Wetlands: Overlooked ecosystem that impacts housing costs and health

 

 

As cities rise and skylines stretch higher across continents, a crisis is unfolding beneath the foundations of modern development. Wetlands — once dismissed as swamps or wastelands — are disappearing at an alarming rate, even as climate change intensifies floods, droughts, and extreme weather.

The irony is striking. The very ecosystems that could protect cities and property markets are being cleared to make way for real estate expansion.

Globally, wetlands cover about six per cent of the Earth’s surface, according to the Ramsar Convention on Wetlands. Yet they provide ecosystem services valued in the tens of trillions of dollars annually, including flood regulation, water purification, carbon storage, and biodiversity support.

The Global Wetland Outlook (2018) estimates that the world has lost approximately 35 per cent of its wetlands since 1970, making them one of the fastest disappearing ecosystems on the planet.

For the real estate sector — both in developed and developing countries — this trend is no longer just an environmental issue. It is an economic and climate risk.

As pressure mounts to convert wetlands into housing estates and farmland, climate change expert Job Kariithi warns that such moves could create long-term environmental and economic disasters.

Kariithi cautions that developing wetlands is “not advisable” because they are natural flood zones that can easily reclaim their space, sometimes affecting hundreds of acres when extreme rainfall occurs.

“These are flood areas by nature. When you interfere with them, water will eventually find its way back,” he said.

Wetlands, he explains, serve as natural water reservoirs and carbon deposits. They store large volumes of water during heavy rainfall, releasing it slowly and reducing downstream flooding. This makes them critical buffers in an era of increasingly erratic weather patterns driven by climate change.

 “When you drain a wetland, you are not just removing water; you are interfering with a carbon storage system. Wetlands are depositories of organic carbon. Once drained, that carbon is released into the atmosphere,” he said.

This release contributes to greenhouse gas emissions, accelerating global warming and intensifying extreme weather cycles — including the floods that threaten developments built on reclaimed wetland areas. 

“Wetlands are very fertile because they are reservoirs of nutrients and organic carbon, but when you continuously drain them for agriculture or construction, you expose the soil to erosion. Over time, fertility declines, and the land degrades. It becomes a cycle,” he said.

Wetlands act as natural sponges. According to the United States Environmental Protection Agency (EPA), a single acre of wetland can store up to 1–1.5 million gallons of floodwater, reducing the intensity of floods and protecting downstream communities. 

In the United States, a peer-reviewed study published in Nature Scientific Reports (2017) found that coastal wetlands prevented more than Sh80.6 billion ($625 million) in direct flood damages during Hurricane Sandy in 2012. Areas where wetlands had been lost suffered significantly more serious damage.

Beyond flood control, wetlands are among the planet’s most efficient carbon sinks. According to the United Nations Environment Programme, wetlands store more carbon than all the world’s forests combined, despite covering only about three per cent of global land area.

Mangroves, salt marshes, and freshwater wetlands trap and store carbon for centuries. When wetlands are drained for construction, the stored carbon is released into the atmosphere, accelerating climate change. The World Economic Forum, citing climate research, estimates that wetlands contain roughly 20 per cent of global soil organic carbon, despite occupying a small fraction of land area.

This creates a feedback loop: wetland destruction contributes to climate change, which then increases flooding and climate risks for properties built on those very lands. For developers and investors increasingly concerned about Environmental, Social, and Governance (ESG) metrics, wetland preservation is becoming a key consideration.

Water security

In Kenya, wetlands cover about three to four per cent of the country’s land surface, according to government and environmental policy documents, and expand during rainy seasons. They include ecosystems such as the Yala Swamp, Tana River Delta, Lake Naivasha basin, and Nairobi’s riparian corridors stretching from Kiambu County.

These ecosystems support agriculture, fisheries, tourism, and water supply for millions of people. They also serve as buffers against floods — a function that has become painfully relevant.

“Kenya is privileged to host some of Africa’s most vital wetlands, from Yala Swamp and the Tana River Delta, to Lake Naivasha and the Uasin Gishu wetlands. These are lifelines for livelihoods, biodiversity, and water security,” said Cabinet Secretary for Environment and Climate Change  Deborah Barasa.

“When water disappears, cranes disappear. And when cranes disappear, our water systems are in danger. Cranes are indicators of a healthy ecosystem. Their voice is a symbol of rich biodiversity. When that voice is missing, our ecosystems are in trouble.” Over the past decade, Nairobi and its surrounding counties have experienced recurrent flooding, particularly in areas where riparian land has been encroached upon.

The United Nations projects that about 68 per cent of the global population will live in urban areas by 2050. Africa’s cities are among the fastest-growing in the world.

Environmental assessments and planning reports have documented degradation of sections of the Nairobi River basin and associated wetlands due to informal settlements, infrastructure expansion, and commercial development.

Climate data from the Kenya Meteorological Department indicates increasing variability in rainfall patterns and more frequent extreme rainfall events in parts of the country. When wetlands in urban catchments are paved over, the result is predictable: flash floods, property damage, and loss of life.

For real estate markets, this translates into declining property values in high-risk zones, higher insurance premiums, and growing investor caution — trends already being observed globally as climate risk becomes embedded in property valuation models.

The challenge is not unique to Kenya. In Europe, rapid urbanisation over the past century led to significant wetland loss. Countries like the Netherlands have adopted the “Room for the River” strategy, deliberately restoring floodplains and relocating dykes to give rivers space to overflow safely rather than relying solely on higher embankments.