Soil salinization has become a serious global problem,which poses a grave threat to ecological environment and agricultural production.In order to assess the effect of soil salinization on ecological environment quickly and accurately in regional-scale,a new remote sensing ecological index was proposed to detect the ecological change in arid area based on the remote sensing method in this paper.Manas river basin,a typical arid inland basin in northwest of China,was selected for the study area.Firstly,four indicators (salinity,surface albedo,vegetation coverage and wetness) which closely related to soil salinization were calculated based on the Landsat image in the Manas river basin on August 25,1989,August 7,2000,and September 10,2015.Then,these indicators were normalized using min-max normalization method.Lastly,the principal component analysis (PCA) method was introduced to couple the four indicators,and the soil salinization ecology index (SSEI) was obtained.This method is different from the previous index overlaid by weighting the indexes from remote sensing and other data.It depends on the data itself,instead of subjective human states.The result shows that there is a significant relationship between SSEI and salt content observed in the fields (R2=0.9035,P＜0.01).This indicates SSEI could be used for retrieving the soil salinization on ecological environment rapidly and quantitatively.Through PCA analysis,we found that the first principal component appears stable and its share of all indicators is greater than 85％.The properties of wetness index (WI),normalized difference vegetation index (NDVI),and salinity index (SI) are consistent with the general ecological environmental parameters.The index was applied to the irrigated area of the Manas river basin.Among the bad,comparatively bad,medium,good,excellent grades,the area of bad grade had increased from 491.6 km2 to 1031.4 km2during 1989 to 2000,but it has been decreased from 1031.4 km2to 636.9 km2 during 2000 to 2015.The area of medium grade also increased at first but then reduced.The change area ranges from 6354.3 km2 in 1989 to 2111.4 km2 in 2015.The good and excellent grades of ecological environment has been increased by 12.9％ in the last 26years,which shows the ecology environment has improved in the irrigation area.The spatial distribution of SSEI shows that the desert area without influencing by human activities still keeps a poor level,and the ecological problem is still very serious.The function of artificial oasis has been improving.Assessment of soil salinization ecological environment change using remote sensing technology could provide insight for land resource development in arid areas.%土壤盐渍化已成为全球性问题,给生态环境及农业生产带来严重的威胁.为了快速、准确评价土壤盐渍化给区域生态坏境带来的影响,该文提出了新的完全基于遥感数据的遥感生态指数(SSEI,Soil Salinization Ecology Index)来监测玛纳斯河流域盐渍化灌区生态环境变化.该指数利用主成分分析的方法耦合与土壤盐渍化相关的土壤盐度、地表反照率、植被覆盖度和土壤湿度四大地表参数,指数构建是数据本身性质所决定,不同于以往遥感与非遥感指数加权叠加易受人为影响.研究结果表明:耦合与盐渍化信息相关的各遥感指数得到的生态指数,能够对土壤盐渍化影响区域的生态环境进行快速、定量、客观的监测.将该指数应用到新疆玛纳斯河流域灌区,结果表明在近26年优和良等级生态环境面积增加了12.89％,这说明灌区生态环境有所改善.该研究对土壤盐渍化监测与评价具有一定参考意义.
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