Estimation of soil moisture using Synthetic Aperture Radar (SAR) backscatter values, over agricultural area, is still difficult. SAR backscatter is sensitive to the surface properties like roughness, crop cover, and soil type, along with its strong sensitivity to the soil moisture. Hence, to develop a methodology for agricultural area soil moisture estimation using SAR, it is necessary to incorporate the effects of crop cover and soil texture in the soil moisture retrieval model. A field experiment was conducted by the authors and used along with Sentinel 1A SAR data to estimate the soil moisture in the paddy agricultural fields. Generally, water used for irrigation in the study region was obtained from ground water. As in the hot climate conditions ground water level would be reduced, and the water for irrigation must be supplied optimally. Hence, available soil moisture in the field was estimated from SAR data on the day of satellite passing the crop fields and utilized for deciding the amount of water to be supplied. The soil moisture values of soil samples that are collected from the agricultural field are calculated with the laboratory experiments. A soil moisture retrieval model is derived and proposed in this paper after a comparative analysis of experimental soil moisture values and satellite values. The feasibility of above model for paddy agricultural fields is validated using the field measurements.
2. Abuzar, M., A. McAllister, D. Whitfield, and K. Sheffield, "Remote sensing analysis of crop water use in the macalister irrigation district," Geospatial Science Research, 1-7, 2012.
3. Li, Z.-X., "Modelling the passive microwave remote sensing of wet snow," Progress In Electromagnetics Research, Vol. 62, 143-164, 2006.
4. Awe, G. O., J. M. Reichert, L. C. Timm, and O. O. Wendroth, "Temporal processes of soil water status in a sugarcane field under residue management," Plant Soil, Vol. 387, 395-411, 2015.
5. Chen, X. Z., S. S. Chen, R. F. Zhong, Y. X. Su, J. S. Liao, D. Li, L. Han, Y. Lia, and X. A. Li, "Semi-empirical inversion model for assessing surface soil moisture using AMSR-E brightness temperatures," Journal of Hydrology, Vol. 456, 1-11, 2012.
6. Wigneron, J.-P., T. Schmugge, A. Chanzy, J.-C. Calvet, and Y. Kerr, "Use of passive microwave remote sensing to monitor soil moisture," Agronomie, Vol. 18, 27-43, 1998.
7. Barrett, B. W., E. Dwyer, and P. Whelan, "Soil moisture retrieval from active space borne microwave observations: An evaluation of current techniques," Remote Sensing, 210-242, 2019.
8. Das, H. P., "Satellite-based agro-advisory service," Satellite Remote Sensing and GIS Applications in Agricultural Meteorology, 347-359, 2013.
9. Mattikalli, N. M. and E. T. Engman, "Microwave remote sensing and GIS for monitoring surface soil moisture and estimation of soil properties," Remote Sensing and Geographic Information Systems for Design and Operation of Water Resources on Systems, 229-236, 1997.
10. Fabbro, V., C. Bourlier, and P. F. Combes, "Forward propagation modeling above Gaussian rough surfaces by the parabolic wave equation: Introduction of the shadowing effect," Progress In Electromagnetics Research, Vol. 58, 243-269, 2006.
11. Skidmore, A., Environment Modelling with GIS and Remote Sensing, Taylor and Francis, New York, ISBN: 0-415-24170-7, 2003.
12. Ulaby, F. T., P. P. Batlivala, and M. C. Dobson, "Microwave backscatter dependence on surface roughness in soil moisture and soil texture, Part I - Bare soil," IEEE Transactions on Geoscience and Remote Sensing, Vol. 16, 286-295, 1978.
13. Dubois, P. C., J. Van Zyl, and T. Engman, "Measuring soil moisture with imaging radars," IEEE Transactions on Geoscience and Remote Sensing, Vol. 33, 915-926, 1995.
14. Shi, J., J. Wang, A. Y. Hsu, E. O. O'neill, and E. T. Engman, "Estimation of bare surface soil moisture and surface roughness parameter using L-band SAR image data," IEEE Transactions on Geoscience and Remote Sensing, Vol. 35, 1254-1266, 1997.
15. Gruhier, C., P. de Rosnay, S. Hasenauer, T. Holmes, R. de Jeu, Y. Kerr, E. Mougin, E. Njoku, F. Timouk, W. Wagner, and M. Zribi, "Soil moisture active and passive microwave products: Intercomparison and evaluation over a sahelian site," Hydrol. Earth Syst. Sci., Vol. 14, 141-156, 2010.
16. Ulaby, F. T., R. K. Moore, and A. K. Fung, Microwave Remote Sensing: Active and Passive, Artech House Inc., Dedham, MA, USA, 1986.
17. Ulaby, F. T., K. Sarabandi, K. Mcdonald, and M. C. Dobson, "Michigan microwave canopy scattering model," Int. Journal of Remote Sensing, Vol. 11, 1223-1253, 1990.
18. Attema, E. P. W. and F. T. Ulaby, "Vegetation modeled as a water cloud," Radio Sci., Vol. 13, 357-364, 1978.
19. Roger, D., D. Roo, Y. Du, F. T. Ulaby, and M. C. Dobson, "A semi-empirical backscattering model at L-band and C-band for A soybean canopy with soil moisture inversion," IEEE Transactions on Geoscience and Remote Sensing, Vol. 39, 864-872, 2001.
20. Aubert, M., N. Baghdadi, M. Zribi, A. Douaoui, C. Loumagne, F. Baup, M. El Hajj, and S. Garrigues, "Analysis of TerraSAR-X data sensitivity to bare soil moisture, roughness, composition and soil crust," Remote Sensing Environment, Vol. 115, 1801-1810, 2011.
