Illustrative: rain routed down a catchment to the flood plain, generated, with the intensity of a scenario rising and falling
Risk Academy, led by the Nexus Consortium · Systems and Nexus Studies · Department of Nexus-Based Risk Management
Water, energy, food and ecosystems as one system: links, trade-offs and synergies
Water-energy-food-ecosystems nexus
The water-energy-food-ecosystems nexus covers the interactions between water, energy, food and ecosystems: how a choice in one sector changes risk in the others, the trade-offs and synergies between them and how policies and investments can be made coherent, applied to basins, cities and national planning.
The Tonle Sap and the Lower Mekong at Phnom Penh, Cambodia. Flat plan of the same data: the lake and rivers, the dams, the plants by capacity, the cropland and tree cover cells and the numbers below. The 3D twin opens on devices that can draw it, once its data and code have been checked; discharge, vegetation, surface water and the annual land cover load in the twin on request, each with its data date.
Terrain 0 to 1,700 m
River 2,956 km
14 dams
6 power plants, 88 MW
Tree cover 37.8 percent of the box
Cropland 39.9 percent of the box
Built-up 0.9 percent of the box
Permanent water 4.7 percent of the box
River discharge, GloFAS via Open-Meteo: read live when the 3D twin opens
Vegetation index, MODIS Terra NDVI 8-day: read live when the 3D twin opens
Surface water extent, OPERA DSWx (HLS): the flood pulse: read live when the 3D twin opens
Land cover classes, MODIS IGBP (annual): read live when the 3D twin opens
Credits and dates per layer are listed under the stage. Relief in the twin is exaggerated ×1.5 for legibility.
Drag to move, right drag or Shift with a drag to turn and tilt, Ctrl with the wheel to zoom. Keyboard: arrows move, Shift with arrows turn and tilt, + and – zoom, 0 resets, V steps through the views, Escape clears.
Power plants The hydropower, oil, waste and biomass plants inside the box with their capacity in MW and primary fuel, the energy node of the loop. Power plants: Global Power Plant Database v1.3.0 (2021), World Resources Institute and partners, CC BY 4.0. release 1.3.0, 2021-06-02.Estimate: A 2021 snapshot, never current operating status.
Cropland, tree cover, water and built-up shares (ESA WorldCover 2021) The share of cropland, tree cover, permanent water and built-up land in each of 200 by 200 cells, summarised at build time from the 10 metre product; the food and ecosystem nodes of the loop. (c) ESA WorldCover project 2021 / Contains modified Copernicus Sentinel data 2021 processed by ESA WorldCover consortium (CC BY 4.0); dataset: Zanaga, D. et al. (2022), ESA WorldCover 10 m 2021 v200, doi:10.5281/zenodo.7254221. read 2026-10-17.Estimate: A 2021 classification at 10 metres summarised to cells of about 1.4 kilometres from 16 sub-samples; not a crop yield, a harvest area or a wetland inventory.
River discharge, GloFAS via Open-Meteo Daily Mekong discharge at the Kratie cell with the member range for the next 30 days, and on click anywhere in the box; the water inflow of the loop. Weather data by Open-Meteo.com (CC BY 4.0); river discharge: contains modified Copernicus Emergency Management Service information 2026 (GloFAS); never a flood warning. Live: this page requests flood-api.open-meteo.com when the layer is opened; the data date is printed with it.Estimate: Model output (forecast or reanalysis), shown with the member range where the API gives one; never a warning. The loop simulator adds one request to the same endpoint with start_date=1984-01-01 and end_date=today for the chosen cell to build the seasonal pulse.
Vegetation index, MODIS Terra NDVI 8-day Vegetation greenness across the basin; the season scrub steps the 8-day periods through the flood pulse. MODIS Terra NDVI 8-day, NASA LP DAAC / LANCE, via NASA GIBS, with the product date. Live: this page requests gibs.earthdata.nasa.gov when the layer is opened; the data date is printed with it.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).Estimate: An indicator of vegetation condition, never yield or production.
Surface water extent, OPERA DSWx (HLS): the flood pulse Open and partial surface water on the date shown: the lake’s seasonal expansion and contraction. OPERA Dynamic Surface Water Extent from HLS, NASA JPL OPERA (contains modified Copernicus Sentinel data; USGS Landsat), via NASA GIBS, with the product date. Live: this page requests gibs.earthdata.nasa.gov when the layer is opened; the data date is printed with it.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).Estimate: A classification from optical imagery; clouds leave gaps in the wet season; never a flood warning.
Land cover classes, MODIS IGBP (annual) The 500 metre annual land cover classes (croplands, wetlands, forests) for the newest year GIBS serves, draped on the terrain beside the WorldCover shares. MODIS land cover (MCD12Q1, IGBP classes), NASA LP DAAC, via NASA GIBS, with the product year. Live: this page requests gibs.earthdata.nasa.gov when the layer is opened; the data date is printed with it.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).Estimate: A classification, not a crop area statistic.
