植被和梯田措施对坡沟系统细沟侵蚀调控作用

坡沟系统作为黄土丘陵沟壑区基本的地貌单元，也是黄土高原侵蚀泥沙的主要来源区。植被和梯田作为坡面水土流失治理的主要措施，对于土壤侵蚀控制和生态恢复发挥着重要的作用，定量评估林草、梯田对坡面细沟侵蚀的调控作用以及多措施协同配置问题对于黄土高原水土流失治理和生态保护具有重要意义。为了揭示植被和梯田的格局和配置对坡沟系统细沟侵蚀的协同调控作用，该研究采用人工模拟降雨，结合三维激光扫描技术，分析了坡面4种措施：上坡位植被（措施A）、下坡位植被（措施B）、梯田（措施C）、梯田+植被（措施D）对细沟侵蚀发生和演变过程的影响。结果表明：1）相同植被覆盖度下，下坡位的植被布设细沟最大长度较上坡位的植被布设细沟最大长度减小量更大；2） 第1次降雨中，侵蚀率最大值达到3 500 g/min以上，第2次降雨过程中侵蚀率最大值仅为1 100 g/min以上，在各产流时间内第2次降雨侵蚀率均为第1次降雨侵蚀率的1/3～1/2；3）对于各措施下细沟沟长发育率由大到小表现为措施A（6.55 cm/min）、措施C（5.71 cm/min）、措施B（3.60 cm/min）、措施D（2.69 cm/min）；4）梯田与植被同时布设（措施D）对于细沟侵蚀的调控作用优于单一措施（措施B和C），梯田和植被对细沟侵蚀指数细沟侵蚀量、细沟面积、细沟密度产生了协同作用（分别为7.71%、13.76%、7.52%）。研究可为黄土高原坡沟治理措施配置和细沟侵蚀调控提供一定的科学参考依据。

Effects of the role of vegetation and terraced measures on the rill erosion in slope-gully system

Abstract: As the basic geomorphological unit of the loess hilly gully area, the slope and gouge system is also the main source area of eroded sediment on the Loess Plateau. As the main measures for slope erosion control, vegetation and terraces play an important role in soil erosion control and ecological restoration, and quantitative assessment of the regulatory effect of forest grass and terraces on slope fine trench erosion, and multi-measure collaborative allocation are of great significance for soil erosion control and ecological protection of the Loess Plateau. Based on the previous research on soil erosion and slope trench erosion, in order to reveal the synergistic regulation effect of vegetation and terraced land pattern and configuration on fine trench erosion in slope and trench system, this paper used artificial simulation rainfall, combined with 3D laser scanning technology, to quantitatively analyze the regulatory effect of different measures on fine trench erosion from the slope surface sand production rate and slope micro-terrain change as a whole, and quantitatively analyze the characteristics of single furrow morphological changes such as the change characteristics of the development process of fine furrow length and the change characteristics of fine furrow width and depth ratio from the single furrow morphology. The development process of fine furrow network was also analyzed, and parameters including but not limited to fine furrow erosion amount, fine furrow area, and fine furrow erosion proportion were quantitatively calculated, and the influence of different slope and ditch treatment measures on the characteristic parameters related to fine furrow erosion was expounded from multiple angles, and finally the synergistic effect of different measures on the erosion amount, area and density of fine trench was quantitatively calculated and analyzed for the synergistic effect between multiple measures. The effects of four slope measures: uphill vegetation (measure A), downhill vegetation (measure B), terraces (measure C), and terraces + vegetation (measure D) on the occurrence and evolution of fine furrow erosion were analyzed. The results showed that: 1) Under the same vegetation coverage, the maximum length of the downhill vegetation furrow was reduced compared with that of the uphill vegetation furrow (including the maximum ditch length of the uphill position reached 238.8 cm and the maximum ditch length in the downslope position reached 142.3 cm); 2) In the first rainfall, the maximum sand yield rate reached more than 3 500 g/min, and the maximum sand yield in the second rainfall was only more than 1 100 g/min. The sand yield rate of the second rainfall was 1/3-1/2 of the sand yield of the first rainfall during each production time; 3) The development rate of fine furrow length under each measure was the highest for measure A (6.55 cm/min), followed by measure C (5.71 cm/min), measure B (3.60 cm/min), and measure D (2.69 cm/min); 4) The simultaneous arrangement of terraces and vegetation (measure D) had a better regulatory effect on fine trench erosion than a single measure (measures B and C), and the terraces and vegetation had a synergistic effect on the erosion amount, area and density of fine trench on the erosion index of fine trench (7.71%, 13.76% and 7.52%, respectively). Based on the above research methods and related conclusions, this study provides a relatively new perspective in the prevention and control of soil erosion in the hilly area of the Loess Plateau, that is, when setting up actual engineering measures, the differences in the influence of the same measures on the erosion of fine ditches at different positions in the slope and ditch system and the impact of multiple measures and the synergistic effect between multiple measures can be properly considered, and the configuration of soil erosion control programs can be continuously optimized to maximize the benefits of each treatment measure. This study can provide a certain scientific reference for the allocation of slope and ditch treatment measures and the erosion control of fine ditches on the Loess Plateau.