Knowledge Resource Center for Ecological Environment in Arid Area
| 库布齐沙漠东缘风沙防治相关问题的实验研究 | |
| 其他题名 | Research on Experiment of Wind-sand Control in Eastern Edge of the Hobq Desert |
| 宗玉梅 | |
| 出版年 | 2017 |
| 学位类型 | 硕士 |
| 导师 | 俎瑞平 |
| 学位授予单位 | 中国科学院大学 |
| 中文摘要 | 受气候变化和人为活动影响，沙漠化已成为西北地区面临的主要生态环境问题和发展瓶颈，而库布齐沙漠就是风沙危害最为严重的地区之一。近30年来，在当地政府、相关企业和当地群众共同努力下，该沙漠地区特别是其东缘的沙害防治工作中取得了明显进展，获得了较好的社会、生态和经济效益。然而，以往防沙工作中所采用的措施较为单一，其中涉及到的一些科学问题也有待解决。本论文通过风洞实验与野外定位监测等手段，对库布齐沙漠东缘风沙防治相关的科学问题开展了研究。通过室内风洞模拟，重点分析了含水率对风沙运动的影响，并对不同高宽比（H/L）组合下格状沙障的流场特征进行了模拟。最后以独贵塔拉防沙实验观测场定位监测数据为基础，对不同材料和不同规格机械防沙措施的防护效益进行了分析和比较。研究结果如下：（1）不同湿度对风沙运动影响的风洞模拟实验研究表明：地表粗糙度随着湿度的增加出现波动状态，但整体呈下降趋势，因此，在地表含水率较高的库布齐沙漠，采用格状沙障等增加地表粗糙度的机械防沙措施能收到比西部沙漠和戈壁地区更为理想的效果；在不同的湿度范围内，风速廓线都随高度呈对数分布。湿度越大输沙率随风速增加的绝对量变小，但相对量有所增加；不同湿度输沙率都出现随高度增加而减少的趋势，当湿度达到2.5%时，不管任何高度风蚀过程几乎停止；干沙输沙量80%集中于近地表5 cm内，但随着湿度增加5 cm以上输沙率所占比重却呈增加趋势。这说明，在地表含水率相对较高的库布齐沙漠，采用的固沙措施的高度也应高于地表含水量较低的地区。（2）不同规格格状沙障流场的风洞实验研究发现：所有实验的不同规格的沙障具有相似的流场结构；在一定的沙障高度下，沙障高宽比（H/L）越小，风速减弱程度相对较大，但没有呈绝对增加的规律；在测量范围内，不同规格沙障在10m/s风速下的防风效能随高度整体呈增加的趋势，而且防风效能随高度变化的梯度逐渐减小，说明所有规格的沙障产生防风作用的有效高度随着沙障高度的增加而增加。综合分析来看，沙障高度H=6 cm，H/L=0.05规格的沙障防风效能最大，其次为沙障高度H=10 cm，H/L=0.1规格的沙障。 （3）野外防沙观测场定位监测结果表明：在布设的5种模式的固沙障内，风速随着高度均呈上升趋势，高1 m，8 m×8 m规格的HDPE网沙障内的风速整体最小，其防风效果最好；实验区所有固沙模式和裸沙地表主要以细沙（100~250 μm）为主，而且迎风坡地表沙粒平均粒径均大于背风坡，高15 cm，1 m×1 m规格的HDPE网沙障表面沙粒平均粒径整体小于其他规格的固沙障，说明其风速较小，起到了较好的防风作用；输沙量都集中在地表10 cm高度内，超过10 cm高度，输沙量很小，基本为0，高15 cm，1 m×1 m规格的HDPE网沙障和植物纤维网沙障内的输沙量最小；在观测期间，5种模式的沙障内积沙凹曲面形态差异显著，积沙高度明显增加，高20 cm，1 m×1 m规格HDPE网沙障方格内积沙高度增速最小，凹曲面形态稳定，起到了较好地稳定沙面的作用，说明其固沙作用较好；从蚀积高度变化来看，高1 m，8 m×8 m规格的HDPE网沙障和植物纤维网沙障的蚀积厚度变化幅度较大，其他不同类型沙障的蚀积厚度变化幅度较小，均以堆积为主，说明铺设沙障可以有效提高地表沙物质的稳定性，起到明显的固沙效果。 |
| 英文摘要 | Influenced by climate change and human activities, desertification has become the main eco-environmental problem in the Northwest China, and Hobq Desert is one of the most serious areas that are threatened by sand damage. In recent 30 years, the sand control of Hobq Desert, especially its eastern part, has made great progress and achieved fine social-ecological-economic benefits under the cooperation of the local governments, relative enterprises and the masses. However, the sand control measures that is used in the past sand control practices is relatively single, moreover, some key scientific issues are still unsolved and need to be solved immediately. This thesis focuses on the influences of water contents on sand movement and sand control measures based on wind tunnel experiments. And the flow field of different specifications of checkerboard sand barriers was also simulated through wind tunnel experiment. Finally, the control effects of sand control measures were analyzed and compared based on in-situ observed data of Duguitala sand control experiment field. And the main results are as follows. (1) The wind tunnel experiment of the influences of different moisture on sand movement indicates that the overall surface roughness shows a fluctuating downward trend with the increasing moisture. Therefore, compared with the western dry desert or gobi, it is more applicable to increase surface roughness by using engineering sand control measures such as checkerboard sand barriers in Hobq Desert that has higher water content. Besides, wind profile follows the law of logarithmic distribution under different range of water contents. The absolute sand transport rate decreses while the relative sand transport rate increases with the moisture increasing. And the sand transport rate decreases with the height increasing for each sand moisture. But the wind erosion tends to disappear over every height while the moisture reaches 2.5%. The sand transport amount of the dry sand distributes under 5 cm over the near surface takes the proportion of 80%, but the proportion of the sand transport amount above 5 cm tends to increase with the moisture increasing. Therefore, compared with dry sand area, the height of sand fixing measures should be higher in Hobq Desert with high water content in sand.