Proposed rejuvenation of a dry river: A case study of Sukapaika River, Odisha

The rejuvenation of ephemeral river systems requires a scientifically robust environmental flow (E-Flow) assessment to ensure sustainable restoration. This study evaluates the Sukapaika River, a historically significant tributary that has remained dry for seventy years, to assess the viability of a proposed restoration plan. Using a validated 21-year daily discharge dataset derived from a hypothetical 10% inflow from the parent Mahanadi River, multiple hydrological methods were applied to examine a design discharge of 11 m³/s. Static approaches, including the Tennant and Tessman methods, indicated that this discharge is insufficient to meet ecological requirements during the high-flow monsoon season. Flow Duration Curve (FDC) analysis further showed low annual dependability (Q40). However, shifting the FDC using the Global Environmental Flow Calculator (GEFC) classified the discharge under ecological management class (EMC) D, validating 11 m³/s as an ecologically acceptable seasonal target with minor deficits in August and September. The assessment suggested that 12.5% of the mean annual runoff is required as E-Flow. Subsequent 1D hydraulic modelling using a validated HEC-RAS model (NSE = 0.83; PBIAS = -4.8313%) revealed low velocities due to degraded channel morphology and encroachment. A dynamic e-flow regime with channel restoration is, therefore, recommended.