黄河三角洲土壤盐分养分空间分异规律研究

Spatial Distribution of Soil Salinity and Nutrients in the Yellow River Delta

以黄河三角洲新生湿地为研究区域,以Landsat-8遥感影像与实测土壤含盐量、总氮、总磷含量为数据基础,引入植被和土壤相关指数,构建反演模型并定量反演新生湿地土壤含盐量、总氮、总磷含量,探讨其空间分布规律。结果表明:土壤含盐量回归模型中,由6个波段地表反射率(B1~B6)和6个光谱指数(RVI、SMI、GVSB、GRABS、ARVI、EVI)共12个因子建立的反演模型最优;总氮含量回归模型中,以B5、B6、SMI、NDVI、MSAVI、GVSB、GRABS、ARVI、EVI、RVI为自变量建立的模型精度最高;总磷含量回归模型中,以7个波段地表反射率(B1~B7)和1个光谱指数(SBI)共8个因子建立的反演模型最优。黄河三角洲新生湿地总氮含量整体上呈现出由河道两侧向外递减,高值区多集中于河道两侧,低值区多为近海滩涂地区;土壤含盐量呈现出由海向陆递减、由河道两侧向外递增的趋势,黄河三角洲新生湿地总磷整体上呈现由海向陆递增、由河道向外递减的趋势,1976—1996年形成的湿地的土壤含盐量和总磷含量整体上明显高于1996年后新生湿地的。河水、地下水和海水复杂的相互作用主导了黄河三角洲湿地盐分的空间分异规律。

The new-born wetland in the Yellow River delta was selected as the research area. The Landsat-8 remote sensing images acquired from USGS and soil salinity,TN and TP obtained by the laboratory test were used as the data source. Vegetation index and soil correlation index were used to build the quantitative inversion model of the soil salinity,total nitrogen and total phosphorus in the wetland. The spatial distribution rules of soil salinity,TN and TP were analyzed in the wetland of the Yellow River delta. The results show that the optimal inversion model of soil salinity is established by using 12 factors as independent variables,including 6 vegetation indices( RVI,SMI,GVSB,GRABS,ARVI and EVI) and 6 bands( B1-B6). The optimal inversion model of TN is established by using 10 factors( B5,B6,SMI,NDVI,MSAVI,GVSB,GRABS,ARVI,EVI and RVI) as independent variables. The optimal inversion model of TP is established by using 8 factors( B1-B7 and SBI) as independent variables. The Yellow River delta wetland of TN shows a trend of decreasing from both sides of the river,and the high value area is mostly concentrated in the two sides of the river and low value area is mostly concentrated in the coastal area near the sea.There is a tendency that the soil salinity decreases from the ocean to the land,increasing from the river to the outside. TP in the Yellow River delta wetland is an increasing trend from the ocean to the land,and the trend is decreasing from the river to the outside. In 1976-1996 on wetland soil salinity content and TP whole freshmen are significantly higher than that of 1996 wetlands. The complex interactions of river water,groundwater and sea water lead to the spatial variation of salinity in the wetland of the Yellow River delta.