Using Thematic Mapper data for change detection and sustainable use of cultivated land: a case study in the Yellow River delta, China

Preservation of cultivated land is one of China's four basic strategic policies. Timely land use monitoring is a prerequisite of cultivated land management and sustainable utilization. Using digital satellite remote sensing techniques, the intention is to develop a workable procedure for cultivated land change detection in the Yellow River delta region. Four detection methods were assessed. The assessment, in general, suggests that it is difficult to find a single efficient method for cultivated land change detection in the study area, where spectral confusion is widespread due to soil salinization and juxtaposed land use patterns. The knowledge-based visual change detection and classification-result overlay methods are more appropriate than the multi-temporal composite and classification, and image ratioing. The latter two methods are useful and efficient when remote sensing data acquired in the suitable season are available, and distinct spectral characteristics of different land use types exist. The results show that the area of cultivated land in this region decreased by 5321.8 ha over the period 1987 to 1998, i.e. 483.8 ha every year, mainly concentrated in the central paddy field region and northeast dry land region.