(2) The wind tunnel experiments of different specifications of checkerboard sand barriers show that the flow field is very similar despite the different specifications. Under critical height, the wind speed reduces dramatically with the decreasing of height-width ratio of the checkerboard sand barriers. The windproof performances of different specifications of checkerboard sand barriers tend to increase under the inlet wind speed of 10 m/s within the measuring range. Moreover, the gradient of windproof performances gradually decreases with the height increasing. The above results indicate that the effective windproof height is increasing with the height increasing for every specifications of checkerboard sand barriers. Comprehensively, the checkerboard sand barriers with H=6 cm and H/L=0.05 has the best windproof performances, and the next one is H=10 cm and H/L=0.1.(3) The field in-situ observation experiments indicate that the wind speed tends to increase with the height increasing over five kinds of checkerboard sand barriers, and the checkerboard of the specification of 1 m high and 8 m×8 m square possesses the best windproof performance with the lowest wind speed in the checkerboard area. The sediments of the experiment field is mainly fine sand (100 ~ 250 μm), and the mean diameter of the sand particles on windward slope is coarser than leeward slope. The mean diameter of the sand particles in the specification of H=15 cm and 1 m ×1 m checkerboard is finer than other kinds of checkerboards, which indicates that the wind speed of this kind of checkerboard is lower and it has better performances than the others. The sand transport is concentrated in 10 cm height over the surface, but the sand transport is little while the height over 10 cm, basically 0. Besides, the sand transport rate is the least for HDPE and plant fiber net checkerboard sand barriers with the specification of H=15 cm and 1 m×1 m. During the observing period, the differences of surface concave morphology is very apparent for the five kinds of checkerboards, and the height of sand deposition increases apparently. However, the sand deposition changing height of HDPE checkerboard with the specification of H=20 cm and 1 m×1 m has the smallest amplitude which indicates that the surface concave is relatively stable and has better sand fixing performance. From the view of deposit height, the HDPE and plant fiber net checkerboard sand barriers with the specification of H=1 m and 8 m×8 m have the largest changing amplitude than the others which are characterized by sand deposition. The field experiments indicate that the stability of surface sand materials could be effectively improved by building checkerboard sand barriers, which will play a significant effect of sand fixation. |
| 中文关键词 | 格状沙障 ; 防护效益 ; 风洞模拟 ; 定位监测 ; 库布齐沙漠 |
| 英文关键词 | Checkerboard sand barriers control effects wind tunnel simulation in-situ observation Hobq Desert |
| 语种 | 中文 |
| 国家 | 中国 |
| 来源学科分类 | 自然地理学 |
| 来源机构 | 中国科学院西北生态环境资源研究院 |
| 资源类型 | 学位论文 |
| 条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/287932 |
| 推荐引用方式 GB/T 7714 | 宗玉梅. 库布齐沙漠东缘风沙防治相关问题的实验研究[D]. 中国科学院大学,2017. |
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