Flood Management in Bangladesh: Traditional and Integrated Approach

Abstract

At the present time 130 million people of Bangladesh are facing a series of environmental problems. The people are repeatedly confronted by natural and human-made catastrophes such as flooding, surface and groundwater pollution, droughts, cyclones, riverbank erosion, air pollution, wetland loss, tornadoes, earthquakes, and coastal erosion. While some of these environmental degradations and calamities are not directly related to human activities and land-use practices (such as earthquakes, tornadoes, and cyclones), others are related to human interactions with the nature. Flooding is one water-related environmental problem that is directly related to human activities. The magnitude and intensity of flooding are very much dependent on land-use practices in the watershed of each rivers or streams. Bangladesh is faced with yet another flood this year. Finding solutions to the flooding problem is imperative. It is important to understand the processes that influence flooding in Bangladesh, before any solution to the flooding problem is prescribed.Riverine floods occur when the amount of runoff originating in a watershed (the area that collects and directs the surface runoff into the rivers, streams and lakes that drain it) exceeds the carrying capacity of natural and constructed drainage system. Flooding can occur due to river overflow or surface runoff. There are two types of floods which occur in Bangladesh: annual floods (barsha) that inundate up to 20% of the land area; and low frequency floods of high magnitude that inundate more than 35% of the area (bonna). While the annual floods are essential and desirable for overall growth of the Bangladesh delta and the economy, the major floods such as those that occurred in 1954, 1955, 1974, 1984, 1987, 1988, 1993, 1998, 1999, 2000 and 2007 are destructive and cause serious threat to lives and economy. We need to analyze possible underlying causes of recent unusual and frequent floods in Bangladesh in light of hydrodynamic processes that operate in the watershed and the land use practices that take place in this region.