黄土高原不同类型暴雨的降水侵蚀特征

本文对黄土高原的三种类型暴雨的降水、侵蚀特征进行了统计分析，结果表明：Ａ型暴雨的雨量多为１０－３０ｍｍ，历时一般为３０－１２０ｍｉｎ，最大６０ｍｉｎ降雨量占总雨量的８５％－１００％；Ｂ型暴雨的雨量一般为３０－１００ｍｍ，降雨历时多在３ｈ－１８ｈ之间，最大６０ｍｉｎ降雨量占总雨量的３０％－７０％；Ｃ型暴雨的雨量一般为６０－１３０ｍｍ，历时大于２４ｈ，最大６０ｍｉｎ降雨量占总雨量的８％－２５％。三种类型暴雨的空间分布不均匀程度是Ａ型大于Ｂ型，Ｂ型大于Ｃ型，且Ａ型比Ｂ型、Ｃ型大得多。Ａ型暴雨是引起土壤侵蚀的主要暴雨，其侵蚀性降雨发生的比例占侵蚀性降雨总次数的５２．７％，其侵蚀量占总侵蚀量的６４％。在坡面和沟道小流域，７０％的极强烈侵蚀是由Ａ型暴雨产生的。

PRECIPITATION AND EROSION CHARACTERISTICS OF RAIN-STORM IN DIFFERENT PATTERN ON LOESS PLATEAU

In this paper,the precipitation and erosion characteristics of three rainstrom types on the Loess Plateau are statistically analyzed.The results show that the individual rainfall amount of pattern A,pattern B and pattern C storm is generally 10-30mm,30-100mm and 60-130mm respectively,and the rainfall duration of the pattern A,B and C storm is usually 30-120minutes,3-18 hours and more than 24 hours,the proportion of maximum rainfall in 60 minutes in total amount is 85-100% of pattern A,30-70% of pattern B,and 8-25% of pattern C.The nonuniformity of spatial distribution of three strom types is pattern A more than pattern B,pattern B more than pattern C,and pattern A more than pattern B and C greatly.Pattern A is the main strom that causes soil and water loss,and it's proportion of erosive rainfall and soil loss in total is 52.7% and 64% respectively.In slope ,gully and watershed,70% of the extreme erosion is caused by pattern A strom. \ \