基于GIS空间分析技术的新月形沙丘表面输沙率模型研究

A Sand Flux Model for the Surface of Barchan Dunes Using GIS-based Spatial Analysis

输沙率研究是风沙物理学与风沙工程学的重要内容。为了尝试GIS空间分析技术在新月形沙丘表面不同部位输沙率分布及模型建立中的应用,选取塔克拉玛干沙漠腹地典型孤立新月形沙丘,对其表面进行粒度采样和风速采样,并对沙丘表面的五个典型部位进行输沙率的采集。经过对风速数据归一化处理之后,根据粒度和风速采样特点,分别应用克里格方法和反距离方法对粒度和风速样点插值,得到新月形沙丘表面栅格形式的粒径分布和风速分布图。利用3种常用输沙率模型分别对沙丘表面5个典型部位进行输沙率计算,并与实测值进行对比。选取拟合优度最佳的Srensen模型,整合粒径和风速分布图,利用地图代数方法对沙丘表面输沙率分布进行计算,得到栅格形式的沙丘表面输沙率分布图。利用GIS的空间分析技术研究沙丘表面的输沙率分布,克服了传统定点观测的诸多不足。

Research on sand flux is an important component of blown sand physics and engineering.In the present study,we used GIS-based spatial analysis to calculate the distribution of sand flux above the surface of a barchan dune and to develop a sand flux model.We sampled the diameters of sand grains and wind velocity above the surface of a barchan dune in the Taklimakan Desert,then observed sand flux at five positions above the dune.Data of sand grain diameters and wind velocity were interpolated by means of the Kriging and the Inverse Distance Weighting methods,respectively.The analysis produced graphs of the distribution of sand grain diameters and wind velocity above the barchan dune.The sand fluxes at five positions were calculated by means of the three common sand flux models,and the results were compared with the observed values.The Srensen sand flux model has an optimal fitting,it was used to integrate the data on sand grain diameters and wind velocity so as to compute sand flux above the surface of the barchan dune.Based on this analysis,we obtained the total sand flux above the surface of the barchan dune.This approach has overcome some deficiencies of traditional fixed position observation method.