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Rivers and flood warningRivers and floods, measured before the water arrives.
Flood warning depends on knowing how much rain fell, how high the river is and how fast it is rising, upstream of the people at risk. Gauging stations, rain gauges and cameras report every few minutes to a record that hydrologists and forecasters trust, and the warning authority issues its alerts with the evidence in hand.
Plan a deploymentHow it worksStation Builder- Industry
- Water
- Measurements
- 5
- Sources cited
- 5
Water · Rivers and flood warning
Minutes that decide a flood
A flood warning is only as good as the measurements upstream of the people at risk. Rain falls on a catchment, the river rises, and forecasters have hours or minutes to warn. Gauges, rain gauges and cameras that report reliably, especially when the river is at its worst, give them that time.
What is measured
Level, rain, images and extent
Level sensors at stable sections measure the river; rating curves turn level into flow, checked by field measurements. Rain gauges across the catchment measure the cause, cameras confirm what the numbers show, and satellite imagery maps the extent of a flood once it spreads.
- Instruments
- Level sensors · Rain gauges · Cameras · Satellite imagery
The base node
A node that speeds up as the river rises
Each station’s node reads its sensors, signs every value and keeps it through any lost link. As the river rises it reports more often, checks for debris spikes and raises an alarm locally when a threshold is crossed, so the alarm does not wait for a central system.
Radio and links
Two paths out of the valley
Cellular coverage is the everyday path for most gauges, and a satellite terminal keeps the station reporting when cellular fails in the flood. Rain gauges and small sensors in the catchment report through LoRaWAN gateways on high ground. The second path is tested every month.
- Links
- Public cellular · Satellite · LoRaWAN
How it works
From a gauge to a warning
A level reading is signed by the station’s node and sent over cellular, or satellite when cellular fails, to the forecasting centre. There it joins rainfall and the model; when a threshold is crossed, the alarm reaches the warning authority, which issues the warning through its own channels.
From order to operation · Order
Scope the basin and the warning
The scope reads the flood risk plan, the existing gauge network and the warning arrangements. Nexus Observatory Inc. returns the station plan by reach, the dual-path radio design, the integration with forecasting and warning systems and a price per station and per service.
Plan a deploymentFrom order to operation · Survey
Find stable sections above the flood
Crews survey candidate sections with hydrologists: stable control, access in a flood, the highest recorded levels, coverage and sky view. They record benchmarks, take reference photos and note where field flow measurements can be made safely. Sites that cannot be reached safely in a flood are rejected at this stage.
From order to operation · Permits
Rivers, bridges and land
Stations on bridges or banks need the consent of the asset owner, the landholder and often the water authority. Data sharing and warning roles are agreed in writing, so the authority that warns is always the one that decides. Every consent is kept with the station it covers.
From order to operation · Build
Build stations that survive floods
Level sensors, rain gauges, cameras, nodes, modems and satellite terminals are built and tested, enrolled with their identities and configured with the station’s thresholds. Mounts are chosen for debris and ice, and every part is labelled for quick replacement. Thresholds come from the warning plan.
Open the Station BuilderFrom order to operation · Install
Install at low water
Installation is planned for low water. Each station is levelled to its benchmark, the rain gauge is sited clear of obstructions, the camera is aimed at the staff gauge and the dual-path link is tested. Every station is photographed for the record.
From order to operation · Commission
Commission against the staff gauge
Each node proves its identity, then level is compared with the staff gauge and the rain gauge with a reference. The rating curve is loaded and checked by a field flow measurement, and alarms are tested to the forecasting centre and the warning authority.
From order to operation · Operate
Forecast and warn on evidence
Forecasters see levels, flows and rainfall across the basin with camera images, feeding their models. When thresholds are crossed, alarms arrive with their data, and the warning authority issues its warnings through its own channels, with every step logged. After each event the record is reviewed with the authority.
From order to operation · Maintain
Check the rating, keep the record
Field flow measurements continue on schedule and after floods, so rating curves follow the channel. Sensors are cleaned and checked, stations are repaired after events and every change is recorded, so long series stay consistent for planning. Gauges damaged in floods are repaired first, because the next flood may follow soon.
Book field servicesData products
For forecasters, warners and planners
Hydrologists and forecasters receive level, flow and rainfall series; warning authorities receive alarms with images; emergency managers and insurers receive flood extent maps; planners receive long, consistent records. Each product carries the quality codes and rating behind it. Series are published openly where the agreement allows.
See the data productsEvidence
Records hydrologists accept
Benchmarks, rating curves, every field flow measurement, every alarm and every change are signed and kept. Measurements follow international hydrological practice and stream gauging methods, and series are exchanged through open water data standards, so any agency can verify them.
