Cover Story

When it Rains, it Pours

Nader Rahman
photo: zahidul I. khan and Star File

One of the first nursery rhymes taught in school is “rain, rain go away come again another day”, these days in Dhaka that simple nursery rhyme has far more serious connotations. While rain is inevitable in Bangladesh its consequences have reached epic proportions for Dhaka, the past two weeks have been a precursor of what is to come next if the rains continue and our rampant urbanisation goes on unabated. Currently 30 minutes of rain is all that is needed to temporarily flood the city. The result, hundreds of thousands of people left stranded and the capital coming to a standstill, all because of a simple monsoon shower. If the problem is not tackled now we may unwittingly turn Dhaka into the Venice of the great delta.

Wading to school may become more frequent in the future

There are a few questions that need to be answered before we map out a plan of action. Firstly why is it that only brief showers are needed for the city to be waterlogged? The answer to that question is quite simple. Normally when it rains, the rain water is usually soaked up by the ground, that is to say unpaved land, and the rest of the water builds up in small to large scale water bodies such as ponds, lakes and even rivers. The remaining rain that falls on a city should be carried away by a functioning drainage system. Dhaka's rain water follows none of the above mentioned rules because over the last few decades most of Dhaka has been paved over, the number of water bodies has decreased and a faltering drainage system has all but failed.

Little pieces of the lake are taken into the developer's fold, first a small pathway, later a large chunk of an apartment building

So why has the situation come to this? The truth is that while Dhaka's expansion has always been on the agenda for economic growth for successive governments, the growth of the city has happened without any kind of supervision or foresight. This unsupervised urbanisation is what has led to the current crisis. The blame must be shared equally. Dhaka suffers from two types of water logging, the first is categorised as river flooding and the second rainfall induced flooding.

River flooding is a common concept but it is not as simple as one may think. The common perception is that when the rivers surrounding Dhaka are high enough the water spills over into the city. That concept is wrong, Dhaka is surrounded by the Buckland Flood Protection Embankment and that essentially protects the city from major floods; but there is a catch. While the embankment protects the city from direct flooding from the rivers themselves, the flooding the Dhaka goes through is almost entirely drainage based. Floods occur when the surrounding rivers levels are higher than the internal drainage levels, thereby meaning internal drainage is heavily dependant on the peripheral river system. Currently the drainage system is heavily dependant on the difference between the water levels of the river outside Dhaka and the drains inside Dhaka. Therefore when the river levels increase the drainage capacity decreases and what little water enters the city subsequently cannot leave the city.

'Akkach Nagar' another housing project to take over the low-lying areas

While that is the major problem for river flooding, the water logging caused by rain is aggravated by the lack of drainage as well. This monsoon could be Dhaka's worst nightmare, that is if surrounding river water levels rise and then if it rains in the capital we could be done in by both river and rain flooding. But while drainage may be the main problem for water flooding, the current water logging crisis has many more variables most of which revolve around the culture of making illegal money from filling up lakes, rivers and our natural wetlands along with alarming unplanned urbanisation.

According to Dr Sirajul Islam, Assistant Professor, Department of Environment and Management unplanned urbanisation, in fact, is the root of the problem. "Our previous governments should have planned the city out and overseen its expansion by advancing the infrastructure needed to support it" Islam explains. "Essentially what happened was that the numbers of people coming into the city grew rapidly that seemingly coincided with a housing boom and overnight the city was paved and buildings popped up out of no where. While one may argue even that could have been dealt with had the infrastructure grown along with the city, but the drainage system did not expand its net. Aside from drainage even water and electricity lines did not increase.” The unplanned urbanisation had other effects as well, the current traffic situation could also be blamed on the uneven expansion of the city and that coincides with our air pollution problems.

For Dr Islam there is a clear link between the urbanisation and our current water logging problems, he continues, “There are and should be no problems with a city growing; what happened with Dhaka was that the urbanisation came with a price tag. The price was that to house a few million more people we had to continue making new buildings, and even that was not bad. But constructing new buildings on open grounds, over lakes and on the fringes of our natural wetlands, that was where we went wrong. As the percentage of the paved area increases the water infiltration levels go down. In simple words, before the rain water was soaked up by the soil, now with only concrete to fall on it is no longer retained by the soil but instead builds up on paved land, which coupled with an inadequate drainage system, is what leads to rain induced water logging.” The outcome is shocking, and then again so is the problem. It is a basic element of city planning that open spaces will remain intact and in fact even be encouraged rather than paved over with high-rise buildings.

