Radarsat Data for Operational Rice Monitoring and its Potential for Yield Estimation

摘要

Rice monitoring and yield estimation has special significance to China, as rice is the staple grain and accounts for 42% of the crop yield for this country. Radar remote sensing is appropriate for monitoring rice, as cultivated areas are most often cloudy and rainy. For this reason, SAR is anticipated to be the dominant data source in tropic and sub-tropical regions and also provide re-visit schedules suitable for agricultural monitoring. This paper presents the results of a study examining the backscatter behavior of rice using multi-temporal RADARSAT dataset acquired in 1996 and 1997. A rice-type distribution map was produced, showing 4 types of rice with different life spans ranging from 80 days, to 120-125 days. The life span of a rice crop has significant impact on yield, as well as the taste and quality of the rice. The yield of three counties and two administrative regions, totaling 5000 square kilometers, are estimated in this study. The accuracy was found to be 91%, providing confidence that multi-temporal RADARSAT data is capable of rice monitoring and yield estimation. Based on the studies carried out in the Zhaoqing test site, it is suggested that rice yield estimations require three radar data acquisitions taken at 3 stages of crop growth circle. That is at the end of the seedling development period, in the ear differentiation period, and at the beginning of the havest period. Alternatively, if multiparameter radar data is available, only two data acquisitions are required: at the end of the seedling period, and at the beginning of the harvest period. In 1999, we started a pilot experiment on operational rice monitoring and potential yield estimation using multi-temporal RADARSAT data. Finally, this paper proposes a pilot scenario for operational rice monitoring and yield estimation.