Tracking the spatio-temporal change of the main food crop planting structure in the Yellow River Basin over 2001-2020

Accurate extraction of crop planting structure is the fundamental for estimating regional crop yield and crop water consumption in the Yellow River Basin (YRB). However, the planted area of the main food crops in the YRB in recent 20 years is still unclear. Therefore, the MODIS image data was used to extract the growing area of the main food crops (winter wheat, summer maize, spring wheat and spring maize) in the YRB over 2001-2020 by the combination of the differential algorithm, spectral mutation algorithm and threshold method. The results revealed that the combined method could be used to track the planted area of the main food crop in the YRB, with R2 and RMSE values ranged from 0.51 to 0.82 and 11.01 to 68.92 x 103 hm2, respectively. The planted area of winter wheat and summer maize in the down-stream irrigation district accounted for 74.7% and 86.7% of the total in the YRB, respectively. Inner Mongolia and Ningxia autonomous regions are the main producing areas for spring wheat and spring maize, accounting for 73.8% and 83.5% of the total in the YRB, respectively. The planted area of winter wheat, summer maize and spring maize had an increasing trend with the rate of 1.440 x 104 hm2 per year, 2.375 x 104 hm2 per year and 2.257 x 104 hm2 per year over 2001-2020. Whereas, the planted area of spring wheat had a decreasing trend with the rate of-2.019 x 104 hm2 per year. Implementation of water-saving irrigation measures, variations of diverted water from the Yellow River, local policies improvement and agricultural market might be the main driving forces for the changes of the planted area for food crops. The results can provide a fundamental agricultural information dataset for further study of regional crop water consumption in the YRB.