The population of Dhaka city is constantly increasing and its area is increasing along with it. The natural drainage system of Dhaka city is dying today.
The biggest blessing of Dhaka city was natural drainage management. The natural management of drainage in Dhaka city is under threat today and the reliance on artificial management is increasing. Today, about 80 km of natural canals in Dhaka are almost dead due to pollution and grab. The destruction of natural canals has resulted in waterlogging in Dhaka city with little rainfall.
Drainage management in a modern city works in a combination of both natural and artificial processes. It is not possible to eliminate waterlogging in Dhaka city with artificial drainage management only. On the one hand, the natural canals have been severely polluted and on the other hand, road, houses, factory have been constructed by filling those canals.
According to experts, a city should have 20 to 25 percent green areas and 10 to 15 percent wetlands. There were such canals and reservoirs in Dhaka city for normal drainage but we have destroyed them day by day. According to a study, in the main city of Dhaka, the concrete covered area is over 80 percent where the water body is 5 per cent and the green is 10 percent. From this study it is clear that the system of natural drainage is very miserable in Dhaka. There is also a deficit in artificial management. Rainfall during the monsoon season is much higher than the current capacity of the drainage system, resulting in waterlogging.
According to a recent newspaper report, 98 percent of the total sewage in Dhaka city is being discharged into river and canal water without any purification. This is creating serious health and environmental risks. 1 percent of the total sewage of Dhaka is dumped under the open sky. 69 percent of sewage is overflowing and coming into the drains. 9% of the waste is collected from the houses but it is being discharged into the reservoir without any purification. Only 2% of the waste is completely purified and mixed in the reservoir. 175 crore liters of sewage is generated every day in Dhaka. These water channels are directly connected to rivers and canals. As a result, sewage is flowing into canals and rivers. The canals in Dhaka have been under WASA for a long time and they have been handed over to the City Corporation. Now the process of eviction of illegal occupants of these canals has started. Dhaka North City Mayor Atiqul Islam says there will be no more garbage in the canals and fish will be farmed there and canals will be used to navigate the river by boat. It has also been proposed to hand over the lakes in Dhaka city to the city corporation.
The government has been conducting vigorous operations to rescue river, canals and reservoirs in recent times. Various development plans are being taken up focusing on canals and reservoirs. Experts believe that if such initiatives continue, it will be possible to increase the interconnection of Dhaka's canals and restore their proper flow. Experts believe that Dhaka WASA could not maintain the canals properly. Again other agencies involved in canal conservation and development management cannot avoid liability. Waste removal and cleaning campaigns should be carried out to keep canals and sewers flowing properly. Concrete waste often makes the drainage system ineffective so special attention should be paid to concrete waste management. The canal must be cleared of illegal occupation at any cost otherwise development of drainage system is not possible. Public participation is needed to keep drainage and box culverts effective.
We have been noticing a number of initiatives since the two city corporations took over the responsibility of rescuing the canals in Dhaka. The City Corporation has taken steps to remove waste from many canals and box culverts which is really commendable. Canals and reservoirs are an integral part of the river network. The High Court has directed to keep all the rivers and canals of the country alive and vibrant. To grab water bodies is a punishable offense under our existing Environmental Protection Act 1995 and Water Conservation Act 2009.
Recently, the National River Conservation Commission Act 2020 has been drafted which provides for maximum punishment of 10 years imprisonment or a fine of taka 5 crore or both for grab and pollution of river canals and reservoirs. Drainage and manhole entrances are blocked due to pollution and solid waste and this halts excess water from flowing, so waterlogging occurs.
There is a lack of effective waste management and maintenance and as a result sewers and natural canals have been filled with garbage. There is a considerable lack of coordination among the agencies involved in drainage management. Unplanned urbanization and public unawareness have further exacerbated the problem. Regulators and switch gates often break down and are not repaired timely leading to problems. Dhaka WASA made Drainage Master Plan in 2015 but its notable effectiveness has not come to the notice of the people. There are mentions of 47 canals in that master plan. It is very important to determine and preserve the boundaries of natural canals and reservoirs and sinks. Drainage through natural canals instead of box culverts is more effective. It is important to establish Dhaka City Corporation Drainage Circle. Plastic waste needs to be strictly prohibited. Regular excavation of rivers and canals around Dhaka and increase navigability is required. There needs to be a high level technical committee to take care of these. Of the total drainage lines in Dhaka city, 385 km are under Dhaka WASA and about 2500 km are under Dhaka City Corporation. In addition, WASA is responsible for the maintenance of 26 canals of 74 km length and 10 km box culverts.
There is a lack of coordination among the agencies working to alleviate the waterlogging in Dhaka and there is a tendency to blame each other. Various solid and heavy wastes accumulate on the surface of drains and in the mouths of canals which are not removed on time and there is lack of supervision. Occasionally, illegal occupants are evicted and canals are decontaminated but after a while it returns to its former position. This requires strict monitoring and proper enforcement of the law. Large eviction operations have been carried out around the capital. There are guidelines for creating digital databases of all river, canals and reservoirs in the country.
About 6,250 tons of waste is generated in Dhaka city every day but in this megacity, modern, sustainable and improved waste management has not yet emerged. Unwise disposal of waste has become a major threat to the environment and public health. Huge waste is generated every day in Dhaka city and the total waste cannot be collected by city corporations and this uncollected waste goes to rivers, canals, ponds and drains. The amount of waste recycling is relatively low. Dhaka North City Mayor Atiqul Islam said common people consider Dhaka's canals as dustbins and it is really difficult to decontaminate them if they are not aware. The mayor also said that without waste incineration, it would be difficult to control Dhaka's waste in the future. It is learned that there is a master plan to set up ecopark with two incineration plants for waste management.
Waste of Dhaka city is disposed in open landfill system which is not suitable for environment. A landfill site is a place where waste is accumulated for removal. There are several rules for building an ideal landfill site. In 1991 the Environmental Protection Agency (EPA) formulated a number of policies for landfill sites. No reservoir can be kept within 30 meters of a landfill site and no drinking water tube well can be kept within 160 meters. No home, school or park can be placed within 65 meters of the landfill site. But experts believe that all these rules have not been followed properly at the two landfill sites in Dhaka city (Matuail and Aminbazar).
The two common methods of waste management are Area Method and Trench Method. According to the first method, rubbish is piled on the ground and according to the second method, the waste is covered with soil. Although the implementation of area method at landfill site is moderate, the trench method is not fully implemented resulting in dirt in the open space. These rubbish get mixed up in the canal and river water gradually. According to a World Bank study, Dhaka generates 7,000 metric tons of waste per day, of which 3,800 metric tons is dumped. Household waste is generated at 5950 metric tons. 560 grams of waste per capita is generated in this city every day.
There are not enough cleaners in city corporations to remove such a huge amount of waste. From 2022 onwards, there will not be enough space to dump garbage at the Aminbazar landfill site. Therefore, it is necessary to take a master plan now for waste management in the coming days.
A lot of money is spent every year to reduce waterlogging in Dhaka city but it is not very effective due to lack of proper waste management and conservation. Dhaka city has more than 2200 kilometers of drainage. Necessary equipment and people are required to maintain this drainage system.
City corporations can collect 60 to 70 percent of the total waste of Dhaka city but the rest goes to the canals and rivers. This results in severe waterlogging. Experts believe that a separate commission could be set up to deal with waste management. Experts believe that special strategies are needed for solid and liquid waste management. It is only possible to ensure a beautiful waste management through proper coordination among the waste management agencies.
The writer is Assistant Professor, B A F Shaheen College Kurmitola