山区城镇扩张受山区地形和山地灾害等因素限制,而常用的土地利用模型难以有效表达这一特征。本文通过对Dyna-CLUE(Dynamic Conversion of Land Use and its Effects Model)模型进行改进并结合系统动力学(System Dynamic,SD)模型,充分发挥这2个模型在微观土地分配,及宏观情景模拟上的优势,很好地表达了山区地形和山地灾害等因素对山区城镇扩张的限制作用,为山区城镇扩张情景模拟提供了一个有效的方法。以岷江上游地区为例,根据研究区历史统计数据构建山区城镇用地SD模型,模拟低速发展、惯性发展和高速发展3种不同发展情景下城镇用地的需求,结合Dyna-CLUE改进模型,预测了对应情景下2011-2030年的城镇用地范围,并探究其对其他土地利用类型的影响。结果表明,发展速度越快,城镇主体越快达到地理限制区域的上限,并开始沿山间平地向两端扩张。耕地受山区城镇扩张的影响要远远超出其他土地利用类型,离城镇越近受影响越大。随着城镇扩张的加剧,其对自然环境的影响也逐渐增大。模型模拟结果能为山区城镇用地规划、评估由城镇扩张造成的生态环境问题和制定相应的对策提供有效的技术支撑。

Urban land expansion in mountain area is constrained by the hill-shaped terrain, mountain hazards and some other geographic factors, making it difficult to be expressed by the commonly used land use models, thus the research in this area is relatively inadequate. By modifying the Dyna-CLUE model and combining it with the SDM, the advantages of land allocation in microcosmic aspect and scenario simulation in macroscopic aspect are well developed. Moreover, this method clearly expresses the constraining effect of the geographic constraint factors toward mountainous urban land expansion. Therefore, it provides an effective approach to the scenario simulation of urban land expansion in mountain area. This article takes the upper reaches of Minjiang River as the study area. The mountainous urban land SDM is built based on historical statistical data of the study area and is used to simulate urban land demands under three different developing scenarios, which are slow development, inertial development and fast development. Combining with the modified Dyna-CLUE model, the distributions of urban land from 2011 to 2030 for the corresponding developing scenarios are predicted respectively. The results indicate that, the faster the mountainous town develops, the faster it comes up to the upper limit of the geographic restricted filed for downtown areas, then it will expand toward both ends along the intermountain plain. The arable land is influenced by the urban land expansion much more evidently than the other land use types. The closer it is to the downtown areas, the more it is influenced. As the urban land expansion reaches a higher level, its influence to eco-environment is getting more intense. The simulation result of the model can offer effective technical support to mountainous urban planning, estimating the environmental problem caused by urban expansion and making relevant policy.