Scientists Release 10-meter-resolution Cotton Map in Xinjiang, China
October 18, 2023
Scientists from the National Engineering Research Center for Satellite Remote Sensing Applications under the Aerospace Information Research Institute (AIR), Chinese Academy of Sciences (CAS), together with collaborators from Shihezi University (Xinjiang, China) and University of Toronto (Toronto, Canada), proposed a generalized cotton mapping strategy that provides cotton maps throughout Xinjiang with high-resolution performance.
This study entitled "The 10-m cotton maps in Xinjiang, China during 2018–2021" has been recently published in Scientific Data.
Xinjiang is the leading and largest cotton production region in China and has accounted for over 80% and about 20% of cotton production in China and the world respectively. Xinjiang covers about one-sixth of China’s total land area, with an area of more than 1.66 million square kilometers (km2), and is characterized by typical heterogeneous desert-oasis ecotones.
The accurate and detailed mapping of cotton in Xinjiang is vital for cotton management, disease prevention and control, and yield forecast. However, there were currently no fine-resolution large-scale cotton maps covering the entire Xinjiang.
The team employed a two-step mapping strategy, i.e., cropland mapping followed by cotton extraction, to produce cotton maps (10 m) of Xinjiang (XJ_COTTON10, Figure 1) from 2018 to 2021. To address the high heterogeneity, on the one hand, they used multi-source remote sensing data, including the optical remote sensing imagery (Sentinel-2) and the synthetic aperture radar imagery (Sentinel-1), to extract spectral, textural, structural, and phenological features. On the other hand, they deployed the auxiliary data such as topographic and meteorological variables.
The results showed that the cotton/non-cotton classification model achieved overall accuracies of about 95% and 90% on the test samples of the same and adjacent years, respectively. The proposed two-step cotton mapping strategy proved promising and effective in producing multi-year and consistent cotton maps (Figure 2). XJ_COTTON10 agreed well with the statistical areas of cotton at the county level (R2？=？0.84–0.94).
It is the first cotton mapping for the entire Xinjiang at 10-meter resolution, which can provide a basis for high-precision cotton monitoring and policymaking in China.
Figure 1. Interannual spatiotemporal changes of cotton fields during 2018–2021 at seven selected cases (a and b are in Southern Xinjiang, c is in Eastern Xinjiang, and d–g are in Northern Xinjiang). (Image by AIR)
Research News
Scientists Release 10-meter-resolution Cotton Map in Xinjiang, China