The Global Centre for Risk and Innovation (GCRI)
Agriculture takes about seventy percent of freshwater withdrawals worldwide; wetlands, fisheries and floodplains depend on the flows left behind. Food, water and ecosystems are one system drawn three ways. This page sets out the links, how they are measured, and what the evidence serves for the institutions that allocate water and land.
Water NexusWireframe of the working environment, not a live screen. Names and values are placeholders.
Irrigation, soil, wetlands and ecological services. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Irrigated land feeds much of the world from a small share of cropland. Expanding it in a drying basin takes water from cities, industry and rivers; retiring it changes rural livelihoods.
Fisheries, floodplain agriculture and wetlands need the timing of flow as much as its volume: the flood pulse, the dry-season minimum, the sediment it carries.
Fertiliser and livestock runoff drive eutrophication; salinisation from irrigation returns degrades soils and downstream water. The damage returns to the farm as lower yields.
A drought cuts yields, a flood destroys stores, and both move food prices beyond the basin. The food system transmits a water shock to places that saw no weather.
Where this page’s subject sits in the world: boundaries and context now, the field layers when the interactive map loads.
MapWorld map in the Equal Earth projection, land and boundaries from Natural Earth (public domain). The interactive map loads through the Nexus Foundry plugin (globe or flat view).
The systems this subject touches, the method at its core and the decisions it informs.
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Irrigated area and water use | hectares; cubic metres per hectare | seasonal | Satellite mapping, district records | ESTIMATED |
| Crop water stress | dimensionless index | weekly | Satellite evapotranspiration against demand | MODELLED |
| Environmental flow compliance | percent of months meeting the regime | annual | Gauges against the agreed regime | OFFICIAL |
| Wetland extent | square kilometres | seasonal | Optical and radar satellites | OBSERVED |
| Nutrient load at the basin outlet | tonnes of nitrogen and phosphorus per year | annual | Sampling, models | ESTIMATED |
| Inland fish catch | tonnes per year | annual | Fisheries statistics | OFFICIAL |
The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.
Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| FAO AQUASTAT and FAOSTAT | Water withdrawal by sector, irrigated area, production | Free and open, attribution |
| MODIS and Sentinel-2 | Cropland, irrigation and wetland mapping | Public domain; free and open |
| Global Surface Water and Ramsar site data | Wetland extent and designation | Free and open; terms per site |
| WRI Aqueduct | Baseline water stress and related indicators by basin | Free and open, attribution |
| National agriculture and fisheries statistics | Production, catch and district water accounts | Public records, terms per agency |
Water Nexus prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| Agriculture and water ministries | How much irrigation a basin can carry in a dry year without failing cities or rivers | Basin accounts by use; allocation scenarios with each loss stated |
| Fisheries and environment agencies | What flow regime sustains the fishery and wetland, and what it costs upstream | Environmental flow compliance; wetland extent against releases |
| Food security planners and finance | Where a water shock becomes a food shock, and what reserves or instruments cover it | Yield-at-risk by district; price-transmission traces; readiness questions with GRA |
Irrigation raises and stabilises yields but can deplete rivers and aquifers, salinise soils and pollute water with nutrients and pesticides. Efficiency gains on a farm often reduce return flows that downstream users relied on, so basin-wide savings are smaller than expected unless total consumption is capped.
Ecosystems are not only users of water; they also regulate it. Healthy soils store water and reduce runoff, wetlands and floodplains absorb floods and recharge aquifers, and forests influence local rainfall and water quality. When they degrade, the water services they provided must be replaced by engineering, if they can be replaced at all.
Satellite estimates of crop water use, through Earth observation. Accuracy varies with method and conditions.
Methods that relate flow regime to ecological condition. They range from simple hydrological rules to detailed habitat models, with different data needs.
Water accounts that trace consumption and return flows across a basin, built with geospatial information systems and hydrology and water science. Informal abstraction is hard to observe.
| Method | Applied here | Canonical page |
|---|---|---|
| Hydrology and water science | Hydrology and water science in this field | STEM Commons |
| Earth observation and remote sensing | Earth observation and remote sensing in this field | STEM Commons |
| Geospatial information systems | Geospatial information systems in this field | STEM Commons |
| Spatial statistics and geostatistics | Spatial statistics and geostatistics in this field | STEM Commons |
| Uncertainty quantification and model validation | Uncertainty quantification and model validation in this field | STEM Commons |
Irrigation water use is mostly unmetered and is estimated from satellites and crop models with wide error. Environmental flow needs are set by ecological judgement as much as by measurement. Price transmission depends on markets and policy that the basin model does not contain.
The current service level is R0: information and enquiries. An enquiry receives a reference and names the next step; applications, payments, compute allocations and registrations open only when their team, terms and review capacity exist.