用哨兵1号和辅助数据高精度反演矿区土壤湿度,精度达3.7%以上。
High Resolution Sediment-Specific Surface Soil Moisture Retrieval Using Sentinel-1 Time Series and Auxiliary Data

- 融合雷达、光学、地形与温度数据,构建多源特征提升反演精度。
- 最佳模型在不同沉积物上实现0.037–0.050 m³/m³的误差,决定系数达0.90。
- 基于沉积物特性的校准显著提升精度,尤其对黏土和有机土效果好。
本研究通过结合现场土壤湿度传感器与多源合成孔径雷达(SAR)影像,评估并改进地表土壤湿度的反演方法。研究区域为芬兰东南部石灰岩采石场,重点关注典型地质材料——沉积物的高分辨率土壤湿度估算。利用欧洲航天局哨兵-1 C波段SAR数据,辅以哨兵-2光学数据及物联网电容式传感器实测数据,采用Xgboost、LightGBM、随机森林、线性回归和K近邻回归等机器学习方法。最全面特征集包含哨兵-1后向散射、时序土壤湿度指数、哨兵-2光学、地形和温度变量,在最优沉积物分区配置下,均方根误差降至0.037–0.050 m³/m³(3.7–5.0体积百分点),决定系数达到0.90。树模型(尤其是LightGBM、RF和XGBoost)表现最佳。精度随沉积物类型变化,黏土和有机土误差最低,浮选砂和砾石误差较高。引入沉积物信息使仅用哨兵-1的数据提升超过2体积百分点,但在多源特征集下增益有限。
原文摘要 · Abstract (English)
In this study, we examine the potential of continuous ground moisture monitoring over a mining site using a combination of in-situ soil moisture sensors and multi-sensor SAR images. We focus on assessing and improving methodologies for retrieval of surface soil moisture, i.e. ground moisture, from SAR measurements focusing on detailed in situ reference observations for several key geomaterials, i.e. sediments, typical in the study site. The mining site represents a limestone quarry locate in the southeastern Finland. Our hypothesis is that sediment-specific well-calibrated models can be instrumental in improving soil moisture retrieval under different weather conditions to produce spatially explicit soil moisture estimates at high resolution compared to baseline approaches. Studied SAR data are represented by Copernicus Sentinel-1 C-band images, while auxiliary datasets include optical Sentinel-2 data. Reference data were collected using IoT enabled capacitance sensors. The examined machine learning methods include Xgboost, LightGBM, RFs, linear regression and k-nearest neighbors regression. The best performance was achieved with the most comprehensive feature set which combines Sentinel-1 backscatter, time-series based soil moisture indices, Sentinel-2 optical, topographic, and temperature predictors. In the best sediment-area-level configurations, RMSE decreased to 0.037-0.050 m^3 m^(-3) (3.7-5.0 volumetric % points), with R^2 values reaching 0.90. Tree-based ensemble methods, especially LightGBM, RF, and XGBoost, provided the most accurate and stable predictions. Accuracy varied by sediment texture, with the lowest errors for clay and organic soil and higher errors for flotation sand and gravel. Adding sediment information improved Sentinel-1-only retrievals by more than 2 vol-%, but provided little additional benefit when richer multi-source feature sets were used.
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