潮白河上游土地利用的时空变化特征与驱动力分析

本文以1990年和2000年两期土地利用数据和社会经济数据为基础，采用变化率、土地利用转移矩阵、动态度等指数分析方法，对潮白河上游1990~2000年间土地利用的变化及驱动因子进行了分析。结果表明，在1990年到2000年10年间，由于生态保护和植树造林，潮白河上游土地利用发生了很大变化，突出表现为草地与耕地往林地的转移。从变化的空间差异看，赤城县以及几个县的交界地区土地利用变化最剧烈。从土地利用变化的原因看，生态建设和农业结构调整对土地利用影响深刻，是区域土地利用变化最重要的驱动因子。

A Spatiotempral Analysis of Land Use Change and its Driving Forces in the Upper Reaches of the Chaobai River, North China

The upper reaches of the Chaobai River are the water supplying source of the Miyun Reservoir that supplies a major part of water consumption of Beijing. In the past decades, the runoff in the Chaobai River showed a decreasing trend. In addition to the increased water use in the reaches, land cover change is also acknowledged as an important one of the factors affecting the runoff. To contribute to the understanding of hydrological variation in the river, this paper conducts a spatial and temporal analysis of land cover changes in the 1990s, taking small watersheds as the study unit using digital land use maps in 1990 and 2000, with the help of ARCVIEW and EXCEL software. Further, it identifies major factors affecting the land cover change. In this region, a large amount of grassland and cultivated land was transferred to forestland in 1990~2000, and thus resulted in a substantial increase of forest coverage but a great shrinkage of farmland and grassland. In the 10 years, forestland increased 24.02×104 ha, while farmland and grassland reduced 6.28×104 ha and 17.19×104 ha, respectively. Water area shows a great shrinking, with the area decreased by 60%, reflecting the decreased availability of water resource. Built-up area had a marketable expansion, increased by 36.5%. Spatial analyses indicate that land use changes are greater in Chicheng County and in the bordering areas of several counties than in other areas. Three major factors contributed to the land use changes in this region, i.e., ecological rehabilitation, afforestation, and agricultural restructuring. Population growth and urbanization rate were low in the period of 1990~2000, and have a limited effect on the land use change.