西藏一江两河地区人口分布与地形要素关系分析

地形条件是影响区域人口分布的最基本的因素之一,本文基于1 km×1 km人口空间分布公里网格数据定量分析一江两河地区人口分布基本特征及其与高程、坡度、坡向、地形起伏度等地形要素之间的关系,有助于揭示西藏高原人口分布现状的本质、理解人口空间分布结构特征,对于今后宜居地选址、改善农牧民人居环境、制定区域经济发展政策,促进区域内人口、资源与环境可持续发展具有重要意义。研究结果表明：① 一江两河地区90%的区域人口密度不足10人/km²,80%的人口分布在不足5%的土地上,人口分布比较集中。当前一江两河地区有2个主要的人口集中区,分别是拉萨市城关区和日喀则地区日喀则市,拉萨市城关区尤其显著。② 一江两河地区人口沿河分布,80.46%的人口居住在距离河流10 km以内区域,人口总数、人口密度与距河流距离呈明显的指数关系,距离河流2 km以内的区域人口密度高于50人/km²;③ 近99%的人口分布在海拔4500 m以下,当高程超过3800 m时,人口密度随海拔升高呈下降趋势;④ 近70%的人口分布在坡度小于15°的区域,而且随着坡度越大,人口密度越小,人口分布受坡向的影响不明显;⑤ 地形起伏度对人口分布的影响显著,近85%的人口分布在地形起伏度小于800 m的区域,人口密度与地形起伏度之间为倒指数关系。

Analysis of Population Distribution and Its Spatial Relationship with Terrain Elements in the Yarlung Zangbo River,Nyangqu River and Lhasa River Region,Tibet

The Yarlung Zangbo River, Nyangqu River and Lhasa River Region (the YNL River Region) is the political, economic and cultural center of Tibet, with large population and more developed economy. In this region, there are a variety of complex terrain units, such as mountain plateau, valley plains, and the geomorphological conditions directly or indirectly affect population distribution in this region. Study on the relationship between population distribution and complex topography can be helpful to reveal the present situation of population distribution and understand the spatial structure of population distribution. This study will play an important role in selecting a livable site, improving living environment of the farmers and herdsmen and making the policy of regional economic development. This study will have great significance on the sustainable development of the population, resources and environment in this region. Based on the STRM DEM (30 m) and 1km×1km population density raster data in 2010, we used spatial analysis of ARCGIS 10.1 and raster calculation to extracted terrain features data from DEM. This paper analyzed the population distribution in the YNL River Region, Tibet and quantified the relationship between population distribution and topographical parameters, i.e. elevation, slope, aspect and relief degree of land surface (RDLS). The results showed that: (1) The population density in 90% of the total area of the YNL River Region is less than 10 persons / km², and 80% of the population distributes in less than 5% of the land. The population distribution is relatively concentrated. At present, there are two main population gathering area in YNL River Region, Chengguan District in Lhasa and Shigatse City in Shigatse Region. Lhasa Chengguan District is particularly significant. (2) Population shows a significant characteristic of distribution along the river. 80.46% of the population lives in the area less than 10 km to the river and there is a significant exponential correlation between population and the distance to rivers. The population density within 2 km from the river is higher than 50 persons / km². (3) Nearly 99% of the population locates at an altitude of 4500 m or less. When the altitude exceeds 3800m, population density with elevation shows a downward trend. (4) Nearly 70% of the population distributes in the area with slope gradient less than 15°. The greater slope, the smaller population density. The slope aspect has no significant influence on population distribution. (5) RDLS has a relatively significant influence on population distribution. 85% of the population is located in the regions with RDLS less than 800 m. The population density and RDLS are in inverse exponential relationship.