- Drawn against
- WMO-No. 168 · WMO-No. 1044 · Directive 2007/60/EC · OGC WaterML
What you get
Hydrometeorological and flood observing networks
Stream gauges, rain gauges, weather radar and automatic weather stations built to WMO practice, reporting through WIS 2.0 where the agency requires it. Delivered as hardware + software, managed service and build-operate-transfer, for national meteorological and hydrological services, river-basin agencies, utilities.
Talk to salesNext step
Plan rivers and flood warning with us
Tell us the site, the measurements and the rules it answers to. We reply with a survey proposal, a design and a scope for rivers and flood warning. An engineer replies with a survey proposal and a scope, and the plan grows from one site to the network you need, at your pace.
Plan a deploymentOpen the Station BuilderOpen the Studio
01The place and its hazards
Where it runs, and what can go wrong.
Operating contextRiver basins are measured by networks of gauging stations, rain gauges and weather stations run by hydrological agencies, utilities and local authorities. Level is measured continuously and converted to flow through rating curves checked by field measurements. Forecasting models turn rainfall and upstream levels into predictions, and the warning authority alerts people downstream.
Hazards
- Riverine floods that outrun warnings
- Flash floods in small, steep catchments
- Station loss or damage in the flood it is measuring
- Rating curves that drift after the channel changes
- Debris and ice affecting sensors
02What must be measured
What, where, how often, and under which rules.
Each measurement names where it is taken, how often, and the public standard or regulation behind it. Numbers in the sources column open the cited source below.
| Measurement | Where | Cadence | Sources |
|---|---|---|---|
| River level | Gauging stations at stable sections upstream of communities | Continuous, reported at short intervals during floods | 12 |
| Discharge | Gauging sections, from rating curves checked by field measurements | Derived continuously; field checks on a schedule and during floods | 2 |
| Rainfall | Rain gauges across the catchment, sited to recognised practice | Continuous | 3 |
| Visual confirmation | Cameras at gauges and known flood points | Images on schedule and on alarm | 4 |
| Flood extent | The floodplain, from satellite imagery | Each available pass during events | 5 |
03The observation stack
From one base unit to a network.
The same blocks at every scale: instruments and a base node, a site with its radio, a fleet run as one, and a network federated on the open protocol.
- 01
Base unit
A gauging station: a level sensor, a rain gauge and a camera read by a solar node that signs every value and keeps it through a lost link.
Build a station → - 02
Site
A reach: gauges upstream and at the community, rain gauges in the catchment and a dual-path link to the forecasting centre.
Plan a site → - 03
Fleet
Every gauge of a basin run as one fleet, with one quality process and one record.
Managed offers → - 04
Network
Hydrological agencies, utilities and warning authorities exchange series and warnings through open standards.
The open protocol →
- 01Water level gauge
- 02Compact weather station
- 03Fixed camera
- 04Micro node (Nano)
- 05Cellular modem/router
- 06LEO flat-panel terminal
- 07Solar array
- 08Pole
Radio and links
Public cellular
Most gauges near communities have cellular coverage, the cheapest everyday path.
Radio and links
Satellite
A satellite path keeps stations reporting when cellular networks fail in the flood itself.
Radio and links
LoRaWAN
Rain gauges and small level sensors in a catchment report through gateways on high ground.
Edge computeThe station’s node raises its reporting rate as the river rises, checks readings for spikes and debris and sends an alarm locally when a threshold is crossed.
PowerStations run on solar and batteries sized for long wet spells, mounted above the highest recorded flood.
04How it works
From the instrument to the product.
One observation’s path, tier by tier, with the interface on every link and a bill of materials below; then how the one node grows to a site, a fleet and federated networks.
