To create the world's most sophisticated flood monitoring and forecasting system, the US State of Iowa's Flood Centre (IFC) uses more than 200 Senix ToughSonic 30 and ToughSonic 50 ultrasonic sensors to measure water levels in streams across the state. Data collected from the sensors are automatically sent to the Iowa Flood Information System (IFIS), where real-time information is integrated into an advanced hydrological model. System data and river stage hydrographs are shared with the public and emergency management officials.

With easy online access to water-level data from sensors, Iowa residents and state agencies can now get the reliable, real-time information they need to manage flooding in their areas. 

Ultrasonic sensors chosen for ruggedness and reliability

The IFC needed a reliable, cost-effective way to obtain accurate, real-time stream-level readings. Project Engineer Daniel Ceynar decided to try Senix ultrasonic sensors because they had been used for years for water level measurement in the hydrology research labs at IIHR Hydroscience & Engineering at The University of Iowa. The University of Iowa has long been a world leader in hydrological research.

Senix ultrasonic sensors were selected because they are designed to integrate easily with other equipment, including the system's cellular modems, solar panels, on-board clock, and other components. Senix sensors were also chosen for their ruggedness, programmability, and Senix's excellent engineering support. "Senix sensors and the Senix technical team have been pivotal to the success of this project," Ceynar said, noting that the IFC and Senix worked closely to design a special threaded collar for the ToughSonic 50 so it could be mounted to the IFC Stream Gauge enclosure using the same threading as the ToughSonic 30. That ToughSonic 50 Rear Mount model has since become a standard product for Senix.

The sensors are programmed to measure at intervals of 5 minutes to 1 hour, using a boxcar average of a preset number of individual measurements. The system sleeps until it's commanded to wake up to take measurement data and send it to the IFIS. Sensor data is provided via RS-485 serial communication.

The entire IFIS flood warning system depends on the ruggedness and reliability of the Senix ToughSonic sensors and the IFC system. The Senix sensors are potted in water-tight steel housings and operate over a humidity range of 0-100% at temperatures from -40 to +70°C.

After assembly in the IFC lab, each stream gauge is submerged for 3 days to verify its water-tightness. This testing has proven useful. In the field, numerous sensors were submerged by flash flooding, and once the flood waters subsided, the sensors resumed sending accurate stream level data without requiring any repairs.

"Once installed, the IFC stream gauges are practically 100% maintenance-free," Ceynar said. "Most stream gauge sites have not been re-visited since they were installed, 4+ years ago."

Real-time water levels facilitate disaster management

The Senix ToughSonic sensors have provided the IFC and the people of Iowa with critically essential data for flood forecasting and managing the aftermath of flooding. "The system - stream gauges and other Hydromet data - is routed through the IFIS where it is regularly used by all levels of government, law enforcement and the general public," Ceynar said. "We've had first-hand experience working with our local emergency management coordinator during floods in 2013 and 2014, where we participated in the daily briefings using IFIS." The stream gauges identify where the flood crest is located and track it as it approaches sensitive roads, bridges, and towns.

Before the system was in place, it was common for emergency personnel to be dispatched to assess the flooding in threatened locations. But with stream gauges collecting data in real time, emergency responders can focus on helping people instead of tracking flood waters.

Iowa Flood Centre is a model for the world

Ceynar and his colleagues have been contacted by officials from other states and from countries as far away as Australia. The Washington State Department of Transportation is also evaluating the stream gauges.

The State of Iowa is clearly at the forefront of flood-control monitoring systems that enable everyone from private landowners to emergency personnel to make informed decisions during a flood event. "The IFC is the only flood centre in the US, and IFIS is the only system of its kind that we are aware of," Ceynar said. "We continue our efforts to create a National Flood Centre."

Senix is proud to work with innovative research and educational institutions, such as the University of Iowa, both in the lab and in the field.