Environmental flows: issues and gaps-a critical analysis

The concept of environmental flows (E-flows) is not very old and is still evolving. The central theme associated with the E-flows is allocation of water for economic benefits and maintenance of sustainability of the riparian and instream ecosystems, riverine environment, and its habitats. Assessment of E-flows involves different methodologies with numerous criteria and thresholds. However, there is little consensus and more debate on criteria and flow thresholds, and regarding priority between development and environment. While many criteria and flow thresholds are relevant, some are inadequate or even inappropriate. Besides, there are other relevant and important issues related to flows and E-flows, which are either ignored or overlooked in the existing E-flows framework. This article through critical examination has pointed out the overlooked crucial issues (such as E-flows for temporary rivers, water quality criteria, impact of water stagnancy on water balance and hydrological cycle, and possible impact of climate change on E-flows), identified gaps in E-flows' policy framework and has recommended modifications in the E-flows policy and practice. Incorporation of the recommended criteria will surely make the E-flows policy robust and effective.