Upstream water extraction threatens to destroy Okavango Delta

In the highlands of central Angola a quiet crisis is unfolding. Here, where miombo forests stretch toward the horizon and rivers thread through deep sands, the Cubango River begins its long journey toward Botswana’s Okavango Delta. But not all of it makes it there.

A new report commissioned by by researcher John Mendelsohn warns that substantial volumes of water are being lost along the way — drawn off by farms, towns and irrigation schemes with almost no oversight or accountability. And the Okavango Delta, hundreds of kilometres downstream, is starting to feel the pressure.

“The Delta is so vast and natural that it is easy to become complacent about its protection,” writes Mendelsohn. “Yet, as magical as it seems, this wetland does not just appear from nowhere.”

The water that spreads out like a many-fingered hand that eventually evaporates or sinks into the Kalahari sands in Botswana has travelled more than 1,000km from the highlands of central Angola and then along the border of Namibia. Consequently, what happens to the rivers in Angola and Namibia can threaten the health of the Okavango Delta in Botswana.

Land cover in the catchments of the Cubango, Cuito, Cuando and upper Zambesi in Angola. (Image: CI Report)

The Cubango is no ordinary river. Along with its major tributary, the Cuito, it feeds the Okavango Delta — one of the most biologically rich and culturally significant wetlands in the world. Each year, its floodwaters nourish a million hectares of wetlands, grasslands and forests, sustaining iconic wildlife as well as thousands of people who depend on its rhythms for food, water, and tourism.

But this lifeline is drying out at its source.

Delta hippos are the lords of the thousands of meandering channels. (Photo: Don Pinnock)

Alarming losses

Using satellite data, field surveys and hydrological records, Mendelsohn paints a troubling picture. Measurements along the Cubango River between Katwitwi and the Cuito confluence — just upstream of the Namibian town of Rundu — found that up to 22% of the river’s flow was lost in that stretch during the dry season in 2021. By 2023, the figure was still a worrying 16%.

Locations of mapped offtakes between Katwitwi and the Mahango Game Reserve. (Image: CI Report)

What’s more, in November 2022, flow measurements taken near Divundu, on the border of Botswana, logged an even more sobering reality: the volume of water lost between Katwitwi and Botswana was equivalent to the total amount of water contributed by the Cubango.

This means that the Okavango Delta — already vulnerable to seasonal variability and climate change — is now increasingly dependent on a single tributary. And as more water is drawn from both rivers, the ecological balance of the delta could tip toward collapse.

Why the water is disappearing

The cause of the Cubango’s dwindling flow is no mystery. Irrigation, town water supply, and small-scale farming along the river’s course have expanded rapidly in recent years.

In Namibia, the number of small river water offtakes quintupled between 2017 and 2023 — from just 25 pumps to 130. Medium-sized pipes also doubled in number. Many of these supply household gardens or small commercial farms, but some feed large irrigation schemes — such as those at Mashare and Musese — which can draw millions of litres of water during the dry season. And this expansion isn’t limited to Namibia.

Fields along drainage lines with maize, sugar cane, melons, onions, cabbages, sweet potatoes and other vegetables. (Image: CI Report)

In Angola, previously undeveloped stretches of the Cubango basin are seeing rapid transformation. Private investors have established vast commercial farms — such as the 27,500-hectare Mumba project — and use powerful pumps to divert water from the river. Angola’s state-run irrigation schemes are also being revitalised through private leases.

Stretches of the Cubango River are undergoing rapid transformation. (Image: CI Report)

Together, these developments have pushed the total area of irrigated land in the basin from 6,199 hectares in 2020 to 8,025 hectares in 2024 — a 29% increase in just four years. Most of this growth is driven by private operators, who now control 66% of irrigated land.

“There’s a clear shift from subsistence farming to profit-driven water use,” the report states. “But this is happening without regulation, without oversight and without any limits.”

A dangerous vacuum of governance

Perhaps the most disturbing element of the report is the absence of any real water management system. Neither Angola nor Namibia requires water users to monitor or report their extractions. There are no quotas in place, no regional agreements on sustainable withdrawal limits and no enforcement of conservation practices. Water from the Cubango and Okavango is treated, the report says, as a free and limitless resource.

The implications of this are stark. Even if only a few large users abstract small volumes, the cumulative impact across hundreds of pumps — large and small — is enough to significantly reduce downstream flows. During the dry season, when Okavango Delta ecosystems rely on a trickle to sustain life, that missing water could mean scorched wetlands, failed elephant migrations and fish die-offs.

In 2021, during one such low-flow period, water quality measurements near Rundu found high levels of contamination — including bacteria, fertiliser runoff and dissolved solids — posing a direct health risk to communities and a long-term threat to Okavango Delta integrity.

Commercial riverside farmers sell their produce directly to some of the big shops in Rundu. (Image: CI Report)

Plans to extract even more

Despite these trends, both Angola and Namibia are eyeing even larger-scale extractions. Angola is constructing two substantial dams — Ndúe and Calucuve — on ephemeral rivers in the Cuvelai-Etosha Basin.

These are designed to store water from local rainfall but could soon be filled by pumping water from the Cubango during low-flow periods. The combined storage capacity of the dams is more than 300 million cubic metres — nearly the annual discharge of the river at times of drought.

Meanwhile, Namibia’s government is dusting off long-standing plans to pipe water from the Okavango to Windhoek, hundreds of kilometres away. Though the proposed withdrawal is modest — around 0.4% of the Cubango’s flow — it comes at a time when existing offtakes are already unsustainable. And crucially, it would draw water from above the Cuito confluence — the stretch where the most loss is already occurring.

These projects have prompted concern from Botswana, which depends on the Okavango Delta for tourism revenue and biodiversity. Yet, in the absence of a robust multilateral framework, objections remain diplomatic rather than legal.

A vanishing wonder?

The Okavango Delta is one of the last great untouched wildernesses. It is a Unesco World Heritage Site, a sanctuary for endangered wildlife and a source of deep spiritual and economic significance for southern Africa. But its future now hinges on decisions made far upstream — in dryland farms, pump stations, and political boardrooms in Angola and Namibia.

Without action, says the report, the Okavango Delta risks becoming another tragedy of over-extraction — an ecological marvel sacrificed for short-term gain. With the right governance and cooperation, however, it could be a model of transboundary sustainability in an increasingly water-stressed world.

The choice, as the report makes clear, is still ours. But not for much longer. DM 

Read the full report: Threats and developments in the Catchment of the Cubango/Okavango River in Angola and Namibia: Update and Perspectives in 2024