黄河下游历史泥沙灾害的宏观特征及其与流域因素和人类活动的关系（Ⅱ）：—人类活动、历史地震及地形因子的影响

以历史上黄河下游的决溢频率为泥沙灾害的代用指标，研究了人类活动，历史地震及地形因子对黄河下游历史泥沙灾害的影响，研究表最，人类活动是影响黄河下游泥沙灾害的重要因素，历史上人口的增加使下游决溢频率增大，人口低谷与决溢频率的低值时段相应，历史上农牧交错带的南移与下游决溢频率的减小相伴发生。北移则导致决溢频率的增大，历史地震对黄河下游历史泥沙灾害有一定的影响，黄河下游历史泥沙灾害表现出明显的空间分异，这种分异与平原地貌条件的沿程变化有密切的关系。

Historical sediment-related disasters in the lower Yellow River in relation with drainage basin factors(Ⅱ): influence of human activities, earthquakes and landforms

The Yellow River is famous in the world for the extremely serious sediment-related disasters in history. The avulsion frequency of the lower Yellow River is adopted as a proxy index to study the historical sediment-related disasters, and then it was related to various indices describing the natural and human factors of the Yellow River basin. Consequently, some correlations have been established. Human activities are the major factor influencing sediment-related disasters in the lower Yellow River. In history, the increase in population led to an increased avulsion frequency, and low -value periods of population corresponded to the periods with low frequency of avulsions. The increase in avulsion frequency of the lower Yellow River occurred in association with the northward shift of the agriculture-animal husbandry transitional zone. When the agriculture-animal husbandry transitional zone shifted southward, the avulsion frequency declined. It has been found that there is positive relation between the frequencies of avulsions and earthquakes, which indicates that the periods with high frequency of earthquakes on the Loess Plateau are also the periods with high frequency of avulsions in the lower Yellow River. In the lower Yellow River, the avulsion frequency showed a clear differentiation downstream, which can be related to the downstream differentiation in plain landforms.