Use of Remote Sensing and GIS to Assess the Effects of Agricultural Land Production Capacity on Spatial Extension of Construction Land in Chengdu

As a major commodity grain base in the Chengdu Plain, the city of Chengdu has played a significant role in the grain security of the Sichuan Province and the stability of national economy. However, with the urbanization process, the cultivated land quantity reduces and quality drops, which further affect the security of the grain production. In this study, we integrate remote sensing and geographic information systems to detect land-use change and reveal the increase in urban built-up land between 1992 and 2002. The result shows that the built-up land increased from 31280 hm² to 41196 hm². The net gain of the built-up land was 9916 hm² between 1992 and 2002. The quality of the cultivated land was in the third, fourth, fifth, and sixth grades, occupying 0.02%, 87.70%, 5.53%, and 6.75%, respectively. Meanwhile, according to the database of soil attributes and spatial parameters in classification and gradation for farming land in Chengdu, the correlation relationship between the land utilization index and the realistic productivity was established. The results indicated that the cultivated land with high productivity and favorable facilities in the suburbs was decreasing much faster because of their close contiguity to the expanding city, and the total loss of the capacity of cultivated land caused by land shrinkage reached 1.48 ×10⁸ tons.