基于ALOS PALSAR影像的莫勒切河洪积扇地貌面定量分期  

QUANTITATIVE MAPPING OF THE MOLEQIE RIVER ALLUVIAL FAN MORPHOLOGIC UNITS IN CHINA BASED ON ALOS PALSAR DATA

作　　者：苏强 任俊杰[1] 梁欧博 郭菲 SU Qiang;REN Jun-jie;LIANG Ou-bo;GUO Fei(Key Laboratory of Crustal Dynamics,Institute of Crustal Dynamics,China Earthquake Administration,Beijing 100085,China)

机构地区：[1]中国地震局地壳应力研究所,地壳动力学重点实验室,北京100085

出　　处：《地震地质》2020年第1期79-94,共16页Seismology and Geology

基　　金：国家重点研发计划项目(2018YFC1504104);国家自然科学基金(41572193,U1839204);中国科学院重点部署项目(KFZD-SW-422);中国地震局地壳应力研究所基本科研业务专项(ZDJ2017-24)共同资助。

摘　　要：洪积扇是干旱-半干旱地区最普遍、最基本的地貌,洪积扇地貌面记录了第四纪以来构造活动、气候变化的重要信息,为构造运动、古环境和地貌演化等方面的研究提供参考,但目前缺少可靠的区域洪积扇地貌面定量分期方法。洪积扇地貌面的粗糙度是地貌演化过程中一个重要的特征。本研究利用合成孔径雷达(SAR)技术,选择公开的空间分辨率为15m的L波段ALOS PALSAR数据,采用横剖面线法获得不同级洪积扇地貌面的后向散射系数,实现阿尔金断裂带西段莫勒切河洪积扇地貌面的大范围定量分期。结果表明:1)L波段HH极化方式的SAR数据对洪积扇地貌面的粗糙度特征敏感,适合划分莫勒切河地区不同级的洪积扇地貌面;2)在相对平坦的干旱-半干旱地区,SAR数据的后向散射系数主要表征地表的粗糙度,利用后向散射系数可对洪积扇地貌面进行大范围定量分期;3)SAR数据的后向散射系数为划分不同级的洪积扇地貌面提供了一种定量参考指标,可减少因洪积扇地貌面的空间分布不连续导致的地貌面分期误差。Alluvial fans are the most common landforms in arid and semi-arid regions,which record important information on tectonic and climatic changes,and provide a reference to the Quaternary tectonic activity,paleogeographical environment,and geomorphic evolution.However,there is a lack of reliable quantitative methods for the classification of regional alluvial fan topography.Surface roughness is a terrain parameter that has been supposed to be an inherent property of alluvial fan topography.The smooth of the alluvial fan surface is a gradual,continuous and internal geomorphological process from bar-swale high relief of younger and rough surface to small relief of older and smooth surface over time.Alluvial fan surface roughness declines with the age of abandoned alluvial fan units,indicating that the surface roughness could be used as a parameter to determine the sequence of alluvial fan units.In semi-arid and arid conditions,the subdivision sequence of alluvial fan units is regularly distinguished according to specific qualitative and quantitative techniques.The traditional field mapping provides relatively high levels of accuracy,but it is labor-intensive,time-consuming and applicable for small-scale areas.Aerial or spaceborne optical image quantitative mapping will be limited to the light,weather and the resolution of the image.The infrared and thermal infrared image quantitative mapping is susceptible to the parent material lithology of alluvial materials.Quantitative mapping requires more accuracy and high-resolution data for digital terrain data,which will be timeconsuming and expensive when applied to large and remote locations.In-situ cosmogenic radionuclide method should consider the time and expensive sample testing cost of applying alluvial fan unit mapping.Meanwhile,the uncertainty of the analysis,as well as samples collecting issues and the lack of appropriate dating materials can also limit the application of dating methods to the semi-arid and arid areas.Synthetic Aperture Radar(SAR),an initiative micro

关 键 词：ALOS PALSAR 莫勒切河 洪积扇地貌面 后向散射系数 定量分期 

分 类 号：P315.2[天文地球—地震学]