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 · Course catalogue · Earth and Environmental Sciences

Water and Food Systems

Water security and hydrology

Water security and hydrology, taught twice over: as the working methods of the field and as its frontier since 2024, with labs on the Academy's tools, open data and the Nexus Standards.

Core course Frontier course

The discipline

01Core course · L2 Intermediate

Water security and hydrology: foundations and practice

Water security is the capacity of people, economies and ecosystems to have reliable water of acceptable quantity and quality with an acceptable level of water-related risk.

Level
L2 Intermediate
Study time
about 24 hours (planning estimate)
Status
In authoring
Prerequisites
An L1 course in the area, or an entry review

Why now

Basin-scale baselines are shifting; supply, hydropower and drought planning built on historical flows now risk underestimating both scarcity and swings between extremes. World Meteorological Organization, State of Global Water Resources 2025, 17 September 2026

Learning outcomes

  1. Define water security and the other key terms of the discipline and use them correctly in a written case
  2. Explain catchment hydrology and the water balance and groundwater and aquifers with a worked example and its source
  3. Apply the discipline's method to a documented case and explain each result with its source
  4. Analyse a named case against water stress and scarcity indicators, stating evidence, date and limits

Modules

  1. Catchment hydrology and the water balance
    • Catchment hydrology and the water balance
    • Groundwater and aquifers
    • Water stress and scarcity indicators
  2. Drinking water, sanitation and hygiene
    • Drinking water, sanitation and hygiene
    • Water and wastewater utilities
    • Shared river basins and transboundary cooperation
  3. Water quality
    • Water quality
    • Integrated water resources management
    • Water-energy interdependence
  4. Lab: the discipline's method
    • Annual rainfall and evaporative demand set how much of a catchment's water reaches its rivers; withdrawals set against that runoff, after the share rivers need, give the water stress indicator; the allocation decision follows from the stress, not from the rainfall alone.
    • Work the method through a documented case and explain each result
    • Read the method's sources and stated values

Labs with Academy tools

Nexus Standards

Teaches

  • NRS-N1 Water risk and resilience
  • NRS-N7 Water-energy-food-health-biodiversity-infrastructure nexus coupling
  • NRS-H9 Hazard family: Freshwater inundation
  • NRS-H10 Hazard family: Water deficit
  • NRS-H13 Hazard family: Water-quality degradation
  • NRS-H85 Hazard family: Water and wastewater system failure
  • NRS-M13 Method fabric: Water risk

Relies on

  • NS-1 The UNI and the artefact catalogue
  • NS-16 UNI application profile (how articles, documents, code, data, APIs and interfaces carry the UNI)
  • NRS-C1 Risk vocabulary and ontology
  • NRS-C2 Risk assessment method
  • NRS-C3 Hazard, exposure, vulnerability and capacity data
  • NRS-C4 Risk data model, identifiers and exchange
  • NRS-C6 Systemic and cascading risk
  • NRS-C7 Early warning, triggers and anticipatory action

Assessment

  • 40%Lab recordWork the discipline's method through a documented case and explain each result with its source and date
  • 40%Case memoApply the discipline's methods to a named place or organisation, stating evidence and limits
  • 20%Key terms checkShort answers on the key terms, marked against the definitions

Delivery

  • Self-paced online, with the labs in the browser
  • Cohort study over six to eight weeks, with a weekly lab review
  • Co-delivered with a partner institution, inside its own courses

Partner on this course

  • Co-teach a module and bring a current case from your work
  • Host a cohort for your learners, with your own schedule and review
  • Contribute a lab: a dataset your institution publishes openly, or a model
  • Review the course content and its references before it opens
  • Translate the course and adapt its cases to your region

How institutions and experts take part

In the Academy LMS

Course on the learning platform
Intermediate, 4 topics
Cohort group
A community group for each cohort of learners
Achievement
Recorded on completion of the assessed work

Open now in this discipline

References

  1. World Meteorological Organization, State of Global Water Resources 2025, 17 September 2026
  2. Zhang, Dawes and Walker, Response of mean annual evapotranspiration to vegetation changes at catchment scale, 2001
  3. Vicente-Serrano, Begueria and Lopez-Moreno, A multiscalar drought index sensitive to global warming: the SPEI, 2010
  4. Milly et al., Stationarity is dead: whither water management?, 2008
02Live map

Water now in Ethiopia

Rain, flood water and root-zone soil moisture from NASA satellites and models, with long-term water stress, over Ethiopia.

