When it rains, it pours: The impact climate change has on flooding in Africa

Fresh in our memory is the April and May flooding across parts of KwaZulu-Natal and the Eastern Cape.

We witnessed entire buildings, homes and schools ravaged by the intense force of the overflowing water, sweeping away an estimated R17 billion in infrastructure damage.

The heavy rainfall— estimated to be an excess of 300mm over a period of 24 hours — left roads and bridges disintegrated and washed away.

By far, the most devastating impact was the lives lost during that time. Officials estimate over 430 people died as a result of the floods and more than 12 000 houses were destroyed.

To a much lesser extent, Cape Town and surrounding areas were also affected by floods in mid-June, leaving several informal settlements waterlogged.

The African continent itself has had a long history of recorded flooding.

In 2007, the African floods were reported by the United Nations (UN) to have been one of the worst floods in recorded history.

Over 14 countries were affected including Ghana, Uganda, Kenya, Sudan, Ethiopia and Rwanda.

It was reported that 250 people were killed by the flooding and 1.5 million people were affected or displaced from their homes.

With the destruction to land and property, and the lives lost as a result of flooding, scientists are now looking into factors that influence the frequency and intensity of floods that we are witnessing globally.

Some recent research suggests that climate change has played a role in extreme weather events that have taken place over the past two decades.

The link between climate change and flooding

The UN defines climate change as the long-term shifts in temperatures and weather patterns.

It’s the increase in the earths average surface temperature and the large-scale changes in weather patterns, caused by a significant increase in the levels of greenhouse gases that are produced by the use of fossil fuels.

In a special report from the Intergovernmental Panel on Climate Change (IPCC), experts say that climate change has already caused more frequent and more severe storms, floods, droughts, and wildfires.

It holds that while increasing temperatures and global warming may not induce floods directly, it exacerbates many of the factors that do.

Earlier this week, a team of climate scientists published a study in the journal Environmental Research: Climate, saying that climate change is increasingly manifesting through more intense extreme weather events.

The study, Extreme weather impacts of climate change: an attribution Perspective, with lead author, Ben Clark, said that increasing extreme rainfall is resulting in destructive flooding over a large portion of the world’s surface.

“Evidence from attribution-science literature shows that growing numbers of floods have been made more intense by the effect of climate change on precipitation.

“This leads to impacts upon people, property and nature that would not have occurred in the absence of these increases in events’ likelihood and intensity,” said Clarke and his fellow researchers.

Due to the increasing temperature in the Earth’s atmosphere, warmer air is able to hold more moisture. Storm clouds are “heavier” before they eventually break.

It is estimated that air can hold up to 7% more water vapour for every one-degree Celsius rise in temperature. When air rapidly cools, the water vapour turns into droplets which forms heavy rainfall.

Globally, episodes of heavy rainfall are becoming more common and more intense. Heavy rainfall over a short period of time can cause flash floods.

According to the World Meteorological Organization (WMO), the frequency and intensity of floods can be caused by several factors.

“Increasing population pressure, continuous degradation of ecosystem services and climate variability and change, can contribute to a further increase in flood risks worldwide.

“In many parts of the world, this increase is further exacerbated by inadequate flood planning and management practices,” said the organisation.

According to Action Aid, an international non-governmental organisation working against poverty and injustice, several East African countries that experience drought are also susceptible to intense rains and flooding.

Countries such as Somalia, Djibouti, Ethiopia, and Kenya with recurring droughts and dried out soils are often affected by sudden and heavy rainfall.

The arid lands are not able to soak up the moisture fast enough. This can result in flash floods and with poor land management and degradation, which makes certain communities particularly vulnerable.

Clarke said that changes in the risk of flooding due to heavy precipitation also depend on changes in other factors.

“Including the susceptibility of areas to flooding, land use change and river management, as well as other climate-related factors such as soil moisture, storm extent and snowmelt”

Finding solutions to flooding

Another study published in Science Direct earlier this year suggests that there can be more comprehensive, cost-efficient and multifunctional measures in flood disaster risk management.

The South African-based researchers, with lead author Emmanuel Tolulope Busayo, said the emergence of ecosystem-based adaptation (EbA) can stabilise or reduce flood impacts and damages associated with flood disasters.

“Flood governance in South Africa needs to be more dedicated to creative and reliable approaches such as EbA, and local organisations and policies need to follow suit and implement appropriate approaches to mitigating the country’s flood disasters,” said the researchers.

Some of the suggested solutions in the study include:

• Implement rainwater harvesting systems where rainwater is stored from roofs

• Build and maintain permeable pavements that allow water to sink into the soil

• Construct green roofs to create vegetation on the roof surface to reduce surface runoff

• Plant more canopy trees which captures rainwater while also providing green spaces, and prevent the ground from the force of rainfall

• Build soakaways and infiltration basins which aids water infiltration and the control of groundwater discharge

What role can society play?

The IPCC says that institutions are critical in accelerating the transition towards sustainable development.

“They can help to shape climate change response strategies in terms of both adaptation and mitigation.

“Local institutions are the custodians of critical adaptation services, ranging from the mobilisation of resources, skills development and capacity-building to the dissemination of critical strategies,” said the organisation.

Civil society institutions, such as NGOs or research centres, as well as the general public can play a role in challenging the way governments handle extreme weather events, how they assist in rebuilding the damage and how they prepare for future such events.

Turner is a health and environmental multimedia journalist

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