Flooding and Drainage

73 Because of its location in the flood plains of three major river systems, the urban areas of Dhaka, most of which are low-lying areas except for the Mirpur highlands, have historically been flooded during periods of heavy rainfall in the upper catchments of these rivers. Once the rivers reach their hydraulic draining capacity, they tend to backflow into the city through the interconnected drainage channels and the peripheral rivers (Turag, Tongi, Sitalakhya, and Balu) thereby flooding the low-lying areas in and around the city. As a result, the Dhaka urban area has repeatedly witnessed flooding events. Severe river floods have occurred periodically during 1954, 1955, 1974, 1987, 1988 and 1998. In 1988, most of Dhaka was inundated by the flood except for the DND area, which was protected by embankment constructed earlier and the part of

the city near Mirpur. Following the floods of 1988, the western embankment was constructed under FAP 8B (Dhaka Integrated Flood Protection Project). After construction of western embankment, the western portion of Dhaka i.e. west of the central highland has now become almost flood free, but the eastern fringes of the city is still very much vulnerable to floods resulting from the backflow of primarily the Balu River. Due to the flooding from the Balu River in 2004, 40% of the area on the eastern side of the city was inundated for approximately a fortnight.

74 The urban flooding problem in Dhaka may get aggravated because of two main causative factors and they are briefly discussed below:

2.5.1 Illegal Filling of Low Lying Areas

75 The DMDP fringes areas mainly comprise of riverine flood flow zones. As most areas in the city i.e. the DCC areas have already been urbanized the fringe areas would have to be developed for making space for future growth (accelerated Growth Policy as per DMDP). Most of these areas are low lying areas and are presently inundated annually during the monsoon months as the water level in the rivers around Dhaka rises. To make these areas suitable for urbanization, these areas have to be raised by filling up to 2-3 m. As per existing regulation, development permission from RAJUK is mandatory before developing any land as per the Land Development Act for Private Housing 2004. However, the weak institutional structure and the lack of political will of RAJUK to implement the provisions of the act (regulated filling and protection of low-lying areas etc) have resulted in unplanned land filling in

these fringe areas of Dhaka for the purpose of setting up large real estate projects, targeted only at the affluent sections of the society who comprise about 5 - 10% of Dhaka’s population.

76 Most of these proposed real estates do not have required approvals from appropriate authorities, including the RAJUK or have obtained the same using their political influences or using unfair practices. In addition, without there being any systematic plans by RAJUK for land development and development control in such fringe areas, the intrinsic ability of these flood flow zones to retain or store excess water during periods of high rainfall is getting reduced. As a consequence, the risk of flooding continues to increase in Dhaka and adjoining low lying areas which are now being charted for future development.

77 The private developers' body (REHAB) through a public appeal had suggested to regularize through the Detailed Area Plans (DAPs) all the ongoing housing projects in such areas, many of which are in violation with provisions of law. This move had been strongly criticized by the civil

society and environmental groups but still no action has been taken against the erring land developers by RAJUK. Even though the law permits action against the land developers who violate the provisions of the act or even publish public advertisement without obtaining clearance from RAJUK under the Land Development Act, cases have been booked against only a few errant land developers.

78 It was reported by an expert from BUET in one of the workshops that in a recent study conducted in Boro Beraid, Santarkul, Kathaldia and Dumni moujas in the city's eastern fringe areas, severe socio-economic impacts have been reported on the original residents due to the earth filling. These people now face forced displacement from their ancestral homes as well as their traditional livelihood based on agriculture. Even though they are provided compensation amounts, in the absence of any comprehensive rehabilitation policy and with the low skill sets of the displaced people, the signs of impoverishment are even more pronounced. It has even been reported that due to the unlawful modalities adopted by the land developers, 53.2% of the affected locals are forced to sell their lands due to the tactics adopted by the developers, while 25.8% were compelled to sell just because their lands were turned into enclaves within areas filled up by developers.

Illegal filling of ditches and drainage channels

79 Dhaka is surrounded on all side by river systems and crisscrossed by drainage channels. The highland areas within the city have already been developed. Population pressures and requirement for more urban land within the city boundaries have resulted in encroachment of the water canals and wetlands which acted as flood retention ponds.

