GCRI · Water Nexus
Water, food and ecosystem links
Agriculture is the largest user of freshwater withdrawals worldwide, as FAO AQUASTAT records show; 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, food and ecosystem links on the record.
Water, food and ecosystem links: how the risk develops.
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.
Irrigation and allocation
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.
Environmental flows
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.
Quality feedbacks
Fertiliser and livestock runoff drive eutrophication; salinisation from irrigation returns degrades soils and downstream water. The damage returns to the farm as lower yields.
Shocks and prices
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.
Water now in the Nile Basin.
Root-zone soil moisture, crop greenness and land cover over the Nile Basin, from NASA GIBS. Each layer carries its own date.
The interactive map needs JavaScript; the layer list and sources are below.
Layers 3
Water now, for this page
About this layer
- Evidence
- Modelled
- Source
- SMAP Level 4 (NASA NSIDC DAAC)
- Provider
- NASA NSIDC DAAC
- Licence
- NASA open data
- Vintage
- daily; Model with satellite data assimilated
- Newest at build
- 2026-10-11
- Resolution
- about 2 km grid
- Uncertainty
- Model with satellite data assimilated. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed (clouds leave gaps)
- Source
- MODIS Terra NDVI (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite index; clouds leave gaps
- Newest at build
- 2026-10-13
- Resolution
- about 250 m grid
- Uncertainty
- Satellite greenness index over the 8 days to the date shown; an indicator of crop and pasture condition, not a yield estimate or a food security warning.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Modelled (latest year GIBS publishes)
- Source
- MODIS Terra and Aqua land cover (MCD12Q1) (NASA LP DAAC)
- Provider
- NASA LP DAAC
- Licence
- NASA open data
- Vintage
- yearly; Satellite classification; latest year GIBS publishes
- Newest at build
- 2024-01-01
- Resolution
- about 500 m grid
- Uncertainty
- Satellite land cover classes for the year shown, including croplands; a classification with known errors, not a farm register.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Observed
- Source
- VIIRS NOAA-20 corrected reflectance (NASA LANCE)
- Provider
- NASA LANCE
- Licence
- NASA open data
- Vintage
- daily; Satellite image
- Newest at build
- 2026-10-14
- Resolution
- about 250 m grid
- Uncertainty
- Satellite image. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Modelled (latest 8-day period GIBS publishes)
- Source
- MODIS Aqua GPP (MYD17) (NASA LP DAAC)
- Provider
- NASA LP DAAC
- Licence
- NASA open data
- Vintage
- 8-day; Satellite-driven model; latest 8-day period GIBS publishes
- Newest at build
- 2026-09-30
- Resolution
- about 500 m grid
- Uncertainty
- Model estimate of carbon taken up by plants over the 8-day period shown; an indicator of growth, not harvest or production.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
About this layer
- Evidence
- Estimated
- Source
- GPM IMERG (NASA GES DISC)
- Provider
- NASA GES DISC
- Licence
- NASA open data
- Vintage
- daily; Satellite estimate, near real time
- Newest at build
- 2026-10-12
- Resolution
- about 2 km grid
- Uncertainty
- Satellite estimate, near real time. Satellite or model raster as the provider publishes it. Clouds, swath gaps and retrieval error leave gaps and noise; values are indicators, not measurements at a place.
- Reached through
- gibs.earthdata.nasa.gov, only after you allow the live map
Keyboard, with the map focused
Hold Ctrl or ⌘ and scroll to zoom
Latest available
NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Blue Marble (NASA) · © OpenStreetMap contributors (ODbL) · Natural Earth
Loading the latest NASA imagery.
Drag to move. Ctrl or ⌘ and scroll, pinch or the buttons to zoom; hover for the values under the pointer; reset returns to the region.
Water now, framed on the Nile Basin.Satellite and model products as NASA publishes them, each with its own date. They are indicators, not assessments of any place.
