| Abstract |
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._x000D_
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 – 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. |
