IMHE OpenIR  > 山地表生过程与生态调控重点实验室
横断山区耕作侵蚀强度分级及主要影响因子临界值确定
Alternative TitleClassification of Tillage Erosion and the Threshold’s Determination of Key Impact Factors in the Hengduan Mountainous Region
贾立志
Subtype博士
Thesis Advisor张建辉
2017
Degree Grantor中国科学院大学
Place of Conferral北京
Degree Discipline土壤学
Keyword横断山区 耕作侵蚀 影响因子 WEPP模型 临界值
Abstract耕作侵蚀是横断山区坡耕地土壤侵蚀的一种重要形式,目前关于横断山区耕作侵蚀强度分表标准的研究还未涉及。本研究以东川砾石土区和元谋燥红土区坡耕地为研究对象,采用模拟耕作、磁性示踪技术和WEPP模型模拟等方法进行研究,从而得出影响耕作侵蚀的各关键因子的临界值,主要研究结果和结论如下:1、横断山区耕作侵蚀强度分级标准制定在东川砾石土区,坡度范围为0.0522 m m-1~0.7489 m m-1,耕作位移距离随坡度的增加呈指数增加,平均耕作侵蚀速率为83.94 Mg ha-1 tillage pass-1。在元谋燥红土区,坡度为0.0874 m m-1~0.5773 m m-1以及耕作深度为0.05、0.10、0.15和0.20 m范围内,耕作位移距离随坡度增加呈线性增加。本研究将耕作侵蚀分为微度、轻度、中度、强烈、极强烈、剧烈等六个等级。其中,将小于1000 t/(km2·a)(5°坡面0.05 m耕作深度下的耕作侵蚀速率)划定为微度侵蚀;将1000到2500 t/(km2·a)(10°坡面0.10 m耕作深度侵蚀速率)划定为轻度侵蚀;将2500到5000 t/(km2·a)(15°坡面0.15 m耕作深度侵蚀速率)划定为中度侵蚀;将5000到10000 t/(km2·a)(20°坡面0.20 m耕作深度侵蚀速率)划定为强烈侵蚀;将10000到13000 t/(km2·a)(砾石土休止角坡面侵蚀速率)划定为极强烈侵蚀;将大于13000 t/(km2·a)划定为剧烈侵蚀。2、地形因子临界值确定坡长和坡度是影响耕作侵蚀速率的两个重要的因子,耕作侵蚀速率随着坡度的增加而增加,而随着坡长的增加呈减小趋势。因此,缓坡耕作和增加坡长是减少耕作侵蚀的有效的措施。对于0.20 m耕作深度下,坡长小于40 m的坡面,耕作侵蚀控制在微度侵蚀下,不存在坡度的临界值;在坡长分别为40 m、60 m和80 m坡长的坡面,耕作侵蚀强度控制在微度侵蚀的情况下,进行耕作操作的坡度应该分别为≤1°、≤7°和≤13°。在缓坡(5°),耕作侵蚀强度控制在微度侵蚀下坡长应当大于54 m;在中坡(10°),耕作侵蚀强度控制在微度侵蚀下的坡长应当大于70 m;在陡坡(25°),耕作侵蚀强度控制在微度侵蚀下的坡长应当大于121 m。3、人为因子临界值确定耕作深度是影响耕作位移距离以及耕作侵蚀速率的重要因子。耕作侵蚀强度控制在微度侵蚀下,在坡度为5°~12°的坡耕地,耕作深度应当小于0.05 m;在坡度为13°~30°的坡耕地,耕作深度应当小于0.04 m。这表明在整个坡度范围内耕作深度小于0.04 m才能将坡耕地耕作侵蚀强度控制在微度侵蚀。与顺坡耕作相比较,45°耕作角度可使耕作侵蚀速率减少26.72%。等高耕作可以使耕作侵蚀速度减少77.73%;135°耕作以及逆坡耕作都可以有效地减少耕作侵蚀。在缓坡(5°),耕作侵蚀强度控制在微度侵蚀下耕作角度应当大于91°,即在缓坡应至少采取等高耕作的措施。在中坡(10°),耕作侵蚀强度控制在微度侵蚀下的耕作角度应当大于105°,即在中等坡度的坡耕地,至少采取斜向上耕作的措施。在陡坡(25°),耕作侵蚀强度控制在微度侵蚀下耕作角度应当大于139°,即在陡坡的坡耕地,至少采取斜向上耕作或逆坡耕作方式,才能控制耕作侵蚀强度在微度侵蚀。4、耕作年限临界值确定在建立WEPP模型所需的数据库以及适用性验证的基础上,运用WEPP模型模拟耕作年限对水蚀的影响,进而确定耕作年限的临界值。在水蚀和耕作侵蚀的共同作用下,各坡度上坡位置土层损失。在5°坡面下坡位置土层堆积,而在10°、15°和25°坡面下坡位置土层损失。在坡度为5°坡耕地,年径流量以及产沙量在耕作年限为0~14年随着耕作年限增加显著降低,在耕作年限为15~20年,年径流量与产沙量基本保持不变。这表明在坡度为5°坡耕地,耕作侵蚀导致的土壤再分布会抑制水蚀作用。在坡度为10°、15°和25°的坡耕地,年径流量以及产沙量在耕作年限分别为0~12年、0~10年和0~7年内随着耕作年限的增加而缓慢增加;当耕作年限分别超过12年、10年以及7年时,年径流量以及产沙量随着耕作年限的呈显著的增加趋势。因此,对于坡度为10°、15°和25°的坡耕地,连续耕作年限应当分别控制在小于12年、10年以及7年。
Other AbstractTillage erosion is an important form of soil erosion in the Hengduan Mountainous Region. However the classification of tillage erosion has not been studied on slope land of the Hengduan Mountainous Region. In order to ensure the classification of tillage erosion and the threshold of key impact factors, a series of simulated tillage experiments were conducted in Dongchuan and Yuanmou. The simulated tillage by hoeing and magnetic tracer technique were used to examine the combined effects of multiple factor on tillage erosion rate. The WEPP model was used to examine the effect of tillage age of water erosion. The main results and conclusions are as follows:1. Classification of tillage erosion in the Hengduan Mountainous RegionMean displacement distance for gravelly soil exponentially increased with increasing slope gradients on the slopes of 0.0522-0.7489 m m-1 in Dongchuan. Mean tillage erosion rate for gravelly soil is 83.94 Mg ha-1 tillage pass-1. However, mean displacement distance for 0.05 m, 0.10 m, 0.15 m and 0.20 m tillage depths linearly increased with increasing slope gradients on the slopes of 0.0874-0.5773 m m-1 in Yuanmou. Tillage erosion rate was classified by six grades: micro tillage erosion, mild tillage erosion, moderate tillage erosion, intensive tillage erosion, severe tillage erosion, extremely severe tillage erosion. Micro tillage erosion is designated as less than 1000 t/ (km2·a) (tillage erosion rate for 0.05 m tillage depth on 0.0874 m m-1. Mild tillage erosion is designated as between 1000 and 2500 t/ (km2·a) (tillage erosion rate for 0.10 m tillage depth on 0.1763 m m-1). Moderate tillage erosion is designated as between 2500 and 5000 t/ (km2·a) (tillage erosion rate for 0.15 m tillage depth on 0.2679 m m-1). Intensive tillage erosion is designated as between 5000 and 10000 t/ (km2·a) (tillage erosion rate for 0.20 m