Lessons from this year’s floods: The challenges and solutions are actually intertwined 

This year's floods are a bad omen in many respects.

This is only June, the beginning of the rainy season as we know it. Still, we already have a major flood, starting in the northeast, but gradually engulfing the rest of the country, preceded by two flash floods affecting the haors.

Bangladeshi climate scientists like Dr Ahsan Uddin Ahmed have been saying that we are only beginning to see the first signs of climate change here in Bangladesh.

The first victims of the ongoing flood, the people of Sylhet and Sunamganj are saying that they have not seen a flood of this intensity in their lifetime.

These floods are primarily triggered by excessive rainfall in the northeast Indian states of Assam and Meghalaya. These two states have seen a record rainfall of 1,000 millimetre in 24 hours on 17 June. Cherrapunji, a town in Meghalaya, had recorded a total 3,539 mm in the previous eight days.

According to the meteorological department of India, the state has already recorded 109% excessive rainfall this month – 528.5 mm of rainfall until 19 June against the normal 252.8 mm for June. Another Indian city in the east, Agartala, received the highest rainfall in 60 years.

And now in the north and northwest, the parts of Teesta and Brahmaputra rivers of both Bangladesh and India are swelling, inundating the villages in the respective basin.

If this is the "early sign" of climate change, we should be able to imagine what awaits us in the future.

It is clear that excessive, and early rainfall is going to be a huge problem challenging Bangladesh against the backdrop of global climate catastrophe.

It is also evident that the country's rivers are not ready to carry the excess water. This year, the people of the haor areas have raised specific demands to take up projects to enhance navigability of the rivers. This goes in the opposite direction of a stronger embankment based solution that received attention from both the government and the media since the devastating 2017 early flood that damaged around 80% of paddy grown in the haors that year.

It is good to see that apart from raising the demand to take good care of the rivers, many have spoken up against the Austogram-Itna-Mithamain all season road constructed in the haor, which impedes free flow of water.

In a nutshell, Bangladesh has a major drainage problem to solve in the changing context.

And it is not limited to the issue of flood control. The country is going to have a severe waterlogging problem across the country, and the symptoms are showing in the cities and rural areas alike.

Too much, too little

Just three months back, many places in the country suffered from water scarcity. Two Santal farmers even killed themselves by ingesting pesticide in Rajshahi's Godagari upazila when Barind Multipurpose Development Authority failed to irrigate their lands despite their continued plea. 

What is more shocking is that even the areas on the edge of the haors now suffer from declining groundwater table, a major source of water for irrigation and household use.

It is clear that under the existing circumstances, Bangladesh is not going to get its rightful share of water from the transboundary rivers in the dry season. And in the monsoon, these rivers, with all the gates of the dams and barrages in the upstream open, are going to flood the country, washing away houses, farms and fisheries, and human lives. 

It is worth mentioning that northeast India has several dozens of small and medium projects with dams and barrages that hold back or divert water from the transboundary rivers, although only large ones on the west - Ganges and Teesta - are usually in public discussion.

It is really comforting that the Bangladesh government, under the auspices of Delta Plan 2100, has taken up programmes to excavate many rivers across the country. It is an important step to enable the rivers to carry the excessive rainwater. 

What is rather unsettling is that in most cases, the excavated earth and sand is piled inside the river, narrowing the stream down. 

What we really need now is wider and deeper rivers and canals, not narrow 'drains.' We also need to remove infrastructures, built both by the government agencies and encroachers, that impede natural water flow. And this is the first important lesson we can draw from the ongoing disasters.

Surface runoff

The second lesson we get from the analysis of the current situation is that our cities, and even towns, are at the risk of increased temporary inundation and severe waterlogging due to excessive rainfall. This is already a familiar issue in Dhaka and Chattogram. A 20-minute rainfall sees these cities' streets under water for several hours. 

Apart from the clogs in the drainage system due to pollution and the encroachment of canals, there is this issue of surface runoff of rainwater, which is missing in the ongoing conversation on our drainage problem.

For the last couple of decades, we've been building a drainage system which is totally dependent on storm sewers. Water flows downward and also gets soaked by the soil. Rainwater gets little chance of infiltration in the soil in urban areas as the ground is mostly paved. Also, the natural depressions and wetlands around the cities are vanishing fast under the pressure of urban expansion, leaving little scope for rainwater to end up there, which would in turn recharge the groundwater table.

Unfortunately, our smaller towns are heading in the same direction. An example would be befitting here. With two global financial institutions' funding, many municipalities are getting new sewers. I had the chance to witness the construction of one in Bhairab, a river port town flanked by numerous canals, rivers and wetlands. The town's Hospital Road runs parallel to a canal that runs into the Meghna river. 

The town planners, despite protests from some of the residents, chose to build the sewer on the opposite side of the road in respect to the canal. The gradient of the road, meant for directing the flow of rainwater, faces the opposite direction of the canal too.

Here, what should have been done is to use the natural gradient of the land that has directed the overland flow toward the canal from time immemorial. The houses that are popping up along the road are also blocking the natural path of surface runoff, thanks to the thought that the sewer would suffice. However, the experience of the big cities of Bangladesh, and rising rainfall pattern say, it would not suffice in the long run.

Intertwined problems and solutions

Even if the human race manages to limit CO2 emission at an unimaginable pace, which is quite unlikely, the impacts of the climate catastrophe are here to stay for a long time.

Luckily, Bangladesh is being served its problems and solutions on the same plate.

The low-lying country is a route for monsoon and glacial meltwater, naturally susceptible to flooding with an annual discharge of 1,400 billion cubic metre water. On the other hand, the country also gets 2.5 billion tons of sediment every year through its river systems, a potential solution to the low-lying problem.

As flood water inundated the banks during the monsoon in the past, the sediment deposited on the land, and this is how Bangladesh came into being. Now, as embankments prevent sediment-laden water from flooding the adjacent land, the riverbed gets silted, the rivers are choked, increasing the flood risk even further. Deforestation and mining in the Indian hills are only exacerbating the situation.

Desperate times require desperate measures that would be sustainable in the long term.

Maybe it is time we rethought embankments. For in the future, more rivers will overflow, and the embankments will hold the otherwise receding water, creating waterlogging.

Or, we can use the sediment in a planned and controlled way to flood-proof more lands.

Also, the excessive rainfall is the antidote to the seasonal water scarcity; we just need to facilitate the recharging of groundwater through the use of well-maintained wetlands: lakes, ponds, and beels.

Nature has bestowed upon Bangladesh abundant gifts. It is through the preservation of natural design, not working against it, that the country should strategise its fight against the calamities that the Anthropocene has brought to us.