Researchers propose way to end killer floods in Dar es Salaam

Sunday May 30 2021
Dar pic

Motorcycle riders and commuter buses cross at the flooded section of Kigogo Road in Dar es Salaam following the heavy rainfall that pounded the city recently. PHOTO | MICHAEL MATEMANGA

By Jacob Mosenda

Dar es Salaam. When Jumanne Abdul, 45, built his house 18 years ago, Msimbazi River was almost 60 metres away from his plot.

By then, he couldn’t have imagined that the river bank would have eroded the huge chunk of land to just a few metres from his house today. Now, he is forced to relocate whenever the rainy season arrives as he fears for his family.

For years, floods have significantly impacted Dar es Salaam residents living in lowland areas.

Meanwhile, town planners and government officials have been promising to address the issue and their strategies have also shown the need for more investment to address the problem.

However, researchers from the University of Dar es Salaam have shown that in the short-term, the problem doesn’t require much expense, as it will only require the planting of bamboo trees along the edges and also constantly deepening the depth of the Msimbazi River, and people like Mr Abdul, will live without fear of relocation.

In their study titled: Building Resilience through Integrated Approach under Climate Change: A case study of Msimbazi River, these scholars are convinced that there is no need for people to evacuate, instead their research has shown an alternative way to prevent the effects of flash floods.

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“Countries like Singapore use rivers that run through downtown areas as an attraction and even for transportation by boat. This is because they have strengthened the river banks in various ways,” Brian Mbaze, an assistant researcher explains to The Citizen.

He says, reduction in river conveyance capacity has been growing concerns along Msimbazi River, which is associated with eroded sediment deposition on the water course as a result of river morphological factors.

“One of the most effective ways to mitigate floods and associated impacts is the control of erosion and sedimentation along Msimbazi River and its catchment,” he says.

He says by planting bamboo trees along the Msimbazi River or any other river in the city, the problem of water breakage and flooding will be hugely mitigated.

“The first step is to make sure that the watercourse is not too cluttered with sand and pile up, which makes it easier for water to break the bank, and then to plant these trees in a proper way,” he explains.

Explaining to The Citizen during the sixth week of research and innovation at the University of Dar es Salaam, the researcher says through the study they are convinced resilience against erosion on the upstream of Msimbazi River would be built.

“Our research proposes the use of affordable and locally available materials as a measure to control floods along this river,” he says.

In recent years, climate change has already led to increased temperatures and rising sea levels in Tanzania and that floods will always hit the city residents, says the Tanzania Country Environmental Assessment Report(2019) compiled by World Bank.

The report says that without major investments in adaptation, an annual average of 800,000 Tanzanians stand to be impacted by flooding caused by rising sea levels in future.

Like Abdul, residents of this commercial city are seemingly very happy when they do not hear of the rainy season warnings from the Tanzania Meteorological Authority (TMA), especially those living along the river basins.

The main reason is that as soon as heavy rains begin to fall, the government, concerned for the safety of its citizens, begins to require people living in high-risk areas to evacuate to safer zones, a step that many consider costly in view of their poor living conditions.

The flood situation has not only been affecting those living in high-risk areas, but also the residents who carry out their activities away from where they live, especially those who have to use the ‘Jangwani’ highway for work in the Central Business District (CBD).

You may be wondering how long it will take for people to keep on relocating, yet reports show that over a million people flock to the city every day.

Of course, it is in this context that academics from universities are now focusing on contributing to finding a possible solution which would alleviate the suffering experienced whenever it rains.

“In many cases, the government and investors have argued that this problem requires a significant amount of money thus delaying its solution,” says Dr Mvita Andrew, a development expert based in Dar es Salaam.

“Now that researchers have shown an easier way, it is only a matter of the government or any other development partner supporting the group so that they can put the research into practice,” he advises.

Dr Andrew says technology is now being given more prominence in solving social challenges so it is time now for city planners and leaders to make better use of research from universities to facilitate solutions to challenges such as constant havoc caused by heavy downpour.

“You can’t relocate people all year in a growing city like Dar es Salaam. We must now embrace every means that can alleviate this problem, otherwise it will mean that some people are benefiting from these challenges,” argued Dr Andrew.

Economically, the World Bank’s study on poverty and resilience in Dar es Salaam in 2019 quantified the magnitude of the impact of flooding by rains for the first time.

It reveals that in the commercial capital of Dar es Salaam in 2018, some 17 people were killed as a result of heavy downpour which also caused damage to infrastructure estimated at $100 million.

The losses incurred are estimated to be close to two per cent of the gross domestic product (GDP) of the country’s largest metropolis, which is repeatedly hit by rain-caused disasters.

The study also reveals that the Msimbazi River basin is the most flooded part of the city, loosening an average of 950,000 cubic metres of soil each year. The resulting sediment slows the passage of water to the Indian Ocean, thus adding to flood-related woes in the city.

The engineers now say they are ready to work with the government and other development partners to implement the results of the study with the aim of becoming part of a lasting solution.

“We are ready to work with the government as soon as we have completed this study so that we can demonstrate this approach and ensure that our research does not end here at the university,” says Lucius Mugisha.

Prof Bernadeta Killian, the Deputy Vice-Chancellor (Research) of the University of Dar es Salaam, says the institution’s focus is to ensure that research and innovation from its experts, aims to solve various challenges in society.

“We will continue to fund productive research, which aims to help solve community challenges. That is why we are organizing these exhibitions so that together we can identify the best research that needs to be developed or its results implemented,” says Prof Killian.

In this regard, Prime Minister Kassim Majaliwa after witnessing this and other research/innovations in the exhibition realized the need for the government to work with researchers and innovators in solving challenges in society.

“As a government we are going to address this budget issue that hinders conduction of productive research in our universities and promise to use them all effectively to improve the lives of Tanzanians,” he says.