Heavy downpours in Meghalaya and Assam regions are causing flash floods in Bangladesh's northeastern Haor region at regular intervals. A high volume of water access to the Surma river through the downstream river network, the Haor region faces heavy damage almost every year. Literature review of past flood scenarios have shown that Sunamganj District directly faces the wrath of flash floods each year and witnesses tremendous damage. The major focus of the study was to assess the risk of flash floods in the greater Sylhet region. A geospatial multi-index model was developed which considered four major indices (hazard, exposure, sensitivity, and resilience) for the risk assessment. This model systematically accounted for various flood risk indicators related to the economic, social, and physical environment of the Sunamganj District. Geostatistical methods were used to calculate the risk from the indicators and Principal Component Analysis (PCA) was used for composite analysis. The result showed that the high- and very high-risk zones occupied almost 40% (~ 1452.51 Km2), while the very low- and low-risk zones covered about 45% (~ 1554.66 Km2) of the Sunamganj District. Based on the risk rank, Dharampasha upazila had high percentage (~ 60%) which followed by Sulla, Derai, Jamalganj, Daksin Sunamganj, and Tahirpur upazilas respectively. The proposed methods will help the researchers to identify the causes of flash floods and the results will be helpful for policymakers and developers to take steps for flash flood risks reduction.

Heavy downpours in Meghalaya and Assam regions are causing flash floods in Bangladesh's northeastern Haor region at regular intervals. As high volume of water enters into the Surma river through the downstream river network, the Haor region faces heavy damage almost every year. The major focus of the study was to assess the risk of flash floods in the greater Sylhet region. Literature review of past flood scenarios have shown that Sunamganj District directly faces the wrath of flash floods each year and witnesses tremendous damage. A geospatial multi-index model was developed which considered four major indices (hazard, exposure, sensitivity, and resilience) for this risk assessment. The model systematically accounted for various flood risk indicators related to the economic, social, and physical environment of the Sunamganj District. Geostatistical methods were used to calculate the risk from the indicators and Principal Component Analysis (PCA) was used for composite analysis. The result showed that the high- and very high-risk zones occupied almost 40% (~ 1452.51 Km2), while the very low- and low-risk zones covered about 45% (~ 1554.66 Km2) of the Sunamganj District. Based on the risk rank, Dharampasha upazila had high percentage (~ 60%) which followed by Sulla, Derai, Jamalganj, Daksin Sunamganj, and Tahirpur upazilas respectively. The proposed methods will help the researchers to identify the causes of flash floods and the results will be helpful for policymakers and developers to take steps for flash flood risks reduction.