New technology means better water management when flood season arrives

Hydrographers prepare to check stream gage data, circa 1965. Before satellite technology, data had to be relayed in person or over a telephone. (U.S. Geological Survey photo)

Hydrographers prepare to check stream gage data, circa 1965. Before satellite technology, data had to be relayed in person or over a telephone. (U.S. Geological Survey photo)

 

By Diana Fredlund, Public Affairs Office

Rivers are the lifeblood of many communities. They irrigate crops and provide transportation and drinking water and generate electricity to power our lives. Without rivers, many communities would never have been settled. Rivers have a dark side, too. They can, with little warning, swallow entire communities, move buildings off their foundations and sweep away anything in their paths.

The Christmas flood of 1964 was one such flood.

Before the snow started falling in December 1964, the stream gage readers, known as hydrographers, who worked for the U.S. Geological Survey saw little to be worried about. The gages were located upstream and downstream of several U.S. Army Corps of Engineers dams and helped hydrologists maintain a balance between inflow and outflow. In 1964, hydrographers had to physically check each gage, write down the results and find a phone to call in the data.

Stream gages have become fully automated. From this gage house information is transmitted via satellite or internet to the U.S.G.S (U.S. Geological Survey photo)

Stream gages have become fully automated. From this gage house information is transmitted via satellite or internet to the U.S.G.S (U.S. Geological Survey photo)

“Before satellite technology, reading a river gage took time and could be a wet, messy job,” said Glen Hess, a surface water specialist with the U.S. Geological Survey. “When floods are forecast, that’s when we need the most up-to-date information. In 1964 before the big flood hit, our hydrographers were out in snow, wind and rain to help us know in real-time what was happening.”These days, technology means most visits to stream gages are for maintenance; the gages upload information hourly via satellite, radio or telephone to the USGS.

While each gage uploads its data independently, they are viewed collectively to get a broader picture of what’s going on in the system, Hess said.

Standard stream gages monitor river depth, but newer gages also monitor temperature, turbidity and the amount of dissolved gas near Corps dams. (U.S. Geological Survey photo)

Standard stream gages monitor river depth, but newer gages also monitor temperature, turbidity and the amount of dissolved gas near Corps dams. (U.S. Geological Survey photo)

“There was a lot of water introduced into the system in a short amount of time in 1964,” Scullion said. “Many people don’t realize that even today the Corps’ Willamette Valley dams control only 27 percent of the water by the time it reaches Portland. All the agencies work as a team to limit the flood risk, but if Mother Nature throws more water at us than the system can handle, all we can do is minimize, not prevent flooding.”

“River depth is important for flood risk management,” Scullion said. “When the depth changes at a gage upstream of our dam, it tells us how much more water is flowing into the reservoir. Based on predictions of outflow we can determine how we will maintain target levels of the river.”

One critical reason the Corps uses upstream gages is to be sure a dam doesn’t overfill. (The cardinal rule of reservoir regulation: Don’t overfill and don’t overtop your dam.)

“Between inflow and outflow at our dams – and the unregulated rivers – we decide how to manage the water flows. If we have to hold some water in the lake, we change the outflow,” Scullion said. “If the downstream gages also show water levels rising, that confirms that yes, something new is occurring and we may need to change the flow to stay within our target points.”

Stream gages don’t just check river elevations these days. Technology allows them to multi-task, offering an array of data. “Gages today collect data on water flow rates, river depth, water temperature and, if they’re located near a dam, they can monitor turbidity and total dissolved gas levels,” said Art Armour, a hydraulic engineer with the Portland District’s Reservoir Regulation and Water Quality Section.

Stream gages have become fully automated. Information is transmitted via satellite or internet to the U.S.G.S. (U.S. Geological Survey photo)

This graphic illustrates how a stream gage works, from river intake to satellite delivery of data. (U.S. Geological Survey image)

“Measuring temperatures and total dissolved gas helps us know we’re doing right by the fish. We need to know if the water was warm before it reached the dam, or did the reservoir affect the water temperature? Advances in technology have allowed us to monitor water temperature upstream and downstream of our dams for the past 10 years; we’ve been monitoring dissolved gas for at least two years.”

Water regulators don’t look just at the rivers; they also search the skies for clues to what is coming their way. Technology has brought the next generation of radar to weather forecasters like Andy Bryant with the National Weather Service. “Compared to 1960s, NEXRAD, the newest radar, offers greater detail, sees farther and updates more frequently. That helps the National Weather Service develop its short term forecasting by telling us what’s happened in the past several hours and what will happen in the next several hours,” Bryant said.

The hydrographer from 1964 would hardly recognize his modern-day counterpart. One rarely does a physical check of a gage anymore, except for maintenance; gages upload their data via satellite to the USGS computers. That data helps all the water management agencies make better decisions about how best to manage the watersheds. Today’s technology could have helped residents better understand the dangers before the 1964 flood even arrived.

Amazingly, the 1964 flood wasn’t even the biggest the region has seen. “Gage records began in 1858, and based on historic data, the December 1964 flood was not a record-breaking flood in many areas,” Hess said.

For some river basins in southern Oregon the 1964 flood is the largest in available stream gage records, Hess added. “Some locations exceeded the record by several feet.”

Hydrographers in 1965 monitor river levels near Bonneville Dam, Ore.

Hydrographers in 1965 monitor river levels near Bonneville Dam, Ore.

Populations have expanded and the Portland, Salem and Eugene metropolitan areas are home to many more people than in 1964. That makes managing the rivers even more important, and Hess and his colleagues deploy every technological advantage they have. Usually it’s enough.“River forecasts are based on weather forecasts. We have a lot more confidence multiple days ahead of time based on all this new technology,” Bryant said. “We don’t have to wait until the water’s on the ground to make decisions that help keep people safe.”

Stream gages have become fully automated. From this gage house information is transmitted via satellite or internet to the U.S.G.S. (U.S. Geological Survey photo)

Stream gages have become fully automated. From this gage house information is transmitted via satellite or internet to the U.S.G.S. (U.S. Geological Survey photo)

 

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