table 2.5
 

The floods of 1954, 1955, 1974, 1987, 1988 all caused enormous damages to properties and considerable loss of life. The consecutive floods of 1987 and 1988 caused heavy damage. Again during 1998 Bangladesh experienced most devastating and prolonged flood in the history and caused serious disruption on the economy of the country. Areas of Bangladesh was flooded in 1998 is shown in Figure-2.4.

According to government sources, the 1998 flood inundated about 100,000 km2. The 1998 floods affected 68% of the country, and seriously impacted the livelihoods of 30 million people. Overall damage was estimated at two to three billion U.S. dollars. Final estimates showed that 51 districts and 307 Upazilas were inundated, about 1400 people were killed, 1.77 million houses were damaged, and 23,45,8713 people became homeless. The 1998 floods lasted for over 10 weeks (WB, 2000).

The origin and wide-ranging impacts of the 1998 flood, which began in July and ended in September, are summarized below.

• The magnitude and duration of the 1998 flood can be explained in large part by the simultaneous realization of the impacts from three factors:
• Heavy rainfall/snowmelt in India and Nepal (which increased the flow in the rivers entering Bangladesh.)
• Increased July rainfall within critical river basins in Bangladesh (Ganges, Brahmaputra, Meghna, Southeastern Basin) .
• Tidal surges in the Bay of Bengal.

The first and second factors help explain the magnitude of the 1998 flood. In this respect, it is worth noting the extent to which the 1998 July rainfall totals within some of Bangladesh's critical river basins exceeded the typical July average.

The third factor, tidal surge levels in the Bay of Bengal, with back water effects, reduced the Bay's capacity to receive the floodwaters. This, in part, contributed to the duration of the flooding.