横比降对糙率的影响

通过理论及广西武宣水文站的实测资料分析，得出水文测验断面设于河弯处，由于水流离心力的作用，会产生横比降，对糙率的计算产生影响，且有系统误差。指出水文测验断面设于河弯处是不合理的，如受自然条件限制必须设在弯道附近时，应同时观测左右岸断面水位，这样才能较准确地计算出河道的比降和糙率。

Influence to roughness with cross slope

Through theory and observed data analysis of Guangxi Wuxian hydrologic station ,the author gave out that if the hydrologic measuring section was setted up at river bend, the cross slope exists and brings influence to roughness calculation and system error because of water flow centrifugal force's action .The author pointed out that it is unreasonable that the hydrologic measuring section was setted up at river bend.If it has to be setted up nearby river bend becaus of natural condition limitation,people should observe simultaneously the sections' water level of left and right bank,so as to calculate accurately the river channel's slope and roughness.