基于GIS的甘肃省土地利用程度高程模型构建

Elevation model for land use degree of Gansu province based on GIS

土地利用垂直分异规律是土地利用空间分异规律研究的重要内容之一,其定量研究可为模拟和预测土地利用程度变化提供理论基础和途径。以甘肃省土地利用程度垂直分异为研究对象,运用GIS空间分析技术对土地利用数据和数字高程模型(DEM)数据进行处理,结合数理统计分析方法构建了甘肃省土地利用程度高程模型。研究表明:甘肃省土地利用程度随高程变化呈现出4个趋势:1)海拔高度600～1120m之间,土地利用程度随海拔增高表现为线性递减趋势;2)在1130～3600m高度带内,土地利用程度呈先增后减趋势,且在2600m附近达到最大值;3)在3610～5530m高度带内,土地利用程度呈先减后增趋势,即土地利用程度与海拔高度呈"U"型关系,且在4550m附近达到最小值;4)在海拔高度5530m以上,土地利用类型单一且均为水域,因此土地利用程度保持不变。最后,结合各区域自然条件和经济发展水平对土地利用垂直分异规律成因进行了探讨,分析发现数量众多的未利用和难利用土地是导致土地利用程度整体较低和呈现不同垂直分异特征的主要原因。

Land use vertical differentiation is one of the main research content of land use spatial differentiation. Its quantitative research can supply an approach and a theoretical basis for simulating and forecasting change of land use degree. Based on the GIS technology and mathematical statistics methods, some available data including land use and digital elevation model （DEM） were used to build the elevation model of land use degree in Gansu province. The results show that there is an intensive relation between the comprehensive index of land use degree and altitude. Its representation is described as follows ： （ 1 ） The comprehensive index of land use degree has a linear decreasing tendency from 600 m. a. s. 1 to 1120 m. a. s. 1; （2） The comprehensive index of land use degree from 1130 m. a. s. 1 to 3600 m. a. s. 1 first ascends and then descends with the rise in elevation, and arrives at the maximum value 221 in 2600 m. a. s. 1; （3） Compared with the variation tendency from 1130 m. a. s. 1 to 3600 m. a. s. 1, the relation between the comprehensive index of land use degree and altitude exhibits as a reverse trend similar to a ＂U - shape＂ curve from 3610 m. a. s. 1 to 5530 in. a. s. 1, and its minimum value appears in 4550 m. a. s. 1; （4） The comprehensive index of land use degree above 5530 m. a. s. 1 is 200 because there is only one land use type which is water. Finally, based on analysis on regional physical endowments and economic development, numerous unutilized land and wasteland are found to be the main factor leading to a low compre- hensive index of land use degree and a different characteristic of vertical differentiation in Gansu province.