Assessment of environmental flow for sustainable ecosystem management and livelihood security: A case study in Lower Damodar River Basin, India

Abstract

<p>Rivers are one of the prime sources of freshwater, governed by disparate hydrological and social factors. In the era of extensive large and small-scale water infrastructures, maintaining the river's natural flow is vital for sustainable ecosystem management. Hence, it is essential to acknowledge and implement the concept of environmental flow as a part of functional policies for better planning and reservoir operation. This research study highlights the importance of analysing and maintaining the environmental flow through computing the degree of deviation from the natural flow conditions of the river. It used the Range of Variability Approach (RVA) to calculate the degree of deviation while also lending a special focus on the implications of altered river flow regime on fishing as a livelihood practice for downstream riverine communities. The river discharge data from lower Damodar River basin were used to demonstrate the proposed methods. For the estimation of the degree of deviation, daily discharge data during pre (1934-1948) and post (1981-2013) dam construction periods were considered.  A high degree of alteration was found from indicators such as 90-day maximum and minimum annual extreme flows suggesting a regressive alteration post dam construction. Significant degree of deviation was also observed in the seasonal flow patterns across the time period. Furthermore, the study applied a convergent parallel mixed method whereby qualitative data gathered from the fishing communities was analysed alongside quantitative computations. The fishing communities also substantiated the computational findings by reporting declining water levels to have the highest relative risk (21%) followed by lack of fish availability (19%). These analyses emphasized the importance of maintaining the environmental flow for effectively managing the ecosystem and ensuring a secured livelihood for the community.</p>