Mapping winter rapeseed in South China using Sentinel-2 data based on a novel separability index
2023
TAO Jian-bin | ZHANG Xin-yue | WU Qi-fan | WANG Yun
Large-scale crop mapping using remote sensing data is of great significance for agricultural production, food securityand the sustainable development of human societies. Winter rapeseed is an important oil crop in China that is mainlydistributed in the Yangtze River Valley. Traditional winter rapeseed mapping practices are insufficient since they only usethe spectral characteristics during the critical phenological period of winter rapeseed, which are usually limited to a smallregion and cannot meet the needs of large-scale applications. In this study, a novel phenology-based winter rapeseedindex (PWRI) was proposed to map winter rapeseed in the Yangtze River Valley. PWRI expands the date window fordistinguishing winter rapeseed and winter wheat, and it has good separability throughout the flowering period of winterrapeseed. PWRI also improves the separability of winter rapeseed and winter wheat, which traditionally have been twoeasily confused winter crops. A PWRI-based method was applied to the Middle Reaches of the Yangtze River Valley tomap winter rapeseed on the Google Earth Engine platform. Time series composited Sentinel-2 data were used to mapwinter rapeseed with 10 m resolution. The mapping achieved a good result with overall accuracy and kappa coefficientsexceeding 92% and 0.85, respectively. The PWRI-based method provides a new solution for high spatial resolutionwinter rapeseed mapping at a large scale.
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