Rivers and flood warning: data path
– of 06
01 Instruments Measurement with sensor identity andcalibration 02 Node – Wrap in an observation envelope with timequality– Measure quality and uncertainty, attachquality flags– Buffer locally (store-and-forward when thelink drops) 03 Backhaul Commit with transactional outbox andpublish, delivered at least once 04 Site Consumer inbox deduplicates and applieseach record once into governed data 05 Data store Governed product through API, map orexport, correction-aware 06 Products OGC WaterML 2.0OGC SensorThings APICommon Alerting Protocol 07 Power and structure Supplies 12 V DC, 48 V DC to the fieldequipment 01 Water level gauge SDI-12 · RS-485 · Ethernet 02 Compact weather station SDI-12 · RS-485 · Ethernet 03 Fixed camera Ethernet 04 Micro node (Nano) Ethernet · USB · Analogue I/O ·RS-485 · CAN 05 Cellular modem/router Ethernet · USB · RS-232 06 LEO flat-panel terminal Ethernet Site MQTT 5 with Sparkplug B Governed data store Versioned, correction-aware River level and flow series Rainfall across the catchment Threshold alarms with images Flood extent maps 07 Solar array RS-485 08 Pole RS-485 RS-485 Ethernet Ethernet Ethernet LTE/NR Satellite IP| Item | Equipment | Data ports | Protocols | Power in |
|---|---|---|---|---|
| 01 | Water level gaugeRadar, pressure or float gauge for river, lake, reservoir or tide level. | SDI-12RS-485Ethernet | SDI-12, Modbus, MQTT 5, OGC SensorThings API | 12 V DC |
| 02 | Compact weather stationAll-in-one or compact station for temperature, humidity, pressure, wind and rain at a site. | SDI-12RS-485Ethernet | SDI-12, Modbus, MQTT 5, OGC SensorThings API | 12 V DC |
| 03 | Fixed cameraFixed visible-light camera for site security, scene monitoring and machine vision. | Ethernet | RTSP with ONVIF profiles, MQTT 5 | PoE |
| 04 | Micro node (Nano)Single-board or module-class node for sensor sites, gateways and low-power deployments. | EthernetUSBAnalogue I/ORS-485CAN | MQTT 5, OMA LwM2M, CoAP | PoE, 12 V DC, USB PD |
| 05 | Cellular modem/routerLTE or NR modem or router that uses a public carrier or private network as backhaul. | EthernetUSBRS-232 | 3GPP E-UTRA air interface, 3GPP NR air interface, OMA LwM2M | 12 V DC, PoE |
| 06 | LEO flat-panel terminalElectronically steered flat-panel user terminal for low-Earth-orbit broadband constellations. | Ethernet | — | PoE, 48 V DC, AC mains |
| 07 | Solar arrayPV modules with charge controller sized to the site’s load and climate. | RS-485 | Modbus | — |
| 08 | PoleUtility, street or dedicated pole with clamp positions. | — | — | — |
How it scales
01 Instruments Arbitrary qualified sensors and instruments whosemeasurements are ingested with calibration, units,geometry, time, custody and uncertainty. ×n 02 Node The minimum useful deployable unit: server, ruggedappliance, radio node, sensor gateway, satelliteterminal, AI, scientific, vehicle or virtual node. Node Node agent 03 Site The minimum independently operable localgovernance and failure domain: one or more nodesplus local network, identity, policy, evidence,storage, products and operator surfaces.SITE
Node Node Node ×n 04 Cluster An optional scale or specialisation domain forscheduling, shared storage, accelerators or datalocality.CLUSTER
×n 05 Fleet Coordinates plans, acknowledgements,convergence evidence, update campaigns andcorrection propagation across nodes and sites.FLEET
Fleet controller ×n 06 Federation An exchange of products, capabilities, events orwork across approved, independently administeredtrust domains, using explicit trust, policy,data-locality, version and correction contracts.TRUST DOMAIN
TRUST DOMAIN
TRUST DOMAIN
×n Verifier Applications Data in the field Telemetry Control Data upstream Control Data upstream Control Exchange Evidence Events Exchange- Data in the field
- MQTT 5 with Sparkplug B; connectors for LoRaWAN, OPC UA and instrument buses.
- Telemetry
- OpenTelemetry OTLP.
- Control
- TLS 1.3 with mutual authentication; protobuf messages over gRPC or HTTP/2.
- Data upstream
- At-least-once publication with repeat-safe keys over the control channel or NATS JetStream; QUIC MAY be used on lossy links.
- Evidence
- DSSE-signed in-toto statements; SLSA provenance; SCITT transparency receipts.
- Events
- Event envelopes mapped to CloudEvents 1.0; channels described in AsyncAPI 3.
- Exchange
- OpenAPI 3.1; the OGC API family; SensorThings; STAC; WIS 2.0.
05From order to operation
Every step, from the first call to a running site.
The same crew and the same record carry the work from scope to maintenance.
- 01 Order
Scope the basin and the warning
The scope reads the flood risk plan, the existing gauge network and the warning arrangements. Nexus Observatory Inc. returns the station plan by reach, the dual-path radio design, the integration with forecasting and warning systems and a price per station and per service. 4
- 02 Survey
Find stable sections above the flood
Crews survey candidate sections with hydrologists: stable control, access in a flood, the highest recorded levels, coverage and sky view. They record benchmarks, take reference photos and note where field flow measurements can be made safely. Sites that cannot be reached safely in a flood are rejected at this stage.
- 03 Permits
Rivers, bridges and land
Stations on bridges or banks need the consent of the asset owner, the landholder and often the water authority. Data sharing and warning roles are agreed in writing, so the authority that warns is always the one that decides. Every consent is kept with the station it covers.
