基于USLE的甘南川西北土壤侵蚀研究

甘南川西北位于黄河和长江上游源区,量化研究该区土壤侵蚀对河源区生态安全保障和地方经济可持续发展具重要意义。论文采用多种数据方法,基于USLE就甘南川西北2000—2015年间土壤侵蚀的时空分布特征及变化规律进行量化评估。结果表明:(1)降雨侵蚀力因子R值介于65~411(MJ·mm)/(hm²·h·a),高值区主要分布在东南部,空间分布与该区降雨格局基本一致;(2)土壤可蚀性因子K值介于0.19~0.41(t·hm²·h)/(hm²·MJ·mm),高值呈斑块状零星分布,与地带性土壤物化性状有关;(3)坡长坡度因子LS值介于0~8.24,高值主要分布在中北部高山地带,低值分布在东北部和西南部地形较平缓区域;(4)植被覆盖管理因子C值介于0~1,高值集中分布在研究区的西北部与西南部,与该区植被覆盖稀疏有关;(5)基于USLE的甘南川西北年侵蚀量为3.3×108 t/a,总体表现为轻度侵蚀;(6)2000—2015年间,研究区土壤侵蚀呈减弱态势,与增温背景下植被活动增强有关。

Study on Soil Erosion in Northwestern Sichuan and Southern Gansu (NSSG) Based on USLE

Northwestern Sichuan and southern Gansu (NSSG) is located in the source areas of Yellow River and Yangtze River. Quantitative study of soil erosion in this area is of great significance for ecological security of large river source region and sustainable development of local economy. In this study, variously sourced data, combined with a variety of methods were used to quantitatively evaluate the temporal and spatial distribution characteristics and change rules of soil erosion in NSSG from 2000 to 2015 based on USLE. The results showed that:(1) R values representing rainfall erosivity ranged from 65 to 411 (MJ·mm)/(hm²·h·a), and the high values were mainly found in southeast part, and the spatial distribution of high values was consistent with the rainfall pattern. (2) Soil erodibility K ranged from 0.19 to 0.41 (t·hm²·h)/(hm²·MJ·mm), the high values sporadically distributed in space, which was mainly influenced by the physical and chemical properties of zonal soil. (3) The slope length and slope gradient factor LS ranged from 0 to 8.24, the high values were mainly distributed in high mountains of the middle and North parts of research area, while the low values were found more in the northeast and southwest regions with gentle terrain. (4) Factor C of vegetation cover management ranged from 0 to 1, the high values were concentrated in the northwest and southwest parts, where the vegetation cover was relatively low. (5) Based on USLE, the annual erosion amount of NSSG was 3.3×10⁸ t/a, which was generally characterized by mild erosion. (6) From 2000 to 2015, soil erosion in NSSG showed a weakening trend, which was related to the enhancement of vegetation activities under the background of warming.