摘要
以陕北黄土区坊塌流域内7条大切沟及其谷缘上的小切沟为研究对象,通过Arc GIS和MATLAB从基于1976、1997年1:10 000比例尺地形图生成的数字高程模型(DEM)上提取沟沿线,进而获得1976、1997年大切沟的面积、周长和大切沟上小切沟沟头前进距离,并结合当时的土地利用图和植被覆盖图,定量研究了退耕前陕北黄土区切沟发育的速率,以及土地利用类型和植被覆盖度对切沟发育的影响。结果显示:在1976-1997年间,7条大切沟的面积、周长增长率分别为11.01%~180.46%和8.07%~86.75%,大切沟上小切沟沟头年均前进速率为0.26~0.84 m;由溯源侵蚀导致的小切沟沟头前进是研究区内大切沟上的主要侵蚀方式,大切沟沟谷拓宽和形成新的小切沟分别是对大切沟的面积和周长增长具有较高贡献率的侵蚀方式;林草覆盖能控制切沟发育,集水区内覆盖度大于65%的植被能更加有效地控制大切沟内以沟谷拓宽为主的、多过程、多部位的综合切沟侵蚀,覆盖度大于45%的植被能更加有效地控制大切沟上小切沟沟头的溯源侵蚀。研究表明基于GIS技术和不同年份的地形图,可以确定切沟侵蚀的方式及速率,实现对切沟发育的动态监测。
Gully erosion is a serious environmental problem and the primary source of sediment loss on the Loess Plateau.However, due to the limited technologies and approaches for monitoring gully, most of the early studies focused on the qualitative description of gully morphology and the division of gully development stages, confining the advancement of quantitative research for gully erosion and leading to insufficient knowledge about gully erosion. The objective of this study was to quantitatively estimate the gully development rates as well as assess the effect of land use and vegetation coverage in upslope drainage area on gully development over 1976-1997 period, after which the Grain-for-Green Programme had been completely implemented since 1999. The study area was in Fangta watershed in Ansai County（109°19＇E, 36°52＇N）, which is located in the northern Shaanxi hilly loess region. Seven large gullies, as well as the small gullies which occurred along the large gullies, were selected along a transect placed randomly and throughout Fangta watershed. ArcGIS and MATLAB software were used to obtain boundary lines of the selected large gullies based on the DEM（digital elevation model） derived from topographic maps at the scale of 1：10000 in 1976 and 1997. By applying LOG（Laplacian of Gaussian） edge detection approach in MATLAB, the gully boundary lines were initially extracted; furthermore, in order to improve the accuracy of the boundary lines, visual interpretation based on the morphology reflected by contour line was conducted in ArcGIS. According to the gully boundary lines, the area and perimeter of large gully and the head retreat distance of small gullies within each large gully in 1976 and 1997 were calculated, respectively. Details about land use and vegetation coverage were extracted from the historical maps of land use and vegetation cover, respectively. The results showed that the rates of area and perimeter development of the 7 large gullies from 1976 to 1997 ranged from 11.01% to 180.46% a
作者
陈一先
焦菊英
魏艳红
赵珩钪
Chen Yixian Jiao Juying Wei Yanhong Zhao Hengkang(Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, China Institute of Soil and Water Conservation, Northwest.4 ＆F University, Yangling 712100, China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2017年第17期120-127,共8页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家自然科学基金面上项目(41371280)
国家重点研发计划项目课题(2016YFC0501604)
关键词
土地利用
侵蚀
植被
切沟
沟沿线
退耕还林(草)
land use
erosion
vegetation
gully
gully boundary line
Grain-for-Green Programme
