Assessing the effects of human interventions on the morphodynamics and health of a lowland tropical river: A case study of the river Dwarkeswar, India

The present study tries to analyze the impact of human activities on the physical and chemical health of the Dwarkeswar River. The river flows through a densely populated area. As a result, nearly 4000 t of sand are being extracted per day from the four segments of the river. Moreover, huge materials are extracted from the river to supply the raw materials of 97 brick kilns developed along the banks of the river. An industrial plant extracts 2,200,000 L d⁻¹ of water from the Dwarkeswar River, besides nearly 80 water lifting pumps. Similarly, a number of bridges are constructed across the river, and embankments are made along the banks. Per day 15.10 million liters of untreated sewage drain into the Dwarkeswar River from Bankura Town. The town also generates 63,111 kg/d of solid waste, some parts of which are disposed on the bank of the river. Intensive field surveys, analysis of multi-dated satellite images, and water quality parameters of the last ten years (2011–2020) were carried out in the present study to assess the impact of these interventions on river morphology, hydrology, and water quality. The comprehensive pollution index (CPI) was used to assess water quality. Results reveal that the Dwarkeswar River is highly affected, including the planform change, reduction of mean discharge and increase in the concentration of pollutants in the river water. The CPI value increased from 0.72 (2011) to 2.81 (2020), which indicates a severe increase in the level of pollution.