Lahar Risk Division Research Of Changbai Mountain Region Based On RS And GIS

Obvious disturbance of Changbai Mountain volcano appeared in2002-2005andshowed on increase of the volcanic eruption risk gradually. There is a crater lake onthe top of Changbai Mountain, named Tianchi Lake，that contains2.04billion m3water. Once the volcano erupts again, causing collapse of Tianchi lake, triggered laharwould be one of the most major volcanic disasters.At present, the study of lahar deposition was also limited to just consider severalmajor influence factors only. Our research selected2hierarchies containing9majorinfluence factors of lahar deposition. Using Changbai Mountain region lahardistribution influence as evaluation target, the geological conditions, topography andvegetation were taken as the first hierarchy of evaluation factors, and the stratigraphicage, lithology, weathering degree, accumulation thickness, elevation, relative height,longitudinal gradient, vegetation type and vegetation coverage were taken as thesecond hierarchy of evaluation factors.Stratigraphic age, lithology, weathering degree and accumulation thickness wereacquired through1:200,000and1:250,000geological maps and appropriate fieldinvestigation GIS was used for zoning of these factors.3D DEM model was built byexsisting elevation data,1:50,000,1:2000,000,1:250,000topographic maps andsatellite images to calculate the elevation, relative height and longitudinal gradientthrough GIS software. Vegetation type and vegetation coverage was extracted throughremote sensing interpretation by ENVI software. The remote sensing data includeaeropholographs, false color synthesis image, TM, etc. Each influence factor wasdivided into four levels, i.e. the levels of biggest influence, bigger influence, mediuminfluence and slight influence respectively according to a certain influence divisionstandard. The subjective and objective weights were obtained respectively by theiteration method-based multi-expert determination and rough set. Synthesis weightswere acquired by combining subjective and objective weights. The risk level divisionmap of Changbai Mountain region was eventually obtained through superpositionanalysis by GIS software according to the synthesis weights of9influence factors.0Lahar risk zoning improves the ability of lahar disaster prediction and preventionin the Changbai Mountain region obviously. It is also helpful to reasonable overallarrangement of tourist resources development areas, healthy economic construction,land use and environmental protection of Changbai Mountain region. Lahar riskdivision of Changbai Mountain region would provide a reference to the correspondingwork in other volcanic regions.