Remote Sensing Discriminating Technology of Geohazard, Loess Platean, in the Baoji Ctiy, Shaanxi Province

摘要

Lying in the southwest side of Loess plateau, Baoji City locates in the intersection part of three structural units, that is, Qinling tectonic zone, Helan-Liupan tectonic zone and North China block. Wei River graben runs through the region. which is one of the known areas where active neotectonic movements is intense, avalanche, landslide and debris flow take place frequently. RS and GIS spatial analysis, 3D visualization of high-special interpretation of remote sensing and fieldwork geological survey are mostly used in the article. Form the role of RS, GIS and 3D Technique in landslide study, interpretability, causative condition that influence landslide identification, accuracy assessment and RS data source selection et. al. The author chose SPOT-5 multi-band remote sensing data as information source, via projection transformation, geometric rectification, information fusion, ortho-rectification, digital mosaic and image enhancement, got the color composite image whose spatial resolution is 2.5m, registered it with corresponding scale map, geological map and DEM data, analyzed the overlay of remote sensing image and DEM data, greatly improved the interpretability and precision of geohazards by using the realistic scenes offered by 3D image visualization, and passed the special interpretation of remote sensing.In the article, the remote sensing identified technique for avalanche, landslide and debris flow in this area are emphasized.The remote sensing discriminatory mark of avalanche, landslide and debris flow in fieldwork are defined, the geohazards (avalanche, landslide and debris flow)are interpreted in detail, the remote sensing image features of types of the geohazards are concluded, six points that influence the interpretation of remote sensing in this area should be worthy of attention and the solution for the interpretation that are wrong or missing detection are put forward. The accuracy evaluation of interpretation of remote sensing is based on the remote sensing data sources and accuracy of interpretation made by the professional. Through fieldwork geological survey, it is proved that the accuracy of interpretation reaches 73.93%. It is made sure that the geohazard sites (avalanche, landslide and debris flow)of interpretation reach 731 in this area, including 678 sites of avalanche, 29 sites of landslide and 24 sites of debris flow. According to regional geography and geo-environmental characteristics, the avalanche, landslide and debris flow Geohazards are mainly controlled by landforms, neotectonics and lithology in the region. All the information offers the basic data for the risk assessment and accuracy evaluation of geohazards.