Perennial problem of waterlogging

This year has been a particularly wet year. Even after the rainy season is officially over it has been raining heavily at regular intervals. And traffic jams, already terrible in the city in the best of times, worsens even further, during the wet days. In these days in a modern city such a situation should not be expected. However, in Bangladesh one learns to expect the unexpected and also live with it.

Almost on an annual basis Dhaka WASA and the two city corporations trade blame over the recurrent failure to keep the 360 square km capital free from waterlogging in rainy days.

The three entities repeated the same old story that none of them controlled the facilities for the drainage of the entire capital. The blame game does little good to the residents as they see no progress in bringing the capital’s drainage system under a single authority, though a move was initiated in this direction more than a decade back.

Dhaka Water Supply and Sewerage Authority has the responsibility to look after the drainage of 39 per cent area of the capital. DWASA with its 10 km of box culverts and four pumping stations drains 140 square km of the 360-square km capital into 65km open canals. DWASA’s drainage pumping stations are located at Dholaikhal, Kallayanpur, Rampura and Janapath. The two city corporations maintain around 2,500 km of surface drains and around 4,000 km of underground drains.

According to experts until and unless DWASA recovers its 26 canals there can be no improvement of the situation. WASA’s clogged outlets obstruct the passage of water into its canals and WASA rarely if ever cleans its outlets. As said earlier the situation can improve only if the three entities worked together. On July 11, 2003, the government decided to bring the drainage system either under the control of either then Dhaka City Corporation or DWASA. There has been no progress on the issue ever since. A total of Tk 303 crore was spent in last four years of the project launched for reducing the waterlogging problem of the capital city Dhaka.

Garbage keeps piling on the roadside or beside the drains and many manholes are kept uncovered. So the solid waste is washed into the drains after rainfall. Thus, crores of taka are wasted in the name of sewerage clean up. It is vital to clear the drains before the rainy season. Besides, Dhaka WASA should ensure transparency of the drainage cleanup fund.

Now when it rains in Dhaka rather than people being out on the streets singing and dancing in the rain, they have to worry about flooded major connecting roads, waterlogging and falling trees. The situation is quite similar in other parts of country as well. A major cause of the problem is that cities have become less dependent on their own water sources. The number of water bodies in all major cities has drastically come down over the last three decades. The builder-politician nexus has knowingly and intentionally suffocated the city’s open spaces for commercial purposes. This loss of and subsequent commercialization and concretization of open spaces has meant that water, which previously could seep into the soil has practically nowhere to go, leading to flooding.

The floodplains and lakes in the low-lying parts of a city, did not just fulfil the water needs of a city, but also drained it off the excess rain water. When construction blocked the path of water, it led to waterlogging on the city roads.

The blame then fell on the storm water drains which in most cases, were designed very long ago and were not capable of handling the excess.

Dhaka’s drainage system was designed for a maximum rainfall of 25 mm per hour, assuming that half the rain would be absorbed by the soil and only half would flow into the drainage system. With the onset of rampant and indiscriminate urbanization, most areas are now paved, concreted or asphalted. As a result very little rainwater is absorbed into the ground. Thus even at one inch per hour, the drainage system has to cope with almost twice its intended capacity.

Natural drainage or the slope of a city was never kept in mind when it was planned. The government should start cleaning drains in February at least so that passage for rain water is clear. But they wake up only in May when monsoon is right in the face and then too, debris collected from the drain is left on the banks of water bodies for it to flow back when rain comes.

Water harvesting in lakes and ponds is a time-tested solution and need of the hour, not just to mitigate floods but also to fulfil our water requirements locally. Rain water is actually meant to become ground water so every citizen has to take the initiative to recharge it. When somebody constructs a house it is their responsibility to take care of the excess water from that plot of land, which would otherwise go into a storm water drain or else create waterlogging around the plot.

The solution is a proper rain water harvesting system in the house itself. It would not just replenish ground water but also improve its quality and mitigate flooding. Five per cent of any built up area, be it an apartment complex or individual house, if used for rainwater harvesting, can mitigate floods and also reduce water bills. Some towns in Germany have made it mandatory for construction projects to take responsibility for their excess run-off or pay more for putting pressure on storm water drains.Rain water harvesting is what all individuals can do but the administration can contribute to this effort as well. Storm water drains could be utilized as water harvesting measure rather than just act as carriers of excess water to the sea. Recharge wells can be constructed in open spaces around storm water drains. Water in drains can be intercepted and directed to these wells. In areas where open spaces are not available, recharge wells can be dug in the drain itself under the man-hole so that it can be cleaned also from time to time.

Every drop of rainwater contributes to floods, so permeable gravel or stone lined parking spaces and footpaths that can absorb water rather than concretized floor would also help. And there is no substitute to planting trees in whatever area is available to promote absorption of water and control run-off of soil.

Waterlogging has a serious impact on public health as rain water mixes with dumped waste, toxins of the drains and even weak sewerage systems. In many areas, water supply connections are contaminated and people have to go far to collect drinking water. People often face common skin diseases, malaria and water-borne diseases.

The writer is Senior Assistant Editor of The Business Post