Red Beds In Western Yunnan Geological Disaster-prone Evaluation

Being the highly frequency and the ponderance of the geological hazards' upgrading, the forecasting, preventing the occuring of the hazards,reducing it's losses have become an urgent problem. Therefore, as the nucleus factor of danger evaluation of geological hazards, evaluation on the susceptibility of geological hazards has turned to be the emphases for the geologic survey work recently."The red bed in western Yunnan" distributs widely in the Lanping-Simao Mesozoic and Neozoic basin regions, western Yunnan Province, and is a typical representative of the red bed system which is mainly made up of the formation including Jura and Cretaceous. It has the special charateristics of the lithology, the rock combination and the unique conditions in western Yunnan"three-river"region, such as terrain, morpthology, hydrogeology, precipitate rain and human activity in these regions make the geological hazards happen frequently, then brought forth to great economic losses.This paper takes "the red bed in western Yunnan" as an example to study red bed system and combines with county(city) geological hazards survey data and regional characters. In the paper, Yongping county is the key study region, since the geological hazards is relatively serious as a typical red bed regions in western Yunnan. Through collecting and analyzing the western regions background information in the red bed in western Yunnan.The systemic fieldwork of geological hazards and the evaluation on the susceptibility of geological hazards in the region was carried on.The following results have been obtained in this research:(1) Through systematic field investigation and laboratory work, it's known that the geological hazards in Yong ping County is more growth,and the main geological hazard types are collapse, landslip and debris flow ,which have the character of the grouped and zonal distribution.(2) In this region, the character of lithology and rock combination are the crucial factors to affect the geological hazards growth extent,but the outside factors such as precipitate rain, the large-scale human engineering activity are also the main controllability factors,which act as different effect in every geological hazard process. (3) Established a suit of AHP-Fuzzy evaluation system to aim at red bed in western Yunnan ,and the concrete evaluation process is listed as follow:1) choosing the primary evaluation indexes according to the different types of hazards and building hiberarchy map.2) using the analytic hierarchy process to count the weight of every evaluation indexes.3) constructing the Fuzzy comprehensive evaluation matrix.4) passing the fuzzy operation, to work out the evaluation result.5) putting the evaluation result into computer, and using the spatial analysis function of the software MapGIS to create automatically the susceptibility of geological hazards regional map.6) analyzed the evaluation result.(4) Applied the evaluation system, the systemic analysis to the geological hazards in Yong ping County is carried on,And through making an evaluation result contrastive analysis between the AHP-Fuzzy menthod and traditional Information Content method,the results are approximately same. It's showed that the evaluation system is feasible, the evaluation model is reasonable.It has better practicability, maneuverability and promotional applying value in red bed in western Yunnan.(5) The AHP-Fuzzy synthesis evaluation system is mainly directed against the red bed in western Yunnan,which remedies effectively the regional-difference in traditional method,and achieves the organic combination of qualitative analysis and quantitative analysis; The abundant account in the evaluation process is completed by procedure, realizes the convenience and shortcut; The evaluation map on the susceptibility of geological hazards is protracted automatically by using the spatial analysis function of MAPGIS and SUFFER software.The result is direct-viewing and easy to understand, which can provide scientific basis for better preventing and reducing hazards work.(6) The evaluation result shows that the susceptibility zone of red bed geological hazards in Yong-ping County is:extremely-high susceptibility region (I),high susceptibility(II₁,II₂)mostly distrubuts Daoliu and Yinjiang river basin of Shan-yang,Yong-he,and Shui-xie towns in the middle-southern of Yong-ping Count.The other high susceptibility region(II₃) distributes Bei-dou,Long-men,and Long-jie towns in the north-eastern of Yong ping County .One middle susceptibility region is distributed in Long-men westward to Laojie westward to Qu-dong towns,which is ribbon region.And the other middle region is Dahuangshan hill in the south of Bei-dou town. The evaluation result provides direct basis for the prevention and cure and program of the geological hazards in this region.