大伙房水库上游流域土地利用变化及地形梯度效应分析

Terrain Gradient Effect Analysis of Land Use Change in the Upper Reaches of Dahuofang Reservoir

为揭示大伙房水库上游流域的土地利用空间变化在地形差异上的转变过程,探讨流域内自然和人文等因素在土地利用空间变化中的作用,以大伙房水库上游流域的1987,2002和2015年3期Landsat TM/OLI遥感影像和DEM数据为数据源,分别进行土地利用分类、构建土地利用变化图谱和计算地形位指数并进行梯度分级,分析研究区土地利用变化情况以及利用分布指数,分析各土地利用类型和土地利用变化图谱类型的地形梯度效应,探讨地形因子对土地利用变化的影响。结果表明:研究区内主要土地利用类型为林地和农田,林地主要分布在中、高地形梯度,而农田、建设用地和水体主要分布在低地形梯度,草地主要分布在低、中地形梯度。1987~2015年间林地和草地面积减少,农田、建设用地、矿体面积增加;土地利用变化图谱以稳定型为主,占总研究区面积的65.56%,其中稳定型在中高和高地形位梯度占优势,且以中高地形位上的林地稳定不变为主要类型,占稳定型图谱的78.46%;前期变化型、后期变化型、反复变化型和连续变化型的优势区段均在低、中地形位梯度上,各变化图谱中均以中、低地形梯度上的林地和农田的互相转化为主要变化类型,且1987~2015年间农田有从低向较高地形较梯度推进的趋势。土地利用变化及其地形梯度分布特征是自然因素、社会经济因素和政策因素共同作用的结果。目前研究区土地利用空间变化整体较为稳定并趋于合理,但仍存在不合理的毁林开荒和侵占农田的现象,需要加强土地利用的科学规划和合理布局。

In order to reveal the change process of land use spatial change in the upper reaches of Dahuofang Reservoir in terms of topographic differences and to explore the role of natural and human factors in the spatial change of land use,Landsat TM/OLI remote sensing images and DEM data of the upper reaches of Dahuofang Reservoir in 1987,2002 and 2015 were used as data sources.Land use classification and land use change TUPU and topographic niche index were constructed to analyze the Land use change,the topographic gradient effect of the land use types and the land use change TUPU in the study area.The results showed that forest and farmland were the main types of land use in the study area,forest was mainly distributed in middle and high topographic gradient,farmland,construction land and water are mainly distributed in low topographic gradient,grass is mainly distributed in low and middle topographic gradient.From 1987 to 2015,the area of forest and grass decreased,and the area of farmland,construction land and orebody increased.Land use change TUPU is dominated by stable type,among which the stable type was dominant in mid-high and high terrain position.The stability of forest land distributed in middle and high topographic gradient was the main type,accounting for 78.46%of the area of stable type.The dominant regions of prophase change type,anaphase change type,repeated change type and continuous change type were all in low and middle topographic gradients,and the main variation types were the conversion of forest and farmland on low and middle topographic gradients,and the trend of farmland advancing towards higher topographic gradient during 1987 to 2015.Under the joint action of natural,social and policy factors,the pattern of land use in the study area was changed.At present,the spatial change of land use in the study area was relatively stable and tended to be reasonable,but there are still unreasonable phenomena of deforestation,reclamation and occupation of farmland.It is necessary to strengthen the scientific planning and rational distribution of land use.