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Abstract:
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In Vietnam karst caused land subsidence is serious problem, especially when it is occurring in limestone rocks covered by upper soil layer with the thickness of 30-40m. The deformation of the ground is dominantly resulted in colapsed depression or hole with circle shape on the ground surface. The diameters vary from 2 to 5m, reaching upto 5-10m in some places. Although funnel type of the subsidence is less common, it has widely impacting diameter. The main factors causing this type of hazard are the water table drawdown due to drought and groundwater overextraction, mining exploitation…. This paper studies the land subsidence hazard related to karst topography in some areas in Vietnam and suggests the preventive measures for reducing this type of disaster. The preventive solutions are relocating population from dangerous areas, strictly control the exploitation regulations and procedures, maintaining rational water use in the regions of karst topography. The question how to improve kart surveying is also disscused. |