Index-q Method for Streamflow-Gauging Using a Horizontal Acoustic Doppler Current Profiler

This paper presents an index-q method for streamflow-gauging using a horizontal acoustic Doppler current profiler (H-ADCP). The principle of the index-q method is to establish a relation between the channel discharge (Q) and an index-unit-discharge, named as index-q. The index-q is defined as the product of an index-velocity measured by an H-ADCP and the water depth at the middle of the index-velocity sampling range. An advantage of the index-q method over the existing index-velocity method is that it generates a well-defined and unique relation between the channel discharge and an index-q even at a site where the water level has a large variation. Thus, an index-q rating can be displayed as a single curve and does not require a multiple regression analysis.