基于栅格的豫西山区地形起伏特征及其对人口和经济的影响

地形起伏是约束山区人口分布和经济发展的关键因素,尤其在山地平原过渡带其约束作用更为显著。以位于秦岭-黄淮平原过渡带的豫西山区为例,基于200 m分辨率DEM数据,采用均值变点法确定地形起伏度的最佳统计单元,并提取地形起伏度;以1∶10万土地利用、乡镇人口和县域各产业数据为基础,建立人口和经济空间化模型,同时生成200 m分辨率的栅格人口和经济密度图;在系统分析地形起伏度、人口和经济密度空间分布规律的基础上,借助统计分析方法基于栅格单元定量揭示了地形起伏度对人口和经济的影响,并与其他地形因子的影响进行对比分析。结果表明：① 豫西山区地形起伏度以低值为主,58.6%的区域地形起伏度小于等于0.5个基准山体的高度（相对高差≤ 250 m）;空间上呈西高东低、中间高南北低的格局,与海拔、坡度均呈较强的正相关,且与坡度的相关性更大。② 被选作验证的人口和经济数据与对应模拟值的线性拟合度分别为0.943和0.909,表明空间化结果能反映人口和经济分布的实际状况。③ 地形起伏度对人口和经济的影响强于其他地形因子的影响,与人口密度和经济密度呈较好的对数拟合关系,拟合度分别为0.911和0.874;豫西山区88.65%的人口居住在地形起伏度不超过0.5的地区,88.03%的生产总值分布在地形起伏度不超过0.3的地区。相对人口分布,研究区的经济发展向地形起伏度低值区的集聚态势更加明显。

Spatial variation of terrain relief and its impacts on population and economy based on raster data in West Henan Mountain Area

Topographic relief can be the constraining factor for the population and economic development in an area. This is especially the case in transitional zones from mountains to plains. In this study, West Henan Mountain Area, situated in the transitional zone from the Qinling Mountains to the Huang-Huai Plain (i.e. the second step to the third step of Chinese macro-topography), was selected as a case study area. Based on the optimal statistical unit (OSU) as determined by the mean turning-point analysis method (MTPAM), a DEM of 200 m resolution was used to extract the relief degree of land surface (RDLS). Integrating the 1:100, 000 land use map, statistical population data at township level and economic data of various industries at county level, raster models of spatial patterns of population and economy were formulated, and then the spatial distributions of population density and economic density at a resolution of 200 m by 200 m were produced using the models. Subsequently, statistical analysis was carried out to reveal the effects that RDLS had on population and economy based on raster data (i.e. RDLS, population density, and economic density), and the differences between the effects of RDLS and those of other terrain factors on the population and economy were also analyzed. The results showed that: (1) the RDLS in the West Henan Mountain Area was prevailed by low value, with 58.6% of the area having the RDLS lower than 0.5 (relative altitude of ≤ 250 m). Spatially, RDLS was higher in the west and lower in the east, higher in the central part and lower in the south and the north. Moreover, there existed strong positive correlations between RDLS and altitude and slope, especially correlated with slope significantly. (2) The relationships between the statistical values (i.e. population density and economic density which were selected to test and verify the models) and the corresponding simulated values were fitted to linear models with 0.943 and 0.909 levels of goodness-of-fit. This fitness indicated that the spatialization results reflected well the actual spatial patterns of population and economy in the study area. (3) The effect of RDLS on population and economy is stronger than that of other terrain factors. RDLS had a good logarithmic fit with population density and economic density, with 0.911 and 0.874 goodness-of-fit, respectively. Specifically, 88.65% of the total population lived in the areas where RDLS was less than 0.5 and 88.03% of the gross regional production was distributed in the areas where RDLS was less than 0.3. It can be clearly seen that economic development was more inclined to agglomerate in areas of lower RDLS values compared with population distribution.