Ecological flow assessment using hydrological and hydrodynamic routing model in Bhogdoi river, India
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ORIGINAL ARTICLE
Ecological flow assessment using hydrological and hydrodynamic routing model in Bhogdoi river, India Anupal Baruah1 · Arup Kr Sarma1 Received: 24 August 2020 / Accepted: 1 October 2020 © Springer Nature Switzerland AG 2020
Abstract Rainfed perennial streams have a highly disturbed ecosystem. Seasonal drying and wetting are stressful for the spawning and breeding activities of aquatic faunas in those stretches. In this work, an integrated hydrological and hydrodynamic modelling study is carried out to estimate the ecological flow requirement in Bhogdoi river, India, a southern tributary of Brahmaputra river. Escalating anthropogenic activities continuously deteriorating the flow scenarios and degrading the aquatic health in the study area. The consequence of hydrological alterations is addressed in terms of the environmental flow regimes derived from FDCA (flow duration curve analysis) and FDC (flow duration curve) shifting method. Flow rates under different environmental management scenarios are evaluated and based on the analysis it is found that under the existing basin condition a minimum flow of 13.42–18 cumec is required for the river ecosystem. The flow depth and the current speed corresponding to the observed maximum flow and the ecological flow rates are computed from a two-dimensional hydrodynamic routing model. The model is calibrated and validated with the measured data. This eco-hydrological approach will be helpful to undertake the conservation and restoration strategies in the study site. Keywords Environmental flow · Eco-hydrology · Hydrologic model · Mean annual runoff · Two-dimensional hydrodynamic model · Shallow water equation
Introduction Sustainability and conservations of the river ecosystems are governed by the interaction between the physical, biological and chemical processes at the multiple temporal and spatial scales (Frothingham and Brown 2002; Thoms and Parsons 2002; Dauwalter and Fisher 2008). Highly dynamic nature of the aquatic ecosystems are generally governed by the hydrologic alterations, variation in hydraulic characteristics and sediment-nutrient regimes that may produce a variety of geomorphological features and habitats conditions to sustain the diverse ecological species in fresh, saline and marine water. The ecohydrological study is a way of understanding these parameters in riverine systems (Lytle and Poff 2004; Folkard and Gascoigne 2009; Nikora 2010; Dollar et al. 2007; Hannah et al. 2007, Shang 2014). Increase in anthropogenic activities and rapid urbanisations mostly impact the riparian * Anupal Baruah [email protected] 1
Department of Civil Engineering, IIT-Guwahati, Guwahati, India
system, deteriorates the aquatic habitat quality and a gradual loss in ecological functions of the water resources eventually leading to serious eco-environmental problems (Li et al. 2009; Karmokar and De, 2020). A comprehensive understanding of different factors and components that provides a suitable environment for river health sustainability is essential
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