tillage depth on 0.3640 m m-1). Severe tillage erosion is designated as between 10000 and 13000 t/ (km2·a) (tillage erosion rate for gravelly soil on angle of repose). Extremely severe tillage erosion is designated as more than 13000 t/ (km2·a).2. Threshold's determination for terrain factorSlope gradient and slope length are two main factors effecting tillage erosion. Tillage erosion rate increased with increasing slope gradient and decreased with increasing slope length. Thus tillage on gentle slope and increase the slope length are two effective measures in reducing tillage erosion. For 0.20 m tillage depth, there are no thresholds for slope gradient for slope length larger than 40 m if tillage erosion rate is controlled under micro tillage erosion. For 40 m, 60 m and 80 m slope length, the thresholds are ≤1°, ≤7° and ≤13° respectively, if tillage erosion rate is controlled under micro tillage erosion. In order to control tillage erosion under micro tillage erosion, the slope length for gentle slope (5°), middle slope (10°) and steep slope (25°) need to be larger than 54 m, 70 m and 121 m, respectively.3. Threshold's determination for human factorTillage depth is a significant factor effecting mean displacement distance and tillage erosion rate. In order to control tillage erosion under micro tillage erosion, tillage depth should be less than 0.05 m on the slopes of 5°~12° and should be less than 0.04 m on the slopes of 13°~30°. In summary, tillage depth should be less than 0.04 m for the total scope of slope. Comparing with downslope tillage, the mean tillage erosion rate for 45° tillage and contour tillage decreased by 26.72% and 77.73%, respectively. Moreover, 135° and upslope tillage can reduce tillage effectively. To control tillage erosion under micro tillage erosion, tillage direction should be larger than 91° for gentle slope (5°) which means that tillage measures should be at least contour tillage. To control tillage erosion under micro tillage erosion, tillage direction should be larger than105° for middle slope (10°) which means that tillage measures should be at least slantwise upslope tillage. To control tillage erosion under micro tillage erosion, tillage direction should be larger than139° for steep slope (25°) which means that tillage measures should be at least slantwise upslope tillage or upslope tillage.4. Threshold's determination for tillage ageBased on the meteorological data and soil parameter data we built the meteorological database, soil database, topographic database and crop management database. Then the simulated result of runoff and sediment yield was compared with the observed data to verify the applicability of the model. Under the combined effects of tillage erosion and water erosion, soil loss at the upslope position. Soil accumulated at the downslope position for 5° slope and loss at the downslope position for 10°, 15° and 25°slope. There exists a slope gradient on which tillage erosion rate is equal to water erosion. Runoff and sediment yield for 5° slope decreased with increasing tillage age for 0 to 14 tillage year. However, runoff and sediment yield keep unchanged with the increasing tillage age for 15 to 20 tillage year. This indicated that the soil redistribution caused by tillage erosion can reduce water erosion for 5° slope. Runoff and sediment yield for 10°, 15° and 25° slope increased slowly with the increasing tillage age for 0 to 12, 0 to 10 and 0 to 7 tillage year, respectively; however, runoff and sediment yield increased significantly with tillage age when tillage year is larger than 12, 10 and 7. Thus the tillage age should be less than 12, 10 and 7 for 10°, 15° and 25° slope. 
Pages149
Language中文
Document Type学位论文
Identifierhttp://ir.imde.ac.cn/handle/131551/24596
Collection山地表生过程与生态调控重点实验室
Affiliation中国科学院成都山地灾害与环境研究所
First Author Affilication中国科学院水利部成都山地灾害与环境研究所
Recommended Citation
GB/T 7714
贾立志. 横断山区耕作侵蚀强度分级及主要影响因子临界值确定[D]. 北京. 中国科学院大学,2017.
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