【摘要】 地形条件与山地灾害的发育密切相关,是山地灾害危险性评价的重要因子。以四川省芦山县"4·20"7.0级强烈地震灾区的芦山、宝兴、天全3县为研究区,应用GIS技术计算研究区坡度、地形位指数与地形起伏度,通过流域水文分析方法实现宝兴县子流域划分并提取沟床纵比降,分析灾区地形因子特征,结合灾后崩塌滑坡遥感解译结果,探讨次生山地灾害分布与地形因子的关系。结果表明,研究区坡度大于25°的面积占区域总面积的73.89%,地形位指数大于0.4的区域面积占总面积的85.92%,起伏度大于500 m的占87.41%,各地形因子面积比率最大的区段分别为坡度35°～40°、地形位指数0.648～0.666、起伏度500～1 000 m;宝兴县子流域沟床纵比降数值集中于100‰～300‰范围内。坡度30°～50°的区域为崩塌滑坡的高发地段;崩塌滑坡的优势地形位处于地形位指数0.228～0.246和0.34～0.61之间的区域;起伏度在500～1 000 m的区域为崩塌滑坡的集中分布区。研究结果可为灾害评估及灾后恢复重建提供参考依据。更多还原

【Abstract】 Important factors for mountain hazard risk assessment—terrain conditions,are closely related to the occurrence of mountain hazards.The worst earthquake-hit areas in Ms7.0 Sichuan Lushan earthquake are Lushan county,Baoxing county and Tianquan county.This paper takes these three counties as study area,applies GIS technology to compute slope gradient,relief amplitude and terrain niche index,divides mudslides sub-basins and extracts longitudinal gradient by hydrological analysis methods.Topographic factors are analyzed and the relationship between seismic secondary disaster distribution and topographic factors are discussed by combining collapse and landslides remote sensing interpreted results.It shows that areas with slope gradient more than 25° occupy 73.89% of study area,regions have terrain niche index greater than 0.4 account for 85.92% of study area and zones possess relief amplitude greater than 500 m hold 87.41% of study area.Zones which contain the most widespread ratio of each topographic factor respectively distribute in areas with slope gradient 35° ～ 40°,terrain niche index 0.648 ～ 0.666 and relief amplitude 500 ～ 1 000 m.Baoxing county debris flow gully longitudinal gradient values are overall high and concentrated within the range of 100‰ to 300‰.Regions with 30° ～ 50° slope gradient occur collapse and landslides most.Superior terrain niche of collapse and landslides includes grade 8(terrain niche index from 0.228 to 0.246) and grade 14 to 28(terrain niche index 0.34 ～ 0.61).Areas with relief amplitude within the range of 500 m to 1 000 m are collapse and landslides concentrated distribution ones.The result could be a reference for disaster assessments and disaster recovery and reconstruction.更多还原