1 research outputs found
Measuring soil moisture with spaceborne synthetic aperture radar data
This report describes the methodology and preliminary results obtained within the NEE6881S
Innovation Flexible Fund project funded by the British Geological Survey (BGS) aimed at
assessing the capabilities of active radar satellite imagery in deriving soil moisture values.
The first part of the report introduces the project in the context of the most recent methodologies
used to assess soil moisture with a particular focus on spaceborne technologies. The second part
details the datasets and workflow adopted for the two case studies chosen in this work: Chobham
Common and Hollin Hill, both in the UK.
Around 1.7Tb of Synthetic Aperture Radar (SAR) imagery from Senintel-1 satellite have been
processed to detect changes of the hydrological conditions at the two sites for the 2015-2018
period. The backscattering coefficient retrieved from Sentinel-1 images has then been compared
with ground truth data on the Volumetric Water Content (VWC) and analysed against the
ZOODRM recharge model. The main findings are that: the SAR signal has been able to penetrate
down to a maximum depth of 15 cm in the terrain (i), the best correlation with the VWC changes
is observed with the vertical transmit β vertical receive polarization of the SAR antenna (ii) and
for every unit change in the backscatter signal, VWC varies by about 25% to 33% at Chobham
Common and ~20% to ~50% at Hollin Hill which translate into a sensitivity of 0.04 dB/[vol.%] to
0.03 dB/[vol.%] and 0.05 dB/[vol.%] to 0.02 dB/[vol.%], respectively.
The Discussion and Conclusions detail the significance and benefits of these findings, current
limitations in our methodology and how it can be improved