Rainfall-runoff modelling of a basin
A conceptual or process-based model is built for each sub-catchment, calibrated on gauged flows and run with observed and forecast rainfall to give flow at the points where decisions are taken.
The Global Centre for Risk and Innovation (GCRI)
Hydrology is the core science of this platform: it turns rainfall, snow, soil, vegetation and geology into the river flows, groundwater levels and storage that every water decision depends on.
Water NexusWireframe of the working environment, not a live screen. Names and values are placeholders.
Hydrology studies the movement, distribution and quality of water across the land surface, subsurface and atmosphere. It underpins the assessment of floods, droughts and water supply, which affect food, energy, health and infrastructure together. In water, climate and hazards and critical infrastructure, hydrological estimates set design standards for dams, levees and drainage and inform water allocation between competing users. They link climate hazards to downstream effects on power generation, crops and public health. The canonical description is on the STEM Commons.
A conceptual or process-based model is built for each sub-catchment, calibrated on gauged flows and run with observed and forecast rainfall to give flow at the points where decisions are taken.
Inflows, abstractions, evaporation, returns and storage change are reconciled by season and by user, so allocation decisions start from a closed account rather than competing estimates.
Annual maxima and peaks over threshold are fitted to give return-period flows for levee, culvert and reservoir design, with confidence bands that widen as the record shortens.
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).
Data from the source register feeds the methods; calibration and an independent test gate the estimate and its limits; the decision stays with the competent authority.
Fig. 01Nodes carry their type, metrics and state; connectors show what feeds what; the gates are the validation steps; the timeline is one application. Design of the method’s use, not a record of a run.
Datasets and records used by hydrology and water science on this platform, with the role each plays and the label its values carry. Sources are listed in the source register.
| Data | Role | Label |
|---|---|---|
| Stream gauge records | Calibration and validation of flow | OBSERVED |
| Gauge and radar rainfall | Model forcing | OBSERVED |
| Reservoir operation records | Storage and release terms of the balance | OFFICIAL |
| Digital elevation model | Catchment delineation and routing | MODELLED |
| Land cover and soil maps | Runoff and infiltration parameters | ESTIMATED |
Models are calibrated on one period of observed flows and tested on an independent period or neighbouring catchment. Skill scores and comparison with surveyed flood extents are used to judge performance.
| Check | How it is done |
|---|---|
| Split-sample calibration | Fit on one period of flows, test on an independent period or a neighbouring catchment, report skill on the test period only |
| Mass balance closure | Every run reconciles inflow, outflow and storage change; an open balance is a finding, not a tolerance |
| Flood extent comparison | Modelled inundation is compared with surveyed or satellite extents of past events |
| Stationarity check | Trends in the record are tested before a return period is quoted from it |
Assumptions of stationarity weaken as climate and land use change. Ungauged basins, karst aquifers and rapid urbanisation are poorly represented by parameters fitted elsewhere.
Water Nexus stewards hydrology and water science for the Consortium and reviews how it is applied across platforms.
| Link | Relationship | Why |
|---|---|---|
| Hydrology and water science | Canonical method page | Platform application links to the canonical method page. |
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.