Impact on endangered Gangetic dolphins due to construction of waterways on the river Ganga, India: an overview

Abstract

The charismatic Gangetic dolphin, Platanista gangetica gangetica, is distributed in the Ganges–Brahmaputra–Meghna and Karnaphuli–Sangu river systems of India, Bangladesh and Nepal. The Gangetic dolphin is an important freshwater mammal since it is not only an indicator species of the river ecosystem, but also occupies the apex position in the aquatic food chain. Their habitat is severely stressed due to dams and barrages, habitat degradation and fragmentation, river water pollution, poaching, accidental killing and over-exploitation of prey. Further, the dry season water depths and flow in Ganges have severely diminished in recent years due to higher water allocation to canals for drinking, industrial and irrigation projects. In 2016, the Government of India proposed the National Waterways Act, initiating the construction of 111 inland waterways, along a total length of about 20,275 km across 24 states and two union territories of India. The Ganga watercourse, also called the National Waterway 1 or NW1 (Varanasi–Haldia stretch), is being designed to transport passengers and cargo from the eastern seaport of Haldia (West Bengal, India) to Varanasi (Uttar Pradesh, India), about 1360 km inland. Of the total 111 inland waterways proposed, 38 are habitats of the Gangetic dolphins. The intended waterways overlap with approximately 90% of the endangered dolphin population. The proposed scale of development—the two-way movement of large barges including intrusive methods of making the river navigable—has the potential to wipe out the dolphin habitats in these water bodies. Without suitable habitat, population of dolphins cannot be sustained. This paper primarily focuses on the impacts of dredging, vessel traffic, and pollution resulting from the construction of NW1 on the endangered Gangetic dolphins. The paper recommends for a critical re-consideration of the various hydrological and ecological functions of river before commissioning of the project.