Junki KINOSHITA
Study on stage-discharge relation curves of mild-slope river channels affected by the downstream water depth
Minjiao LU Hongxuan YANG
A precise stage-discharge relation curve is necessary and important for water resources management. However, in river with a mild slope, the correlations between the water level and the flow rate become very poor, especially under situations of low flow rate or water depth, as the river flow may much affected by the water depth at the downstream.
Our work is to give a precise stage-discharge relation curve at Sanai gauging station in Hogura river, which has a very mild slop of 1/1226. The estuary of Hogura river is about 3100 meters down stream of Sanai gauging station. Even under the same flow rate, the water levels at Sanai gauging station may vary much with the fluctuations of the water levels at the estuary.
In order to take into account the contributions of the water level at the estuary of Hogura river, calculations of steady non-uniform flows are performed in this study, Using a averaged bed slope and a characteristic corss-section of Hogura river. As a result, h-H-Q (h: the water levels at the estuary, H: the water levels at Sanai gauging station, Q: flow rate) relation curves based on the steady non-uniform flows are proposed in this study.It can predict more precise flow rate than either non-uniform flow based H-Q curve or the best fit curve of Takada Kasen Kokudou Jimusyo.
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