Zambezi Basin Can Triple Food and Double Clean Energy Without Harming Wetlands, Study Finds

A new study has revealed that the Zambezi River Basin—Africa’s fourth-largest river system—has the ability to triple food production and double clean-energy output without damaging its iconic wetlands.

Published in Chinese Geographical Science, the research is led by Prof. WU Bingfang from the Aerospace Information Research Institute, Chinese Academy of Sciences (AIRCAS). By integrating 1-km evapotranspiration data, CHIRPS rainfall records and GRACE satellite gravimetry, the team quantified how irrigation expansion and planned hydropower schemes interact with environmental flow needs across the 1.39 million km² basin between 2003 and 2019.

A basin at a crossroads
The Zambezi River Basin shared by Angola, Botswana, Malawi, Mozambique, Namibia, Tanzania, Zambia and Zimbabwe sustained the livelihoods of 32 million people—70% of whom still depend on rain-fed agriculture. Its wetlands, including the Barotse flood-plain and Zambezi Delta are ecological hotspots supporting globally significant biodiversity.

Yet the region faces deep development challenges: poverty ranges from 18 to 71% and food insecurity affected up to 64 % of the population in Zambia. To address, these issues, riparian states have placed irrigation expansion and hydropower construction at the heart of their national development plans. Yet, the lack of reliable, spatially detailed water data has long hindered efforts to assess how far these plans can proceed without compromising environmental flows.

Solving data scarcity from space
Hydrological monitoring across the ZRB is sparse: only five of 22 discharge gauges provide usable data, and t ten temperature stations provides usable data over an area larger than South Africa. To overcome this limitation, the AIRCAS team harnessed Earth observation and big data.

They merged 13 global evapotranspiration (ET) products, validated them against eddy-covariance towers in Zambia (R² = 0.76, RMSE = 7.15 mm), and combined them with 0.05° CHIRPS precipitation records and GRACE-derived water-storage changes. The result is a 1-km, monthly ET dataset—publicly available on Google Earth Engine that allowed the researchers to close the basin-scale water balance for the period 2003-2016 without relying on ground-based measurements.

Current and future pathways analysis

Currently, only 1.8 % of cropland in the basin is irrigated, while reservoir evaporation totals 14.2 km³ yr⁻¹. Combined, water consumption stands at 15.1 km³, which remain safely within the ecological envelope.

Scenario modelling shows that expanding irrigated land to 20 % of cropland and increasing dam density to the global norm of 0.56 per 10 000 km² would raise consumptive use to 12.7 km³ yr⁻¹—still leaving a buffer even in dry years.

Reaching the safe envelope would increase irrigated area to 40 953 km²—enough to raise basin-wide cereal output by 29 %, enough to meet the UN “Zero Hunger” target. Hydropower capacity would grow by 3.2 GW, delivering clean electricity to a roughly additional 15 million people.

Because the irrigated farmland yields 2.67 times more than rain-fed fields, even modest expansion would deliver disproportionate food-security gains.

A clear line for policy

"With its abundant water and heat, the basin has the potential to become a global breadbasket," said Prof. WU Bingfang, corresponding author and leader of the CropWatch team. "The key is to use verifiable Earth-observation big data to draw a clear line—so policymakers know exactly how wide they can open the tap."

The study was conducted jointly with partners from the University of Zambia (Elijah Phiri) and the University of Zimbabwe (Emmanuel Mashonjowa), and supported by the National Natural Science Foundation of China.