高原环湖城镇聚落的景观格局及空间形态演变特征 ——以滇池为例

城镇景观格局及空间形态的演变是对快速城镇化的响应，西部高原环湖地区特殊地理环境下的城镇聚落时空演变特征明显有别于平原、山地等地区。以Landsat TM/ETM+/OLI影像为数据源，解译了滇池1990、2000、2010及2018年4期城镇斑块，并采用景观格局指数深入分析16个城镇的演变特征与形态规律。结果表明：（1）1990～2018年城镇聚落经历了“低速增长-高速增长-理性增长”的演变波过程，2000～2010年城镇扩张最快且速率为54.2%，不同时期不同方向演变模式差异显著；（2）城镇斑块的空间特征与发展方向具有明显的依赖性和紧凑，且K-means聚类将城镇斑块分为4种类型，大斑块主导型占6.7%、高密度团簇型占35.8%、中密度团状型及低密度散点型占48.6%和8.9%；（3）城镇斑块在空间上表现为“中心-外围”的扩张特征，前卫、矣六等街道扩张迅速，而碧鸡、海口等街道增长缓慢，五华、官渡区域内城镇斑块数量、聚合度和凝聚度呈递增趋势，且各乡镇间的连通性和聚集性随斑块增长对破碎化影响较小；（4）基于影响因素，城镇斑块主要分布在海拔1 900~2 100 m和坡度小于9°的地区，并与人口和GDP具有强相关性，体现出强烈的交通指向性和河流指向性。

Landscape Pattern and Spatial Form Evolution of Urban Settlements around Lakes in Plateau：A Case Study of Dianchi Lake

The evolution of urban landscape pattern and spatial form is a response to rapid urbanization, and the special geographical environment of the areas surrounding lake in western plateau makes the spatial and temporal evolution of urban settlements different from plains, mountains and other regions. Landsat TM/ETM+/OLI remote sensing imageries were used to interpret urban patches in Dianchi region from 1990 to 2018, and landscape indices were calculated and then used to deeply analyze the evolution characteristics and morphological regularities of sixteen towns. The results show that from 1990 to 2018, urban settlements in the areas experienced the undulated evolution which displays a “low-speed growth-high-speed growth-rational growth” pattern. From 2000 to 2010, urban settlements expanded fastest and the expansion rate had reached 54.2%. The patterns of evolution in different periods and different directions were significantly different. The spatial characteristics and development direction of town patches are obviously non-independent and compact. Using K-means clustering to divid urban patches into four types of agglomeration, the result showed that the large patch dominant type accounted for 6.7%, high-density cluster type accounted for 35.8%, medium-density cluster type and low-density scattering point type accounted for 48.6% and 8.9%, respectively. In term of the spatial pattern, urban expansion of these areas appeared as a “central-peripheral” expansion characteristic: Qianwei, Yiliu, and other peripheral neighborhoods expanded rapidly, while Biji, Haikou, and other central neighborhoods grew slowly. In Wuhua and Guandu regions, the numbers, degrees of aggregation and cohesion of urban patches showed an increasing trend, and both the connectivity and aggregation between towns were increasing with the increase of patch numbers, though these two indices had little impacts on fragmentation of patches. The town patches were mainly distributed in areas with an altitude of 1 900-2 100 m and a slope of less than 9°. They had strong correlation with population and GDP, and showed strong transportation and river directionality.