黄河口生态脆弱区土地利用时空变化及驱动因素分析

黄河三角洲是典型的生态环境脆弱区,在人类活动及自然环境相互作用下土地利用变化剧烈,是研究土地利用变化的热点地区。该文以黄河口垦利县为研究区,选用1989年、1995年、2000年、2005年及2011年5个时相的遥感影像,获取各时相土地利用信息,利用土地利用变化相关模型,分析了研究区20余年来土地利用的时空变化特点,并对其驱动因素进行了探讨。结果表明:研究区土地利用变化的主要特征是旱地、林草地面积减少和建设用地、水域、盐荒地、滩涂面积的大幅增加。2000年之前总体土地利用变化程度高于后期,单一土地利用动态度,河流水面、水域及建设用地表现较明显。研究时段内旱地、盐荒地、水田、建设用地重心均向西南方向迁移,林草地、河流水面、滩涂重心则向东北方向迁移,水域重心转向西南,但整体地域分布特点变化不大。蒸降比大、偏砂质地土壤、地下水埋深浅且矿化度高、黄河断流等气候水文因素是该区土地利用覆盖变化的主导自然驱动,人类不合理的农业开发活动是主要人为驱动。该研究为黄河口生态脆弱区资源环境的利用保护和社会经济的可持续发展提供依据。

Land use spatiotemporal changes and its driving forces analysis in vulnerable ecological region of Yellow River Estuary

The Yellow River Delta is a typical eco-environmental fragile region where land use changed intensively due to the interaction of human activities and natural environment; hence, it is a hot spot area for land use and land cover change (LUCC) research. This study was conducted in Kenli county of the Yellow River Estuary using five temporal remote sensing images of 1989, 1995, 2000, 2005 and 2011 to extract land use information of different times. Land use temporal and spatial characteristics in more than 20 years of the study area were analyzed using land use dynamic degree model, land use degree composite index model and land use gravity center transfer model, and their driving factors were further explored. The results showed that the main characteristics of land use changes in the study area were that the dry land and forest-grassland were decreased, and the construction land, water area, salt wasteland and shoaly land were increased. The overall degree of land use changes before 2000 was 2-3 times higher than that of the later period, which indicated that the trend of changes was rapid before 2000 and slow after that. The single land use dynamic degree of river water surface, water area and construction land was comparatively distinct. The land use spatial pattern appeared obvious features in distribution with regular variation. Within the studied time period, the gravity center of dry land, salt wasteland, paddy fields and construction land all moved to the southwest, while the gravity center of forest-grassland, the river water surface and shoaly land moved to northwest, and that of water area turned to the southwest with little changes in distribution as a whole. Driving forces of land use changes in the study area included two aspects of natural and human related factors. The climatic and hydrological factors including high ratio of evaporation to rainfall, sandy soil texture, shallow ground water with high salinity, and cutoff of the Yellow River were the dominant natural driving forces for land use changes, and unreasonable farming exploitative activities of local people were the main artificial driving forces. This study provides a reference for the utilization and protection of resources and environment, and sustainable development of society and economy in the vulnerable ecological region of the Yellow River Estuary.