Using Drop Structures for Stream Gaging

A long term monitoring program of 15 watersheds, for the purpose of studying channel response to erosion control measures being constructed in north Mississippi, is being conducted by the Hydraulics Laboratory of the U.S. Army Engineer Waterways Experiment Station (WES). As part of the monitoring program, a study is in progress to evaluate the utility of using grade control structures for stream gaging on small ungaged streams. A low-drop structure has been instrumented with continuous stage recording gages to measure the head and tailwater conditions at the structure. Channel thalweg and cross-sectional data have been obtained upstream and downstream of the structure to provide geometric data for calculating hydraulic parameters necessary for developing discharge ratings from the stage data and physical model discharge coefficients. A cableway has been installed upstream of the structure to provide prototype gaging data for comparison with rating curves developed from the physical model discharge coefficients.