The gauge has to survive
the event it exists to record
Optical precipitation measurement and capacitive level sensing for catchment studies, with low-power SDI-12 integration for remote sites where the maintenance burden is part of the measurement quality.
The record fails on the day it matters most
A catchment study pairs precipitation with river response, and the pairing only has value across the events that define the catchment. A record that is complete for eleven months and missing the storm is not most of a dataset.
That is precisely when instruments fail. A tipping bucket cannot keep up with high intensity rainfall and under-reports the peak, or it blocks with debris and reports nothing. A level sensor with a float finds the moving water that the study exists to measure.
Remote gauges compound it. A site chosen for hydrological reasons is usually a site chosen against access, so the visit that would have found the fault does not happen until after the event has passed.
Every research question starts at a measurement point
A research site measures across the whole landscape. Three-dimensional wind above and below the canopy. A vertical profile across several heights. Reference conditions, radiation, precipitation and the river the catchment drains to.
Above-canopy flux measurement
Eddy covariance resolves the vertical wind component fast enough to see the flux itself, which is a data-rate problem before it is anything else.
Sub-canopy and understorey measurement
Below the canopy the flow is slow, sheltered and three-dimensional, and a sensor designed for storm survival will not resolve it.
- HS-50 horizontal head, minimal geometric disturbance to vertical flow
- WindMaster HS horizontal head, 32 Hz, stainless steel
- WindMaster 3-axis to 20 Hz with a 32 Hz option
Profile mast at several heights
A vertical profile is what turns a point measurement into a gradient, and the sensors have to be separated properly rather than stacked.
- MetConnect THP WMO-compliant separation, Pt100 and analogue inputs
- WindSonic 60 0.5 kg, low cost per additional level
- WindObserver 70 heated head for the exposed upper level
Reference weather enclosure
The reference station is the record everything else is compared against, so siting and continuity matter more than headline accuracy.
- MetConnect THP temperature 0.2 degrees C, humidity 1.5 percent RH, pressure 0.5 hPa
- MaxiMet GMX551 wind, T, H, P, solar and rainfall in one housing
- MaxiMet GMX300 temperature, humidity and pressure only
Precipitation measurement
A tipping bucket blocks with leaf litter and under-reads in drizzle, which on a ten-year dataset is a systematic error rather than a gap.
- TruMet PW100 optical, 0 to 200 mm/hr, 5 percent, 0.1 mm resolution
- MaxiMet GMX603 integrated optical rainfall, 5 percent or better
- MetConnect THP contact-closure input for the TruMet pulse output
Surface energy balance plot
Closing the energy balance needs radiation, soil and turbulent fluxes measured together, and the wind term is the one most often under-resolved.
- R3-50 50 Hz 3-axis for the turbulent flux terms
- MaxiMet GMX301 solar radiation, 0 to 1600 W per square metre
- MetConnect THP four-wire Pt100 input to IEC 60751 for soil probes
Canopy roughness and footprint
The flux footprint moves with wind direction and stability, so the tower has to see the whole rose rather than one prevailing sector.
- R3-100 100 Hz for high-frequency loss correction
- WindMaster Pro symmetrical head for all-direction work
- WindMaster asymmetrical head where the flow has a known direction
Crop and land-use plots
Comparing plots only works if the meteorology over each is measured the same way, with the same instrument and the same calibration history.
- MaxiMet GMX551 one unit per plot, one cable, one output string
- MaxiMet GMX550 wind, T, H, P and rainfall without solar
- WindSonic 60 a repeatable wind reference at plot scale
River gauging and hydrometeorology
Catchment work pairs rainfall with what the river actually does, and both records have to be continuous through the events that matter.
- TruMet PW100 no moving parts, less to block at a remote gauge
- MetConnect One SDI-12 v1.3 into an existing hydrometric logger
- MaxiMet GMX400 temperature, humidity, pressure and rainfall
Air quality and dispersion
A concentration reading without the meteorology beside it cannot be attributed to a source, and attribution is usually the point.
- WindMaster Pro 3-axis to 32 Hz for dispersion and turbulence
- MetConnect THP two analogue inputs for third-party gas analysers
- WindObserver 75 long-duration wind reference on the same mast
Remote power and telemetry
On a solar and battery site the power budget decides what can be measured at all, so draw is a specification, not a footnote.
- R3-50 9 to 30 V DC, under 4 W in operation
- MetConnect THP 5 to 30 V DC, less than 70 mA at 12 V DC
- MaxiMet GMX200 0.5 kg, wind only, for a minimal-power node
Portable and campaign deployments
A field campaign is judged on whether it came back with a complete record, and setup time in bad weather is where records get lost.