The interactive map needs JavaScript; the layer list and sources are below.

Layers 2

Water now

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 Ethiopia.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 EONETSources 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 H3 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 H3 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 H3 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 H3 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 H3 cells where shown (modified). NASA open data
  • GRACE and GRACE-FO JPL mascon solution, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 cells where shown (modified). NASA open data
  • GHRSST Level 4 MUR analyses, NASA Jet Propulsion Laboratory; distributed by the NASA Physical Oceanography DAAC (PO.DAAC); imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 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 H3 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 H3 cells where shown (modified). ODbL
  • Blue Marble, NASA Earth Observatory; imagery via NASA GIBS. Colours redrawn from the published colour map; values averaged into H3 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.
  • Globe: MapLibre GL JS 6.9.1, BSD-3-Clause, © MapLibre contributors.
  • Live events: NASA Earth Observatory Natural Event Tracker (EONET); events are indicative and keep their original source links.
  • 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 (13 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

  • Precipitation rate, daily mean: GPM IMERG, NASA GES DISC · 12 Oct 2026
  • Flood water, 3-day composite: VIIRS Global Flood Product, NASA LANCE · 14 Oct 2026
  • Root-zone soil moisture, 0 to 100 cm: SMAP Level 4, NASA NSIDC DAAC · 11 Oct 2026
  • Snow cover: VIIRS NOAA-20 NDSI, NASA LANCE · 13 Oct 2026
  • Water storage anomaly, monthly: GRACE-FO JPL mascons, NASA JPL PO.DAAC · July 2022
  • Sea surface temperature anomaly: GHRSST MUR25, NASA JPL PO.DAAC · 12 Oct 2026
  • True colour: VIIRS NOAA-20 corrected reflectance, NASA LANCE · 13 Oct 2026

03How learning runs

How learning runs, as a process you can run

Select a scenario and press Play: course, pathway, practice, faculty, cells and record.

04What is changing

Frontier course · L3 advanced, programme courses and standards

Water security and hydrology: frontier methods

The methods, data, tools and studies that changed water security and hydrology between 2024 and 2026, taught by reproducing them on open data.

Level
L3 Advanced
Study time
about 28 hours (planning estimate)
Status
Planned
Prerequisites
Water security and hydrology: foundations and practice; Working knowledge of a scripting language (Python or R) for the labs

Why now

Basin-scale baselines are shifting; supply, hydropower and drought planning built on historical flows now risk underestimating both scarcity and swings between extremes. World Meteorological Organization, State of Global Water Resources 2025, 17 September 2026

Learning outcomes

  1. Explain what changed in water security and hydrology since 2024 and cite the studies, data or rules behind each change
  2. Reproduce WMO reports 2025 among the driest years for rivers in decades on open data and state the uncertainty of the result
  3. Evaluate a 2024 to 2026 study: its question, data, method, limits and what it changes for practice
  4. Design an analysis that combines a frontier method with the faculty's instruments, and justify each choice

Modules

  1. WMO reports 2025 among the driest years for rivers in decades
    • The fifth annual WMO water resources report found 2025 river flows among the lowest in more than 35 years, declining land water storage over the past decade, and glacier loss in every region for a fourth straight year.
    • Basin-scale baselines are shifting; supply, hydropower and drought planning built on historical flows now risk underestimating both scarcity and swings between extremes.
    • World Meteorological Organization, 17 September 2026
  2. JMP update: one in four people lack safely managed drinking water
    • The WHO/UNICEF Joint Monitoring Programme reported that by 2024 about 2.1 billion people still lacked safely managed drinking water, including 106 million using untreated surface water, despite large gains since 2000.
    • Service gaps concentrate health and outbreak risk among the poorest; the inequality breakdown helps target where water and sanitation failures turn shocks into crises.
    • WHO/UNICEF Joint Monitoring Programme, 1 August 2025
  3. UN water report puts mountain water towers at the centre
    • The 2025 UN World Water Development Report found mountains supply up to 60% of annual freshwater flows and over two billion people depend on them, while glacier retreat and snowpack change make downstream supply less reliable.
    • Downstream utilities, irrigators and hydropower operators inherit upstream cryosphere risk; mountain governance and data sharing become part of water security assessment.
    • UNESCO, 21 March 2025
  4. Global commission frames the water cycle as a common good
    • The Global Commission on the Economics of Water argued that the hydrological cycle should be valued and governed as a global common good, linking it to land use, climate change and biodiversity loss, and calling for systemic action.
    • It shifts water risk from a local supply issue to a shared, cross-border system risk, supporting valuation and governance approaches that reach beyond individual catchments.
    • Global Commission on the Economics of Water, 17 October 2024
  5. Reproduction lab
    • Extend the discipline's method with one frontier method and compare its results
    • State the uncertainty and the limits of the result
    • Peer review against a shared checklist
  6. Technology that helps and the risks it carries
    • Earth observation for the water balance, smart metering and digital twins of water networks.
    • Attacks on utility control systems, and the water demand of data centres.