Why this place: One box of about 270 by 275 kilometres holds the Tonle Sap lake, whose flow reverses with the Mekong flood pulse each year, the Mekong main stem from Kratie to Phnom Penh, the rice plains that the pulse irrigates, the fisheries that feed the country, and the hydropower and thermal plants of the Global Power Plant Database, so the water-energy-food-ecosystems nexus can be taught where the couplings are strong and well documented. Data quality: Copernicus DEM GLO-30 covers the flat basin in nine tiles, the GloFAS cell at Kratie answered 15,416 cubic metres per second through Open-Meteo on 2026-10-17, ESA WorldCover gives cropland, tree cover and permanent water shares per cell and MODIS the annual land cover classes, and OpenStreetMap maps the dams and the named rivers. It connects to the Water-energy-food-ecosystems nexus, Nexus-Based Risk Management (NRM), Systemic, compound and cascading risk and Complex systems and systems modelling disciplines and to the water, energy and food nexus field maps of the ecosystem sites, which draw on the same rows.
Flat plan of the same data: the lake and rivers, the dams, the plants by capacity, the cropland and tree cover cells and the numbers below. The 3D twin opens on devices that can draw it, once its data and code have been checked; discharge, vegetation, surface water and the annual land cover load in the twin on request, each with its data date.
The boundaries, names and designations shown do not imply any judgement on the legal status of any territory, or any endorsement or acceptance of such boundaries. Countries: Natural Earth (public domain).
03The subject
The subject, methods and measures and debates and bodies
The field and its scope
For basin planners, utility and agriculture analysts and policy advisers who must trace how a choice in water, energy, food or land changes risk in the other sectors and make the trade-offs explicit.
Quantities and units
Methods and their limits
Each method is listed with what it assumes and where it fails.
What the field debates
Bodies that set practice, and the data they publish
Bodies and standards are named so that learners can find and apply their published work. The Academy teaches the use of that work and links to the publisher. No affiliation is implied.
04The method
Lifting water to grow grain: how a falling water table becomes an energy bill and a water bill of its own
Pumping groundwater costs energy in proportion to the depth it is lifted; the energy to grow a tonne of grain follows from the crop’s water footprint, and when that electricity comes from thermal plants the energy consumes water in turn, so a water choice, an energy choice and a food choice are one choice seen three ways.
Sources: D’Odorico et al., The global food-energy-water nexus (2018); Mekonnen and Hoekstra, The green, blue and grey water footprint of crops and derived crop products (2011); Albrecht, Crootof and Scott, The water-energy-food nexus: a systematic review of methods for nexus assessment (2018); Hoff, Understanding the Nexus: background paper for the Bonn 2011 Conference (2011).
05Signature
How water-energy-food-ecosystems nexus connects the sectors
Select corners to build a signature, then hover a line to read what each sector gives and receives.
Signature
How water-energy-food-ecosystems nexus connects the sectors
6 sectors
Select corners · hover lines6 / 15 relations
Signature
Water, Energy, Food and Biodiversity
Food gives biodiversity land conversion (0.6); water gives energy cooling water and hydropower (0.6): the strongest relations between the sectors this subject joins.
W · E · I · F · H · B
Imikhakha
4 of 6
Ubudlelwano
6 of 15
Ukuhlanganiswa
0.43 share of total
Strongest relations in play
Food → Biodiversity · land conversion0.6
Water → Energy · cooling water and hydropower0.6
Water → Food · irrigation0.8
Water → Biodiversity · environmental flows0.6
Teaching values for a typical city-region, not measurements for any place. Coupling is the summed strength of the relations in play, as a share of all fifteen.
06At a glance
At a glance, standards and evidence, research and evidence, what is changing and learning
Water-energy-food-ecosystems nexus at a glance
risksacademy.comsystems-nexusdiscipline
Water-energy-food-ecosystems nexus at a glance
Open, 0
In preparation, 0
Also taught here, 5
Subtopics, 8
Drawn as a network cascade: the discipline as the source, its courses as the first tier and connected disciplines as the second.Course codes from the curriculum; study levels L1 to L4.
A completion record: the course, its version, the date and what was assessed, private by default and shared by you. It stacks into discipline, department and programme achievements. A record states what was studied and assessed and does not certify competence. A record is not a licence, a professional title or an employment status.
Idatha nezindawo zivelaphi?
Every faculty teaches on a twin of a real place built from open data. Each layer carries its provider, licence and date, and every result on the Academy states its source. Maps and figures are indicators for teaching, never an assessment of a place.
How do I take part beyond the courses in water-energy-food-ecosystems nexus?
Yakha iseli lekhono labantu abathathu kuya kwabayisikhombisa, fundani indlela yokufunda eyabelanayo, thatha umsebenzi ogadiwe emaqenjini okusebenza kazwelonke, noma lethe iqembu lesikhungo sakho. Open the page for organisations.
Amagama abalulekile
Igama
Water-energy-food nexus
The interdependence of water, energy and food security and the need to manage them together.
Igama
Trade-off
A gain in one sector that comes at a cost in another.
Igama
Synergy
An action that brings benefits in more than one sector.
Igama
Embedded water
The water used to produce a good, also called virtual water.
ImibikoNikela
Nikela ngobufakazi kusuka kuleli khasi.
Reports is the Consortium’s quarterly publication. What you know about this subject can become evidence, a case or a correction in the next edition, credited to you and published under CC BY 4.0 where it is your own work.
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Water-energy-food-ecosystems nexus
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