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Arid Land Geography ›› 2024, Vol. 47 ›› Issue (5): 850-860.doi: 10.12118/j.issn.1000-6060.2023.541

• Biology and Pedology • Previous Articles     Next Articles

Early identification of rice and corn planting distribution in Qingtongxia irrigation area based on Sentinel-2

ZHU Lei1,2(), WANG Ke1,2, DING Yimin1,2(), SUN Zhenyuan1,2, SUN Boyan1,2   

  1. 1. School of Civil and Water Conservancy Engineering, Ningxia University, Yinchuan 750021, Ningxia, China
    2. Key Laboratory of Digital Water Network Management of the Yellow River in Ningxia Hui Autonomous Region, Yinchuan 750021, Ningxia, China
  • Received:2023-10-01 Revised:2023-12-28 Online:2024-05-25 Published:2024-05-30
  • Contact: DING Yimin E-mail:nxuzhulei@163.com;haojingdig03@hotmail.com

Abstract:

Timely and accurate understanding of crop distribution within irrigation areas is essential for the efficient allocation of irrigation water resources and precise field management. This study focuses on the Qingtongxia irrigation area in Ningxia, China, employing multitemporal Sentinel-2 satellite data to analyze early characteristics of rice and maize. Key “flooding” and “vegetation” signals are extracted, and a time-series dataset comprising the modified normalized difference water index (MNDWI) and normalized vegetation index (NDVI) is constructed. By analyzing sample thresholds for these key features, a decision tree model for the early planting distribution of rice and maize is established, facilitating the extraction of the spatial distribution for rice and maize planting in the Qingtongxia irrigation area in 2022. The results reveal the following: (1) During the latter half of the maize and rice seedling stages, from May 15 to 31, flooding and vegetation signals are crucial for differentiating between the two crops. (2) Based on the early crop phenological characteristics, the mapping accuracy of rice and corn images obtained from May 16 to May 31 was higher than 90%, with user accuracy exceeding 91% and overall accuracy exceeding 90%. The Kappa coefficient was higher than 0.88, significantly higher than the classification accuracy of the random forest classification method during the same period. (3) The proposed method demonstrates strong applicability in the early extraction of rice and maize planting distribution, requiring fewer ground samples for extension across both spatial and temporal scales. Therefore, this method provides significant support for early investigations of rice and maize planting distribution in the Qingtongxia irrigation area.

Key words: Qingtongxia irrigation area, Sentinel-2, normalized vegetation index, normalized difference water index, decision tree, rice, maize