Research On WebGIS Based Landslide Early Warning Information System Of The Three Gorges Reservoir Area

Landslide is an important disarster among all the geological disarsters, and is also one of the nature disarsters which happens frequently and makes the greatest impact to the human society and their living environment. The landslides in the Three Gorges reservoir area are with large amount and area, and it is quite difficult to conduct a comprehensive treatment in a short period. In order to reduce or even avoid all the adverse impact caused by the landslide, we must make landslide prevention by using science methods, and it is an important work to give a timely and effective early warning before the landslide really happens.Combining with the project"Software development and database construction of the monitoring and early warning information system for the high slope in the Three Gorges reservoir area", this paper develops its research. By doing the research on the theories, technologies and methods related to WebGIS and landslide forecast, and exploring the technical route and method which combines WebGIS technology and various landslide time and spatial forecast models together for landslide early waring, this paper develops the WebGIS based landslide early warning information system of the Three Gorges reservoir area.First of all, this paper makes a research on the theories and technologies related to WebGIS, including the basic principles, realization methods, technical features and functions of WebGIS, the technical contents, advantages, main realization methods and its WebGIS applications of AJAX, and the architecture and characteristics of ArcGIS Server. Besides this paper has a full discussion about the AJAX based Callback methods in ArcGIS Server ADF framework.Second, this paper makes an introduction of the landslide stability analysis method, and gives a disussion of several classic landslide displacement forecast models and time forecast models, including the Grey Model and Time Sequence Model for mid-long-term forecast, and the Verhulst Model, Saito Model and Synergetic Model for short-temp-term forecast. Considering when using various models for landslide forecast there will be various forecast results, this paper proposes a method for forecast results integration.Based on the research of the theories, technologies and methods related to WebGIS and landslide forecast, this paper develops the WebGIS based landslide early warning information system of the Three Gorges reservoir area by using ArcGIS Server as the development platform. The system consists of three function modules: the GIS function module, the forecast-analyzing module and the evaluation-publication module, and these three function modules are designed to meet the users'needs for landslide information accessing, processing and publication.Finally, the paper chooses three typical landslide cases in the Three Gorges reservoir area: the Xintan landslide, the Jimingsi landslide and the Lianzi Cliff dangerous rock body, and tests the system by applying in these three cases. The test results demonstrate the applicability of the landslide time and spatial forecast models used in the system, and also indicate that the system has a good practicality in real landslide forecast work.