Data: NASA GIBS · ASTER GDEM · Blue Marble · © OpenStreetMap contributors · Natural Earth · NASA EONET · NASA JPL OPERA DIST-ALERTSources and licences
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- SMAP Level 4 soil moisture and snow mass, NASA Global Modeling and Assimilation Office; distributed by the NASA National Snow and Ice Data Center DAAC; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- MODIS land products (vegetation indices, gross primary production, land cover), NASA LP DAAC and LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- VIIRS near-real-time products (flood, land surface temperature, snow cover, corrected reflectance), NASA LANCE; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- GPM IMERG precipitation, NASA Precipitation Processing System; distributed by the NASA Goddard Earth Sciences Data and Information Services Center (GES DISC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- ASTER GDEM is a product of METI and NASA (ASTER Global Digital Elevation Model V003, NASA LP DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). Cite as: NASA/METI/AIST/Japan Spacesystems and U.S./Japan ASTER Science Team (2019). ASTER Global Digital Elevation Model V003. doi:10.5067/ASTER/ASTGTM.003. NASA open data
- Made with Natural Earth. Free vector and raster map data @ naturalearthdata.com. Public domain
- © OpenStreetMap contributors (ODbL), via NASA GIBS (coastlines, boundaries, roads and place names). Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). ODbL
- Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into hexagonal cells where shown (modified). NASA open data
- Context on the globe and flat map: coastlines, boundaries, roads and place names from NASA GIBS reference layers (OpenStreetMap data, ODbL, © OpenStreetMap contributors); Blue Marble imagery as an optional base; 3D terrain and the elevation read-out from the ASTER GDEM elevation colour index (5 m to 200 m classes, exaggerated for legibility). Boundaries are drawn as published and imply no position on any territory.
- Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
- Live: NASA EONET Events are indicative, not authority warnings.
- Observed (EO): NASA JPL OPERA DIST-ALERT (contains modified Copernicus Sentinel data 2026). We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- NASA GIBS: We acknowledge the use of imagery provided by services from NASA’s Global Imagery Browse Services (GIBS), part of NASA’s Earth Science Data and Information System (ESDIS).
- River discharge forecast, 30 days with range (GloFAS via Open-Meteo): Contains modified Copernicus Emergency Management Service information 2026; not a flood warning.
- Past year, daily temperature (ERA5 via Open-Meteo): Contains modified Copernicus Climate Change Service information 2026.
- Past year, daily temperature and sunshine (NASA POWER): These data were obtained from the NASA Langley Research Center (LaRC) POWER Project funded through the NASA Earth Science/Applied Science Program..
- Weather data by Open-Meteo.com (https://open-meteo.com/), licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/).
- Optional layers (14 sources in the layer list: live, forecast, observed and context) print their provider credit on the map and here when switched on; forecasts are model output and derived indices are estimates.
Layers and dates
- Root-zone soil moisture, 0 to 100 cm: SMAP Level 4, NASA NSIDC DAAC · 11 Oct 2026
- Vegetation greenness (NDVI), rolling 8 days: MODIS Terra NDVI, NASA LANCE · 13 Oct 2026
- Land cover type (IGBP), yearly: MODIS Terra and Aqua land cover (MCD12Q1), NASA LP DAAC · 2024
- True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026
- Gross primary production, 8-day total: MODIS Aqua GPP (MYD17), NASA LP DAAC · 30 Sep 2026
- Precipitation rate, daily mean: GPM IMERG, NASA GES DISC · 12 Oct 2026
Irrigation, environmental flows and the ecosystems in between.
| Domain | How it couples here | What to watch |
|---|---|---|
| Food | Irrigated land produces a large share of food from a small share of cropland, and draws most freshwater withdrawals in many basins. See agricultural production. | Water productivity in kilograms per cubic metre |
| Biodiversity | Environmental flows keep rivers, wetlands and deltas functioning; the Brisbane Declaration (2007, updated 2018) set the global agenda. See ecosystem services. | Environmental flow requirement met, by month |
| Energy | Pumped irrigation ties food to electricity and diesel prices. | Irrigation energy cost per hectare |
| Health | Irrigation schemes can expand habitats for malaria and schistosomiasis vectors. | Vector surveillance near new schemes |
SDG indicator 6.4.2, water stress, is computed by FAO as freshwater withdrawal relative to available resources after environmental flow requirements, so the environmental flow assumption changes the result.
