Effects of changing rice cultural practices on C-band synthetic aperture radar backscatter using Envisat advanced synthetic aperture radar data in the Mekong River Delta

Lam-Dao, Nguyen and Le-Toan, Thuy and Apan, Armando and Bouvet, Alexandre and Young, Frank R. and Le-Van, Trung (2009) Effects of changing rice cultural practices on C-band synthetic aperture radar backscatter using Envisat advanced synthetic aperture radar data in the Mekong River Delta. Journal of Applied Remote Sensing, 3 (1). pp. 1-17. ISSN 1931-3195

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Abstract

Changes in rice cultivation systems have been observed in the Mekong River Delta, Vietnam. Among the changes in cultural practices, the change from transplanting to direct sowing, the use of water-saving technology, and the use of high production method could have impacts on radar remote sensing methods previously developed for rice monitoring. Using Envisat (Environmental Satellite) ASAR (Advanced Synthetic Aperture Radar) data over the province of An Giang, this study showed that the radar backscattering behaviour is much different from that of the reported traditional rice. At the early stage of the season, direct sowing on fields with rough and wet soil surface provides very high backscatter values for HH (Horizontal transmit – Horizontal receive polarisation) and VV (Vertical transmit – Vertical receive polarisation) data, as a contrast compared to the very low backscatter of fields covered with water before emergence. The temporal increase of the backscatter is therefore not observed clearly over direct sowing fields. Hence, the use of the intensity temporal change as a rice classifier proposed previously may not apply. Due to the drainage that occurs during the season, HH, VV and HH/VV are not strongly related to biomass, in contrast with past results. However, HH/VV ratio could be used to derive the rice/non-rice classification algorithm for all conditions of rice fields in the test province. The mapping results using the HH/VV polarization ratio at a single date in the middle period of the rice season were assessed using statistical data at different districts in the province, where very high accuracy was found. The method can be applied to other regions, provided that the synthetic aperture radar data are acquired during the peak period of the rice season, and that few training fields provide adjusted threshold values used in the method.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Published version deposited in accordance with the copyright policy of the publisher.
Depositing User: Dr Armando Apan
Faculty / Department / School: Historic - Faculty of Engineering and Surveying - Department of Surveying and Land Information
Date Deposited: 23 Sep 2010 05:54
Last Modified: 02 Jul 2013 23:42
Uncontrolled Keywords: rice crop; cultural practices; synthetic aperture radar data; processing; polarisation; mapping; water conservation
Fields of Research (FOR2008): 07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070108 Sustainable Agricultural Development
07 Agricultural and Veterinary Sciences > 0701 Agriculture, Land and Farm Management > 070104 Agricultural Spatial Analysis and Modelling
09 Engineering > 0909 Geomatic Engineering > 090905 Photogrammetry and Remote Sensing
Socio-Economic Objective (SEO2008): B Economic Development > 82 Plant Production and Plant Primary Products > 8204 Summer Grains and Oilseeds > 820402 Rice
Identification Number or DOI: doi: 10.1117/1.3271046
URI: http://eprints.usq.edu.au/id/eprint/7090

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