The formula of depth in open chanel uniform flow and runoff and the calculating method of optimal hydraulic cross section have been deduced, according to the theory of open chanel uniform flow.

• 根据明渠均匀流理论 ；推求了抛物线形渠道正常水深与流量的关系和水力最优断面的计算公式 ；得出了水力最优断面水深与抛物线参数的关系为 ah0 =0 .；94673 2。