Shared basin data exchange.
The screen a team would use to follow this subject: its measures, states and decisions. Names are examples and values are illustrative.
Shared basin data exchange
Water, food and ecosystem links · Shared basin · Riparian states A, B, C
Joint fact-finding
- Data protocolagreed
- Gauge harmonisationdone
- Joint modelrunning
- Scenario setdraft
- Commission review
- Publication
Data exchange status
per agreement annex
| Border gauge 1 | A | Daily | On time |
| Border gauge 2 | B | Daily | On time |
| Dam release log | C | Weekly | On time |
| Water quality set | B | Monthly | Missing |
Flow at border points
- State A
- State B
- State C
Notifications under the agreement
- N-1Planned release change, reservoir C2Prior notice period running10 d
- N-2New abstraction scheme, State AConsultation open15 d
Integrated basin evidence and contributions from the field.
Integrated water, food and ecosystem studies are designed for the Country Systems Risk and Resilience series and draw on the IPBES Nexus Assessment of 2024. The Global Centre for Risk and Innovation (GCRI) does not set environmental flows or allocate water; those are national and basin decisions. Contributions that help: environmental flow studies, wetland condition surveys and records of irrigation expansion with dates.
Model water, food and ecosystem links as a system. Run the cascade.
Assembled from the Nexus Standards area profile Water risk standards: the hazards it names, the systems and sectors that carry the loss, the controls that dampen it and the data that observe it. Choose the components, pick an initiating hazard and step through the cascade. The Map view places the run on an example geography with open data. Every coupling weight is a stated assumption you can change. A teaching model, not a forecast, an assessment or a certification. To model a place of your own choosing, open the full System Builder.
Hazards
- Flash flood
- Meteorological drought
- Groundwater depletion
- Dam failure
- Debris flow (set off downstream)
- Agricultural drought (set off downstream)
- Hydrological drought (set off downstream)
- Wildfire (set off downstream)
- Peat and underground fire (set off downstream)
- Forest dieback (set off downstream)
- Water supply shortfall (set off downstream)
- Acute food crisis (set off downstream)
- Dust storm (set off downstream)
- Land subsidence (set off downstream)
- Saltwater intrusion (set off downstream)
- River flood (set off downstream)
- Mass displacement (set off downstream)
- Amazon rainforest dieback (set off downstream)
Systems and couplings
- Water risk standards
- Energy risk standards Common driver and cascade
- Food and agriculture risk standards Cascade
- Health risk standards Cascade
- Hydrometeorological hazard standards Shared hazard records
Controls
NS-0Constitution and principlesNS-1The UNI and the artefact catalogue (grammar v0.2: domain, sector, region and environment segments)NS-3Risk record UNIs (grammar, legacy crosswalk, allocation authority)NS-3bDataset and product metadata profile (STAC, DCAT, PROV-O)NS-9Contextual UNIs (deployments, instances, programme instances)NS-10Policies and clauses (machine-readable obligations: definition, binding, evaluation and enforcement)NS-11Verification and monitoring (evidence, attestations, zero-trust conformance observation)NRS-U28Universe platform profile: Water NexusNRS-H61Hazard family: Cascading failure (NHS-1 sys.cascade)NRS-K42Domain pack profile: Cross border basins (DOMAIN-042)NRS-N1Water risk and resilienceNRS-N7Water-energy-food-health-biodiversity-infrastructure nexus couplingNRS-H62Hazard family: Compound and multi-hazard events (NHS-1 sys.compound)
Observation
- USGS Water Data APIs (listed for reference)
- GloFAS global flood forecasts and reanalysis (listed for reference)
- GRACE/GRACE-FO terrestrial water storage mascons (listed for reference)
- Aqueduct 4.0 Water Risk Atlas (listed for reference)
- CHIRPS quasi-global gridded precipitation (listed for reference)
- Level of water stress: freshwater withdrawal as a proportion of available freshwater resources
- Proportion of transboundary basin area with an operational arrangement for water cooperation
- Proportion of population using safely managed drinking water services
- Number of disruptions to basic services attributed to disasters
Example geography
- The Ganges and Brahmaputra Basin: 178 hexagonal cells
- Surface water through cloud, 30 m (OPERA DSWx-S1 radar), NASA GIBS
- Rain rate, last half hour (IMERG), NASA GIBS
- Surface soil moisture (SMAP), NASA GIBS
- Night lights tonight, outages (VIIRS Day/Night Band), NASA GIBS
What is measured, and how well.
