Underground water level measurement of dams in the Czech Republic

Challenge

The Olešná and Slezská Harta dams in Northern Moravia, Czech Republic, supply drinking water to residential and industrial areas. It is also being used to generate electricity and avoid flooding on the Moravice River. As with any large reservoir, regularly monitoring the integrity of the infrastructure is a key task.

For the main dam structure, monitoring was assured through sensors connected by cables. But for piezometers measuring the water level in standalone boreholes outside the dam and in the surrounding areas, data was collected manually and infrequently–from once a week through manual measurements to twice a year from single-channel data loggers.

The piezometers could be connected with cables to the dam gallery monitoring system, but this would require digging cable trenches between the boreholes and the nearest multiplexers. The dam monitoring company, Geomonitoring, wanted a better option.

Solution

Geomonitoring chose the Worldsensing wireless monitoring solution to collect data regularly without having to dig cable trenches. The company ran a series of pilot projects with one gateway and seven data loggers for each dam, then extended the setup to include a total of 29 data loggers.

Each vibrating wire node is equipped with a reference barometer for barometric pressure change compensation. In spite of being installed in boreholes with steel cover caps, or behind the body of the dam with no line of sight to the gateway, the data loggers are able to transmit data without the need for repeaters. Data is collected and sent securely to the dam operator’s private network, where it is used for real-time reports and Vista Data Vision visualizations.

Worldsensing uses LoRa connectivity, a long-range, low-power wireless technology used by IoT networks worldwide. The system has a star network topology that can cover a range of up 9 miles/15 km without any repeaters. And wireless data loggers are IP-67 certified and have been tested in temperatures ranging from -40C to +80C, so they are able to withstand the harshest environments.

Benefits

Thanks to Worldsensing, the dam operator can capture real-time data on the condition of key areas beyond the dam itself. This data is easily displayed in visualization software and enables the configuration of alarms and alerts that can be used not only for emergency situations but also for the long-term maintenance of the dam structure.