小尺度山洪灾害区下垫面特征分析——以官山河流域为例韩

为响应国家加强小区域山洪灾害建设和防范预警要求,给小尺度山洪灾害区域建设和预警提供基础数据支撑,以官山河流域为例,采用地学统计、植被指数计算、面向对象与人机交互解译、空间叠加分析、野外调查等方法,获取流域地形、坡度、植被覆盖度、土地利用类型等下垫面特征,分析潜在受灾村落和人口。结果表明:官山河流域地势中间低、边缘高,最低点为流域出水口,平均历史受灾海拔、坡度分别为415 m和21°;平均植被覆盖度为71%,主要土地利用类型为林(草)地,历史受灾主要在低植被的沿河、沟、道路周边;居民房屋为山洪灾害重点承灾体,占总面积的1%,裸地、坡耕地占总面积的2%;潜在受灾房屋主要集中在官山河、袁家河、吕家河、西河两侧地势低的位置,受灾总人口为8 106人,2 023户。官山河流域出口处的弯曲、窄河段、上下游卡口区条件,不利于快速泄洪,易引发山洪灾害。在强降雨下,裸地、低植被陡坡地易产生山洪,沿河、道路周边低植被覆盖的村落易遭受山洪灾害。官山河流域共有12个村存在潜在受灾威胁,需做好山洪灾害预警和防范建设;五龙庄、大河湾、赵家坪、吕家河、马蹄山、西河、官亭村是山洪灾害防御建设的重点。

Characteristics of Underlying Surface in Small-scale Mountain Flood Disaster Area: Case Study on Guanshan River Basin

The purpose of this study is to offer basic data support for the construction of small-scale mountain flood disaster prevention and early warning in response to national requirements. The Guanshan River drainage basin is taken as a case study. By using multiple approaches including geoscience statistics, vegetation index calculation, object-oriented and human-computer interaction interpretation, spatial superposition analysis, field survey, and etc., the underlying surface characteristics, such as the topography, slope, vegetation coverage, and land use pattern are obtained, and the potentially affected villages and populations are comprehensively analyzed. The Guanshan River Basin is characterized by low middle part and high edges with the lowest point as the basin's outlet. The average historical disaster elevation and slope are 415 m and 21°,respectively. The average vegetation coverage of the Guanshan River Basin is 71%. Most of the basin is covered by forest and grass, and historical disasters mainly happened in less-vegetated area along rivers, ditches and roads. Residential houses as the major disaster-bearing body for mountain flood disasters, account for 1% of the total area; bare land and sloping land account for 2% of the total area. Potential disaster-stricken houses mainly concentrate in the lower positions of Guanshan River, Yuanjia River, Lyujia River and Xihe River, with a total of 8,106 people and 2,023 households affected. The bend, narrow river segment, and upstream and downstream bayonet area at the exit of Guanshan River Basin are not conducive to rapid flood discharge and easily lead to mountain flood disasters. Under heavy rainfall, bare land and steep slope in low-vegetation area are prone to breed mountain flood disaster, while less-vegetated along rivers and roads are subjected to mountain flood disasters. Early warning and prevention work should be strengthened as twelve villages in the Guanshan River Basin are threatened by potential hazards, among which Wulongzhuang, Dahewan, Zhaojiaping, Lyujiahe, Horseshoe Mountain, Xihe and Guanting Village are key points of mountain flood disaster prevention and construction.