ABSTRACT
This paper investigates the presence of fine structures in stage–discharge and stage–water-slope relations from unique high-frequency (every 10 minutes) streamflow/stage time series. The time series data have been obtained using a novel acoustic method: fluvial acoustic tomography (FAT) system developed by Hiroshima University. In contrast to the traditional point/transect measurements of discharge, the FAT system enables us to obtain the depth- and range-averaged flow velocity along the ray path to be measured in high temporal resolution. A 115-m wide straight reach of the Gono River, Japan was selected as the survey site. The stage–discharge and stage–water-slope relations were examined for 5 hydrological events in 2016. The streamflow records with uniquely high temporal density shed light on the irregularity in stage–discharge relations. Although the discharge rating curve is usually modeled hydraulically as a power law, the present results reveal that the power function may be too simple to describe a real stage–discharge relationship.
