Modelling of Urban Flooding in Dhaka City

Abstract

Flooding in urban areas is an inevitable problem for many cities in Asia, in the year 2000 Bombay, India and Phnom Penh, Cambodia had serious problems related to urban flooding. In Bangladesh, Dhaka has faced water logging for the last years. Even a smaller rain events may cause that parts of Dhaka have water standing in the streets. The situation was highlighted in September, 1996 when residences experienced ankle to knee-deep water on the streets. Daily activities in parts of the city were almost paralysed. Heavy traffic jams occurred due to stagnant water on the streets. With the advances in computer technology, many cities manage local and small flood problems with the computer-based solutions. But at present, a few studies of urban flooding with the simulation of both a surcharged pipe network and extensive flooding on the surface are available (Gupta et al. 1999; Heywood et al. 1997; Parikh 1990). In this study, modelling of urban flooding with the interaction between the pipe system and the surface flooding, including a description of the interaction between street and pipe network are carried out. BACKGROUND In Bangladesh, the Dhaka Metropolitan area has experienced water logging for the last years. Even a little rain causes a serious problem for certain city areas, so that parts of Dhaka are inundated for several days. The water depth in some of the inundated areas may be as much as 50-70 cm, which creates large infrastructure problems for the city and a huge economical loss in production for the city together with large damages of existing property and goods. In addition, deceases are spread and give problems to the population e.g. in terms of diarrhoea or leptospirosis, which may be spread by bacteria in the urine of rats. E.g. 6 921 cases of Leptospirosis were reported and 244 cases resulted in loss of human lives during the