A faltering drainage system and lack of solid waste management has exacerbated waterlogging

The boom in the housing market has many associated problems. Firstly, new buildings should not have been a problem had they been planned and not eaten up open spaces: aside from devouring fields they have taken to encroaching upon rivers, lakes and even our city's natural Khals. But there is also a sinister side to this crisis; hundreds of crores have been made over illegal deals which have subsequently filled up the green areas of our city. Where there money to be made, lakes have been filled up, rivers have been encroached upon and the natural Khals of our city have been lost. All of them have been environmentally disastrous for the city. Dr Islam says that the loss of lakes has been a huge blow to the capital and water logging can be directly attributed to it. Ponds and Lakes are natural retention spaces, he explains that means when it rains they retain part of the water that builds up around the city. "Now that we have paved over them as well there is even less natural retention space along with more concrete", he says. "That reduces the amount of water that is usually soaked up by the soil and well as increases the amount of water that stays trapped over the surface. That trapped water which normally would have been retained in a pond or lake is now on the surface as well and that is what causes water logging as well.”

Cleaning filthy garbage to make way for the water to go through

While natural ponds and lakes have been filled up, the government even planned to “create” special retention ponds. But that programme was never fully carried out, in fact the space which they had earmarked for the retention ponds are fast being filled up and built on. This will only serve to aggravate the problem as more rainwater will remain stagnant above ground. Dr Islam says “We badly need retention ponds, currently there are not enough retention ponds, it exists only in theory and have been proposed but never implemented. The situation is so bad that we may even need to redesign and increase their numbers. Aside from that once they are made we will need to excavate them regularly, if we don't then they will slowly fill up and will no longer serve their purpose.”

Another river becomes the casualty of the land grabbers

Another 'model town' encroaching upon low-lying areas, so vital to relieve waterlogging

While the low-lying lands are one thing, the Khals must also be dealt with. A Khal is a natural canal, which is used to drain out flood and rainfall water into the surrounding outfall areas. Dhaka was once full of Khals, which helped immensely during the monsoon, many of those Khals have now been filled and constructed over. Suffice to say the results have been disastrous. While the big ones still remain such as Dholai, Gerani, Shegunbagicha and Begunbari, many smaller ones have been filled and the effects are being felt today with our continuous water logging problems. They should be excavated and brought back to life because they played an important role in our excess water management scheme. Seemingly nature is being trampled in Dhaka. Many people have made money over shady land deals which in the long run have affected the city no end, they should be brought to justice.

More and more of Gulshan Lake have been taken and filled up by greedy developers

Solid waste management is another factor that is directly related to water-logging. With a population of over 10 million it creates an enormous amount of solid waste and currently there is no proper plan to tackle the problem of that waste. Waste is dumped very often right on the streets clogging up the drainage system and increasing the risk of water logging. Unless we have a plan for efficient solid waste management, waterlogging is likely to get much worse in the future.

Dhaka never seems safe, with all these problems combined we have to find a way out of the mess, but things could be worse as Dr Islam explains “Currently we only have water logging on our mind but there are greater things at stake as well. Because water is being trapped above the surface less of it is infiltrating the ground, this means the resulting ground water table is also decreasing. That could prove to be deadly for us, because then Dhaka suffers the risk of subsiding as a city. With low ground water levels and insufficient infiltration the capital could slowly start to sink. While this may seem highly implausible now, there is a definite possibility that it may occur. Mexico city is the example we should learn from.” That would be rather catastrophic and there is a way to steer clear of that course but the government must act now.

There are many problems to water logging in Dhaka. Firstly there is the damage to property, which is a huge financial strain on both the people and government. Then there is the obvious disruption to normal life along with massive economic losses. Waterborne diseases increase and stagnant water provides ideal breeding grounds for mosquitoes. The problems caused by water logging are endless and need not be catalogued, but simply accepting the problem and not acting to rectify it would be suicidal for Dhaka.

River banks like this one will be filled up for construction

There are a few ways out of our current predicament, firstly we must stop covering up open spaces with more buildings. We need the land, the soil our country is so famous for needs to breathe and sustain itself in the capital or else Dhaka will be perennially under water. Next we need to stop building on the banks of rivers, by filling up those areas we are further exaggerating the drainage problem. Our drainage leads to the rivers and if the passage to the rivers is blocked then we are in for serious trouble. Aside from riverbanks the lakes and ponds of the capital need to be protected from encroachers and land grabbers. The government proposed retention ponds must be built and implemented as well as maintained. Already some have been filled up and built on, that process must be brought to a halt immediately. The natural Khals must also be reclaimed as well as protecting the ones, which are serving us now. There is still more to do if we are to truly save the capital from the scourge of water logging. A solid waste management scheme must be initiated and implemented, that will be beneficial for more than just clearing clogged drains. Last but surely not least is that fact that we must put together a comprehensive drainage plan that will save the city from drowning itself.

Copyright (R) thedailystar.net 2007