80 These facts were highlighted at the stakeholder consultations during the Cross Sectoral Workshop where the representatives for civil societies presented the case of encroachments in the Hatirjheel and Begun Bari Khal, two important wetlands in the central and southern parts of the city. These two canals are linked to the Norai Khal which drains water from a large part of the city. Both these wetlands have already been encroached; approximately 1200 illegal encroachments have been enumerated by RAJUK in Hatirjheel area. Most of these were constructed by influential people. In addition, during the tenure of the last elected government, land was allocated to Hotel Hilton International, Federation of Bangladesh Chambers of Commerce and Industry (FBCCI), International Arbitration Centre and a few CNG filling stations for setting up offices etc. even though the Wetland Protection Act 2000 prohibits filling up of low lands. It has been reported that land was allotted to Federation of Bangladesh Chambers of Commerce and Industry (FBCCI) at nominal price of approx US $ 1500 without any public bidding even though it is mandatory as per the procedures of the Government of Bangladesh.

81 Some government agencies, including RAJUK, DWASA, and Dhaka City Corporation (DCC), have also submitted proposals for constructing a link road or a circular road in the area to reduce traffic congestion in the city. The proposals also include constructing other structures over these wetlands. Implementation of these projects would result in greater inundation of the city’s central areas.

Potential Climate Change Impacts on Dhaka

82 The city of Dhaka lies at the focal point of three of the largest rivers of the Indian subcontinent in South Asia. Lying in the lower flood plains of the rivers Bramhaputra, Ganga and the Meghna, this area in central Bangladesh itself forms a part of a dynamic and active delta system. Such deltaic systems involve complex interaction between climate, catchments, deltaic deposition, tectonic subsidence and coastal regimes. At the same time, this region in Bangladesh supports an immense human population and contributes strongly to the regional and national economy.

83 However, being a part of such a complex natural system also means that this region is extremely vulnerable to natural events like floods, cyclones and coastal surges. The vulnerability in case of Dhaka is heightened because of the large and concentrated population that it supports and the rapid urbanization that has already caused immense stress on environmental resources. Climate change effects are anticipated to add to such stress with possible adverse impacts on city’s population, especially the economically disadvantaged sections of the society.

84 The onset of potential climate change effects in near future as predicted in the recently published IPPC report may result in a number of interrelated adverse impacts in Bangladesh involving complex interactions between physical processes. The combined effects of subsidence and sea level rise could result in increasing vulnerability to flooding events, serious drainage and sedimentation problems, in addition to coastal erosion and land loss. These changes may result in more frequent tidal surges which may potentially affect many coastal areas, cause inland fresh water resources to be affected by salinity causing serious drinking water supply concerns and limit irrigation over large areas because of reduced flow of fresh water resources from the rivers having sources in the Himalayan glaciers. A combination of such effects will have immense socio-economic impacts in the region. In quantitative terms, for example, a one metre rise could flood almost 30,000 km2 of Bangladesh, affecting over 13% of the population, mostly in the lower deltaic regions of the south.38

85 At the Dhaka level, the height of the DMDP area varies between 2- 6 m above sea level. The area is also known to be undergoing tectonic subsidence at an average rate of 0.62 mm/year, but can reach up to 20 mm/year39_{, thus effectively lowering height compared to the sea level. In} addition, a large part of the fringe areas of Dhaka comprising about two-thirds of the DMDP area

38

Source: IPCC Special Report on The Regional Impacts of Climate Change An Assessment of Vulnerability, Bert Bolin, Robert Watson, Marufu Zinyowera, Narasimhan Sundararaman, Richard Moss,1996

39

are characterized as flood flow zones. These areas are extremely prone to flooding and remains under water for most parts of the monsoon season due to overflow of the channels of the rivers as discussed before.

86 As a result of climate change effects, Dhaka may get adversely impacted in the following way:

• Increase in flood vulnerability in the surrounding low-lying areas would act as a disincentive for the city to expand spatially and disperse the urbanization process to accommodate the rising urban population thereby coming in the way of expansion of the city which may in turn impede the economic growth linked with the capital city;

• The increase in flooding potential would aggravate flooding problems within the city. It has been established during earlier flood events that the aggravation of flood situation in the city has been as a result of backflow from the larger rivers which again could not drain out excess water because of tidal influences. In the case of an increase in sea water levels, this problem may get more severe thus putting the present and proposed flood management system of the city under risk; and

• The associated problems of climate change leading to loss of land and livelihood for economically disadvantaged people residing in the surrounding regions of Dhaka is expected to result in creation of a large inflow of refugees into Dhaka, which is the only large city in the area that can provide them alternative livelihood opportunities.

87 The concerns influencing the flood and drainage of can thus be summarized as:

Box 2-8 Flooding and Drainage Environmental Concerns

• Increasing vulnerability of floods due to unplanned filling up of drainage channels, wetlands, low lying areas and climate change.

88 The analysis above has helped to formulate the environmental priorities discussed below. It was also clear from the above discussion that main causal links leading to environmental degradation are institutional failures, lack of enforcement, policies which provide disincentives for environmental conservation and governance constraints. These issues are discussed in Chapter 3.