Study of the spatial differentiation of hyperconcentrated flows frequency in the Loess Plateau

Based on the data from the Yellow River and its tributaries in the Loess Plateau,a study of the spatial differentia tion of hyperconcentrated flows frequency is made,also the relation between hyperconcentrated flows frequency and influencing factors is analyzed The results show that the high-frequency zone of hyperconcentrated flows shows itself a shape of strip,with the northeast southwest direction There are three high-frequency centers in the strip They are at lat itude 40°N,36°N and 34° N.It seems that different factos have different effecs to cause the hyperconcentrated flows The result of the multiple-factor regression analysis shows that the efficiency of shrub,dry-land fields in hilly,woodland,loess thickness and mean annual pre cipitation to the hyperconcentrated flows are 16.6%,4.4%,6.5%,29.7% and 42.8%,respectively.