5:15 PM - 7:15 PM
[AGE34-P08] Surface soil water content estimation by ground penetrating radar airborne measurements
Keywords:Ground penetrating radar, airborne measurement, soil water content, dielectric constant, smart agriculture
In agriculture, information on the variability of surface soil water content is crucial for predicting field water balance and crop growth. However, soil water content measurement is subject to significant temporal and spatial variability, making it difficult to adequately measure a wide range of soil water content using conventional methods. Because of the heterogeneity observed in the spatial distribution of surface soil water content, a methodology that can measure larger areas with little effort. Ground-penetrating radar (GPR) can be a good option as GPR allows non-destructive and non-invasive scan of the ground to estimate the spatial distribution of dielectric constants of the soil, which are correlated with the soil water contents. Normally GPR is used by putting antennas on the ground, but it is easily affected by plants. To avoid such difficulties, it is desirable to make airborne measurements.
This study aims to investigate the effectiveness and applicability of GPR airborne measurement for estimating surface soil water content of a soybean field. Numerical simulations based on the finite-difference time-domain (FDTD) method were first performed to validate the airborne method. Field measurements were conducted at the experimental fields of FM Fuchu at Tokyo University of Agriculture and Technology. A measurement stand made of PVC pipes was used to fix the GPR antennas at a fixed height above the ground for measurement. The study used the ratio between the reflection amplitude from the field surface and the reflection amplitude from an aluminum foil plate placed at the same height to estimate the dielectric constant. Using this ratio, the dielectric constant was determined along the transects to estimate soil water content distribution. The numerical simulations confirmed that the airborne method is suitable to estimate the dielectric constant of the ground. Field experiments showed that soil water content can be estimated with the airborne method, as confirmed by comparison with sensor data. These results suggest that estimating soil water content at the field surface through the GPR airborne measurements is a viable approach in smart agriculture.
This study aims to investigate the effectiveness and applicability of GPR airborne measurement for estimating surface soil water content of a soybean field. Numerical simulations based on the finite-difference time-domain (FDTD) method were first performed to validate the airborne method. Field measurements were conducted at the experimental fields of FM Fuchu at Tokyo University of Agriculture and Technology. A measurement stand made of PVC pipes was used to fix the GPR antennas at a fixed height above the ground for measurement. The study used the ratio between the reflection amplitude from the field surface and the reflection amplitude from an aluminum foil plate placed at the same height to estimate the dielectric constant. Using this ratio, the dielectric constant was determined along the transects to estimate soil water content distribution. The numerical simulations confirmed that the airborne method is suitable to estimate the dielectric constant of the ground. Field experiments showed that soil water content can be estimated with the airborne method, as confirmed by comparison with sensor data. These results suggest that estimating soil water content at the field surface through the GPR airborne measurements is a viable approach in smart agriculture.