Discharge Estimation in a Backwater Affected River Junction Using HPG

Ji- Sung Kim; Won Kim; Jong Pil Kim
This study presents a method for estimating discharge at a stage- gauging station located in a backwater affected river junction. A hydraulic performance graph (HPG) summarizing the backwater profiles on all possible flow conditions was applied to the river system where the main stream and tributary joinedat the juncture of the main stream and the tributary. The HEC-RAS model for dendritic river was structuredcreated, and the unsteady simulation was implemented for calibration and verification. The relationship between two water levels from existing stage stations at the main stream and the tributary and the discharge at the backwater affected section was was estimated, and the kriging interpolation was carried out. During a flood, event the discharge was calculated using kriging-interpolated HPG and the water level measurements at two stage stations,. It was andthen it was validated by comparing the automatic discharge measurements from ADVM. The result provides an economical and practical method for estimating discharge in a junction with a high hysteresis of looped stage-discharge relationships.
Discharge; Rating Curves; Backwater; Hydraulic Performance Graph; HEC-RAS
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