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 | Published statistics |
| 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 | Published statistics |
The sector signature of water, food and ecosystem links.
The sectors water, food and ecosystem links touches and how strongly they depend on each other: what a study has to observe and model together.
Signature
Water, Food and Biodiversity
Food gives biodiversity land conversion (0.6); water gives food irrigation (0.8): the strongest relations between the sectors this subject joins.
W · E · I · F · H · B
- Sectors
- 4 of 6
- Relations
- 6 of 15
- Coupling
- 0.46 share of total
Strongest relations in play
- Food → Biodiversity · land conversion0.6
- Water → Food · irrigation0.8
- Water → Biodiversity · environmental flows0.6
- Food → Health · nutrition0.7
Where the evidence comes from.
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 |
How water, food and ecosystem links is modelled, measured and tested.
The model, its assumptions, its data and its uncertainty, in the form a scientist or engineer would check. Structures follow published methods. The values drawn are illustrative, not findings.
System model
The couplings between the systems in water, food and ecosystem links: signs of influence, a reinforcing and a balancing loop, and cross-links where stress jumps.
Who decides, and what the evidence serves.
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 the Global Risks Alliance (GRA) |
Outputs this topic produces
- Basin water accounts by use with ecosystem flows made explicit
- Crop stress and yield-at-risk layers by season
- Allocation scenarios with food, city and ecosystem losses stated apart
- Price-transmission traces for a drought year
What researchers ask about water, food and nature.
- How much water do crops and livestock actually consume, and how efficiently is it used?
- Does improved irrigation efficiency save water at basin scale, or does it shift use?
- How do soil health and land management affect infiltration, erosion and drought resilience?
- How much flow do rivers and wetlands need to sustain their functions?
Competition and mutual dependence.
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.
Measuring water in landscapes.
- 01
Remote sensing of evapotranspiration
Satellite estimates of crop water use, through Earth observation. Accuracy varies with method and conditions.
- 02
Environmental flow assessment
Methods that relate flow regime to ecological condition. They range from simple hydrological rules to detailed habitat models, with different data needs.
- 03
Basin accounting
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.
How it is studied, and what the methods cannot say.
- 01Hydrology and water scienceRainfall-runoff modelling of a basin · Water balance accountingApplied here
- 02Earth observation and remote sensingFlood extent from radar · Surface water and reservoir monitoringApplied here
- 03Geospatial information systemsExposure mapping · Catchment and basin delineation · Public-safe basin mapsApplied here
- 04Spatial statistics and geostatisticsRainfall and groundwater interpolation · Regionalisation to ungauged basinsApplied here
- 05Uncertainty quantification and model validationEnsemble and parameter uncertainty · Propagation through the cascade · Evidence labellingApplied here
Where this page’s references lead.
The bodies and documents this page is read against. Status and editions change; each link goes to the issuing body.
- Arthington and others, The Brisbane Declaration and Global Action Agenda on Environmental Flows (2018), Frontiers in Environmental Science 6 (2018)
- FAO AQUASTAT and the SDG 6.4.2 water stress method (FAO)
- Convention on Wetlands (Ramsar, 1971)
- IPBES Nexus Assessment on biodiversity, water, food and health (IPBES, 2024)
Questions and answers.
Why does agriculture use so much water?
What is an environmental flow?
Does a basin model predict food prices?
Why can irrigation efficiency fail to save water?
What are environmental flows?
How do soils affect drought resilience?
Does Water Nexus value ecosystem services in money terms?
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