黄土沟壑区小流域土地利用变化及驱动力分析

小流域综合治理是黄土高原减少土壤侵蚀和发展经济的成功经验。作为黄土高原沟壑区的典型代表,王东沟流域的土地利用变化反映了流域治理的过程。利用其1986、1994和2004年的土地利用数据,研究了该区18 a间的土地利用变化规律,探究土地利用变化的驱动力,并使用GM(1,1)灰色模型对王东沟流域未来的土地利用变化趋势进行了分析。结果表明:1986~2004年间王东沟流域各土地利用类型变化的面积大小依次是农地>果园>林地>非生产地>草地,就土地利用类型的变化速度而言,依次为果园>农地>林地>非生产地>草地;以1994年为界将1986~2004年划分为两个时期,两个时期的土地利用变化规律有所不同;利用矢量图叠加,发现1994~2004年流域45.48%的土地发生了土地类型的变化,土地利用变化类型主要有9种,农地转出的类型和林地转入的类型占多数;社会经济驱动、人为积极治理和政策导向是王东沟流域土地利用变化的主要驱动力;GM(1,1)趋势分析表明在今后一段时间内,影响因子不变的前提下,果园面积仍有增加趋势,农地面积需要进行人工调控以保持一定的规模。

Dynamic Change of Land Use in Wangdonggou Watershed in Gully Region of the Loess Plateau

Small watershed comprehensive management is a new form of decreasing soil erosion and developing economic in Loess Plateau.As a typical representation of gully region in Loess Plateau,Wangdonggou watershed has succeeded in comprehensive management and its land use change can reflect the process.Based on the land use data of 1986,1994 and 2004,this paper firstly discusses the law of land use change and then analyzes its driving forces,finally the trend of land use change is predicted with GM(1,1) model.The results show as follows: Firstly,from 1994 to 2004,the area order of land use changes is cultivated land > orchard > forest land > nonproductive land > grassland.Secondly,the speed of land use changes is in order of orchard > cultivated land > forest land > nonproductive land > grassland.By 1994,1986~2004 can be divided into two phases which have different laws of land use change.The dominating trend of the first phase is Orchard and forest land's decrease and that of the second phase is the decrease of the cultivated land and orchard.Through overlaying vector-graph,the result shows that about 45.48 percent of land changed during 1994~2004,there are nine kinds of land use change and two are in majority,that is cultivated land switched to other land and other land shift to forest.Thirdly,social economic,active management and policy are the main driving forces of land use change.Fourthly,on condition that the affecting factors keep invariable,the analysis of GM(1,1) model shows that orchard will keep increasing and cultivated land will keep decreasing;we must take actions to control the area of cultivated land to keep it within size.