BELSAR-SCIENCE - Soil and crop monitoring from simultaneous mono- and bistatic radar observations

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Context and objectives

The BELSAR-Science project, jointly financed by Belspo’s STEREO III and ESA-PRODEX programs, consisted in the scientific exploitation of the data collected during the BELSAR-Campaign project, financed by ESA and completed in 2018. The dataset exploited consisted of airborne bistatic interferometric SAR measurements in L-band and full polarization, as well as concurrent field measurements of crop and soil bio-geophysical variables in 10 winter wheat and 10 maize fields in the imaged area. The airborne SAR data was collected and processed by MetaSensing B.V. and the in situ data by the partners of BELSAR-Science. The dataset was then complemented with C-band SAR measurements from Sentinel-1.

Project outcome

Scientific results

  • Quality analysis and resolution of the miscalibration issue of the BELSAR-Campaign airborne SAR dataset;
  • Generation of L and C-band InSAR products;
  • Sensitivity analysis of the mono and multistatic SAR system in L-band from BELSAR-Campaign to the maize canopy row structure, as well as to multiple biophysical variables, soil moisture, and surface roughness in vegetated maize and bare winter wheat fields;
  • Development of a semiempirical method based on effective roughness modeling to retrieve surface soil moisture over bare agricultural fields without the need for field measurements of surface roughness and test on full-pol mono-, bi-, and multistatic SAR data in L-band;
  • Implementation and test of multiple methods for the simultaneous estimation of the green area index and the surface soil moisture under the canopy in maize fields using the Water Cloud Model and dual polarized radar backscatter measurements in L and C-band.

Societal (including environmental) relevance

The results of this project on change detection in an urban and agricultural context, as well as on crop and soil moisture variables monitoring, are of increasing importance in a changing world. Soil moisture is an essential variable in the analysis of the hydrological cycle at the global and local scales since it plays a critical role in the water and energy balance, affecting crop development and controlling the runoff process. In addition, monitoring the growth, health, and performance of crops throughout the growing season is an important aspect of agricultural management. Findings from the project can provide decision makers with information on the potential of mono- and bistatic SAR systems for change detection, as well as for soil moisture and agricultural monitoring, and inform their choice for future remote sensing missions. Furthermore, the use of the SAR-based methods implemented during the project can provide timely, cost-effective, weather-independent, and accurate information to the farmers on the current state of their crops and soils.

Products and services

  • Advanced InSAR products in L and C-band;
  • Algorithm to estimate the surface soil moisture of bare agricultural fields from SAR data without the need for field measurements of surface roughness;
  • Algorithm to estimate the green area index and surface soil moisture of a maize crop from dualpolarized SAR data.

Potential users

The results of the project have been published in open-access journals and are therefore usable by everyone, but most likely the scientific community as well as by agricultural consultants.