The Water‑Food‑Energy Nexus describes how water, food, and energy systems depend on each other. Demand in one area often affects the others. Understanding these links helps spot trade‑offs and design sustainable policy.
IB examiners can ask: “Examine the trade‑offs in meeting water, food, and energy needs.” Use examples like China, Mekong, and groundwater depletion to show:
- How solving one problem (ie. urban water supply or hydroelectric power) can hurt another (food production)
- How policy choices (which sector to prioritise, how to charge for water, how to limit extraction) change outcomes
- The importance of sustainable planning: sometimes you can’t just choose more water or more food—balance is needed
How Water Demands Can Cut Into Food Supply
Meeting water demand doesn’t always help all sectors equally. Sometimes supplying water for energy or cities limits food production. In many farming regions, pumping more water to crops can backfire.
From 1990 to 2020, global groundwater withdrawals nearly quadrupled—rising from 227 billion m³ to 879 billion m³. 25% of river basins characterized as overexploited, with top overdraft basins located in India, Pakistan, China, Saudi Arabia, Iran, the United States, and Egypt.
Despite alarming statistics, a 2024 report by the International Food Policy Research Institute (IFPRI) warned that ending groundwater depletion without other changes could cut global rice output by about 7.4% and wheat by 6.7%. Diets in LICs are staple heavy, you can imagine the severe consequences of mandating quit groundwater withdrawal.
A clear example is the Mekong River Basin in Southeast Asia. Upstream countries such as China and Laos have constructed hydroelectric dams to meet growing energy and urban water demands. However, these dams significantly reduce the downstream flow of water, adversely affecting agricultural irrigation and fisheries in Cambodia and Vietnam. Studies by the International Water Association (IWA) show that reduced river flow has lowered crop yields and harmed fish populations, threatening food security for millions in downstream communities.
How Solving One Problem Can Hurt Another
A clear example is the Mekong River Basin in Southeast Asia. Upstream countries such as China and Laos have constructed hydroelectric dams to meet growing energy and urban water demands. However, these dams significantly reduce the downstream flow of water, adversely affecting agricultural irrigation and fisheries in Cambodia and Vietnam.
Reduced river flow has lowered crop yields and harmed fish populations, threatening food security for millions in downstream communities.
How Policy Decisions Shape Outcomes
Government policies deeply influence how water resources are used and conserved. In India, for example, groundwater extraction has soared because agricultural policies heavily support irrigation. The Central Ground Water Board’s 2020 report estimated that about 62% of India’s groundwater units are over-exploited, leading to rapidly declining water tables. This overuse threatens future crop yields, putting food security at risk.
Conversely, Saudi Arabia, facing severe water scarcity due to its arid climate, has historically relied heavily on groundwater for agricultural irrigation. This over-reliance has led to significant depletion of non-renewable fossil aquifers. The Kingdom has introduced water pricing reforms and cut subsidies to encourage more efficient water use in both cities and farms. In 2018, the Kingdom introduced a new National Water Strategy that includes reducing daily per capita consumption from 263 liters to 150 liters, a 43 percent decrease, by 2030.
Read here for more on Ecological Footprint
Read here for more on Malthus v Boserup
Read here for more on Food Security
See rest of Unit 3 for more on resource security