基于微波与光学遥感的石漠化地区r土壤剖面含水率反演模型研究

摘要

土壤水是全球生态系统的重要组成部分,定量遥感估测喀斯特石漠化地区土壤含水率,可为石漠化治理和生态恢复工作提供基础数据和理论支撑.通过Sentinel-1A和Landsat 8影像数据,运用水云模型提取灌木林地和疏林地的土壤后向散射系数,并计算旱地与有林地的TVDI.并结合实测数据,利用拟合分析对不同深度土壤含水率进行建模,从而对土壤含水率进行反演.结果表明VH极化二次曲线模型和VH极化三次曲线模型分别适用于灌木林地0～5 cm和5～10 cm深度的土壤含水率反演,其R2和RMSE分别为0.87、0.87和4.57％、4.29％.疏林地0～5 cm和5～10 cm深度土壤含水率反演宜选用VH极化指数回归模型和VH极化下的线性回归模型,各模型的R2与RMSE分别为0.736、0.72和9.77％、11.28％.三次曲线模型和Logistic回归模型分别适用于旱地和有林地的土壤含水率的反演,各模型的R2与RMSE在0～5 cm深度分别为0.85、0.69和2.88％、4.02％,在5～10 cm分别为0.76、0.23和3.5％、6.37％.%Soil water is an important component of the global ecosystem.Quantitative remote sensing es-timation of soil water content in Karst Rocky Desertification Area can provide basic data and theoretical support for rocky desertification control and ecological restoration.It also provides guidance for agricul-tural activities in Rocky Desertification Areas.Based on Sentinel-1A and Landsat 8 image data, the backscatter coefficients of shrub land and sparse woodland were extracted by using water cloud model, and TVDI of dry land and forest land were calculated by simplified Ts/NDVI feature space.Combined with the measured data, the soil moisture content of different depths was modeled by fitting analysis, which was used to inverse the soil moisture content.The results show that the VH polarization quadrat-ic curve model and the VH polarization cubic curve model are suitable for inversion of soil water con-tent at depths of 0～5 cm and 5～10 cm in shrub lands, respectively.The R2 and RMSE of the two models were 0.87, 0.87 and 4.57％, 4.29％ individually.The exponential regression model of VH polarization was applied to soil moisture inversion of sparse woodland in 0～5 cm depth and the linear regression model of VH polarization was suitable for 5～10 cm depth.The R2 and RMSE of the two models are 0.736, 0.72 and 9.77％, 11.28％respectively.The best soil moisture inversion models of dry land and forested land are the cubic curve model and the logistic regression model respectively. And the R2 and RMSE of 0～5 cm depth soil moisture inversion are 0.85, 0.69 and 2.88％, 4.02％, while in 5～10 cm depth the value of R2 and RMSE are 0.76, 0.23 and 3.5％, 6.37％individually.