Typhoon District Village Residential Land Geological Risk Assessment

The risks of geological disasters represent the loss that geological disasters may cause damage to human. It reflects the probability of occurrence of geological hazard, damage and loss, which is a comprehensive reflection of geological disasters concerned with the natural and the socio-economic attributes.Sanshui District, Guangdong Province, has some problems of poor engineering geological conditions of the mountain, rich rainfall, frequent typhoons, continual heavy rain frequently. The villagers living here cut slope housing more common and easy to cause geological disasters, houses damage, roads block and so on, which is a serious threat to life, property and safety of the villagers. The paper proposed scientific and reasonable management proposals to avoid and mitigate geological hazards by means of geological disaster risk assessment and prediction on the Southwest Town, Sanshui District.The paper in-depth analyzed the geological formation conditions and causes of disaster induced by the rainfall, constructed the system of integrated assessment of geological hazards risks through investigating the local geological conditions based on the Southwest Town, Sanshui District. As a result, it put forward scientific and reasonable proposals on the basis of adopting and applying the fuzzy comprehensive evaluation method, analytic hierarchy process (AHP), information superposition method and method of expertise. The main research contents and results are listed as follows:1. Analysis the geological hazards and their formation conditions based on detailed investigation the geological conditions on the Southwest Town, Sanshui District. This paper analyzed the natural environment in the studied area, including geographical location, climate, hydrology, geomorphology, lithology, geological structure, hydrogeology, human activities, etc.. Then, it concluded that the main type of geological disasters in the study area was landslides, avalanches, debris flow; the study area have a small scale, mass, abrupt and other characters. steep slopes, slope poor physical and mechanical properties. Artificial slope, housing, typhoons and rainstorms, damage to vegetation are the major factors inducing geological disasters. This Paper analyzed the geological formation of the conditions and causes of disasters from the internal factors and external factors.2. The hazard assessment of geological disasters on the Southwest Town. On the basis of full consideration of the existing method and the specific conditions, the paper established the evaluation system for the area-studied by comparison. First, the selection of the evaluation indexes, such that the selection of 12 indexes, including lithology, geological structure, soil structure, slope gradient, slope elevation, vegetation coverage, the exposed situation of groundwater, rainfall intensity, wind load effects, human engineering activities, scale of the disaster, against objects, is for the collapse, landslide. And the selection of 11 indexes, including longitudinal slope of channel bed, upstream catchment area, channel bed elevation, maximum flow rate, lithology, average slope gradient, vegetation coverage, rainfall intensity, human engineering activities, disaster scale, against objects, is for the debris flow. Then, the paper determined the weights of evaluation indexes through AHP after the classification and quantification of each index. Finally, it obtained the hazard level of different disaster points through the application of the fuzzy comprehensive evaluation method for the risk assessment of geological disasters.3. The vulnerability assessment of geological disasters on the Southwest Town. Combined with the specific circumstances of the area-studied, the paper established the assessment system. First, it selected the number of threat, real estate, land, roads as the evaluation index. Then, based on the grading and quantifying of each index, it determined the weight of each index by AHP. Finally, it got the vulnerability level of different disaster points through the application of information superposition for the vulnerability assessment of geological disasters.4. The risk assessment of geological disasters on the Southwest Town. The paper determined the risk level of different geological disaster points by means of application of the risk assessment matrix to superpose the two assessments based on the comprehensive analysis of the results of the hazard and vulnerability assessment of geological disasters, the results can be concluded that there are eight points in the risk of high-risk disaster, eight points in the risk of disasters, five points of low-risk disaster, which is consistent with the results of qualitative risk analysis, and verified the correctness of the evaluation system.