(4)此為次臨界流(subcritical flow )或超臨界流(supercriticalflow)
[ Manning equation :,其中n=0.02,A為流動面積,為
水力半徑,P為潤濕周長,為渠底坡度]

五、河水以平均流速=2m/s,在梯形渠道流動,水深為5m,渠道截面底面寬6m。請回答下列問題?