基于像元二分法的盐池县植被覆盖度与地质灾害点时空格局分析

Spatial-temporal pattern analysis of the vegetation coverage and geological hazards in Yanchi County based on dimidiate pixel model

宁夏回族自治区盐池县地处农牧交错区,生态环境脆弱,地质灾害较为发育。基于像元二分模型,利用1989—2014年间4期Landsat TM/OLI遥感影像,分析了25 a间盐池县植被覆盖度空间格局及其变化特征,结合地质灾害详细调查数据,进一步探讨了植被覆盖度与地质灾害点的关系。结果表明,25 a间研究区植被覆盖度整体偏低,且具有东部相对较高、西部较低的特点,植被表现为恢复—退化—恢复的反复过程,总体处于恢复趋势中。植被覆盖度与地质灾害点密度呈现明显负相关,灾害点密度随着植被覆盖度的增加而降低,植被覆盖度越高,灾害点密度越低。

Based on dimidiate pixel model and using Landsat TM/OLI remote sensing images of 4 periods in 25 years（ 1989—2014） and geological hazards investigation data, the authors analyzed the characteristics of vegetation spatial-temporal pattern in Yanchi County by GIS and discussed the relationship between vegetation coverage and geological hazards. The results showed that the vegetation coverage of study area took on the features of relatively high vegetation coverage in the east and relatively low vegetation coverage in the west. The average vegetation coverage was on the low side generally and presented the characteristics of increase-decrease-increase; correspondingly the vegetation appeared the repetitive process of restoration-degeneration-restoration but had a tendency of recovery as a whole,with restoration distributed in the southeast and northwest and degeneration in the mid-west. Geological hazards point density was high in the south and low in the north,which suggests that the hazards points were concentrated in the south and dispersed in the north. A negative correlation between vegetation coverage and density of geological hazards points was discovered,which suggests the regularity of density of geological hazards points descending with the increasing of vegetation coverage： the higher the vegetation,the lower the density of geological hazards points.