Capital Dhaka: Towards an environmental jeopardy?
Unhygienic dumping of waste (Left ). And Pollution in Gulshan Lake (Right). Photo: Tanjil Al Aziz
DHAKA is the capital city of Bangladesh. Located on the bank of river Buriganga, called its life line it is the most populous city of the country. It is also the most important city of the country for its commerce and education. Dhaka is projected to be the world's 4th most populous city by 2020 with 22 million inhabitants, according to United Nations Population Fund (UNFPA). It is the most rapidly expanding city in the country with present land area of 2000 km2 and population 120 million. But this capital city of ours is affected with various environmental problems staking the lives of its inhabitants. Because of highly dense population, lack of environmental consciousness among the inhabitants and absence of proper role of public agencies it is going to be one of the deadliest cities in world as well. Among its environmental problems huge extraction of ground water, crisis of pure drinking water, incapacitated drainage system, unplanned high rise buildings, discharge of industrial waste in rivers and waterbodies, shortage of electricity and insufficient disposal facilities for solid waste appear most perturbing. Solid waste management: To its inhabitants, the authority and visitors, the most disgusting phenomenon of Dhaka city is possibly the mismanagement of solid wastes. The solid wastes are generated in the city area from various sources like residents, markets, commercial centres, industries, hospitals etc. Wastes generated in Dhaka City are estimated to be 1950, 1050 and 200 ton/ day from domestic, business and street sources, respectively. Dhaka City Corporation (DCC) is the responsible authority for solid waste management. At present DCC uses three landfill sites for dumping of its solid wastes namely Matuail, Bern Band and Uttara. But the collection, processing and dumping are not done in environmentally sound manner. Wastes are found to be spilled over streets polluting the air with malicious odour. The dump sites are open alike. Vectors of many diseases naturally find a heyday. Sewerage, sanitation and hygiene: Condition of Dhaka city in respect to sewage management, sanitation and hygiene is just despondent. The sewerage system of Dhaka city covers only one third of total urban area. Dhaka WASA utilizes the existing canals and sewerage pipes to collect the waste water from different residential areas , carry the effluent to depose, most of it, into surrounding rivers without any treatment . Many canals are cut and transformed into lakes. Even these lakes are getting highly polluted due to disposal of waste waters collected from the municipal sewages. Unhygienic conditions prevail in the markets, industries, roads and even in the parks, play grounds and lakes. The problem of sanitation and hygiene is simply acute in the slums. Water bodies, drainage and floods: Once upon a time there was a good network of natural canals within the city which served as means of draining the rain run off and water during an event of flood .Those canals were also a good means of transportation. But this natural drainage system is almost damaged now. Man made drainage and sewerage system used as drainage system are not sufficient enough for this growing metropolis. Flood almost every year visits the city victimizing millions of people in and around. In this respect the localities situated in the city suffers most, especially the inhabitants of old town. Degradation and demolition of natural drainage systems are two causes of flood's severity in some parts of the city. Ground water extraction: Many ponds that worked as runoff reservoir are filled up yielding space to housing and roads. Being one of the largest mega cities in the world, Dhaka is facing continuos potable water-related problems over the last few decades. Ground water extraction poses a great threat to the sustainability of the city itself. Dhaka WASA mainly depends on ground water extraction to continue its supply to increasing number of inhabitants in the city. Due to increasing population and industrial growth the demand for fresh drinking water is rising rapidly. Currently, DWASA is producing around 1200 Ml/day for the urban water supply from about 423 deep tube wells. About 82% of the municipal water supply for domestic use comes mostly from the groundwater sources. In addition, over 500 private tube wells of different depths also exist in this city, which arc estimated to supply about 300 Ml/day, mainly to commercial and industrial users. In Dhaka city, natural recharge to the aquifer is mainly from two sources -- direct infiltration and deep percolation of rainwater, as well as water accumulated on the land surface. Leakages from sewerage system form critical problems for ground water while the recharge to the aquifer has reduced gradually as the rechargeable areas are being reduced due to urbanization, covering the ground surface with tarmac or concrete and filling of channels and depressions. As a result the ground water table is being lowered with time. Low recharge indicates future unavailability of ground water and risk of land subsidence. Highrise buildings and earth quake: A great source of urban problems is unplanned building construction. In fact Rajuk has no execution plan. By any one and anywhere it's possible to construct a multistoried apartment. It is not considered whether the increasing load on electricity, gas, water, sewerage and the road itself shall be plausible anyway. Even the subsurface hydrogeological conditions are not considered before construction of high buildings. The ongoing process seems to be a mechanism for attracting more people in this city of jeopardy to gain some immediate benefit. Unplanned building of multistoried apartments and commercial complexes also increasingly makes the city vulnerable to an event of earth quake .No one knows what will happen if an earthquake having magnitude of 6 or 6.5 in Richter scale hits Dhaka city. Fire incidents: Recurrence of fire in Islambag of Lalbagh Thana has drawn the attention of people around the city. Unplanned setting up of factories and highly dense population are believed to be the two major causes of such recurrence. Most of the accidents occur in the spring and early summer season when humidity in the air is very low and ambient temperature is very high. Most of the fires started from the polythene and plastic factories. Though production of polythene less than 20µm is prohibited but polythene under the permitted thicknesses is being produced and consumed in the city and beyond. Polluted rivers: Dhaka is surrounded by four rivers -- Buriganga, Shitalakhya, Turag and Balu but all of them have been and are polluted unabatedly. Pollution of these rivers is directly related with the city life. Buriganga, the mother of Dhaka city, although moribund but still nurtures its child. River pollution occurs due to three reasons. Two main causes are discharge of municipal sewage and industrial effluent: 277 tanneries at Hazaribagh are discharging waste water into Buriganga without any treatment. Third cause is waste thrown by water craft. The effect of pollution on the aquatic ecosystem cannot be expressed in words. The rivers around the city are so polluted that Dhaka Water Supply and Sewerage Authority(DWASA) has to depend mostly on ground water to continue municipal water supply for the cost of treatment of river water goes beyond its bearable limit. Waning biodiversity: In the city there are still a few parks and some open spaces such as, graveyards and playgrounds with some vegetation but virtually not rich in biodiversity. Vegetation in the urban locality is the niche of urban ecosystem .Ecosystem services depend on the amount and quality of green spaces. Green spaces are dwindling in unprecedented rate in Dhaka city. This decline must be arrested now. Unplanned industries: Tejgaon is the announced industrial area of the city but you will find industries indiscriminately distributed throughout the city. Special attention is drawn to the highly densey old Dhaka. Residential areas of Hazaribagh, Lalbagh, Kotoali and Sutrapur are increasingly containing many industries. There are so many small industries that are not even documented by the proper authority. The waste water from these industries is directly discharged into nearby river or waterbody. These industries being in the residential areas create acute civic problem by generating huge solid waste that is heaped on the road and air and sound pollution beyond tolerance limit. Concluding remarks: The problems of Dhaka city are multifarious in nature .But roots of all problems are apparently two: rapid population growth due to failure of population control measures and migration of rural people to the capital due to river erosion and other unplanned industrialization and development activities. Rest of the liability goes to the factors, unconsciousness of citizens toward environmental pollution as well as protection, and failure of government agencies responsible for these services. Should we allow things to go on this way to the further jeopardy Dhakaites while celebrating the capital's 400th anniversary? Mahfujur Rahman a Graduate in Environmental Sciences, works for Centre for Environmental and Geographic Information Services(CEGIS).
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