延安极端降雨成因分析及非常规比尺模拟试验研究

发布时间：2018-03-06 01:18

本文选题：暴雨径流　切入点：太阳黑子　出处：《中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)》2017年硕士论文　论文类型：学位论文

【摘要】：坡面暴雨径流特性、侵蚀机理及其降雨径流水动力学特性是坡面水力侵蚀动力学研究的重要内容。本研究基于黄土高原延安地区2013年出现的百年一遇大暴雨,对其暴雨特性、梯田侵蚀灾害及发生原因等进行了研究,为了进一步从本质上探明该类暴雨条件下坡面径流的水动力学特性,在黄土高原小流域水力侵蚀调控实体模拟试验技术基础上,针对坡面流水深小、水力学参数量测困难等问题,对黄土高原坡面暴雨径流非常规比尺进行了初步研究及验证,该方法可为坡面流水动力学特性的研究提供一种新的途径。取得的主要成果如下:1.分析了黄土高原地区暴雨特性、侵蚀灾害及发生原因,结果表明:延安地区2013年降雨总量达959 mm,其中最大月7月降雨量为568 mm,达到万年一遇标准;延安地区2013年极端侵蚀性降雨和暴雨发生次数多,总量大;延安地区2013年极端降雨条件下连片梯田侵蚀剧烈,侵蚀模数和相对高差与汇水面积之间存在显著幂函数关系,梯田中下部侵蚀严重;延安地区最大降雨量主要发生在太阳黑子相对数峰值及其附近2年,太阳黑子相对数和极端降雨之间关系密切;延安地区最大降雨量主要发生在厄尔尼诺次年,而厄尔尼诺当年主要为干旱年,当南方涛动指数为负值时,降雨量总体上呈现一个下降的趋势。2.采用相似论和水力学的基本原理,在前人研究基础上进行补充完善得到适用于黄土高原的坡面暴雨径流非常规模型基本比尺关系式包括几何比尺、流速比尺、坡度比尺和糙率比尺等;在此研究基础上结合文献对坡面暴雨径流侵蚀输沙运动非常规比尺进行了研究,主要考虑起动相似、挟沙相似、床面变形相似及土壤水运动相似,最终得到包含几何相似、水流运动相似、侵蚀产沙运动相似及土壤水运动相似的黄土高原坡面暴雨径流非常规比尺关系式。3.分析了光滑铝塑板、粘沙加糙和草垫加糙三种不同加糙方式的加糙效应结果表明随着下垫面粗糙程度的增加,相应情况下水流的弗劳德数越来越小,在相同坡度条件下,铝塑板和粘沙加糙床面水流的弗劳德数随着流量的增加而增加,草垫加糙床面水流的弗劳德数随着流量的增加逐渐减小而后趋于稳定;在相同流量条件下,三种加糙床面水流的弗劳德数均随坡度的增加而增加。随着下垫面粗糙程度的增加,不同下垫面的阻力系数越来越大,在相同坡度条件下,光滑铝塑板和粘沙加糙床面阻力系数随着流量的增加而减小,草垫加糙床面阻力系数随着流量增加未呈现明显减小趋势;在相同流量条件下,光滑铝塑板、粘沙加糙和草垫加糙三种加糙方式阻力系数均随坡度的增加而增加。4.对坡面暴雨径流非常规比尺关系式径流过程的初步验证。在坡面暴雨径流非常规比尺模型推导的基础上,本研究在室内构建了几何比尺为0.5,坡度为0.017的原型和模型坡面,其中原型水深分别为1.5cm、1.8cm、2.0cm、2.2cm,对应的模型水深分别为3.0cm、3.6cm、4.0cm、4.4cm,在正态条件下,对满足几何相似条件建造的原型坡面和模型坡面的水流流型、水流流态、阻力相似、运动相似等过程进行了验证,其偏离度大都在误差允许范围内,实现了对坡面暴雨径流非常规比尺模型的初步验证。
[Abstract]:The slope runoff characteristics of rainstorm, rainfall runoff erosion mechanism and its dynamic characteristics is an important content of slope surface water erosion dynamics. This research is based on the 2013 Yanan area on the Loess Plateau the hundred years of heavy rain, the rainfall characteristics, terrace erosion disaster and causes were studied, in order to further hydrodynamic characteristics essentially proved the rainstorm conditions of slope runoff in the small watershed of the loess plateau water erosion control based on physical simulation test technology, aiming at the slope water depth, hydraulic parameters measurement difficulties and other issues, on the loess plateau slope runoff unconventional scale were studied and verified, which provides a new way to study the method for dynamic characteristics of overland flow. The main results are as follows: 1. analysis of the rainstorm characteristics in the Loess Plateau, and the occurrence of primary erosion disaster Because, the results show that the Yanan area in 2013 the total rainfall reached 959 mm, one of the largest monthly rainfall in July was 568 mm, reached the million year standard; Yanan area 2013 extreme erosion of rainfall and rainstorm, the total area of Yanan in 2013; extreme rainfall conditions even piece terrace erosion severe, there is significant power function relationship between erosion modulus and relative elevation and catchment area, the lower terrace in the serious erosion of Yanan area; the maximum rainfall occurs mainly in the relative sunspot number and peak near 2 years, the relative sunspot number and the close relationship