Estimating catchment scale soil moisture at a high spatial resolution: integrating remote sensing and machine learning

I. P. Senanayake, I. -Y. Yeo, J. P. Walker, G. R. Willgoose

Research output: Contribution to journalArticleResearchpeer-review

26 Citations (Scopus)

Abstract

Soil moisture information is important for a wide range of applications including hydrologic modelling, climatic modelling and agriculture. L-band passive microwave satellite remote sensing is the most feasible option to estimate near-surface soil moisture (~0–5 cm soil depth) over large extents, but its coarse resolution (~10s of km) means that it is unable to capture the variability of soil moisture in detail. Therefore, different downscaling methods have been tested as a solution to meet the demand for high spatial resolution soil moisture. Downscaling algorithms based on the soil thermal inertia relationship between diurnal soil temperature difference (ΔT) and daily mean soil moisture content (μSM) have shown promising results over arid and semi-arid landscapes. However, the linearity of these algorithms is affected by factors such as vegetation, soil texture and meteorology in a complex manner. This study tested a (i) Regression Tree (RT), an Artificial Neural Network (ANN), and a Gaussian Process Regression (GPR) model based on the soil thermal inertia theory over a semi-arid agricultural landscape in Australia, given the ability of machine learning algorithms to capture complex, non-linear relationships between predictors and responses. Downscaled soil moisture from the RT, ANN and GPR models showed root mean square errors (RMSEs) of 0.03, 0.09 and 0.07 cm3/cm3 compared to airborne retrievals and unbiased RMSEs (ubRMSEs) of 0.07, 0.08 and 0.05 cm3/cm3 compared to in-situ observations, respectively. The study showed encouraging results to integrate machine learning techniques in estimating near-surface soil moisture at a high spatial resolution.

Original languageEnglish
Article number145924
Number of pages17
JournalScience of the Total Environment
Volume776
DOIs
Publication statusPublished - 1 Jul 2021

Keywords

  • Artificial neural network
  • Downscaling
  • Gaussian process regression
  • Regression tree model
  • Soil moisture

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