Study On Geo-hazards Risk Evaluation Based On GIS And AHP

In this paper,relied on the Chinese Geological Survey Project：the Geological DisastersSurvey in Yaozhou District of Tongchuan City in Shaanxi Province.Under the premise of theextensive collection of previous research data and theoretical results,based on geologicalenvironmental background of the study area,using the analytic hierarchy process to establishthe analytic hierarchy process model from the analysis of geological hazards and theircharacteristics and distribution of judgment matrix to determine the indicators of the variouslayers of the weight of a layer of indicators,and construct a mathematical model andcomprehensive evaluation model for risk assessment of the evaluation unit,a single hazard（landslides, avalanches or unstable slopes）.Finally,based on the calculation and analysiscapabilities of GIS space to make the evaluation results of geological hazard in the study areaThrough this research,and ultimately achieve the following results:1In the study area,the total number of landslides, avalanches and unstable slopes is361,which120landslide accounts for33.24%of the total number;66collapseaccounts for18.28%;175unstable slopes accounts for48.48%of the total number.2The factors that affect the risk of geological disasters in the study area can be dividedinto disasters for geological environmental conditions, predisposing factors andhazard-affected bodies, including disaster density, slope indicator, slope height index,slope-type indicators. rock and soil types, vegetation index, rainfall index, human activities,population density, engineering facilities and land type, a total of eleven indicators. The sameindicator at different times has different degree of influence of the body of a disaster, and evenfor the same disaster., the dominant factor affecting its stability is not the same at differenttimes;3The distribution of geological disasters in time and space both showed significantregularity. Mainly in terms of time as follows: the relative concentration of the LatePleistocene and early Holocene; relatively concentrated in a strong period of human activity;relatively concentrated in the rainy season in July to September; Performance in space: theriver valley on both sides banded distribution; controled by topography and vegetation;combination of parts in slippery or collapse strata relatively concentrated;4In this paper the study area was divided into high-risk areas, risk areas and low-riskzone. Geological disasters in high-risk areas are mainly distributed in the central Ju River Watershed,the eastern Qishuihe basin and the the Xichuanhe basin, its area is about308.28km2, accounting for19.00%of the study area; The danger zone are in the central LoessGully area, the northern mountainous and southeast Sunyuan town, loess Sichuan highland itsarea is about792.13km2, accounting for48.84%of the study area; Low-risk areas are mainlydistributed the bedrock mountain and the surface of the loess plateau in the study area, itsarea is about521.59km2, accounting for32.16%of the study area.