基于遥感与可拓层次分析的水盐时空分异特征研究

Spatial-temporal Distribution of Water and Salt Based on Remote Sensing and Extension Analytic Hierarchy Process

为深入了解干旱绿洲规模化节水治盐后区域尺度水盐时空分异特征,有效控制盐渍化,以焉耆盆地为研究区,选取2000、2005、2015、2020年长时序LandSat遥感影像和地表含盐量、土壤含盐量、地表灌水量、地下水埋深及矿化度等指标,借助ENVI和ArcGIS软件,获取各指标的时空分布栅格图件,将各栅格图件进行标准化处理,按照可拓层次分析法权重进行空间嵌套并叠加,定量化揭示区域尺度水盐时空分异进程。结果表明:研究区盐渍化经历了2000—2005年扩张、2005—2015年显著减少、2015—2020年趋于稳定3个阶段,从发展趋势看,研究区盐渍化处于减轻并趋于稳定态势;盐渍化严重的区域主要是博斯腾湖滨;由可拓层次分析法得出各指标因子权重由大到小依次为:地下水埋深(0.325)、地下水矿化度(0.282)、土壤含盐量(0.198)、地表含盐量(0.184)、地表灌水量(0.031),可见,地下水埋深和矿化度是影响区域水盐时空分异的主要驱动因素。研究为焉耆盆地控制盐渍化提供理论依据,同时为定量化揭示区域尺度水盐时空分异进程提供一种新的方法。

The key to effectively control salinization is to deeply understand the spatial-temporal distribution of water and salt at the regional scale after large-scale water-saving and salt control in arid oasis.Yanqi Basin in northwest Xinjiang of China was selected as the research area.LandSat remote sensing and field sampling water and salt data were used to analyze the water and salt migration and accumulation process after large-scale water-saving under changing environment.A total of five indicators,including surface salinity,soil salinity,groundwater salinity,surface irrigation,and groundwater depth were selected in 2000,2005,2015 and 2020.The weights of each indicator factor were determined by extension analytic hierarchy process.With the help of ENVI and ArcGIS software,spatial distribution raster maps of each indicator factor were obtained,and each raster map was standardized,the space was nested and superimposed according to the weight of each index factor,so as to get the spatial-temporal distribution of water and salt in the regional scale.The results showed that the salinization in the study area experienced three stages:expansion in 2000—2005,shrinkage in 2005—2015 and stabilization in 2015—2020.The areas with serious salinization were mainly along Bostan Lake,especially Bohu County in the west and Heshuo County in the north of Bostan Lake.Overall,the area of mild saline land was the largest,accounting for 6.17%~11.39%,followed by moderate saline land,accounting for 3.08%~10.65%,the area of heavy saline land was the smallest,accounting for 0.56%~1.10%during 2000—2020;the weight of each factor affecting the spatial-temporal differentiation process of water and salt on a regional scale was ranked as follows:groundwater depth(0.325),groundwater salinity(0.282),soil salinity(0.198),surface salinity(0.184),and surface irrigation(0.031).Groundwater depth and groundwater salinity were the main driving factors affecting the spatial-temporal differentiation of water and salt at regional scales.From the interpreted salinization development trend,the salinization in the study area was alleviated and tended to be stable.