High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water management

Soil moisture (SM) is vital for comprehending the hydrological cycle and managing climatic extremes. Fine-scale accurate SM products hold more and more significant value to water management and precise agricultural irrigation. While in-situ measurements provide high accuracy, their limited spatial c...

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Main Authors: Zihao Wang, Qi Gao, Michele Crosetto, Maria Jose Escorihuela
Format: Article
Language:English
Published: Elsevier 2025-08-01
Series:International Journal of Applied Earth Observations and Geoinformation
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Online Access:http://www.sciencedirect.com/science/article/pii/S1569843225003498
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author Zihao Wang
Qi Gao
Michele Crosetto
Maria Jose Escorihuela
author_facet Zihao Wang
Qi Gao
Michele Crosetto
Maria Jose Escorihuela
author_sort Zihao Wang
collection DOAJ
description Soil moisture (SM) is vital for comprehending the hydrological cycle and managing climatic extremes. Fine-scale accurate SM products hold more and more significant value to water management and precise agricultural irrigation. While in-situ measurements provide high accuracy, their limited spatial coverage and high costs necessitate alternative approaches. Remote sensing enables large-scale monitoring; however, satellite-based SM products have relatively lower spatial resolution, making them less suitable for practical applications. This study presents an innovative high-resolution surface soil moisture (SSM) retrieval framework combining machine learning (ML), change detection and downscaling (CD-DS) methods. The procedure is applied over Catalonia, Spain. The framework integrates Sentinel-1 SAR, Sentinel-2 normalized difference vegetation indices (NDVI), and DISPATCH background SSM data to generate 30-m resolution SSM. A novel backscatter difference variable, derived from the change detection method, improves model performance by addressing vegetation. The ML model was trained using in-situ SSM data collected from 2017 to 2021 and validated against independent in-situ measurement datasets. Among the evaluated algorithms, XGBoost model performed best, achieving an R2 of 0.933 and RMSE of 0.023 cm3/cm3. Validation with ground measurements with different landcover types showed an average correlation of 0.63, a ubRMSE of 0.045 cm3/cm3, and minimal bias of 0.024 cm3/cm3. Notably, backscatter difference emerged as the second most important variable in the ML model after background SSM, highlighting its significance in improving SSM retrieval accuracy. Comparisons with data from 54 measurement sites, obtained during a 2015 field campaign, yielded an R value of 0.82, a RMSE of 0.06 cm3/cm3. Temporal analysis revealed strong consistency with in-situ data, capturing seasonal trends and abrupt changes after precipitation and irrigation events. Furthermore, the spatial distribution of SSM is closely aligned with irrigation type maps, showing higher SSM values in irrigated areas and lower values in rainfed regions. This approach delivers precise field-scale SSM estimates, making it a valuable tool for drought monitoring and modern agricultural practices.
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spelling doaj-art-a3d1e1414e32427b8328d77c8d834b272025-07-02T04:49:43ZengElsevierInternational Journal of Applied Earth Observations and Geoinformation1569-84322025-08-01142104702High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water managementZihao Wang0Qi Gao1Michele Crosetto2Maria Jose Escorihuela3Centre Tecnològic de Telecomunicacions de Catalunya (CTTC-CERCA), Av. Carl Friedrich Gauss 7, 08860 Castelldefels, Spain; Universitat Politècnica de Catalunya - BarcelonaTech (UPC), Department of Civil and Environmental Engineering, Campus Diagonal Nord, Building C2, 08034 Barcelona, SpainCentre Tecnològic de Telecomunicacions de Catalunya (CTTC-CERCA), Av. Carl Friedrich Gauss 7, 08860 Castelldefels, Spain; Corresponding author.Centre Tecnològic de Telecomunicacions de Catalunya (CTTC-CERCA), Av. Carl Friedrich Gauss 7, 08860 Castelldefels, SpainisardSAT, Parc Tecnològic Barcelona Activa, Carrer de Marie Curie, 8, 08042 Barcelona, SpainSoil moisture (SM) is vital for comprehending the hydrological cycle and managing climatic extremes. Fine-scale accurate SM products hold more and more significant value to water management and precise agricultural irrigation. While in-situ measurements provide high accuracy, their limited spatial coverage and high costs necessitate alternative approaches. Remote sensing enables large-scale monitoring; however, satellite-based SM products have relatively lower spatial resolution, making them less suitable for practical applications. This study presents an innovative high-resolution surface soil moisture (SSM) retrieval framework combining machine learning (ML), change detection and downscaling (CD-DS) methods. The procedure is applied over Catalonia, Spain. The framework integrates Sentinel-1 SAR, Sentinel-2 normalized difference vegetation indices (NDVI), and DISPATCH background SSM data to generate 30-m resolution SSM. A novel backscatter difference variable, derived from the change detection method, improves model performance by addressing vegetation. The ML model was trained using in-situ SSM data collected from 2017 to 2021 and validated against independent in-situ measurement datasets. Among the evaluated algorithms, XGBoost model performed best, achieving an R2 of 0.933 and RMSE of 0.023 cm3/cm3. Validation with ground measurements with different landcover types showed an average correlation of 0.63, a ubRMSE of 0.045 cm3/cm3, and minimal bias of 0.024 cm3/cm3. Notably, backscatter difference emerged as the second most important variable in the ML model after background SSM, highlighting its significance in improving SSM retrieval accuracy. Comparisons with data from 54 measurement sites, obtained during a 2015 field campaign, yielded an R value of 0.82, a RMSE of 0.06 cm3/cm3. Temporal analysis revealed strong consistency with in-situ data, capturing seasonal trends and abrupt changes after precipitation and irrigation events. Furthermore, the spatial distribution of SSM is closely aligned with irrigation type maps, showing higher SSM values in irrigated areas and lower values in rainfed regions. This approach delivers precise field-scale SSM estimates, making it a valuable tool for drought monitoring and modern agricultural practices.http://www.sciencedirect.com/science/article/pii/S1569843225003498Surface soil moistureRemote sensingSARDownscalingChange detectionMachine learning
spellingShingle Zihao Wang
Qi Gao
Michele Crosetto
Maria Jose Escorihuela
High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water management
International Journal of Applied Earth Observations and Geoinformation
Surface soil moisture
Remote sensing
SAR
Downscaling
Change detection
Machine learning
title High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water management
title_full High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water management
title_fullStr High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water management
title_full_unstemmed High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water management
title_short High-resolution surface soil moisture retrieval: A hybrid machine learning framework integrating change detection and downscaling for precision water management
title_sort high resolution surface soil moisture retrieval a hybrid machine learning framework integrating change detection and downscaling for precision water management
topic Surface soil moisture
Remote sensing
SAR
Downscaling
Change detection
Machine learning
url http://www.sciencedirect.com/science/article/pii/S1569843225003498
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AT michelecrosetto highresolutionsurfacesoilmoistureretrievalahybridmachinelearningframeworkintegratingchangedetectionanddownscalingforprecisionwatermanagement
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