纵比降

淤地坝淤积面有一定的纵比降，尾部存在显著的翘尾巴现象。

The depositing surface of soil-retaining dams has certain vertical gradient , the tail exists obvious phenomenon of " raising tails " .

并且由于海平面高度相对稳定在较高位置，河流纵比降较小，流速也较小。

The sea level stops in a high position for a long time , so both drop of water and current velocity are small .

断面极为宽浅，纵比降的塑造，以致河道严重淤积，是黄河下游河床演变的三大基本问题。

It is pointed out that the morphological evolution process of the lower Yellow River has three elementary aspects : shallow cross section , mild longitudinal slope and intensive amount of aggradation .

黄河与长江悬浮沉积物的粒度组成有显著的差异，沉积物物源、河道形态和纵比降以及水量变化可能是造成这一区别的主要原因。

The influential factors for the difference of grain size of suspended sediments between the Changjiang and Huanghe Rivers may be their difference in source of sediments , morphology and longitudinal degradation of watercourse and runoff .

大量采沙对河床演变的主要影响是：大幅度扩大了河槽容积、河床平均高程显著降低、水深明显增加、纵比降减小。

The main impacts of sand dredging on the riverbed evolution include increasing substantially of the channel capacity , lowering of the average riverbed elevation , and deepening of the water depth and decreasing of the longitudinal riverbed gradient .