Analysis Of Spatio-temporal Change Of Land Use Based On RS And GIS In Yucheng District Of Ya'an City

The terrain of low-middle mountain in Yucheng District of Ya'an is representative in western of SiChuan Province. In order to analyze the spatio-temporal change of land use structure in this district, this study processed and analyzed the land use map, topographic map and the Landsat-TM image based on the technology of Remote Sense (RS) and Geographic Information System (GIS), including image reproject, geometric correction, image enhancement, pdygon subset, supervised classification, vetorization, image superposition, space analysis and so on.According to the local terrain and condition, the study divided the whole area into four subareas: subarea Ⅰ (500m~700m), subarea Ⅱ (700m~900m), subarea Ⅲ(900m~ 1200m), and subarea Ⅳ(>1200m). Describe these subareas by the elevation, and discuss separately the saptio-temporal change of land use structure in each subarea. The results indicate: (1) the quantity of dry land is increasing with the rise of elevation, but decrease suddenly at the subarea IV; the quantity of paddy field is decreasing with the rise of elevation, but increase a little at the subarea III; the quantity of shrubbery land and forest land is both increasing with the rise of elevation; the change trend of the construction land quantity is decreasing with the rise of elevation but there exist little wave; (2) the whole dynamic change in Yucheng district is that the cultivated land is changed to forest land and construction land, and the dynamic change in subarea IV is the most distinct, and comparatively the dynamic change in subarea Ⅰ and Ⅱ is not distinct.According to the diagnoses, it is showed that nature factor is the basic condition for the local land use and land cover, such as terrain, physiognomy, hydrothermal condition and so on, and it plays a determination role in the local land use structure. However, the society and economy factor is the dominant influence, such as population growth, economy development, town construction, returning cultivated land to forest or grassland and so on.It is the effective way to realize the sustainable use in the low-middle mountain areas that insisting the principle that protecting the cultivated land, increasing the forest land, and controlling the construction land, giving attention to land quantity and quality, and implementing the measures that reasonable programming, adjusting the industry structure and the agriculture structure, and reforming the medium and low yield paddy field.