基于多光谱遥感的盐渍化评价指数对宁夏银北灌区土壤盐度预测的适用性分析

An applicability analysis of salinization evaluation index based on multispectral remote sensing to soil salinity prediction in Yinbei irrigation area of Ningxia

土壤盐渍化是影响干旱区土壤健康的重要因素之一,因此快速获取土壤盐度信息、监测土壤盐度变化对干旱区土地资源合理利用和土壤恢复至关重要。本研究选取宁夏平原土壤盐渍化较重的银北灌区为研究区域,以野外采集的52个土壤样本和同时期Landsat8 OLI遥感影像为数据基础,采用相关分析和曲线回归分析法对基于多光谱遥感数据构建的土壤盐渍化评价指数与实测土壤电导率(electrical conductivity,EC)的相关关系和拟合度进行了定量化分析。结果表明:①采样时期研究区土壤盐度较轻,非盐渍化和轻度盐渍化土壤样本合计占比82.68%;②盐度指数与土壤EC的相关性整体高于植被指数,全样本中盐分指数S3(salinity index 3,S_(3))、盐分指数S5(salinity index 5,S_(5))、盐分指数S6(salinity index 6,S_(6))和盐分指数SI(salinity index,SI)与土壤EC的相关性均达到0.50以上;③全样本中与土壤EC拟合度较高的为盐分指数S2(salinity index 2,S_(2)),S_(3),S_(5)和SI,其中S_(5)的表现最好(R^(2)=0.406),不同盐度水平下指数与土壤EC的拟合度随土壤盐度升高而显著增加,中重度盐渍化中指数与土壤EC的拟合度最高的为指数S_(1)(salinity index 1,S_(1))(R^(2)=0.730)和S_(2)(R^(2)=0.724);④拟合模型中,基于Cubic模型、Quadratic模型和S模型计算的评价指数与土壤EC的拟合度较高。本研究分析了多种土壤盐渍化评价指数在银北灌区土壤盐度监测中的适用性,得出的初步结论可为宁夏银北灌区土壤盐度遥感监测提供参考依据。

Soil salinization is one of the important factors that affect the soil health in the arid area,so it is very important to obtain the information of soil salinity and monitor the change of soil salinity for the rational use of land resources and soil restoration in the arid area.Based on 52 soil samples collected in the field and Landsat 8 OLI remote sensing images obtained at the same time,the correlation and curve regression analysis were used to quantitatively analyze the correlation and fitting degree between the soil salinization evaluation index based on multispectral remote sensing data and the measured soil Electrical Conductivity(EC).The results are as follows:①The soil salinity in the study area is relatively light,and the total proportion of non-salinized and slightly salinized soil samples is 82.68%;②The correlation between salinity index and soil EC is higher than that of vegetation index.The correlation between salinity index S_(3)(S_(3)),salinity index S_(5)(S_(5)),salinity index S_(6)(salinity index,S_(6))and salinity index Si(salinity index,SI)is above 0.50;③Salinity indexes S_(2)(S_(2)),S3,S5 and Si have the highest fitting degree with soil EC in the whole sample,among which S5 has the best performance(R^(2)=0.41).The fitting degree of index and soil EC increases significantly with the increase of soil salinity under different salinity levels.The highest fitting degree of salinity index and soil EC is S_(1) (R^(2)=0.73)and S_(2) (R^(2)=0.72);④In the fitting model,the evaluation index and soil EC calculated based on cubic model,quadratic model and S model has a high fitting degree.This study has analyzed the applicability of various soil salinization evaluation indexes in soil salinity monitoring of Yinbei irrigation area,and the preliminary conclusions can provide reference for remote sensing monitoring of soil salinity in Yinbei irrigation area of Ningxia.