基于随机森林算法的水土流失影响因子重要性分析  

Importance analysis of soil erosion influencing factors based on random forest

作　　者：陈妙金 汪小钦[1] 吴思颖 CHEN Miaojin;WANG Xiaoqin;WU Siying(Key Laboratory of Spatial Data Mining & Information Sharing of Ministry of Education,National Eng. Research Center of Satellite Spatial Information Technology,Fuzhou University,Fuzhou 350116,China)

机构地区：[1]福州大学空间数据挖掘和信息共享教育部重点实验室卫星空间信息技术综合应用国家地方联合工程研究中心

出　　处：《自然灾害学报》2019年第4期209-219,共11页Journal of Natural Disasters

基　　金：国家重点研发计划资助(2017YFB0504203);福建省高校产学研重点项目(2017Y4010);中央引导地方发展专项(2017L3012)~~

摘　　要：水土流失是诸多因素综合所致,确定水土流失因子的重要性具有重要意义。本文以福建省为例,利用土壤侵蚀强度等级数据及导致水土流失的年侵蚀降雨量、土壤类型、坡度、坡长、植被覆盖度及土地利用类型等数据,引入随机森林算法,提出通过平均精确率减少值(MDA)和平均不纯度减少值(MDG)归一化相加的方法确定要素重要性,并与MDA和MDG排序赋值相加的方法进行对比。结果表明:随机森林算法适用于水土流失影响因子重要性分析;归一化相加法对因子重要性的表征效果较好,优于排序赋值相加法,不仅能判别因子的相对重要性,还可定量表达因子间差异的显著性;在所分析的六个要素中,植被覆盖度最为重要,地形特征次之,而土壤类型对是否发生水土流失重要性影响较弱,与已有的实验和研究结果吻合,结果合理。在判断无流失与其它流失等级间关系时,植被覆盖度的重要性具有很大的优势,量级上是第二位的2倍以上。Soil erosion is caused by many factors, so it is meaningful to determine the factors of soil erosion. This paper took Fujian Province as an example, and used the random forest algorithm and the data of soil erosion grades, the annual cumulative rainfall, soil type, slope gradient, slope length, vegetation coverage and land cover types that lead to soil erosion to determine the importance of elements by adding the normalization of MDA and MDG, which was also compared with MDA and MDG ranking assignment method. The results show that the random forest algorithm is suitable to analyze the importance of factors affecting soil erosion. The MDA and MDG normalized summation method is better than the ordinal ranking assignment method in characterizing the importance of factors, which can not only distinguish the relative importance of factors, but also quantitatively express the significance of differences among factors. Among the six factors analyzed, vegetation coverage is the most important, followed by topographic features. And soil types have a weak influence on the importance of soil erosion, which is consistent with the existing experimental and research results. Vegetation coverage has a great advantage in judging the relationship between loss-free and other loss levels, which is more than twice of the second.

关 键 词：水土流失 因子重要性 随机森林算法 平均精确率减少值(MDA) 平均不纯度减少值(MDG) 

分 类 号：S157[农业科学—土壤学] X43[农业科学—农业基础科学]