基于格网的河西绿洲乡村聚落时空演变及其与水土资源的空间耦合关系

Spatial-temporal Change of Rural Settlements and Its Spatial Coupling Relationship with Water and Soil Resources Based on Grid in the Hexi Oasis

基于1 km×1 km格网,论文综合运用景观指数、分散度、核密度、空间耦合关联等方法,研究河西走廊山丹县1998—2015年乡村聚落景观格局分异及时空演变特征,探讨绿洲乡村聚落与水土资源的空间耦合关系,结果表明:1)乡村聚落用地总面积扩张较快、空间分散化趋势明显,斑块数和斑块密度增大、平均斑块面积减小,乡村聚落景观指数在1998—2008年间相比2008—2015年间变化剧烈,后期逐渐趋于稳定;2)3个年份乡村聚落核密度空间分布格局基本一致,主干道路、渠系等线状地物沿线密集,外围区域稀疏,并以线状地物为中心向外呈阶梯状递减;3)1998—2008年乡村聚落分散度呈增加趋势,2008年后趋于稳定,乡村聚落空间分布由相对集中走向零星分散,聚落"散、空、乱"现象普遍;4)乡村聚落与耕地和渠系空间分布关系密切,存在显著的"耕地指向性"和"渠系指向性";K指数1998年以"人多地少型"为主,2008和2015年转向"人少地多型"和"人地协调型";L指数总体表现为"渠系偏多型"和"聚落-渠系协调型"。水土资源是约束和限制绿洲人口和聚落存在和发展的主要因素,人-水-土系统存在着高度的相互依存性和共生性。

Water and soil resources are the most basic constituents of oasis. In fact, oasis can be simply defined as a place with water. The abundance of water resources determines the scale of irrigated land, which further affect the oasis＇ s carrying capacity for social economy. On the basis of 1 km × 1 km grids, landscape index analysis, kernel density, dispersion degree, spatial coupling, etc., were used to analyze the temporal-spatial differentiation of landscape pattern of rural settlements in Shandan County in the Hexi Oasis. Further, the spatial coupling relationship between rural settlements and water and soil resources was studied. The results were as follows：1） From 1998 to 2015, the total area of rural settlements in Shandan County expanded rapidly and the rural settlements tended to be more dispersed. The number and density of rural settlement plaques increased. The average area of rural settlement plaques decreased. Landscape indices of rural settlements changed more rapidly during 1998-2008 than during 2008-2015. In the second period, landscape indices tended to be stable. 2） The kernel density of rural settlements in 1998, 2008 and 2015 were basically consistent. Rural settlements accumulated along major roads and hydrographic network, and the kernel density of rural settlements decreased in the direction away from these roads and hydrographic network. In 1998, the intensive regions of rural settlements were relatively dispersed. The number of such regions was large but the area of each region was small. In 2008 and 2015, the intensive regions were more concentrated. The number of intensive regions decreased, but the area of each region increased.3） From 1998 to 2008, the dispersion degree of rural settlements showed a rising trend. After 2008, the dispersion degree of rural settlements tended to be stable. In 1998, rural settlements in Shandan County were relatively concentrated, and there were 95.35% grids in which the dispersion degree of rural settlements was below 5.0. In 2008 and 2015, rural settlements tended to be more dispersed, and the proportion of grids in which the dispersion degree was above 6.0 increased to 27.68% and 29.30%, respectively. There were even grids in which the dispersion degree was above 21. The grids with dispersion degree above 21 accounted for 1.52% in 2008 and 1.59% in 2015. These led to the dispersion, emptiness and disorder of rural settlements in Shandan County. 4） The spatial distribution of rural settlements in Shandan County was closely related to the distributions of cultivated land and hydrographic network. Rural settlements distributed around cultivated land and along hydrographic network. In 1998, there was no human-land contradiction. In 2008, however, the human-land contradiction occurred. In 2015,the contradiction was alleviated and there was a harmonic relationship between human and land.