APPLICATION OF GEOGRAPHIC INFORMATION SIMILARITY BASED ABSENCE SAMPLING METHOD TO DEBRIS FLOW SUSCEPTIBILITY MAPPING

Taking Yongji County of Jilin Province as a study area,we investigated the application of the geographic information similarity based absence sample sampling method to debris flow susceptibility mapping,and explored the influence of the selected negative samples under different value ranges on the final susceptibility mapping results. We selected 14 factors including elevation,slope,aspect,plane curvature,profile curvature,mean annual precipitation,normalized difference vegetation index,topographic wetness index,fault density,road density,water system density,population density,land-use,and geotechnical type. Then,we used different methods to calculate single-factor similarity based on two classifications: discrete and continuous. After synthetically obtaining the region-wide geographical information similarity,we sampled negative samples according to their different thresholds. Subsequently,we chose the support vector machine model as the base model,and three methods(ROC,positive sample accuracy and forecast efficiency curves) as evaluate system. The results show that: Firstly,the geographical information similarity based absence sample sampling method can effectively improve the quality of negative samples. Secondly,when the value of geographical information similarity of negative samples gradually increases,the model accuracy and positive sample accuracy gradually decrease,the forecast efficiency first increases and then decreases. At last,the negative sample selected within the geographic information similarity range of 0 to 0.5 balances model accuracy with land-use value and has the highest predictive efficiency,making it an excellent negative sample sampling strategy. The sampling strategy of negative samples based on the similarity of geographical information effectively improves the quality of negative samples,enhances the prediction efficiency,reasonably balances the contradiction between the division of susceptibility zones and land-use,and provides a new way of thinking on the evaluation of regional debris flow susceptibility.