Overflow in the Meghna Basin is usually flash-flood in nature, which occurs in June and July of the year. The torrential rainfall in Cherrapunji of Meghalaya causes rapid runoff and flows downstream to the northeastern districts of Bangladesh, particularly Sunamganj and Sylhet. This extremely heavy flow of rainwater in a short duration exceeds the carrying capacity of the rivers and causes an overflow in the northeastern part of Bangladesh within the Meghna Basin. In recent decades, the severity of flash-flood in this region has intensified due to the deforestation in the southeastern hills of Meghalaya, which triggers surface runoff; reduction of rivers width and depth due to sedimentation and intentional encroachment, and unplanned developments (e.g., roads, dykes, dams, etc.) in the Haor area. A most severe flooding example within the last two decades in this region is the flood of 2022 that occurred in May with a second wave starting on June 15. With the highest recorded rainfall in the last 100 years, that devastating flood affected around 7.2 million people and 105,000 hectares of croplands in the nine northeastern districts of Bangladesh where Sylhet, Sunamganj, Moulivazar, Habiganj, and Netrakona were heavily impacted.
Author: Sanjoy Roy
[GRU is the Geographic Research Unit of Bengal Institute]
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