Innovative Remote Sensors for Streamflow Measurement

The United States Geological Survey operates and maintains over 8,000 streamgages across the United States.  The observations from these streamgages will inform hydrological simulations and provide verification for the new National Water Model.  However, conventional streamgages have limitations: annual maintenance cost of approximately $15k makes gaging some smaller basins uneconomical, establishing and updating stage-discharge rating curves is labor intensive and can be hazardous to operators, and instruments in contact with the water can be damaged or lost during flood events.

A suite of new, non-contact sensors is proposed to address these limitations and add new, previously unmeasured variables.  First, a commercially available radar system has been deployed in a very dynamic stream environment and successfully used to measure stage and surface velocity at a high temporal resolution, on the order of several minutes.  Second, a custom water-penetrating lidar has been developed and demonstrated to map 1-D bathymetry (cross-section) in clear streams.  The combination of cross-sectional area from the lidar, stage and surface velocity from the radar, and a computational scheme to relate surface velocity to mean-channel velocity allows for computation of discharge using non-contact methods without the need to maintain an empirical rating curve.  Finally, development has begun on a bridge-mounted, interferometric radar to generate full 2-D fields of surface height and velocity, offering insight into fine-scale features and along-stream surface slope.  Once mature, these technologies promise to reduce cost and manual intervention, allow proliferation of observations to smaller streams, and introduce previously unmeasured variables to the hydrological scientist’s toolbox.