Soil Moisture and Thermal Behavior in the Vicinity of Buried Objects Affecting Remote Sensing Detection: Experimental and Modeling Investigation

Abstract

Improvements in buried mine detection using remote sensing technology rest on understanding the effects on sensor response of spatial and temporal variability created by soil and environmental conditions. However, research efforts on mine detection have generally emphasized sensor development, while less effort has been made to evaluate the effects of the environmental conditions in which the mines are placed. If the processes governing moisture and temperature distribution near the ground surface can be captured, sensor development and deployment can be more realistically tailored to particular operational scenarios and technologies. The objective of this study is to investigate the effects of the soil environment on landmine detection by studying the influence of the thermal boundary conditions at the land-atmosphere interface and the buried objects themselves on the spatial and temporal distribution of soil moisture around shallow-buried objects. Two separate large tank experiments were performed with buried objects with different thermal properties. Experimental results were compared to results from a fully coupled heat and mass transfer numerical model. Comparison of experimental and numerical results suggests that the vapor enhancement factor used to adjust the vapor diffusive flux described based on Fick's law is not necessary under dry soil conditions. Data and simulations from this study show that the thermal signature of a buried object depends on the complex interaction among a soil's water content and its thermal and hydraulic properties. Simulated thermal and saturation contrasts were generally very different for a buried landmine than for other buried objects.