between the extreme rainfall in Yanan area; the maximum rainfall mainly occurs in the El Nino year, and mainly for the El Nino year dry year, when South oscillation index is negative when rainfall showed a downward trend in.2. the basic principle of the similarity theory and hydraulics, on the basis of previous research On the basis of the supplement by storm runoff in the Loess Plateau, the slope is non conventional model scale relation including geometry scale, velocity scale, slope scale and roughness scale; on the basis of slope rainfall runoff erosion sediment movement of non conventional scale is studied, the main considering the similarity, similarity of sediment carrying, bed deformation and similar soil water movement is similar to that obtained contains geometric similarity, similarity of flow movement and sediment movement similarity and soil water movement similar to the loess plateau slope runoff and non conventional scale.3. analysis of smooth aluminum plate, the roughening effect of three kinds of a rough way sticky brown grass mat and Shaka roughness that along with the increase of surface roughness, the corresponding case of Froude number flow more and more small, on the same slope conditions, aluminum plate and sand The number of Froude roughness bed flow increases with the increase of flow rate, straw bed roughness flow Froude number with the increase of flow rate gradually decreased and then tended to be stable; in the condition of the same flow rate, the number of Froude three roughness bed flow increased with the slope increases with the increase of the underlying surface. The roughness of the surface resistance coefficient under different growing conditions, in the same slope, smooth aluminum plate and sticky Sharjah rough bed resistance coefficient decreases with the increase of flow rate, the grass pad and rough bed resistance coefficient increased as the flow rate did not show significant decreasing trend; in the condition of the same flow rate, smooth plastic Brown sticky board, Shaka and grass mat roughness roughness three way resistance coefficient with the slope increases with the increase of.4. on slope runoff unconventional than the preliminary verification ruler relation runoff process. The slope runoff unconventional ratio Based on the derivation of the model, this study constructs in the indoor geometric scale is 0.5, the slope is 0.017 prototype and model of slope, the depth of the prototype were 1.5cm, 1.8cm, 2.0cm, 2.2cm, corresponding to the depth model of 3.0cm, 3.6cm, 4.0cm, 4.4cm, in normal conditions, the pattern of flow. The construction of the prototype meet the geometric similarity condition of slope and the slope of the flow model, the resistance similarity, similarity process was verified, the degree of deviation mostly in the range of allowable error, the slope runoff and unconventional than preliminary verification model.

【学位授予单位】：中国科学院大学(中国科学院教育部水土保持与生态环境研究中心)
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P426.6;S157

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