降雨过程中地表糙度与细沟侵蚀的关系研究

发布时间：2018-04-03 00:23

  本文选题：黄土高原　切入点：耕作措施　出处：《西北农林科技大学》2016年硕士论文

【摘要】：地表糙度是认为土地管理和土壤侵蚀共同作用的结果,它常常造成地表高低起伏和凹凸不平,严重影响地表径流和侵蚀过程。细沟侵蚀是坡面土壤侵蚀的主要方式之一,细沟侵蚀是指坡面流汇集成股流后对地表冲刷作用下在坡面形成细小侵蚀沟的现象,主要包括水流对土壤的分离、冲刷和搬运过程。地表糙度的形成可以直接或间接的影响细沟的形成、发展以及细沟侵蚀量的大小。本文以黄土高原普遍采用的等高条播、等高点种、人工锄耕和等高等高犁耕管理措施的坡耕地为研究对象,平整坡为对照组。使用杨凌地区的X土,选取不同坡度(3°、5°、10°、15°和20°)、不同雨强(60mm/h、90mm/h和120mm/h)和四种不同耕作措施(等高犁耕、人工锄耕、等高条播和等高点种),通过室内外的人工降雨实验分析不同地表糙度的侵蚀产沙特征;不同地表糙度对细沟的形成、发育过程的影响,以及对细沟侵蚀量的影响关系研究。主要结论如下:(1)四种不同的耕作措施产生不同的地表糙度,大小依次为等高条播等高点种人工锄耕等高犁耕CK。相同耕作措施、相同雨强下,侵蚀产沙量随着坡度的增大而增大;相同坡度和雨强下,随着地表糙度的增大侵蚀产沙量减小(等高点种除外)。但是在降雨过程中存在一个临界的坡度,使得地表糙度由增加侵蚀作用转变为减小侵蚀作用,这个临界坡度随着地表糙度的增大而减小。通过单因素方差分析得出坡度(S)、雨强(P)、地表糙度(RR)对侵蚀产沙量(Es)的影响均是显著的,且四者的关系为Es=0.2654P+0.3941S-0.3822RR-0.0528(R2=0.7189)(2)随着地表糙度的增大,细沟产生的时间越晚;降雨过程中每个小跌坎的位置都分布在坡面的中下部,具体位置具有随机性,与地表糙度无关。细沟发育的过程表现为小跌坎—下切沟头—断续细沟—连续细沟,细沟的最长沟长在不同的耕作措施下的大小依次为等高犁耕人工锄耕等高条播等高点种,细沟深度和平面密度有相似的变化趋势。细沟侵蚀量与坡度呈极显著的指数相关关系;在同一雨强同一坡度下,细沟侵蚀量随着地表糙度的增大呈减小趋势(等高点种除外),二者呈显著的二次多项式关系。通过单因素方差分析得出坡度(S)、雨强(P)、地表糙度(RR)对细沟侵蚀量(Er)的影响均是显著的,且四者的关系为Er=0.2338P+0.4320S-0.1108RR-0.0789(R2=0.6573)。
[Abstract]:Surface roughness is the result of the interaction of land management and soil erosion, which often results in high and low surface fluctuation and uneven surface, which seriously affect the surface runoff and erosion process.Rill erosion is one of the main ways of soil erosion on slope surface. Rill erosion refers to the formation of small erosion gullies on the slope surface under the action of scouring the surface of the slope after the flow converges into a stream, which mainly includes the separation, erosion and transport of soil by water.The formation of surface roughness can directly or indirectly affect the formation, development and erosion of the rill.In this paper, the sloping cultivated land which is widely used in the Loess Plateau, such as isobaric seeding, equal height species, manual hoe plowing and high ploughing management measures, is taken as the research object and the leveling slope as the control group.Using X soil from Yang Ling area, different slopes (3 掳5 掳10 掳15 掳and 20 掳), different rainfall intensity of 60 mm / h, 90 mm / h and 120 mm / h) and four different tillage methods (equal height ploughing and manual hoe tillage) were selected.The characteristics of erosion and sediment yield of different surface roughness, the influence of different surface roughness on the formation and development of rill, and the relationship between erosion and erosion of different surface roughness were studied through indoor and outdoor artificial rainfall experiments.The main conclusions are as follows: (1) four different tillage methods produce different surface roughness, and the order of the surface roughness is CK, I. e., the high point planting, the same height tillage, and the same height ploughing.Under the same tillage practices and under the same rainfall intensity, the erosion sediment yield increases with the increase of slope, and decreases with the increase of surface roughness under the same slope and rainfall intensity.However, there is a critical slope in the process of rainfall, which changes the surface roughness from increasing erosion to reducing erosion. This critical slope decreases with the increase of surface roughness.閫氳繃鍗曞洜绱犳柟宸�鍒嗘瀽寰楀嚭鍧″海�

本文编号：1702800