砒砂岩风化物陡边坡水土流失规律研究

发布时间：2018-06-07 09:09

本文选题：砒砂岩 + 陡边坡　；参考：《西北农林科技大学》2015年硕士论文

【摘要】：干旱半干旱的晋陕蒙交界地区,砒砂岩陡边坡广泛分布,水土流失严重,陡边坡对产沙有重要贡献。对晋陕蒙地区草本植物生长模式进行考察发现,主要存在株状生长和丛状生长两种植物类型。为探明其对砒砂岩风化陡边坡侵蚀的影响。在晋陕蒙砒砂岩分布区修建人工模拟小区,模拟自然状况之下草本植物生长模式,对照裸露陡边坡,进行自然降雨实验和径流冲刷实验。通过过程观察和数据分析,初步得到以下的结论:(1)自然降雨侵蚀产沙的最小I30为0.07mm/min,最小侵蚀产沙降雨量为10.2mm。相关分析没有发现降雨强度和降雨量与侵蚀量之间存在显著相关性。与I30相比,I10更能预测较短边坡和当地降雨特征下的产流产沙发生。各个处理多次降雨的产沙量和产流量之间显示出极显著的相关性,并且决定系数较大。沙水比随株间距和丛间距的增大而增大,径流对产沙的贡献大。(2)降雨过程和冲刷过程产流量随株间距变化没有显示一致的变化特征,但是随丛增大产流量逐渐减小。冲刷过程中,产沙过程主要发生在实验的早期,迅速达到峰值,之后下降,产沙的主要阶段为产流后12min之内。不同草本模式下侵蚀量总体趋势为:株状处理随株间距的增大,产沙量增大,随着丛增大,产沙量也增大,沙水比也有相似的变化特征。株间距增大和丛增大产沙平均粒径呈增大的趋势,大于1mm的泥沙也随着株间距增大和丛的增大而增大,后期产沙平均粒径大于前期产沙平均粒径。坡面细沟的加深主要发生在水流进入坡面到产流后4min的时间段内,侵蚀沟的深占最终侵蚀沟深的43%~84%,之后侵蚀沟缓慢加深,到约30min时侵蚀细沟趋于稳定,最大深度为24.0mm。阵性水流对侵蚀沟以外的地方产生侵蚀作用,对后期产沙有一定的贡献作用。(3)选取坡面水流测量各个参数计算得到水动力参数。但不管是流速、剪切力、水流功率还是达西维斯巴赫阻力系数都没有随植被模式变化而表现出显著的相关性。(4)在相同的植物密度下,稀疏状生长的植物模式,而不是丛状生长的植物模式对砒砂岩风化土陡边坡水力侵蚀的防治更有效。
[Abstract]:In the arid and semi-arid border area of Shanxi, Shaanxi and Mongolia, the soft sandstone steep slope is widely distributed, and the soil erosion is serious, and the steep slope has an important contribution to sand production. The growth patterns of herbaceous plants in Shanxi, Shaanxi and Inner Mongolia were investigated. It was found that there were two kinds of plant types: plant growth and cluster growth. In order to find out its influence on the erosion of arsenopyst weathered steep slope. Artificial simulated plot was built in the distribution area of soft rock in Shanxi, Shaanxi and Mongolia, and the growth pattern of herbaceous plants under natural condition was simulated. The natural rainfall experiment and runoff scour experiment were carried out in contrast to the exposed steep slope. Through process observation and data analysis, the following conclusions are obtained: (1) the minimum I _ (30) of natural rainfall erosion and sediment yield is 0.07 mm / min, and the minimum rainfall of erosion and sediment yield is 10.2 mm 路m ~ (-1). Correlation analysis showed no significant correlation between rainfall intensity, rainfall and erosion. Compared with I 30, I 10 can predict the occurrence of abortion sofa under the characteristics of short slope and local rainfall. There is a significant correlation between sediment yield and runoff of various treatments, and the determinant coefficient is large. The ratio of sediment to water increases with the increase of plant spacing and cluster spacing, and the contribution of runoff to sediment yield is great. 2) the variation of runoff with plant spacing does not show a consistent change in rainfall process and scouring process, but decreases gradually with the increase of cluster. During the scouring process, the sediment yield mainly occurred in the early stage of the experiment, reached the peak rapidly, then decreased. The main stage of sediment yield was within 12min after runoff production. The general trend of erosion amount in different herbaceous models was as follows: with the increase of plant spacing, sediment yield increased, sediment yield also increased with the increase of cluster, and the ratio of sediment to water had a similar change. The average grain size of sediment larger than 1mm also increased with the increase of plant spacing and cluster, and the average grain size of sediment yield in the later stage was larger than the average diameter of sediment yield in the early stage. The deepening of the gully occurred mainly in the period between the flow entering the slope surface and the 4min after runoff generation. The depth of the erosion trench occupied 43 ~ 84m of the final erosion ditch depth, and then the erosion ditch slowly deepened, and at about 30min, the erosion gully tended to stabilize, the maximum depth was 24.0mm. The matrix flow has a certain contribution to the sediment yield in the later stage, besides the erosion of the erosion ditch.) the hydrodynamic parameters are calculated by selecting the various parameters of the slope surface water flow measurement. But there was no significant correlation between velocity, shear stress, flow power and Darcy Weisbach resistance coefficient. The plant model, which is not a cluster growth, is more effective to prevent hydraulic erosion of arsenopyst weathered soil slope.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：S157.1

【参考文献】