Interrill Erosion on Desert Hillslopes, Southern Arizona

在美国和全世界，自然坡面和耕作坡面的土壤侵蚀都是一个严重的问题。由于对降水和侵蚀过程之间的关系缺乏基本的微观理解，有效解决水引起的侵蚀问题受到阻碍。特别是，我们缺乏可靠的数学模型来预测水在宽阔的地表上流动造成的土壤侵蚀(细沟间侵蚀)，这是许多地区，特别是在干旱和半干旱地区的一种重要的侵蚀形式。现有的模型没有考虑降雨(剥离储存)之前在地表积累的松散泥沙，以及忽略的水流侵蚀过程。这项研究将通过纳入和比较这些变量来完善细沟间侵蚀模型。亚伯拉罕教授和他的学生将在美国农业部位于亚利桑那州的核桃沟实验分水岭将模拟降雨应用于配对的试验田。其中一个地块将被一个屏幕覆盖，该屏幕将消散雨滴的影响；另一个地块将接受模拟雨滴的全部影响。因此，第二个地块将同时受到雨滴撞击和水流侵蚀的侵蚀，而第一个地块将只经历水流侵蚀。将在成对的地块上进行的测量将有可能模拟相对流速和雨滴侵蚀的变化，校准细沟间侵蚀模型，从而建立预测方程，并比较被流水和雨滴冲击侵蚀的沉积物的特征。该项目将对一个主要的地貌过程产生基本的见解，对国内外的水土保持项目具有重要的影响。

Soil erosion on both natural and cultivated slopes is a serious problem in the United States and throughout the world. Effective solutions to water-induced erosion are impeded by the absence of basic microlevel understandings of the relationship between precipitation and erosion processes. In particular, we lack sound mathematical models that will predict soil erosion resulting from water flowing across surfaces in broad sheets (interrill erosion), an important form of erosion in many regions, especially in arid and semi-arid areas. Existing models do not take into account loose sediment that has accumulated on ground surfaces prior to rainfall (detachment storage), and the omit processes of flow erosion. This research will refine models of interrill erosion by including and comparing those variables. Professor Abrahams and his students will apply simulated rainfall to matched pairs of experimental plots at the U.S. Department of Agriculture's Walnut Gulch Experimental Watershed in Arizona. One plot will be covered with a screen that will dissipate raindrop impact; the other will receive the full impact of the simulated raindrops. Thus the second plot will be subject to erosion from both raindrop impact and flow erosion, while the first will experience only flow erosion. The measurements that will be taken on the paired plots will make it possible to model variations in relative rates of flow and in raindrop erosion, to calibrate the interrill erosion model and thereby develop predictive equations, and to compare the characteristics of sediments eroded by flowing water and by raindrop impact. This project will yield basic insights into a major geomorphologic process with important implications for soil conservation programs domestically and abroad.