GIS支持下岷江上游土壤侵蚀动态研究

利用TM数据，采用3S技术和通用土壤侵蚀方程（RUSLE）研究岷江上游地区3个典型时期的土壤侵蚀动态，并对影响侵蚀的主要因子进行初步分析.结果表明，研究区3个时期侵蚀面积分别占研究区总面积的1.28%、1.84%和1.70%；年平均侵蚀模数分别为832.64、1048.74和1 362.11 t·km^-2，以微度侵蚀、轻度侵蚀为主，伴有少量的中度侵蚀.侵蚀面积比较小，侵蚀程度比较轻.侵蚀与坡度呈显著正相关，侵蚀大多发生在＞25°的区域，1986年占总侵蚀量的93.65%，1995年为93.81%，2000年为92.71%；在海拔上，中山、亚高山、高山以及干旱河谷是侵蚀发生的主要地带，1986年占总侵蚀量的98.21%，1995年为97.63%，2000年为99.27%；不同类型的植被直接影响到侵蚀的发生，灌木林地以及新退耕的疏林地是3个时期侵蚀的主要发生地，过度放牧导致草场退化，也产生了微度侵蚀；侵蚀的发生和土壤类型密切相关，燥褐土、石灰性褐土最易发生侵蚀，是控制侵蚀的重点区域；人口的增长、户数的增加是侵蚀发生的驱动因子，人口与户数增长导致资源需求压力的增大，侵蚀呈线性增加.

Dynamics of soil erosion at upper reaches of Minjiang River based on GIS

Based on TM and ETM imagines, and employing GIS technique and empirical Revised Universal Soil Loss Equation (RUSLE) model, this paper studied the dynamics of soil erosion at the upper reaches of Minjiang River during three typical periods, with the main affecting factors analyzed. The results showed that the soil erosion area was increased by 1.28%, 1.84 % and 1.70% in 1986, 1995 and 2000, respectively. The average erosion modulus was increased from 832.64 t x km(-2) x yr(-1) in 1986 to 1048.74 t x km(-2) yr(-2) in 1995 and reached 1362.11 t x km(-2) yr(-1) in 2000, and soil loss was mainly of slight and light erosion, companying with a small quantity of middling erosion. The area of soil erosion was small, and the degree was light. There was a significant correlation between slope and soil loss, which mainly happened in the regions with a slope larger than 25 degrees, and accounted for 93.65%, 93.81% and 92.71% of the total erosion in 1986, 1995 and 2000, respectively. As for the altitude, middling, semi-high and high mountains and dry valley were liable to soil erosion, which accounted for 98.21%, 97.63% and 99.27% of the total erosion in 1986, 1995 and 2000, respectively. Different vegetation had a significant effect on soil erosion, and shrub and newly restored forest were the main erosion area. Excessive depasture not only resulted in the degradation of pasture, but also led to slight soil erosion. Land use type and soil type also contributed to soil loss, among which, dry-cinnamon soil and calcic gray-cinnamon soil were the most dangerous ones needing more protection. Soil loss was also linearly increased with increasing population and households, which suggested that the increase of population and households was the driving factor for soil loss increase in this area.