The velocity of flood propagation was great and flood deformation was slightly when flood peak increase to bank full discharge . as the discharge increased to 2 - 2 . 5 times of bank full discharge the velocity reduced to the lowest value and the greatest flood deformation occurred 当洪峰流量接近平滩流量时洪水传播速度最快，洪峰变形最小，当洪峰流量约是平滩流量的2 2 . 5倍时，洪水传播速度最慢，洪水变形最大。
