The Asian Infrastructure Investment Bank (AIIB) has published its flagship annual study, Asian Infrastructure Finance 2026, under the title: Where the Water Flows. Infrastructure and Governance for a Sustainable Water Cycle. The report argues that the hydrological cycle should itself be treated as a form of critical infrastructure, rather than solely as a resource to be extracted, a hazard to be managed, or a service delivered through pipes and pumps.
The report argues that the hydrological cycle should itself be treated as a form of critical infrastructure, rather than solely as a resource
Writing in the preface, Erik Berglof, Chief Economist at the Asian Infrastructure Investment Bank, describes the water cycle as "the planet's own life support system", performing the functions of an environmental pump, a global thermostat and a giant filter. AIIB President Zou Jiayi adds in the foreword that water pressures are "no longer a distant risk but a present and growing constraint" on economic stability and development. The report groups those pressures into what it calls the four-dimensional global water crisis of "too much, too little, too dirty, too variable".
The scale is considerable. The atmosphere holds around 13,000 cubic kilometres of water at any given moment, yet transports more than 500,000 cubic kilometres each year. New analysis commissioned for the report finds that nearly half of all global land rainfall originates from moisture generated over other land surfaces. Landlocked economies in Central Asia receive around 47 per cent of their rainfall from foreign moisture sources, well above the global average of 26 per cent. Large rainforest nations such as Brazil, the Democratic Republic of the Congo and Indonesia generate roughly one quarter of global transboundary moisture flow, despite representing only eight per cent of global land area.
Water risk, the report argues, has moved from a sectoral concern to a macroeconomic one. Citing WHO and UNICEF (2025), the authors note that 2.1 billion people lacked safely managed drinking water services and 3.4 billion lacked safely managed sanitation services in 2024. Some 77 per cent of global croplands rely solely on rainfall, around 31 per cent of the global population now lives in water-stressed basins, and roughly one-fifth of global wheat and maize production takes place in basins facing high water stress.
An econometric study included in the report finds that water stress significantly weakens sovereign creditworthiness in developing countries. For lower-middle-income economies, a 10 percentage point increase in water stress is estimated to produce a decline of nearly one notch in the sovereign credit rating, reflecting greater exposure to water-intensive sectors and heightened social tensions. The effect on advanced economies is described as limited. The report cites estimates from Khemka and Sterte (2024) that the total financing gap for water infrastructure could reach USD 7 trillion globally by 2030.
Evidence from floods, wetlands and upstream land use
An econometric study included in the report finds that water stress significantly weakens sovereign creditworthiness in developing countries
A global study of 3,577 flood events between 2000 and 2020, drawn from the Dartmouth Flood Observatory and cross-referenced with 14,391 water quality monitoring stations in 61 countries, identifies immediate spikes in suspended sediments and more delayed but persistent increases in algal biomass after flood events. Agricultural catchments produce the largest sediment surges and the clearest phosphorus pulses, while forests provide what the report describes as "exceptional natural resilience to flood-related water pollution".
A separate difference in difference analysis of the Ramsar Convention on Wetlands finds that international designation alone has a limited overall causal impact on wetland health. Outcomes are stronger in smaller wetlands and in countries with stronger environmental and water governance capacity, and weaker in larger wetlands and jurisdictions with weaker governance. The report notes that Ramsar sites lost nearly 2,000 square kilometres of permanent water, roughly 12,000 square kilometres of vegetation cover and more than 10,000 square kilometres of forested area between 1995 and 2018, while agricultural land within those sites expanded by nearly 20,000 square kilometres.
The report also cites cross country evidence that improved upstream forest cover can raise the capacity factor of run of river hydropower plants by 13 per cent, and notes that glaciers in the Hindu Kush Himalaya, the largest store of ice outside the polar regions, are projected to lose between one third and two thirds of their mass this century, threatening dry season water security for close to two billion people downstream.
Virtual water and the pricing question
On trade, the report estimates that around 770 billion cubic metres of water were embodied in international trade in 2021, out of a total global water withdrawal of approximately 3,900 billion cubic metres. The largest net exporters of virtual water include India, Indonesia, Thailand and Viet Nam, while the largest net importers include the United States, Japan, Germany and the United Kingdom. Using a gravity model, the authors find that water tariffs predict export patterns more accurately than water endowments themselves, and argue that many countries are underpricing water relative to its availability.
On trade, the report estimates that around 770 billion cubic metres of water were embodied in international trade in 2021
The report also sets out six broad recommendations. These are to invest across water systems by combining natural and engineered infrastructure; to scale adaptation infrastructure for floods, droughts, landslides and sea level rise; to reform water governance so that it reflects basin hydrology and transboundary realities; to advance equity and inclusion in water planning; to leverage technology enabled infrastructure, including hydrometeorological networks and early warning systems; and to mobilise finance for resilience through public risk sharing, targeted guarantees and long term private capital aligned with adaptation outcomes.
AIIB positions multilateral development banks as central to operationalising the shift, with a role that spans project preparation, governance reform and the mobilisation of private capital for nature-based and hybrid infrastructure.
