论文部分内容阅读
基于Wischimeier关于降雨侵蚀力R=EI30的经典算法,以黄土高原南部杨凌天然降雨为研究对象,较详细地分析了一次降雨过程雨滴大小分布;拟合了雨滴中数直径、降雨动能与降雨强度的关系;分别以EI10、EI30、EI60为降雨侵蚀力R指标,计算了该地区6-9月降雨侵蚀力大小,研究分析了降雨侵蚀力与降雨量之间的关系。得出以下结论:雨滴大小分布满足Best提出的分布式;雨滴中数直径反映次降雨过程中雨滴大小的总体趋势,与降雨强度关系密切,其关系式可表示为D50=2.25I0.21;降雨动能由降落雨滴从高空下落而具有的能量,以及与雨滴直径和下落速度有直接关系,得出降雨动能与降雨强度的关系式为E=26.57I0.28;杨凌区降雨量多集中于6-10月,月降雨侵蚀力分布随着月降雨量变化而变化;3种R指标计算的降雨侵蚀力值,EI10>EI30>EI60,且3种指标计算结果与CREAMS月雨量经验模型的相对偏差中,EI10与其相对偏差最小,但波动幅度较大,EI30与其相对偏差居中,但相对较稳定,分析得出EI10更适用于短阵型降雨,EI30适用于普通型降雨。基于上述理论,本研究旨在为今后建立黄土高原南部地区降雨侵蚀力简易计算模型提供理论依据。
Based on Wischimeier’s classical algorithm of rainfall erosivity R = EI30, the natural rains of Yangling in the southern Loess Plateau were studied. The distribution of raindrops in a single raining process was analyzed in detail. The median diameter of raindrops, kinetic energy of rainfall and rainfall intensity EI10, EI30 and EI60 respectively, the rainfall erosivity of the area from June to September was calculated, and the relationship between rainfall erosivity and rainfall was analyzed. The following conclusions are drawn: the distribution of raindrop size satisfies the distribution proposed by Best; the median diameter of raindrop reflects the general trend of raindrop size during sub-rains, which is closely related to the rainfall intensity, the relation can be expressed as D50 = 2.25I0.21; The kinetic energy is directly related to the energy of falling raindrops falling from high altitude and the relationship between raindrop diameter and falling speed. The relation between rainfall kinetic energy and rainfall intensity is E = 26.57I0.28. The rainfall in Yangling District is mostly concentrated in 6- The distribution of monthly rainfall erosivity varied with the monthly rainfall. The rainfall erosivity calculated by three kinds of R indicators, EI10> EI30> EI60, and the relative deviations between the calculation results of three indexes and the empirical model of monthly rainfall of CREAMS , EI10 and its relative deviation minimum, but the greater volatility, EI30 and its relative deviation from the center, but relatively stable, analysis EI10 is more suitable for short formation rainfall, EI30 for normal rainfall. Based on the above theory, this study aims to provide a theoretical basis for the future establishment of a simplified model of rainfall erosivity in the southern region of the Loess Plateau.