皇甫川流域土地利用变化与生态安全评价

基于"3S"技术揭示了皇甫川流域近十多年来的土地利用变化状况,并进一步在像元水平上对流域生态安全进行了综合评价,最后重点分析了流域土地利用变化与生态安全的关系。结果表明：① 近十几年来,皇甫川流域土地利用变化剧烈,土地利用格局持续承受着来自当地快速城市化进程及社会经济发展和生态环境保护及建设两方面相互矛盾的巨大压力;② 1987年到2000年,流域生态安全状况有所好转,但整体好转的状况难掩局部地区生态环境在大规模治理和恢复的背景下发生的恶化;③ 流域内林地、耕地、灌丛、水体、城镇用地和草地从面积上看,基本上均处于生态安全的预警状态,而裸砒砂岩和沙地的绝对大部分属于中警状态或重警 (巨警) 状态;④ 6种不同土地利用类型的安全指数大小顺序基本保持为灌丛 > 林地 > 草地 > 耕地 > 沙地 > 裸砒砂岩,表明林、灌措施是流域生态恢复和重建的首选和重要组成部分,而沙地尤其是分布面积较广的裸砒砂岩则是流域生态环境综合治理的难题和关键。最后,提出了通过优化流域土地利用格局来确保生态安全的初步设想。

Land Use Change and Eco-security Assessment of Huangfuchuan Watershed

Supported by "3S" technology, this paper analyses land use change in Huangfuchuan Watershed from 1987 to 2000, conducts a synthetic eco-security assessment on the watershed by multiplication algorithm model on the pixel scale, and discusses the relationship between different land use patterns and eco-security of watershed. The results showed: (1) In recent 10 years, the general tendency of land use change in the study area was that the proportion of urban land, woodland, cropland and shrub increased constantly and that of water area, grassland, sandy land and bare rock decreased gradually. During this period, the watershed land use pattern was under the tremendous pressure from the conflict between the rapid urbanization, economic development and the conservation and rehabilitation of eco-environment. The distinct decline of water area is the bottleneck of this contradiction. (2) From 1987 to 2000, the average synthetical eco-security index rose from 6.033 to 6.506. It is sure that the eco-environment of the whole watershed has been improved. However, eco-environment in some areas even went worse despite of large-scale comprehensive harnessment. (3) In Huangfuchuan Watershed, most of the sandy and soft rocky lands are in a moderate-warning or serious-warning state of eco-security, and the rest of the land use types basically in a light-warning state of eco-security. (4) Land use types are closely correlated with eco-security. The order of eco-security index is: shrub > woodland > grassland > cropland > sand > soft rock, which indicates that measures taken based on woodland and shrub are the priority and important means for ecological restoration of the watershed. Furthermore, the sandy land and bare rocky land are the key problems of comprehensive harnessment of the watershed, which could not be overlooked. Generally, this paper emphasized the impacts of different land use types and patterns on eco-security of watershed and put forward suggestions concerning the adjustment or optimization of land use pattern and improvement of the technical system for eco-security assessment based on simulation and prediction of land use change, which would have wide application prospectives in the future.