Abstract: The urban development boundary(UDB),often called urban growth boundary(UGB) internationally, is one of the effective measures and methods to restrain immoderation sprawl of city size,promote urban compact growth and improve efficiency of urban land use. Due to water restriction and ecological vulnerability,oasis cities are the typical region having the densest human activities and the most sensitive relationship between human and environment. In this paper,Jiayuguan City,a typical oasis industrial city in arid region,Gansu Province, northwest China,was selected to study the delimitation of urban development boundary by 2020 and 2030 with the MCE-CA model of geographic optimization simulation system(GeoSOS) based on multi-temporal Landsat TM/ETM data,combined with "Planning" and "Anti-planning" conception,the aim of this study is to provide basis for the land use and urban management of Jiayuguan. The results show as follows:(1) from 1995 to 2014,Jiayuguan City expanded rapidly,the urban land area in 2014 was 2.1 times as big as that in 1995;the urban compactness of outline decreased from 0.25 in 1995 to 0.14 in 2014,and the characteristic of urban sprawl was obvious; the patch density increased from 0.02 in 1995 to 0.12 in 2014,indicating a more looser urban development tendency; urban land fragmentation increased and urban land connectivity decreased;(2) flexible urban development boundary will be 106.78 km² and 149.35 km² in Jiayuguan by 2020 and 2030,respectively,and rigid urban development boundary will be 246.92 km²;(3) urban development boundary,which has been delimited in this paper,could promote the compactness and connectivity of Jiayuguan,compactness of urban land use may increase to 0.199 and 0.218,the compact index may increase to 0.014 and 0.015,patch density may decrease to 0.043 and 0.023,patch density index may decrease to 0.003 and 0.002;it can optimize the urban space layout and restrain urban sprawl, and met the constructive requirements of ecotypic city better. It is the first time to delimit urban development boundaries based on MCE-CA model,realized the quantification and spatial expression for the factors effecting urban development in MCE-CA model,and applied the "Anti-planning" conception and GIS into planning practices of urban land layout,which was easy to operate with high precision and accuracy of the simulation results.

Key words: oasis city, urban development boundary (UDB), MCE-CA model, Jiayuguan City