Geology of the River
The Umngot River, also called the Dawki River, flows through the West Jaintia Hills district of Meghalaya. Its extraordinary clarity is a direct result of the region's geology. The river originates from the Eastern Shillong Peak and winds its way through hills composed of limestone and sandstone formations. These rocks act as a vast natural filtration system. As water percolates through the limestone, suspended particles and silt are trapped, leaving the water exceptionally pure and transparent. The riverbed, composed of smooth, colourful pebbles and stones, is visible even at significant depths, contributing to the optical illusion of floating boats.
This geological process is most effective during the dry season, from October to April. During these months, with minimal rainfall, the flow is calm and the natural filtration is at its peak. The water becomes so clear that visibility can reach up to 15 feet. In contrast, the monsoon season from June to September brings heavy rains that wash sediment from the surrounding hills into the river, temporarily turning the water murky and opaque. The river's path also forms a natural boundary, separating the Jaintia and Khasi hills before it flows across the border into Bangladesh, where it is known as the Shari Goyain River.