金沙江干热河谷冲沟溯源侵蚀特征与过程规律
文献类型：学位论文
| 作者 | 南岭 |
| 学位类别 | 博士 |
| 答辩日期 | 2011-05-13 |
| 授予单位 | 中国科学院研究生院 |
| 授予地点 | 北京 |
| 导师 | 刘刚才 |
| 关键词 | 冲沟 溯源侵蚀 径流 产沙 |
| 其他题名 | Characteristics and Process Patterns of Headward Erosion of Gully in the Dry-hot Valley of Jinsha River |
| 学位专业 | 自然地理学 |
| 中文摘要 | 冲沟侵蚀是一种重要的土壤侵蚀方式。在金沙江干热河谷区，以冲沟侵蚀为主的土壤侵蚀对当地的土地资源和下游的水利水电工程都构成严重威胁。在冲沟的发育过程中，沟头溯源侵蚀是最为迅速的侵蚀方式。本研究对沟头溯源侵蚀从野外调查和模拟试验两方面进行了研究，得出以下结论： 1. 根据形态特征，可以将冲沟沟头分为跌水状沟头和平缓状沟头。跌水状沟头的沟壁呈直立状态，沟头较高，有利于跌水的形成，沟头与沟道之间有明显的转折点；平缓状沟头沟壁呈弧形弯曲，坡度较平缓，沟头出露土体单一。 2. 以抗剪强度和崩解速率作为土体抗侵蚀性指标，跌水状沟头都存在下层土体抗侵蚀性小于上层土体的情况；在平缓状沟头，土体抗侵蚀性上下较为均一，无明显差异。 3. 当有径流通过冲沟沟头时，会发生膜状流这一特殊现象。膜状流径流量在总径流中所占的比例可达30%。随着总径流量的增大，膜状流的径流量也增大，在总径流量中的比例呈相反的趋势。在一定的流量范围内，膜状流比跌水有更高的侵蚀效率。 4. 溯源侵蚀过程中，沟头土体崩塌会引起径流泥沙量增大。在沟头以下一定范围内，径流输沙量和径流含沙量都随着径流量的增大而增大，土体抗侵蚀性越弱，变化幅度越大。 5. 在试验设置的径流量变化范围内，径流量并不会造成溯源侵蚀的距离侵蚀速率发生明显变化。对于同一土体，不同径流量时的距离侵蚀速率基本维持在同一水平。不同径流量时的面积侵蚀速率和体积侵蚀速率之间存在着较大差异，但不同土体上表现出不同的趋势。这是因为面积侵蚀速率和体积侵蚀速率受到沟头土体崩塌的很大影响，而沟头土体的崩塌具有很大的随机性。针对跌水状沟头和平缓状沟头，分别提出了相应的防护措施，跌水状沟头侵蚀强烈，一般采取工程措施，根据沟头上部流量的大小，采取泄水式或蓄水式沟头防护，而平缓状沟头，土壤侵蚀缓慢，可以采取生物措施。 |
| 英文摘要 | Gully erosion is an important type of soil erosion. In the dry-hot valley of Jinsha River, both local land resources and water conservancy and hydropower projects in the downstream have been threatened with soil erosion dominated by gully erosion. In the procedure of gully development, headward erosion is the fastest one of soil erosion types. In the study, field survey and simulation experiment were conducted to investigate headward erosion. There are some conclusions as follows. (1) According to the morphological features of gully head, gully head is divided into two types including sharp gully head and gradual gully head. Regarding sharp gully head, gully wall exhibits an upright status and gully head is high that is prone to yield waterfall. There is an obvious transition location between gully head and gully channel. Regarding gradual gully head, gully wall shows an arc shaped status with gentle slope. There exists an exposure of gully head and single soil body. (2) Shear strength and disintegration rate were regarded as indicators of erosion resistance of soil body. Sharp gully head exists under the condition that erosion resistance of soil body in low layer is less than that in upper layer. There are not obvious differences in erosion resistance of soil body between various layers in the gradual gully head. (3) There is a typical phenomenon, named as film flow, while runoff is passing the gully head. The runoff of film flow accounts for 30% of the total runoff. With increasing total runoff, the runoff of film flow has got an increase and the proportion of film flow runoff has decreased on the opposite trend. Within a certain amount of runoff, the erosion derived from film flow is more efficient in comparison with the erosion by waterfall. (4) During the procedure of headward erosion, collapse of soil body in gully head results in an increase of sediment in runoff. Within a certain extent below gully head, both sediment discharge and sediment concentration have increased with increasing runoff. Furthermore, the less the erosion resistance of soil body is, the more the range of variation is. (5) Within the variation range of runoff set in the experiment, runoff does not lead to an obvious change in the linear erosion rate of headward erosion. For the same soil body, the linear erosion rate almost keeps a fair level under different runoff, while large differences are found between area erosion rate and volumetric erosion rate under different runoff. For different soil body, the results reveal different trend. It can be attributed to the significant effects of the collapse of soil body in gully head on area erosion rate and volumetric erosion rate. Moreover, there exists substantial randomness in the collapse of soil body in gully head. (6) Control measures are proposed to protect sharp gully head and gradual gully head. In general, engineering measures are adopted to protect sharp gully head because of severe erosion according to the runoff in the upper part of gully head, such as gully head protection by water drain or water storage. To protect gradual gully head, biological measures are usually adopted due to slight erosion. |
| 语种 | 中文 |
| 公开日期 | 2013-01-31 |
| 源URL | [http://192.168.143.20:8080/handle/131551/4869]  |
| 专题 | 成都山地灾害与环境研究所_山地灾害与地表过程重点实验室 |
| 推荐引用方式 GB/T 7714 | 南岭. 金沙江干热河谷冲沟溯源侵蚀特征与过程规律[D]. 北京. 中国科学院研究生院. 2011. |
入库方式： OAI收割
来源：成都山地灾害与环境研究所
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