降雨引发的兰州黄土滑坡时空规律分析和临界降雨量预测

Characteristics of rainfall-induced loess landslides and their threshold rainfall in Lanzhou

开展降雨型黄土滑坡预警对于区域性防治滑坡具有重要意义。本研究在收集1985~2015年兰州市降雨型黄土滑坡历史数据的基础上,运用反距离权重插值(IDW)和核密度估算(KDE)方法揭示了降雨引发黄土滑坡的时空分布规律。该文基于统计学的基本原理,运用相关性和偏相关性等方法建立适合兰州市的有效降雨量模型。通过拟合有效降雨量与滑坡因子的线性回归关系,确定引发黄土滑坡的临界降雨量阈值,设定兰州市黄土滑坡的降雨量危险性预警等级。研究表明:(1)兰州市黄土滑坡灾害点沿着黄河及其支流沿岸分布,城关区滑坡点最多且呈环形分布,西固区次之,其他地区分布较少;(2)降雨是兰州市及其周边地区黄土滑坡的关键诱因,10d有效降雨量与滑坡因子均呈现显著正相关特性,其相关系数达到0.698;(3)依据10mm、20mm和40mm临界降雨量阈值将预警等级划分为低、中、高3个危险性等级。

The implementation of precipitation-induced loess landslide warning is of great significance for regional landslide prevention.Based on collecting the historical data of loess landslides and precipitation in Lanzhou from 1985 to 2015,the spatial and temporal distribution characteristics of precipitation-induced loess landslides were revealed by inverse distance weight interpolation(IDW)and nuclear density estimation(KDE).Based on the basic principles of statistics,this paper used correlation and partial correlation analysis to establish an effective precipitation model for Lanzhou.By fitting out the linear regression relationship between effective rainfall and landslide factors,the critical precipitation threshold for triggering loess landslide was determined,and the warning level of precipitation-induced loess landslide in Lanzhou was set.The findings of the study included:(1)the loess landslide points were distributed along the Yellow River and its branches,loess landslides in Chengguan district formed a circular distribution,its quantity occupied first,it came in Xigu district and other areas were less;(2)precipitation was the critical cause of loess landslide in Lanzhou and its surrounding areas,the 10 d effective rainfall and landslide factors had significant positive correlation characteristics,and the correlation coefficient reached 0.698.(3)The warning level was divided into three risk levels:low,medium and high according to the critical precipitation thresholds of 10 mm,20 mm and 40 mm.