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What role do tides play in the growth of the Ganges delta?

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Physical map showing the Brahmaputra and Ganges river basins and their drainage networks across northern India, Bangladesh, Nepal, Bhutan, Tibet (China), and Myanmar. The map uses color shading to indicate elevation, from the high Himalayas in brown and white to lowland plains in green, and marks major rivers, tributaries, glaciers, dams, irrigated areas, and regions subject to flooding. An inset locator map highlights the region within South Asia. — Ganges River The Brahmaputra and Ganges river basins and their drainage network.

The growth and morphology of the Ganges delta are significantly influenced by tidal processes. Because the Ganges-Brahmaputra system is subject to high tidal ranges, it is dominated by marine incursions, which result in an expansive lower delta plain that occupies more than half of the delta's total surface area.12

In this lower delta zone, the landscape is shaped by the interaction of both fluvial and marine processes, leading to the development of tidal flats, brackish-water marshes, and extensive mangrove swamps, such as the Sundarbans. While the upper delta plain remains above the reach of tidal waters, the lower delta plain is periodically covered by them, defining the boundary between these two physiographic regions. These tidal dynamics, combined with the massive sediment load delivered by the rivers, are fundamental to the delta's ongoing evolution and its characteristic geography.12