Labs with Academy tools

Nexus Standards

Teaches

  • NRS-N1 Water risk and resilience
  • NRS-N7 Water-energy-food-health-biodiversity-infrastructure nexus coupling
  • NRS-H9 Hazard family: Freshwater inundation
  • NRS-H10 Hazard family: Water deficit
  • NRS-H13 Hazard family: Water-quality degradation
  • NRS-H85 Hazard family: Water and wastewater system failure
  • NRS-M13 Method fabric: Water risk

Relies on

  • NS-1 The UNI and the artefact catalogue
  • NS-16 UNI application profile (how articles, documents, code, data, APIs and interfaces carry the UNI)
  • NRS-C1 Risk vocabulary and ontology
  • NRS-C2 Risk assessment method
  • NRS-C3 Hazard, exposure, vulnerability and capacity data
  • NRS-C4 Risk data model, identifiers and exchange
  • NRS-C6 Systemic and cascading risk
  • NRS-C7 Early warning, triggers and anticipatory action

Assessment

  • 50%Method reproductionReproduce one frontier method on open data and state the uncertainty of the result
  • 30%Study reviewA critical review of a 2024 to 2026 study: question, data, method, limits, what it changes
  • 20%Peer reviewReview two other learners' reproductions against a shared checklist

Delivery

  • Self-paced online, with the labs in the browser
  • Cohort study over six to eight weeks, with a weekly lab review
  • Co-delivered with a partner institution, inside its own courses

Partner on this course

  • Co-teach a module and bring a current case from your work
  • Host a cohort for your learners, with your own schedule and review
  • Contribute a lab: a dataset your institution publishes openly, or a model
  • Review the course content and its references before it opens
  • Translate the course and adapt its cases to your region

How institutions and experts take part

In the Academy LMS

Course on the learning platform
Expert, 6 topics
Cohort group
A community group for each cohort of learners
Achievement
Recorded on completion of the assessed work

Open now in this discipline

References

  1. World Meteorological Organization, State of Global Water Resources 2025, 17 September 2026
  2. WHO/UNICEF Joint Monitoring Programme, Progress on household drinking water, sanitation and hygiene 2000-2024: special focus on inequalities, 1 August 2025
  3. UNESCO, Glaciers and mountains: melting water towers will aggravate global crises (report), 21 March 2025
  4. Global Commission on the Economics of Water, The Economics of Water: Valuing the Hydrological Cycle as a Global Common Good, 17 October 2024
  5. Zhang, Dawes and Walker, Response of mean annual evapotranspiration to vegetation changes at catchment scale, 2001
  6. Vicente-Serrano, Begueria and Lopez-Moreno, A multiscalar drought index sensitive to global warming: the SPEI, 2010
  7. Milly et al., Stationarity is dead: whither water management?, 2008
05Take part

Take part in the work

Start from who you are.

06Questions

Questions, answers and key terms

Is the course free?
Yes. Every course and learning material of Risk Academy, led by the Nexus Consortium, is free to study, self-paced or with a cohort. Ordinary participation has no fee; paid work, internships and fellowships are separate arrangements.
What does completing a course give me?
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; it is not a licence, a professional title or an employment status.
Where do the data and the places come from?
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 course?
Form a competence cell of three to seven people, study a shared pathway, take a supervised assignment in the National Working Groups, or bring a cohort from your institution. For organisations.

Key terms

Term

Water security

Reliable access to water of acceptable quantity and quality, with water-related risks kept at an acceptable level.

Term

Water balance

The accounting of inflows, storage changes and outflows of water in a catchment or aquifer over a period.

Term

Water stress

Pressure on freshwater resources measured as withdrawals relative to the renewable resources available.

Term

Blue and green water

Blue water flows in rivers, lakes and aquifers; green water is soil moisture used by plants.

ReportsContribute

Contribute evidence from this page.

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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