Bangladesh

Flood Risk Management in Dhaka: A Case for Eco-Engineering Approaches and Institutional Reform

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Dhaka is the cultural, political, and financial center of Bangladesh. It is one of the largest and most densely populated cities in South Asia, with a population of approximately 17.5 million people in 2015 and growing at the rate of over 3 percent per year (World Bank 2015). By 2025, the United Nations (UN) predicts Dhaka will be home to more than 20 million people—a population larger than that of Mexico City, Beijing, or Shanghai. It is estimated that almost 34,000 people inhabit each square kilometer of the city, yielding a population density that is among the highest in the world (Dasgupta et al. 2015). The city contributes about 34 percent of the country’s gross domestic product (GDP), indicating its economic and strategic importance.

Dhaka is highly prone to water-related hazards such as urban and river flooding, owing to its location, topography, climate, and proximity to rivers. It experiences major floods regularly, as in 1954, 1955, 1962, 1966, 1974, 1987, 1988, 1998, 2004, and 2009. Situated in the lower reaches of the Ganga delta, the Dhaka Metropolitan Area (DMA) is surrounded by rivers and tributaries: the Buriganga to the south, Turag to the west, Tongi Khal to the north, and the Balu-Shitalakhya to the east. The city is low lying, with an elevation that varies from 0.8 to 14 meters above mean sea level, and is drained by numerous natural waterways and canals.

Dhaka is also among the most climate-vulnerable megacities in the world (Maplecroft 2013). Climate variability and change are expected to intensify the city’s exposure to environmental risk and heighten the extent and duration of urban flooding and inundation. With rapid and unplanned urbanization, the vulnerability of the city, and particularly of its poorest residents is likely to increase unless measures to ensure resilience are put in place. During the 1998 floods, most of eastern Dhaka and some parts of western Dhaka were inundated for almost 65 days. The impact of flooding is widespread: it compromises the sewerage system, degrades drinking water, disrupts traffic, and increases the incidence of water-borne diseases. While city-level cost estimates of the damage from extreme floods are scarce, one study estimates the damage from the 1998 floods at approximately $171 million.

At present, Dhaka is at a crossroads of development. The main planning agency, Rajdhani Unnayan Kartripakkha (Capital Development Authority, RAJUK) is drafting a Structure Plan (2016–35) for the next 20 years. The design and implementation of this plan will shape infrastructure development and the pattern of urbanization in the city for decades to come. The emerging plans and their implementation will also affect management of the city’s water and ecological resources, influx of rural migrants into the city, supply of jobs and affordable housing, and adaptation to climate risks.

Management of flood risks is a critical part of this story. As the city urbanizes, it is imperative that it builds on lessons of the past so that flood risks are fully integrated into urban planning and managed effectively. Although there is an extensive literature on Dhaka’s urbanization, flood risk management, and poverty, few studies have assessed the historical drivers of the city’s decision making with respect to flood risk management, linkages between urban planning and flood risk, or the political-economic and institutional issues constraining improved flood and urban resilience. This study aims to fill this gap.