YANG Kai-lin 1, WANG Yi-sen 2
(1. China Institute of Water Resources and Hydropower Research, Beijing 100038, China; 2. The South-to-North Water Diversion Project of the State Council, Beijing 100038, China)

Abstract: This paper studies the relationships between the error of the channel roughness coefficient calibration and that of the hydraulic measurement. According to the principle of hydraulics, the formula of determining the error of the channel roughness coefficient calibration is deduced explicitly. Based upon the measured data from the Beijing-Shijiazhuang Emergency Water Supply Project of South-to-North Water Diversion, the error analysis of the roughness coefficient calibration is carried out for the typical channels. Some important conclusions are attained: (1) tiny hydraulic measurement error may result in significant error of the channel roughness coefficient calibration and for the existing typical channel the error can reach 11%; (2) the relative error of the roughness coefficient caused by the volumetric discharge is approximatly equal to the error of flow meter; (3) if the measurement errors of the water depths are the same, the error of the channel roughness coefficient calibration caused by the inlet water depth is very close to that caused by the outlet water depth. When the channel length is short, the error of the channel roughness coefficient calibration will increase significantly.

Key words: channel; roughness coefficient; calibration; error analysis

Published in: Journal of Hydraulic Engineering, Vol. 43, No. 6, 2012