山区坡谱信息熵与水土流失地形因子关系探讨

Investigation on relationship between slope spectrum's information entropy and topographical factor influencing soil loss in the mountainous region

针对当前以县域为统计单元的坡谱研究较少,且难以满足区域尺度上水土流失地形因子指标的选取等问题,该文采用数字地形分析方法提取山区各县域的坡谱和坡长坡度因子(LS因子),并探讨坡谱信息熵与LS因子之间的关系。实验表明:地貌的差异决定了各县域坡谱曲线的差异,具体可分为L型、S型和钟型。坡谱信息熵变化范围为1.709～2.667nat,反映了地形起伏由平缓到强烈的变化趋势;LS因子平均值介于2.72～18.61之间,在一定程度上表征土壤流失量的大小。坡谱信息熵与LS因子关系拟合良好(R2=0.963 6,P<0.05),结论可为坡谱信息熵在区域水土流失地形因子的建立及应用提供参考。

According to lhe fact that the existing research on slope spectrum counted from county region is scarcity. it is very difficull to meet the requirements of selecting topographic factor influencing soil loss in the regional scale. Slopc spectrum and slope length and slope gradient factor ( LS factor) for different counties in mo un tai nous region were derived with the method of digital terrain analysis based on digital elevation model( DEM ) as well as discussed the relationship between slope spectruni' s information ent ropy ( SSIE) and ( LS factor). The results showed that: Spatial distribution type of slope spectrum of different counties was different,which was depended on the difference of the landforms. In the preliminary result ,it was found lhat there were t hree kinds of slope spectrum curve( L. S and Bell shape): SSIE in different counties ranged from 1709 nat to 2667 nat. Il had increeising trends in great relief amplitude of land surface,while had decreasing trends in small relief amplitude of land surface. Average value of LS factor in the same study area ranged from 2. 72 to 18. 61,which was characterized by soil loss amount;The fitting analysis showed that there was a extremely closed(R^2= 0. 963 6,P<0.05 ) relationship between SSIand LS factor. The results of this research would have important practical significance for rational selection of topographic factor influencing soil loss in large scales with the help of slope spectrum.