求翻译：当底坡小于 1:10、入流逐渐变化(非洪水波)以及在既定横截面的河段水面无侧向倾斜变化时，运动波方程可以借助底坡和曼宁摩擦系数即简单又准确的刻画河流的流量、流速和水深。是什么意思？

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When the gradient less than 1:10, the flow gradually changes (non-flood waves), as well as the well-established cross-sectional area of the river, the surface of the water without side tilts when changes to the campaign wave equation can use the gradient and manning friction coefficient that is simp

When the foothill is smaller than 1:10, the inward flow changes the non-(flood wave gradually) as well as when decides the lateral section the section of river water surface not lateral incline change, the movement wave equation may draw support from the foothill and the graceful rather friction coe

When the slope is less than 1:10, the inflow gradually change (non-flood wave) as well as in established cross section reaches the surface without lateral tilt changes, can make use of bottom slope wave equation of motion and the manning friction coefficient that is simple and accurate characterizat

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