Rice identification and change detection using TerraSAR-X data

Rice is the staple grain in China and accounts for about 42% of the nation's food production. Most of China's paddy rice production is located in the southern provinces of the country where cloud cover and frequent rain severely limit opportunities for optical satellite acquisitions. The small field sizes, typical of paddy rice, also challenge the exploitation of satellite data for monitoring rice production. Synthetic aperture radar (SAR) sensors are able to successfully acquire data under most atmospheric conditions, and the change in backscatter, from rice emergence through to crop maturity and harvest, permits the detection of rice fields using SAR imagery. Recently launched sensors, including TerraSAR-X, can provide data at spatial resolutions suitable for rice monitoring in southern China. The objective of this study was to assess TerraSAR-X imagery for identification of late rice and to develop a change detection methodology to quantify changes in rice acreages. The lowlands of the Xuwen study site in Guangdong Province are dominated by rice paddies. Results of this analysis revealed that the TerraSAR-X data were able to identify rice paddies with a 96% accuracy and acreage change to an accuracy of 99%.