Thematic Information Extraction Of Geological Disaster Supported By Multi-source Data

The Ms8.0 Wenchuan Earthquake on May 12, 2008 made numerous geological disasters. Quick, precise and reliable information detection of earthquake-driven geological hazards is crucial for disaster reduction and emergency management to alleviate life losses and properties. But it is a vast and time-consuming job to finish field survey or get info from high-resolution RS images, also it spends quite much, and the interpretation can only be used for a small part of whole region. On the contrary, medium resolution RS images are easier to get, lower cost and lager overlay. So it acts as an important data source in thematic information extraction of geological disasters. But in recent rare is the study on extracting thematic of geological disasters information from medium-resolution RS images, and less is the effect of topography to be considered.Application of decision tree idea, this study firstly gets a flow direction addressing that derived from hydrology principles, taking a case of geological disasters (collapse, landside) from the study area. Based on multiple data, this paper provides specific AML code.Then, selecting many impact factors of geological disasters, the thesis builds an assessment of geological disasters, in thought of grid modeling to evaluate the geological disasters of the study area. According to the extraction results which had been calibrated, the precision reach 61.20%.The main results can be summarized as follows. Firstly, the method works well for extracting thematic of geological disasters information from medium- resolution RS images. By means of multi-sources information fusion, it also contributes an effective way to extract thematic information. And the precision is 14% more than Maximum Likelihood method. Secondly, the results of accuracy assessment indicates that geological disasters took place mainly along the main stream of Minjiang river from Yingxiu to Yanmen Town, where it joins its branches Shaotang River and Caopo River both running from west to east. The disaster is heavier which distributes along G213, G317 and S303 road from north side to west in Yingxiu. The disaster in Yinxing, and Miansi was worse to Sanjiang, Shuimo and Xuankou in study area. And high risk area took up a high proportion reaching 48.06% while low risk area took up only 3%, the accuracy is 61.20%. So the result is dependable and this method is effective.As the area of geological disasters is large, in recent time post seismic geological disasters could still occur frequently, we should persist on natural avoidance, and help with artificial prevention, take comprehensive treatment to the geological disasters points along the traffic and the residential area, consider a partial relocation in high-risk areas of geological disasters, to select security zone, avoid high-risk areas of geological disasters, reduce the influence of human activities and avoid loss of property and lives.