一种新的坡位定量描述方法及其与滑坡发生的关系

A New Quantitative Description Method for Slope Position and Its Relationship with Landslides

滑坡发生与地形因子的关系是区域滑坡静态规律研究的重点,但以往的研究多注重考虑其与反映几何形态的基本地形属性因子(几何形态属性因子)之间的关系,如坡度和坡向等。首先提出一种新的基于子流域内相对位置定量描述坡位(相对位置因子)的方法,并以温州地区瓯江流域1990～2001年发生的滑坡为研究对象,使用证据权法对比滑坡发生与两种不同类型地形因子之间的关系。结果表明,相对位置因子与滑坡发生的相关性大于滑坡危险性评价经常使用的几何形态属性因子;并且滑坡大多发生在定量坡位值较低的区域,这些地区处在下游,遭受流水侵蚀的强度更大、频率更高。

Relationship between landslide and topographical factors is one of the focuses of study the law of regional landslide ; however , previous research mostly focused on its relationship with factors reflected terrain geometry form（Geometry Attribute Factor）. Generally,there are two kinds of methods for describing topographical factors. Taking the slope position as an example,and it can be depicted by classifying slope position according to geometry attribute factors;and it can also be depicted by some kind of index calculated according to regional relative location information（Relative Position Factors）. This paper first proposes a new method to depict slope position quantitatively based on Height Above the Nearest Drainage （HAND）. HAND is defined as the elevation difference between a point and corresponding outlet through the point which drop the water into the river. And the quantitative slope position is the ratio between the point＇s HAND value and maximum elevation difference within the sub basin. The another research is to examine the relationship between landslides and two different types of topographical factors named geometry attribute factors and relative position factors. The research area is located in Ou River in Wenzhou area and the landslides occurred during 1990-2001. The relationship is calculated by the weights of evidence method, which is a good candidate for calculating the landslides and some single topographical factor. The results show that higher correlation exits between relative position factors and landslide than geometry attribute factors which are common used in the risk evaluation of landslide, which indicate that the regional relative position information is more related to the landslide than the simple basic terrain geometry information, and most of the landslides oecurred in relatively-low-HAND region in the watershed, which is suffering from water rushing with greater intensity and more frequency.