Tracking Floods is Exciting Work for USGS Hydrologists

As heavy rains continue to pound northern and central California, hydrologists with the U.S. Geological Survey are reporting small stream flooding from Ventura County on the south to Eureka on the north. In addition, small streams and rivers are forecasted to reach flood stage on the western slope of the Sierras during the next 48 hours. The recent storms have sent USGS scientists scurrying to rivers and streams throughout California to make measurements of above normal streamflows.

The USGS, known primarily for earthquake and volcanic science, has crews in the field leaning precariously over bridges and hanging from cables over swollen streams in an effort to make accurate measurements of streamflows and stream capacities. This information is used by flood forecasters and the National Weather Service to accurately predict floods in California and throughout the nation.

Flood forecasters need to understand streamflow, or discharge, to accurately warn the public of pending floods. To determine discharge,hydrologists need to know stream channel capacity, which is always changing. Therefore, streams must be measured often, and especially during high flow periods when the stream channel is most apt to change.

According to USGS Surface Water Specialist, Robert Meyer, in Sacramento, "We have concerns for our people in the field during times of flooding. On the one hand it is critical to have the accurate data to save lives, but the on the other hand collecting the data can be extremely dangerous."

To make the measurements, USGS field crews hang weighted measuring devices over bridges into the swollen streams or while hanging from small cable cars. According to USGS hydrologic technician, William Boults, "You are about 15 feet above the raging waters in a cable car with a 100 pound weight, your feet dangle over the water . . . it can get scary."

The USGS staff in California has been working throughout the recent storms to make accurate streamflow measurements. Field crews in Salinas, Ukiah, Redding, Sacramento, and Carnelian Bay near Lake Tahoe have been hampered by road closures, and extremely dangerous conditions. The USGS operates an extensive network of over 340 stream gauging stations throughout California.

From News Release, Feb. 3, 1998