Flood Prediction and Risk Assessment at the South-western Region of Bangladesh

Abstract Although Bangladesh has been experiencing frequent flooding that has made colossal damages to lives and properties, overseeing floods remains a difficult task. Due to the complexity, scale, and multidisciplinary nature of flood management, it is a multisectoral activity. Khulna and Satkhira districts, located in the south-western region of Bangladesh, are considered as one of the most vulnerable areas to flooding due to their economic potential, demographic makeup, and adaptive capacity of the population. This research focused on finding the most vulnerable areas to flooding for each polder within the study area. Water level data from fourteen stations of seven rivers (Sibsa, Rupsa-Pasur, Kobadak, Bhadra, Kobadak, Ichamati (Western Border), Betna-Kholpetua, and Satkhira Khal) were analyzed to calculate water levels for 2, 5, 10, 25, and 100-year return period applying normal distribution, Extreme Value Type-I (EV-I), and Log Person Type- III (LP-III) distribution methods. The EV-I distribution method was showing the best fit. The study revealed that station SW243 (Rupsa-Pasur river) in the Dacope region has the most extreme water level, station SW259 (Sibsa river) has the second-highest water level, and station SW254.5 (Satkhira Khal) in Satkhira Sadar has the third-highest water level for the return period of 100 years. A flood inundation map was prepared using the EV-I method's 10-year return period value. The Analytic Hierarchy Process (AHP) was used to demonstrate the polders' vulnerability depending on several factors. Overall, polder15 (Ghubra, Satkhira) is the most vulnerable polder, while polder 33 and polder 32 respectively are the second and third most vulnerable polders for flooding, both located in the Dacope region.