基于GIS考虑准动态湿度指数的滑坡危险性预测水文–力学耦合模型研究

RESEARCH ON HYDROLOGY-MECHANICS COUPLING MODEL OF LANDSLIDE HAZARDS PREDICTION BASE ON GIS BY USING QUASI-DYNAMIC WETNESS INDEX

降雨在区域浅层滑坡灾害危险性预测研究中起着关键作用。为综合斜坡地形因素和由降雨引起的地表水下渗、地下水径流对斜坡稳定性的影响,结合基于物理过程的无限斜坡模型和基于数字高程模型DEM的简化运动波模型,提出考虑准动态湿度指数的滑坡危险性预测水文–力学耦合模型。该模型基于地理信息系统GIS平台,采用矢量–栅格复合单元对斜坡进行危险性分析(即以斜坡单元为基本研究对象,用栅格数据进行单个斜坡单元稳定性分析)。首先,基于极限平衡理论推导无限斜坡模型;然后,在考虑降雨强度以及持续时间的情况下应用简化的运动波模型计算降雨入渗和地下水径流作用过程中的地形准动态湿度指数,得到滑坡土体饱和因子在时间和空间上的分布情况,并在此基础上实现水文模型与无限斜坡模型的耦合;最后,以三峡库区巴东新城区滑坡灾害危险性预测为例,验证模型在区域浅层滑坡灾害危险性预测中具有较高的精度。

Rainfall plays a key role in the regional shallow landslide hazards prediction. Considering quasi-dynamic wetness index,a hydrology-mechanical coupling model in landslide hazards prediction is proposed. It has combined the physical processes of the infinite slope model and simplified kinematic wave model based on digital elevation model(DEM),and considered the comprehensive effect of topography and surface water infiltration and groundwater run out converted from rainfall to landslide stability. Based on geographic information system(GIS), vector-raster coupled data is used in the slope unit hazard prediction(taking slope unit as basic study object,and using raster data to analyze the slope units' stability). Firstly,it deduces and modifies the infinite slope model by limit equilibrium theory. Then,considering the rainfall intensity and duration,it calculates quasi-dynamic wetness index during rainfall infiltration and groundwater run out by simplified kinematic wave model,and the time and spatial distribution of landslide saturation factor are obtained. The hydrology model and infinite slope model is coupled on this basis. Finally,it approves the high accuracy of this model in regional shallow landslide hazard prediction by the example study in new Badong County.