- 04 Build
Build stations that survive floods
Level sensors, rain gauges, cameras, nodes, modems and satellite terminals are built and tested, enrolled with their identities and configured with the station’s thresholds. Mounts are chosen for debris and ice, and every part is labelled for quick replacement. Thresholds come from the warning plan.
- 05 Install
Install at low water
Installation is planned for low water. Each station is levelled to its benchmark, the rain gauge is sited clear of obstructions, the camera is aimed at the staff gauge and the dual-path link is tested. Every station is photographed for the record.
- 06 Commission
Commission against the staff gauge
Each node proves its identity, then level is compared with the staff gauge and the rain gauge with a reference. The rating curve is loaded and checked by a field flow measurement, and alarms are tested to the forecasting centre and the warning authority.
- 07 Operate
Forecast and warn on evidence
Forecasters see levels, flows and rainfall across the basin with camera images, feeding their models. When thresholds are crossed, alarms arrive with their data, and the warning authority issues its warnings through its own channels, with every step logged. After each event the record is reviewed with the authority.
- 08 Maintain
Check the rating, keep the record
Field flow measurements continue on schedule and after floods, so rating curves follow the channel. Sensors are cleaned and checked, stations are repaired after events and every change is recorded, so long series stay consistent for planning. Gauges damaged in floods are repaired first, because the next flood may follow soon.
06Data products and integration
What it delivers, to whom, and into which systems.
Data products
- River level and flow seriesHydrologists and forecasters
- Rainfall across the catchmentForecasters and planners
- Threshold alarms with imagesForecasting centres and warning authorities
- Flood extent mapsEmergency managers and insurers
Integration
- Hydrological databaseSeries are exchanged through OGC WaterML and SensorThings with their quality codes.
- Forecasting modelsLevels and rainfall are delivered as model inputs at the rate the models need.
- Warning systemsAlarms reach the authority’s warning system, which issues alerts in the Common Alerting Protocol.
Exchanged through OGC WaterML 2.0, OGC SensorThings API, Common Alerting Protocol.
07Questions buyers ask
Before you scope it.
Who issues the flood warnings?
The warning authority. The network supplies the measurements and alarms; the authority decides and warns.
Will stations keep reporting in a flood?
Stations are mounted above recorded floods, run on their own power and use two independent paths.
Can we connect our existing gauges?
Yes. Gauges with standard outputs are read by the same node, and their data joins the same record.
How is flow measured?
From the level, through a rating curve that field flow measurements check on schedule and after floods.
08Resources
The sources behind this page.
Public standards, regulations and guidance, cited where they apply. Each applies only where its jurisdiction or scope does.
- 1Guide to Hydrological Practices (WMO-No. 168)World Meteorological Organization
- 2Manual on Stream Gauging (WMO-No. 1044)World Meteorological Organization
- 3Guide to Instruments and Methods of Observation (WMO-No. 8)World Meteorological Organization
- 4Directive 2007/60/EC on the assessment and management of flood risksEuropean Union · 2007
- 5Copernicus Sentinel-2 optical missionEuropean Space Agency
09Related
Use cases and solutions.
Use caseLow-cost stream gauge network
Radar or pressure level sensors with low-power radio and solar power, as a cheaper tier beside a national gauge network.The full use case →Use caseStreet flood observatory
Ultrasonic depth sensors on poles report street-level water depth as open data and alerts.The full use case →SolutionHydrometeorological and flood observing networks
Stream gauges, rain gauges, weather radar and automatic weather stations built to WMO practice, reporting through WIS 2.0 where the agency requires it.Solutions for water →SolutionObservation data products and evidence bundles
Licensed feeds and archives with metadata, quality flags and provenance on every value; evidence bundles for audits and claims processes.Solutions for water →10Water: specialized fields
Other fields of this industry.
Specialized fieldGroundwater and aquifers
Water levels, salinity and abstraction in monitoring and production wells, on battery endpoints and LoRaWAN, for aquifer management, licensing and drought planning.The full field →Specialized fieldDrinking water treatment and networks
Water quality from source to tap, pressure and flow by district, acoustic leak detection and treatment plant monitoring, on secure networks kept apart from plant control.The full field →Specialized fieldWastewater and sewer networks
Sewer levels and overflow events, pumping station status, treatment plant effluent and receiving water quality, to cut overflows and prove compliance.The full field →Specialized fieldLakes and reservoirs
Buoys and profilers for temperature, oxygen and algae, inflow and level, satellite views of blooms, so water suppliers and lake managers act before a bloom closes a source or a beach.The full field →Bring us the site.
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