- MaxiMet GMX200 0.5 kg, wind only, quick to mount on a temporary mast
- WindUltra compact 2-axis, IP69k, low power, built for mobile use
- WindSonic 60 0.5 kg, straightforward to configure with MetSet
UAV atmospheric profiling
Airborne profiling puts the sensor on a platform where every gram is traded against endurance.
- WindUltra compact 2-axis, IP69k, low power
- WindSonic 60 0.5 kg ground reference for launch and recovery
- MaxiMet GMX200 portable wind reference at the operating site
Cold climate and harsh sites
The seasons that break the instrument are usually the seasons the study is about, and a gap in winter is a gap in the conclusion.
- WindObserver 75 heated, icing tested to MIL-STD-810F
- WindSonic M heated aluminium body, operating to -40 degrees C
- R3-50 operating -40 to +60 degrees C
Logging, outputs and data continuity
A dataset that changes instrument or protocol mid-series carries a step change that has to be explained in every paper that uses it.
- R3-100 14-bit digital, RS422 native, RS232 and analogue via PCI
- MetConnect One ASCII, Modbus RTU and ASCII, NMEA 0183, SDI-12 v1.3
- MetConnect THP MetSet and MetView configuration and logging software
Calibration and traceability
Published work is defended on traceability. An accredited certificate is the part of the method section nobody argues with.
- UKAS-accredited air velocity calibration traceable certification for anemometers
- Multi-parameter calibration six parameters, equipment from any manufacturer
- Recalibration scheduling intervals, reminders and turnaround
Intensity, accumulation and level, all through the same storm
Rainfall intensity drives the hydrograph. Accumulation over an hour tells you the volume and hides the shape, and the shape is what produces the peak flow a catchment study is trying to explain.
A tipping mechanism measures by counting discrete tips, which caps the intensity it can resolve and introduces error that grows with rate. Optical measurement counts the precipitation passing through a beam, so high intensity is measured rather than approximated.
Water level is the other half. Capacitive sensing gives continuous level with no float, in a channel carrying debris, silt and whatever the catchment has picked up upstream.
Both then have to report from a site with no mains power, on a power budget that assumes nobody is visiting until spring. That makes low-power integration a measurement decision, not an installation detail.
Optical measurement does not block or miss the peak
A tipping bucket depends on a mechanism, and mechanisms fill with leaves, insects and silt. Once blocked it reports a dry catchment during the event, which is the failure that costs a season of work.
TruMet PW100 uses infrared optical measurement rather than a tipping mechanism, measuring 0 to 200 mm/hr with 5 percent accuracy and 0.1 mm resolution. It outputs one pulse per 0.1 mm, replicating a tipping bucket, so it drops into a logger that already expects one.
The peak measured, not clipped
View TruMet PW100Everything is designed against the site visit
A gauge sited for hydrological reasons is usually awkward to reach, so every service visit costs a day and often a vehicle. The specification decision that matters is how rarely the instrument needs one.
Capacitive level sensing has no float and fully sealed solid-state electronics, with LevelSlick FEP coated for particulate and viscous liquids. Combined with low-power SDI-12 output into a logger, a site can run through a season unattended.
Specify for the visit you will not make
Explore level sensorsA catchment dataset outlives the project
Flood studies, consent applications and model calibration all reach back into catchment records collected years earlier by someone else, and they ask which instrument, sited where, calibrated when.
That makes traceability part of the dataset rather than part of the paperwork. An instrument on a traceable interval keeps a record usable long after the project that funded it has closed.
Labcal is an independent UKAS-accredited laboratory operating to ISO/IEC 17025:2017, calibrating equipment from any manufacturer, which matters across a catchment instrumented over several funding rounds.
What a catchment site carries
Precipitation measurement that survives the storm, level sensing that survives the channel, and the meteorology behind evaporation and snowmelt.
Precipitation and level
TruMet PW100
Infrared optical rain gauge
Optical rainfall measurement to 0 to 200 mm/hr, so the intensity that drives the hydrograph is measured rather than clipped by a mechanism.
Level sensing
Capacitive liquid level sensors
Continuous level with no float, including a FEP-coated variant for water carrying particulate and silt.
MaxiMet
All-in-one weather station, no moving parts
One unit and one cable for the supporting meteorology, including solar radiation and wind for evaporation estimates.
