GIS支持下的东川区泥石流危险度区划

GIS-based Criticality Zoning of Debris Flows in the Dongchuan District

在建立东川区泥石流信息系统的基础上,根据泥石流形成原因,初步选择面积、相对切割度、主沟沟床比降、相对高差、主沟长度、圆状率作为评价指标,利用东川区21条典型泥石流沟的数据,通过主成分分析,选择出面积、圆状率、相对高差三个指标,由主成分载荷得到危险度评价公式,在ARC/INFO和ARCVIEW软件的支持下,把东川区划分为60个评价单元,计算出各个单元内的危险度总分值,依据分值划分为四个级别,重度危险区、危险区、轻度危险区和基本无危险区,最后根据泥石流危险度区划原则,得到东川区泥石流危险度区划图。

Dongchuan District is located Kunming City, Yunnan province in southwest China, under it there are 154 administrative villages in 4 towns and 10 townships, and the population is 279000. In the district rock slides and debris flows occur frequently because the Xiaojiang deep fault zone extends through most of Dongchuan District from south to north and the natural vegetation is seriously destroyed due to the rapid economic development including road building, mining, farming on steep-sloped lands, etc. since recent years. According to on-the-spot investigation and the available data and images, it is recognized that there are 95 debris flow gullies and more than 1 000 slope debris flow sites in Dongchuan District. Based on the formation causes of debris flows and developing the debris flow information system about Dongchuan District, in this paper the factors of gullyareas, relative dissected depth and density, gradient and length of the main gullies, relative height difference, and ratio of gully perimeter and length are preliminarily selected to be as the evaluation indexes. By using the data of 21 debris flow gullies, three indexes, i.e., the gully area, ratio of gully perimeter and length and relative height difference are selected using principal analysis model. Dongchuan District is divided into 60 debris flow evaluation units under the support of ARC/INFO and ARCVIEW software, and the total scoring values of the criticality of all the units are calculated. According to the model of principal analysis, a dangerous zoning formula is derived. After summarizing the total dangerous value of each unit, four dangerous zones are derived, they are the seriously dangerous area, dangerous area, less dangerous area and slight dangerous area. At last, a zoning map of the criticality of debris flows in Dongchuan District is charted.