Poor urban planning at the heart of severe floods in cities

Journalists use a boat to access Nairobi's Runda houses. [Jenipher Wachie, Standard]

Cities in East Africa face double pressure from rapid urbanisation rates and changing climate risks that led to the recent massive flooding, experts have said.

According to a study carried out by an international team of leading climate scientists, rapid urbanisation in cities within the region continues to amplify flood risks.

The study notes that large informal areas which are located on flood-prone land that lack adequate structural protections from the rains were more prone to destruction.

The scientists explained that extreme rainfall that led to destructive floods in Kenya, Tanzania, and other parts of East Africa, became more intense due to climate change. “East Africa has some of the fastest urbanisation rates worldwide. During the current and widespread floods, every capital in Ethiopia, Somalia, Kenya, Tanzania, and the economic capital in Burundi has been flooded, causing deaths, displacement, and destruction of critical infrastructure and widespread concern of spreading infectious diseases,” the researchers note.

The researchers drawn from Kenya, the Netherlands, Germany, Sweden, Denmark, and the UK, collaborated to assess what extent human-induced climate change altered the likelihood and intensity of the rainfall that led to severe flooding in the most affected regions.

In their study, areas that emerged as most affected in the region included the region around Lake Tanganyika, Lake Victoria, the central Highlands (including Nairobi), the southeast lowlands of Kenya, and coastal Tanzania.

Researchers noted that unplanned urbanisation often goes hand in hand with the formation of informal settlements in marginalised and hazard-prone land.

“Urbanisation compounds these risks, as rapid and unplanned growth in cities like Nairobi and Dar es Salaam results in vulnerable informal settlements lacking adequate infrastructure and increasing flood susceptibility,” said the experts.

“The recurrent flooding in capital cities demonstrates the pressing need for improved urban planning and resilient infrastructure,” the scientists said.

In Kibera, the researchers estimated that more than 200,000 people live within 30-metre proximity to water bodies, and in Mukuru, houses along waterways were demolished following a 48-hour evacuation order issued by the government to prevent further deaths from flooding.

“Populations in informal settlements throughout the study area are particularly vulnerable to flooding due to a combination of external factors such as inadequate road infrastructure, land tenure, housing infrastructure, access barriers to potable water services, location (in flood-prone areas like riparian, wetlands), drainage systems, and limited access to health systems,” they said.

The study also revealed that land-use changes, including deforestation and conversion to agricultural land, are also occurring to different degrees in each of the countries studied, adding to flood risk.

“In Kenya, a drastic reduction in forest cover has been observed over the past two decades, with a 14 percent average decline from 2002 to 2022, and up to 39 per cent in areas like Narok,” the study revealed. Kenya’s 14 per cent forest cover reduction, they say, has heightened surface runoff and peak river discharges, exacerbating flood hazards.