A multidecadal change analysis for irrigation ponds in Taoyuan, Taiwan, using multisource data

A multidecadal change analysis of the irrigation ponds in Taoyuan, Taiwan, was conducted by using multisource data including digitized ancient maps, declassified single-band CORONA satellite images, and multispectral SPOT images. Ponds and paddy fields are texturally similar but spectrally different, whereas the paddy fields and built-up are texturally different but spectrally similar. In this study, supervised land-use/land-cover classifications were conducted using four textural features derived from the single-band CORONA images and spectral features derived from SPOT images. Post-classification analysis revealed that the number of irrigation ponds in the study area decreased during the post-World War II farmland consolidation period (1945–1965) and the subsequent industrialization period (1970–2000). However, efforts on restoration of irrigation ponds in recent years have resulted in gradual increases in the number (9%) and total area (12%) of irrigation ponds in the study area.