Case Study: Validating Satellite Water Levels at Googong Dam
Project Overview
Googong Dam, managed by Icon Water, supports Canberra and Queanbeyan’s drinking supply and forms part of CSIRO’s Dark-Water Inland Observatory Network.
Under SmartSat CRC Project P6.08, CSIRO and Kurloo deployed a GNSS-IoT water level monitoring system to generate independent, AHD-referenced water surface elevation (WSE) data for validating satellite missions including SWOT.
The objective: deliver autonomous, centimetre-level WSE measurements over months — with traceable processing suitable for AusCalVal workflows.
The Challenge
At Googong:
- Typical 6-hour water variation: ~3 mm
- Reference dataset standard deviation: ~6 mm
- Validation data needed explicit QC flags and AHD alignment
- System had to operate through wind, rainfall and pontoon motion
- Manual or conventional GNSS buoy systems were costly and complex
CSIRO required a system that was precise, autonomous, quality-controlled and scalable.
The Kurloo Solution
Kurloo deployed:
- A pontoon-mounted GNSS device with ultrasonic water measurement
- A short-baseline (~0.5 km) base station on the dam embankment
- Multi-constellation PPK processing (GPS, Galileo, BeiDou, QZSS)
- Automated RINEX generation, QC screening and cloud processing
- API integration into CSIRO’s Senaps IoT platform
GNSS data was captured at 15-second epochs during daily 6-hour sessions over four months (Feb–May 2024).
The architecture linked directly to the Australian Height Datum (AHD) via AUSPOS processing.
The Results
Kurloo delivered independent, AHD-referenced water surface elevation data suitable for satellite Cal/Val under AusCalVal workflows.
Short-baseline PPK processing aligned precisely with Icon Water’s AHD-referenced data.
Sub-centimetre agreement meets the ±6 mm validation target required for meaningful satellite calibration.
High-quality, QC-coded datasets maintained across four months of operation.
Solar-powered GNSS-IoT architecture operated autonomously with LTE connectivity.
Multi-constellation GNSS processing, AHD alignment, and automated QC workflows delivered defensible Cal/Val-grade ground truth suitable for national satellite validation programs.
the best-quality SWOT “PIXC” and “Raster” products showed an accuracy of 7–8 cm when compared with Kurloo’s water-height data — meaning those products met SWOT’s accuracy goal at this site.
CSIRO presented the Googong Reservoir SWOT validation findings at IGARSS 2025
Robust Through Real Conditions
- Rainfall up to ~29.5 mm/day did not degrade accuracy
- Wind gusts to 56 km/h shifted the pontoon ~11 m, yet usable data continued
- Tilt <4° contributed <5 mm error
Quality codes transparently flagged affected days for scientific defensibility.
Why This Matters
Kurloo provided:
- Independent geodetic ground truth
- AHD-referenced validation-ready datasets
- Automated ingestion into satellite workflows
- A reusable architecture for other reservoirs and EO programs
The system now forms a scalable template for satellite Cal/Val networks supporting Australian and international Earth observation missions.
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