四川省不同类型山洪灾害与主要影响因素的关系

以四川省为例,在明确溪河洪水及其引发的滑坡、泥石流三类山洪灾害分布格局的基础上,构建概念模型,分析降雨、地形、人口资产易损性等引发山洪灾害的基本因子和土壤、河网密度、土地利用等一般因子对不同类型山洪灾害的影响程度,并比较它们的异同。结果表明:(1)四川省山洪灾害主要分布在盆周山区、川西高原和横断山脉一带;(2)如果3项基本因子可以解释山洪灾害空间分布100%的变化,则它们对三类灾害的影响程度分别为:溪河洪水,降雨59%、地形28%、人口资产13%;泥石流,降雨15%、地形73%、人口资产12%;滑坡,降雨48%、地形34%、人口资产18%;(3)总体上,泥石流灾害对地形、岩性、土地利用等下垫面因子的依赖更高,而溪河洪水和滑坡灾害受降雨要素的影响更大。

RELATIONSHIPS BETWEEN DIFFERENT TYPES OF FLASH FLOOD DISASTERS AND THEIR MAIN IMPACT FACTORS IN THE SICHUAN PROVINCE

The flash flood disasters of mountain torrent,landslide and debris flow are common in mountainous areas of China.Though the developmental background of the three types of disasters are similar to some extent,the concrete impact factors of them are different.Previous studies paid great attentions on effects of specific factors on these disasters,but the quantitative relationships of different impact factors to the three types of disasters in comprehensive analysis remain unclear.As a result,the weights of impact factors were hard to design impersonally in risk or hazard assessment of corresponding disasters.Accordingly,taking the Sichuan province as an example,a conceptual model was constructed to evaluate the impacts of basic factors,e.g.,rainfall,landforms and population-property vulnerability,and general factors on different types of flash flood disasters based on making clear the distributed pattern of disasters of mountain torrents and corresponding landsides and debris flows.The results show that:1) the flash flood disasters in Sichuan Province mainly distributed in the mountainous and plateau areas around the Sichuan basin and part of the Hengduan mountainous area,in which the mountain torrent disasters mainly developed in the northeastern and southern mountainous areas around the Sichuan basin;landslide disasters located mostly in the western and southwest mountainous areas around the Sichuan basin;and the debris flow disasters mainly distributed in the western and southwest mountainous and plateau areas around the Sichuan basin and part of the Hengduan mountainous area.2) If 100% variation of flash flood disasters on distribution was assumed to be decided by the rainfall,landforms and population-property vulnerability,the impact degrees of the three basic factors to the different types of disasters are:for the mountain torrent disasters,59%,28%,13%;for the landslide disasters,48%,34%,18%;for the debris flow disasters,15%,73%,12%.The factors of rainfall and landforms both play the most important roles in developing and distribution of the local flash flood disasters.3) Besides the three basic factors,the soil is the most important factors to the development of disasters of mountain torrent and landside,and the factor of lithology is critical to the distribution of debris flow disasters.Generally,the underlying surface condition plays a more important role on the distribution of debris flow disasters,while the rainfall condition is more critical to the disasters of mountain torrent and landslide.