Meteorology and profiles
MetConnect
Separable sensors for WMO-compliant siting
Separable sensors where temperature and humidity need to sit at defined heights alongside the hydrological measurement.
WindSonic
Lightweight 2-axis ultrasonic anemometer
Lightweight ultrasonic wind measurement for evaporation and snowmelt work, with heated options for upland sites.
WindObserver
Heated 316 stainless open-head 2-axis anemometer
Heated 316 stainless for exposed upland catchments where icing would otherwise create the gap.
Where catchment measurement does the work
Rainfall and response
Pairing intensity with river level through the events that define the catchment.
Exposed gauges
Sites where snow, ice and access all argue against a mechanism.
Fast response
Small catchments where the hydrograph is sharp and hourly accumulation explains nothing.
Long series
Records used to calibrate and then to re-calibrate hydrological models years apart.
Discharge and abstraction
Level and rainfall records supporting regulatory positions.
Instrumented basins
Sites carrying instruments from several projects on one power and telemetry budget.
UKAS-accredited calibration for six measurement parameters
Labcal is an independent UKAS-accredited calibration laboratory, Lab 0625, operating to ISO/IEC 17025:2017. It provides calibration across gas and air flow, air velocity, liquid flow, pressure, temperature and humidity.
For a catchment carrying rain gauges, level sensors, thermal probes, pressure instruments, temperature and humidity probes and data loggers, one accredited laboratory keeps instruments installed over several funding rounds on a single traceable schedule.
Gas meters · Mass flow controllers · Dispensing systems
Anemometers · Pitot tubes · Thermal probes
Flow meters and sensors · Process control equipment
Gauges · Transducers · Manometers · Transmitters
Thermometers · Probes · Thermocouples · Data loggers
Hygrometers · Probes · Transmitters
Getting data off a site nobody is visiting
A catchment gauge reports from a location with no mains power, often no mobile coverage and no routine visit, and it has to keep doing so through the season it exists to measure.
Gill supports environmental monitoring, industrial sensing, embedded electronics and systems integration, so agencies, consultants and research groups can bring measurement into loggers, telemetry and catchment databases.
Whether the requirement is SDI-12 into a low-power logger, a pulse output replacing a tipping bucket, or analogue into an existing channel, Gill engineers can support integration from specification through commissioning.
Outputs and options
- SDI-12 : Low-power loggers on remote gauges
- Pulse output : One pulse per 0.1 mm, replacing a tipping bucket
- 4-20 mA & 0-10 V : Existing analogue channels
- Modbus RTU : Telemetry and catchment systems
What the specification looks like in practice
The peak is measured, not clipped
Optical measurement to 0 to 200 mm/hr resolves the intensity that drives the hydrograph, where a tipping mechanism caps it.
Nothing to block
No tipping mechanism means no leaves, insects or silt stopping the gauge during the event.
Drops into the logger you have
One pulse per 0.1 mm replicates a tipping bucket, so an existing installation does not need rewriting.
Level without a float
Capacitive sensing has no moving component in water carrying debris and silt, with a FEP-coated option for the worst of it.
Built for a season alone
Low-power SDI-12 operation and sealed construction, for sites where the next visit is in the spring.
Traceable years later
Independent UKAS-accredited calibration across six parameters, for equipment from any manufacturer.
Questions about catchment and hydrometeorology
Because it measures by counting discrete tips, which caps the intensity it can resolve and introduces error that grows with rate. It also blocks with leaves, insects and silt, and a blocked gauge reports a dry catchment during the storm.
TruMet PW100 uses infrared optical sensing measuring 0 to 200 mm/hr with 5 percent accuracy and 0.1 mm resolution.
Usually. TruMet PW100 outputs one pulse per 0.1 mm, replicating a tipping bucket, so an existing logger configuration generally continues to work.
Because there is no float to foul in water carrying debris and silt. LevelSlick uses a FEP-coated construction for particulate, viscous and corrosive liquids, and LevelPro is stainless at IP66 and IP68.
SDI-12 output suits low-power loggers, which is the usual arrangement on a battery and solar site. The power budget should be reviewed as part of specifying the station.
If the work includes evaporation, snowmelt or gauge undercatch, yes. Ultrasonic wind measurement avoids the rotating element that ices on upland sites, with heated options where that matters.
Yes. Labcal is an independent UKAS-accredited calibration laboratory, Lab 0625, operating to ISO/IEC 17025:2017, calibrating equipment from any manufacturer across gas and air flow, air velocity, liquid flow, pressure, temperature and humidity.
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