基于RUSLE模型的太行山区土壤侵蚀时空分异特征及影响因子研究

Spatio-temporal variations in soil erosion and its influence factors in Taihang Mountain area based on RUSLE modeling

  • 摘要: 土壤侵蚀特征及区域分异规律的研究对生态环境保护具有重要的意义, 为探明太行山区土壤侵蚀特征, 本论文应用归一化植被指数(NDVI)、数字高程模型(DEM)和土地利用等数据, 结合GIS和RS技术, 根据修正的通用土壤流失方程(RUSLE)模型, 计算了太行山区2000年、2005年、2010年和2015年4期的土壤侵蚀模数, 在此基础上分析了土壤侵蚀的时空变化特征, 并探究了土壤侵蚀模数与坡度、土地利用类型和NDVI的关系。结果表明: 1) 2000—2015年4期平均土壤侵蚀模数分别为4434.14 t∙km−2∙a−1、2984.65 t∙km−2∙a−1、1761.93 t∙km−2∙a−1和1833.81 t∙km−2∙a−1, 呈现明显的减小趋势, 16年间土壤侵蚀模数减少58.64%。2)太行山区土壤侵蚀强度降低1级的面积始终比增加1级的大, 至少74.77%的地区未表现出等级上的变化, 2005—2010年是侵蚀强度降低变化率最高的时间段。3)中低山区集中了2015年侵蚀总量(2.5×108 t)的86.54%, 此区域的侵蚀模数与海拔无明显的相关性, 而在亚高山区两者才呈现明显的正相关关系。4)土壤侵蚀总体上随坡度增加而增大, 坡度阈值为40º左右; 草地是太行山区土壤侵蚀模数最高的土地利用类别, 平均达3605.73 t∙km−2∙a−1; 土壤侵蚀模数随年平均NDVI的增加呈显著降低趋势, NDVI达0.66后侵蚀降低速度放缓。土壤侵蚀是生态环境质量评价的重要指标, 本研究可为太行山区水土流失治理和生态工程措施制定提供一定的科学依据。

     

    Abstract: The study of soil erosion characteristics and their spatial heterogeneity is of great significance for ecological environmental protection. Soil and water conservation is important in Taihang Mountain area. This study was conducted to explore these characteristics. Supported by the normalized difference vegetation index (NDVI), digital elevation model (DEM), and land use data combined with geographic information system (GIS) and remote sensing (RS) technologies, the soil erosion modulus in Taihang Mountain area was calculated from 2000 to 2015 based on the revised universal soil loss equation (RUSLE) model. The spatiotemporal variation in soil erosion in the study area was analyzed, and the relationship between soil erosion, slope gradient, land use type, and NDVI was explored. The results showed that: 1) The average soil erosion modulus were 4434.14 t∙km−2∙a−1, 2984.65 t∙km−2∙a−1, 1761.93 t∙km−2∙a−1 and 1833.81 t∙km−2∙a−1 in 2000, 2005, 2010 and 2015, respectively. The erosion modulus showed a notably decreasing trend from 2000 to 2015 with a decreasing rate of 58.64%. 2) The areas where erosion intensity decreased by one level were always larger than those where it increased by one level. However, erosion intensity did not change in more than 74.77% of the total area. The maximum reduction in the erosion intensity occurred in the period of 2005–2010. 3) From 2000 to 2005, the decline in erosion intensity level in Taihang Mountain area was mainly distributed in higher elevation regions near the border of the Shanxi and Hebei Provinces. The areas with decreasing soil erosion intensity from 2005 to 2010 were uniformly distributed in the study area and were mainly located in the south of Yangquan and Shijiazhuang from 2010 to 2015. 4) In 2015, 86.54% of the total soil erosion (2.5×108 t) was concentrated in the mid-mountain and hilly zones, where accounted for approximately 91.12% of the study area. There was no obvious correlation between the erosion modulus and altitude in this area, whereas it showed a positive relationship in the subalpine zone. 5) The erosion modulus had a positive correlation with slope gradient; the threshold value was 40º, and the erosion modulus reached a maximum value of 4693 t∙km−2∙a−1. With an increase in slope gradient, the possibility of soil erosion increased gradually with higher grades of erosion intensity. Cultivated land, forest land and grassland were the three main land use types in the study area, and their average soil erosion modulus were 501.72 t∙km−2∙a−1, 2475.46 t∙km−2∙a−1 and 3505.73 t∙km−2∙a−1, respectively. The average slope gradient of the cultivated land was 4.90º, which resulted in the minimum soil erosion modulus. Grassland was the land use type with the largest erosion modulus. The soil erosion modulus decreased significantly with an increase in annual NDVI, and the rate gradually slowed down when NDVI reached 0.66. Soil erosion is a significant index for eco-environmental quality appraisal. This study provides a scientific basis for soil erosion control and ecological engineering measures in Taihang Mountain area.

     

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