中国历史山洪灾害分布特征研究

Distribution Characteristics of Historical Mountain Flood in China

中国山洪灾害发生频繁,区域分布差异性明显且难以预报,关于山洪灾害分布特征的研究对于山洪灾害预警、山洪灾害防治区规划等具有重要意义。本文以历史山洪灾害点为基础数据,以6个一级地貌大区(东部平原低山丘陵大区(Ⅰ)、东南低山丘陵平原大区(Ⅱ)、华北-内蒙东中山高原大区(Ⅲ)、西北高中山盆地高原大区(Ⅳ)、西南中低山高原盆地大区(Ⅴ)、青藏高原高山极高山盆地谷地大区(Ⅵ))为基本分析单元,统计对比不同地貌区域内山洪灾害数目、密度,并进一步分析山洪灾害随高程、高程标准差以及50年一遇6 h雨量(H6-50)的分布情况,从而获得中国历史山洪灾害的主要分布特征。结果表明:山洪灾害集中分布于东南低山丘陵平原大区及西南中低山高原盆地大区,占全国山洪灾害的60%左右。6 h雨量(H6-50)处于240~280 mm区域山洪灾害密度最大。高程标准差小于30 m区域山洪灾害密度较大。东南低山丘陵平原大区高程处于10~50 m间,高程标准差小于30 m,雨量(H6-50)在150~270 mm间地区山洪灾害密度较大;西南中低山高原盆地大区山洪灾害集中分布于高程600 m以下,高程标准差小于50 m,雨量(H6-50)大于120 mm地区。以地貌区划结果为基本分析单元相对于行政界线而言更有助于分析山洪灾害分布特征。

Mountain flood is difficult to predict and distributes differently. It is one of the major natural disasters in China. Analysis on the distribution characteristics of mountain flood is helpful to disaster prevention. This paper takes historical mountain flood disaster points as based-data and analyzes the relation between disaster points and altitude, rainfall （H6-50）, altitude standard deviation in different geomorphologic zones. Results shows that among the 6 geomorphologic zones, the historical mountain flood disasters mainly distribute in zone II and zone V, nearly 60% of the whole disasters. Also, density of mountain flood disaster reaches its high point with rainfall （H6-50） ranging from 240 to 280 mm, altitude standard smaller than 30 m. With the increase of rainfall （H6-50）, the mountain flood density tends to increase first and then decline, taking 280 mm as a turning point. What＇s more, the mountain flood density reaches its climax with altitude standard smaller than 30 m. In zone I, mountain flood disaster density reaches its high point with rainfall （H6-50） ranging from 240 to 300 mm, altitude from 60 to 120 m, altitude standard smaller than 30 m. For zone II, mountain flood disaster density reaches its high point when rainfall （H6-50） ranging from 150 to 270 mm, altitude from 10 to 50 m, altitude standard smaller than 30 m. Mountain flood disaster in zone V mainly distribute in the area where rainfall （H6- 50） higher than 120 mm, altitude under 600 m, altitude standard smaller than 50 m. It is clear that taking the geomorphologic zoning as an analysis unit is much better than administrative boundary.