE STUDY
Riverine ecosystems are among the most impacted ecosystems worldwide. Human activities, such as the construction of dikes, dams, groynes and weirs, the straightening and deepening of river channels, the conversion of floodplains to agricultural land, water abstraction, water transfer and pollution; etc., have heavily modified most large lowland rivers. As a result, a large number of fish species became threatened or endangered and the fish productivity of most riverine ecosystems has declined. To balance the interests of different stakeholder groups, many countries have implemented water resources management plans. Water policy decisions are typically made with little or no consideration of fish conservation and fisheries, despite a high public perception of fish. Therefore, the need of the hour is to adopt a holistic approach bringing hydrologists, ecologists, fisheries scientists, geo-morphologists and policy makers in one platform. Realizing the importance, Govt. of India has brought environmental flows as a mandatory for all the river valley projects. Environmental flow refers to the water considered sufficient for protecting the structure and function of an ecosystem and its dependent species. Environmental flows are required to be maintained through a river reach for sustaining its ecosystem and dependent species. It means enough water is to be released in the downstream of the river system after utilizing the water for the development projects in order to ensure downstream environmental, social and economic benefits. In this backdrop a study was carried out to estimate the environmental flows in river DRI, Arunachal Pradesh for protecting the riverine fisheries. The results indicated that During the monsoon season (June-September) the flow regime (Figure inserted) exhibit high flows up to 1400 m3/sec with several daily spikes which ensure not only base flow but also high pulses occurring in the monsoon. However, to provide adequate river width during monsoon, a higher flow of 50 m3/sec is recommended. Moreover, all the flood spikes must be released to the downstream in order to mimic the natural flow regime in the river.
