干旱区绿洲城镇扩张对耕地空间影响及预测——以河西走廊区域为例

绿洲城镇是干旱地区人类活动最剧烈、人口集聚度最高、“人—地”关系矛盾最为突出的生态环境脆弱区。受全球气候变化影响及西部大开发战略推动,区域城镇与绿洲耕地之间的动态变化及利弊权衡成为当前关注的热点。基于1990—2015年多时相遥感影像数据,以典型绿洲城镇河西走廊为研究区,引入Markov和ANN-CA模型对河西走廊城镇用地与耕地的时空动态转换特征与规律展开探索,揭示了城镇扩张对耕地的影响过程与机制。研究结果表明：（1）河西走廊土地总体以未利用土地和草地为主,城镇用地与耕地仅占区域总面积的0.63%、6.35%,且城镇与耕地面积共同经历了先减少后增加的“V”型变化趋势。（2）1990—2015年河西走廊城镇面积扩张了1.53倍,其中15.67%的城镇扩张用地来自耕地占用,其他主要来源于草地,沙漠和戈壁等未利用土地。另外,区域内5个地市城镇扩张的耕地占用差异较大。（3）结合Markov与ANN-CA模型的模拟和预测结果表明,2015—2030年河西走廊79.77%的城镇扩张用地将来源于周边耕地,且城镇空间扩张方式以外延扩展为主,未来耕地被城镇侵占压力较大。研究结果将为干旱区相似区域空间规划和耕地保护提供决策支持。

Spatial influence and prediction of oasis urban expansion on cultivated land in arid areas: A case study of the Hexi Corridor

Oasis city and town is a fragile ecological environment area with the most densely population, the most intense human activities and the most prominent contradiction between human and land in arid regions. Affected by global climate change and China's western development strategy, the dynamic changes between regional towns and oasis cultivated land and the trade-offs between them have become the hotspots of current concern. Based on the multi-temporal remote sensing land use data from 1990 to 2015, this paper takes the oasis cities and towns of the Hexi Corridor, a typical arid area as the research region, introduces Markov and ANN-CA models to deeply explore the land change process, quantifies the temporal and spatial dynamic transformation of urban land and cultivated land, and reveals the process and mechanism of urban expansion from cultivated land. The results show that: (1) The land types in Hexi are mainly unused land and grassland, and the urban and cultivated land accounted for 0.63% and 6.35%, respectively. The urban land and cultivated land areas showed a V-shaped change trend of first decrease and then increase. (2) From 1990 to 2015, the urban area of the expanded by 1.53 times, of which 15.67% was converted from cultivated land, and the others were mainly from unused land such as grasslands, deserts, and Gobi. The proportions of cultivated land occupied by urban expansion in five cities were quite different. (3) The simulation and prediction results combined with the Markov and ANN-CA models show that 79.77% of urban expansion land will come from cultivated land in 2015-2030, and the mode of urban spatial expansion is mainly extended. In addition, the pressure on cultivated land occupied by urban expansion will be greater in the future. The results will provide decision making support for future urban development planning and cultivated land protection.