Hydrological–Hydrodynamic Nexus for Evaluation of Fish Habitat Suitability in the Bhogdoi River, India

Abstract

Seasonal drying and wetting highly influence ecosystem diversity in intermittent streams. Hydrological alterations are responsible for the spawning and reproduction of aquatic habitats. The present study attempts to understand the impact of streamflow variations on the adult Bhangun fish (Labeo bata) in in Bhogdoi River, India, using eco-hydraulic modeling. Increased anthropogenic activities are constantly deteriorating the flow conditions and endangering the fish abundance in the reach. The eco-sustainability and habitat suitability of the target species are evaluated from the integrated hydrodynamic-habitat modeling under the various flow regimes. The ecological flow rates are obtained from flow duration curve analysis and flow duration curve shifting methods to indicate the hydrological changes under different environmental management scenarios. Two-dimensional depth-averaged shallow water equations are used to estimate the flow depth and current speed in the domain for different streamflow events. The hydrodynamic model is validated with the field observed data. Results of the study indicated that with the degradation in ecosystem protection, the environmental flow rates decrease. The hydrodynamic-habitat simulations indicate that the maximum flow and the ecological flow rate in the stream deprived the target species of a favorable environment to survive. The model outputs provide useful insight for ecosystem richness and diversity maintenance in the domain and help stakeholders in decision-making.