A Novel Remote Sensing Approach to Quantifying Soil Stability.

Soil structural condition and stability are critical soil physical properties subjected to dynamic changes which, in turn, alter soil hydraulic and transport properties. Water storage and flow in soils depend, to a large extent, on the intricate nature and changes in soil structure at and close to saturation. Methods developed to quantify soil structure and aggregate stability are mostly based on laboratory experiments. A common method is based on comparing soil water characteristic (SWC) curve at near saturation between slowly-wetted and rapidly-wetted samples of a structured soil, given that the less stable the soil, the larger difference between SWC curve of the slowly-wetted and rapidly-wetted samples. Remote sensing (RS) technique has been widely used to study a range of soil properties. This study focuses on developing a remote sensing approach for quantifying soil stability. Our hypothesis is that reflectance of the slowly-wetted sample is different from reflectance of the rapidly-wetted sample due to different surface roughness and this difference depends largely on the soil stability. To test this hypothesis, a spectroradiometer (400-2500 nm) was added to the common laboratory experimental setup enabling measurement of reflectance spectra of the samples during the experiment. Our preliminary data promise feasibility of quantifying soil stability using remote sensing observations.