21. El Hajj, M., N. Baghdadi, M. Zribi, and H. Bazzi, "Synergic use of Sentinel-1 and Sentinel-2 images for operational soil moisture mapping at high spatial resolution over agricultural areas," Remote Sensing, Vol. 9, 1-28, 2017.
22. Gao, Q., M. Zribi, M. Escorihuela, and N. Baghdadi, "Synergetic use of Sentinel-1 and Sentinel-2 data for soil moisture mapping at 100 m resolution," Sensors, Vol. 17, No. 9, 1-21, 2017.
23. Paloscia, S., S. Pettinato, E. Santi, C. Notarnicola, L. Pasolli, and A. Reppucci, "Soil moisture mapping using Sentinel-1 images: Algorithm and preliminary validation," Remote Sensing Environment, Vol. 134, 234-248, 2013.
24. Zribi, M., A. Gorrab, N. Baghdadi, Z. Lili-Chabaane, and B. Mougenot, "Influence of radar frequency on the relationship between bare surface soil moisture vertical profile and radar backscatter," Geoscience and Remote Sensing Letter, Vol. 11, 848-852, IEEE, 2013.
25. Prakash, R., D. Singh, and N. P. Pathak, "The effect of soil texture in soil moisture retrieval for specular scattering at C-band," Progress In Electromagnetics Research, Vol. 108, 177-204, 2010.
26. Ballester-Berman, J. D., F. Vicente-Guijalba, and J. M. Lopez-Sanchez, "Polarimetric SAR model for soil moisture estimation over vineyards at C-band," Progress In Electromagnetics Research, Vol. 142, 639-665, 2013.
27. Panciera, R., M. A. Tanase, K. Lowell, and J. P. Walker, "Evaluation of IEM, Dubois, and Oh radar backscatter models using airborne L-band SAR," IEEE Transactions on Geoscience and Remote Sensing, Vol. 52, 4966-4979, 2014.
28. Singh, D. and A. Kathpalia, "An efficient modeling with GA approach to retrieve soil texture, moisture and roughness from ERS-2 SAR data," Progress In Electromagnetics Research, Vol. 77, 121-136, 2007.
29. Kasischke, E. S., J. M. Melack, and M. C. Dobson, "The use of imaging radars for ecological applications - A review," Remote Sensing of Environment, Vol. 59, 141-156, 1997.
30. Li, Z., W. Z. Liu, X. C. Zhang, and F. L. Zheng, "Impacts of land use change and climate variability on hydrology in an agricultural catchment on the Loess Plateau of China," Journal of Hydrology, Vol. 377, 35-42, 2009.
31. Feng, X. M., B. J. Fu, S. Piao, S. Wang, P. Ciais, Z. Z. Zeng, Y. H. Lu, Y. Zeng, Y. Li, X. H. Jiang, and B. F. Wu, "Revegetation in China's Loess Plateau is approaching sustainable water resource limits," Nat. Clim. Chang., Vol. 6, 1019-1022, 2016.
32. Gao, X. D., H. C. Li, X. N. Zhao, W. Ma, and P. T. Wu, "Identifying a suitable revegetation technique for soil restoration on water-limited and degraded land: Considering both deep soil moisture deficit and soil organic carbon sequestration," Geoderma, Vol. 319, 61-69, 2018.
33. Dobos, E., "Albedo," Encyclopedia of Soil Science, 1-3, 2003.
34. Zribi, M., T. Baghdadi, N. Holah, and O. Fafin, "New methodology for soil surface moisture estimation and its application to ENVISAT-ASAR multi-incidence data inversion," Remote Sensing of Environment, Vol. 96, 485-496, 2005.
35. Malik, M. S. and J. P. Shukla, "Estimation of soil moisture by remote sensing and field methods: A review," International Journal of Remote Sensing & Geoscience, Vol. 3, No. 4, 21-27, 2014.
36. Attema, E. P. W. and F. T. Ulaby, "Vegetation modeled as a water cloud," Radio Science, Vol. 13, 357-364, 1978.
37. Lakhankar, T., N. Krakauer, and R. Khanbilvardi, "Applications of microwave remote sensing of soil moisture for agricultural applications," International Journal of Terra space Science and Engineering, Vol. 2, No. 1, 81-91, 2009.
38. Mekonnen, D. F., "Satellite remote sensing for soil moisture estimation, Gumara catchment, Ethiopia,", Master Thesis, International Institute for Geo-Information Science and Earth Observation, Enschede, Netherlands, 2009.
39. Copernicus Space Component Data Access Portal: https://scihub.copernicus.eu /dhus/#/home.
40. U.S. Geological Survey ‘EarthExplorer' website: https://earthexplorer.usgs.gov/.
41. Kirimi, F., D. N. Kuria, F. Thonfeld, E. Amler, K. Mubea, S. Misana, and G. Menz, "Influence of vegetation cover on the oh soil moisture retrieval model: A case study of the Malinda Wetland Tanzania," Advances in Remote Sensing, Vol. 5, 28-42, 2016.
42. El Hajj, M., N. Baghdadi, M. Zribi, G. Belaud, B. Cheviron, D. Courault, and F. Charron, "Soil moisture retrieval over irrigated grassland using X-band SAR data," Remote Sensing Environment, Vol. 176, 202-218, 2016.
43. Sekertekin, A., A. M. Marangoz, and S. Abdikan, "Soil moisture mapping using Sentinel-1A synthetic aperture radar data," International Journal of Environment and Geoinformatics, Vol. 5, No. 2, 178-188, 2016.