Analysis of the Degradation Evolution and Driving Factors of Cultivated Land in the Yellow River Delta Based on the BFAST Algorithm and Multi-source Data

The degradation of cultivated land has profound implications for regional economic development, ecological security, and food security. Notably, the Yellow River Delta (YRD) is one of China's major grain-producing regions. Studying the degradation status and clarifying the driving mechanism of cultivated land in the YRD is crucial for ensuring regional food security and promoting cultivated land protection. Based on the MODIS NDVI data from 2001 to 2021, this paper uses the Breaks For Additive Seasonal and Trend (BFAST) method to explore the degradation status of cultivated land in the YRD. The study also uses the Geographic Detector to investigate the impact and driving mechanism of various natural and human factors and their interactions on the spatial differentiation of the degradation status of cultivated land at different scales, aiming to provide decision support for cropland protection and human activity regulation in the YRD. The results show that: (1) Compared to the linear trend, the non- linear trend method has higher accuracy in detecting the degradation status of cultivated land. It not only detects the overall trend of cultivated land changes but also detects phase-change information in long-term changes, which can comprehensively and accurately evaluate the degradation status of cultivated land; (2) The BFAST detection results indicate that 31.75% of cultivated land in the YRD is undergoing degradation, 61.06% is expirencing improvoment, and 7.19% exhibits non- significant trend. Most of the cultivated land in the YRD exhibits short-term fluctuations due to external disturbances in the long- term change process, e.g., 31.31% of these fluctuations are interrupted decreases, mainly distributed in areas such as Gubei Reservoir, the western side of the old Yellow River, and the southeastern coast. They show a spatial distribution pattern that gradually decreases and becomes more scattered from the coastal areas to the inland. The interruption increase accounted for 55.13%, mainly distributed in the southern region of the Yellow River, freshwater river areas, and near reservoirs, showing a large-scale concentrated distribution pattern; (3) The spatial differentiation of the degradation status of cultivated land at different scales in the YRD is primarily driven by land use, with significantly higher influence from interactive effect of two factors compared to their isolated effects. Specifically, land use ∩ elevation and distance to the sea ∩ land use are the dominant interactive factors affecting the degradation and improvement status of cultivated land, and the spatial differentiation of the degradation status of cultivated land in the YRD results from the dominant human- driven factors and the collaborative effect of natural factors. © 2023 Journal of Geo-Information Science. All rights reserved.