The government has entrusted the Centre for Water Resources Development and Management (CWRDM) to develop a new methodology to calculate the minimum environmental flow (E-flow) required in rivers.
A new methodology is being proposed based on the inference that an earlier directive of the Principal Bench of the National Green Tribunal (NGT) in New Delhi that States need to maintain a minimum E-flow of 15-20% of the average lean season course in their rivers is not practical. E-flow defines the quantity, timing and quality of water flow required to sustain freshwater and estuarine ecosystems, besides human livelihood.
As per the existing NGT order, the minimum E-flow calculation required is 15-20% that is based on flow of Himalayan-fed rivers. As the method cannot be applied to rivers in the southern States that are monsoon-fed, a new methodology is required, according to the River Rejuvenation Committee, Kerala.
To implement a new methodology and validate the calculated E-flow, the CWRDM requires 25 years of fisheries data from the Fisheries department and hydraulic and cross-sectional data from the Hydrographic Wing. A request has been submitted to the respective departments and active follow-ups are being done by the Department of Water Resources, according to the minutes of the committee meeting held on February 17, 2024.
Though the NGT had recommended an E-flow of 15-20% of the average lean season course in rivers, it had permitted the States concerned to approach the Ministry of Environment, Forest and Climate Change, if they are unable to adhere to this average percentage. The Secretary of the Ministry could examine such a representation in consultation with the Ministry of Water Resources, it said.
