【作者】 张建明；

【导师】 李吉均；

【作者基本信息】 兰州大学 ， 自然地理学， 2007， 博士

【摘要】 土地利用／覆被变化研究是全球变化研究的热点，根据多源遥感数据研究区域性土地利用／土地覆被变化特征，探讨其驱动力和环境效应是基本的研究方法。石羊河流域位于甘肃河西地区东部，属干旱区内陆河流域。由于特殊的自然地理条件和不合理的人类活动，生态环境退化，出现了严重的生态危机，成为我国干旱区内陆河流域生态退化的典型和社会各界广泛关注的焦点。本研究立足于这一典型区域，在综合分析评价石羊河流域自然环境和社会经济条件的基础上，采用卫星影像计算机监督分类和目视解译相结合，判读3期土地利用／土地覆被情况，划分石羊河流域生态功能区，以此为基础分析20年来的土地利用变化特征。研究成果可为可为石羊河流域水资源合理开发及生念环境重建提供科学依据，也可为全球变化背景下区域性土地利用／覆被变化研究提供案例。本文的主要内容和研究结论如下：1．土地利用变化特征采用中科院地理所制订的全国土地利用遥感分类系统，采用以分层分类为主的监督分类结合目视解译，对1974年MSS、1987年TM、1999ETM年、2006年CBERS等多光谱遥感数据源划分出六个一级类型、22个二级类型。研究发现，土地利用变化的主要类型是水浇地和建设用地，重点我域主要集中于绿洲与荒漠的过渡地带。20年来总耕地面积增加7％。1999年耕地面积69.55万hm~2，较1987年增加了3.95万hm~2，增加6％。1999-2006年，在旱地面积减小的同时，灌溉面积增加3.52万hm~2，增加6.2％。1999—2006年旱耕地面积缩小可归于西部大开发以来的退耕还林政策利祁连山自然保护区的保护力度加强。许多靠近绿洲边缘、地下水条件相对较好地区被开发为耕地。林地、疏林及灌木林地是绿洲内较为敏感的土地利用类型。林地面积1987—1999年基本稳定，1999—2006年有所减少，主要是疏林地和灌木林地，分别减少12％和16％。草地的总面积变化不大但草地质量下降，表现在高覆盖度草地面积1987—1999年间基本稳定，1999—2006年减少4.46万hm~2、24％，中低覆盖度草地的面积相应有所增加。水域面积变化不大，冰川退缩明显。过去二十年来冰川消融16km~2，约占原有冰川面积的25％。建设用地中，农村居民地的面积增加，城镇和工矿用地面积也有明显增长。其中，1999—2006年，农村居民点用地增加4248 hm~2、15％，工矿用地增加1465 hm~2、48％。沙地面积先降后升，由1987年的9325km~2下降到1999年的9141km~2；1999-2006年又增加到11483km~2。除了解译过程中存在的沙地和盐碱地的错分，也反映出部分半固定沙地活化，以及部分耕地撂荒的后果。未利用土地中，戈壁和盐碱地的面积变化不大，沼泽地面积从1987年的34750 hm~2下降到1999年的29802、再降低到2006年的21568 hm~2。2流域生态功能分区根据石羊河流域的自然地理特征、水资源利用状况及生态系统服务功能，把全流域划分为祁连山水源涵养功能区、走廊盆地绿洲功能区、北部荒漠与绿洲交互功能区和荒漠区等四个一级生态功能区，各功能区的土地利用变化表现出不同的特点。石羊河流域作为一个有机整体，其上下游间相互联系、相互影响，上游祁连山区是流域水资源的汇流区，中下游绿洲是流域社会经济发展的核心地区，绿洲与荒漠过渡带是抵御风沙、防止沙漠化的生态屏障。3．土地利用变化驱动力石羊河流域受到人类活动的强烈影响，人口增长、生活水平提高导致的生产生活需求增加是耕地扩张的原始动力。以种植业为主的产业结构导致生产的“外延式”发展，农业技术进步和市场价格变化加速或者减缓耕地的扩张速度，政策因素对耕地盲目增长起着诱导作用。更多还原

【Abstract】 Land use and land cover changes (LUCC) research has been the focus of global change research and has been paid great attention by scientists all over the world. It’s the basic method to exploit land use changes, their driving forces and environmental effects in regional scale by RS and GIS techniques. Shiyang River Watershed locates in the east of Hexi Corridor, Gansu, Northwest China. Due to unique physiographic conditions and profound effects of human activities, Shiyang River Watershed has been facing the serious ecosystems degradation and ecological crisis, and being the typical ecological degradation area of inland watershed in the northwest China. In this thesis, multi-sources remote sensing data, digital images processing and GIS techniques were combined together to study the land use/land cover changes, and eco-function zones in Shiyang River watershed were identified. Land use was classified as six first orders and twenty-two secondary types by the means of supervised classification and visual interpret with Landsat TM /ETM~+ and CBERS images, land use and land cover changes features in last 20 years was analysed in the watershed and eco-functional zones scale. The result will provide scientific references for water resources rational utilization and eco-environmant recovery in Shiyang River watershed, and would supply land use/land cover change research at regional scale as a case. The contents and conclusions of this study were as follows:1. Land use and land cover changes in Shiyang watershed The landuse/land cover was divided into 6 first orders and 22 secondary types according to CAS land resources classification framework proposed in 1995, based on Landsat TM images in 1987, ETM~+ in 1999 and CBERS CCD 2006. The results show that the key region of land use change focused on transition zone between the oasis and deserts. The irrigated croplands increased 6% in the past 20 years, in the mean while, rainfed croplands decreased from 1999 to 2006. The cultivation occurred in outside of oasis and regions with high groundwater tables. The total farmland in Shiyang River watershed was 6.955×10~55 hm~2, increased 6%.Forest land kept steady from 1987 to 1999, and decreased recently. The sparse forest land decreased 12% and shrubs decreased 16%, mainly occurred in Minqin oasis. Grassland quality decreased, indicating by dense grassland decreased 24% from 1999 to 2006, while middle and low coverage grassland kept steady or increased a little.The areas of waterbody change slowly, but glaciers withdraw was found comparing to Chinese Glacier Inventory, the glacier area was 48km~2, decreased 25%.The town and village occupying land increased greatly, from 15% to 48% respectively. The desert decreased from 1987 to 1999, then increased from 1999 to 2006, indicating desertification trend, although the error exists in images processing and interpretations.The swarm area decreased steadily from 1987 to 2006, indicating climate warming and drying trends in the area.2. Eco-function zones in the basin Based on the topographical characteristics and the ecological functions that should be untaken in Shiyang River watershed, the watershed was divided into four eco-functional zones, including water conservation forest zones of Qilian mountains, oasis zones of corridor-basin, transitional zones of desert and oasis, and desert zone. The water conservation forest zone of Qilian mountains was subdivided into glacier-snow with low vegetation cover zone, alpine meadow, shrub and water conservation forest zone and mountain grassland and hungriness-plain zone; oasis zone of corridor-basin was subdivided into oasis city zone and oasis agriculture zone; transitional zone between oasis and desert was subdivided into Minqin oasis zone, Changning oasis zone, and Jinchuan and Hexi Pu oasis zone; desert zone was subdivided into desert zone and desert-hungriness zone. As an integrated system, the upstreams and downrivers of Shiyang River depends on each other. The upstreams is the natural reservoirs of water resource, the downriver is ecological barriers to withstand blow sand and prevent land from desertification, and oasis in the middle low reach is the key area to sustainable development of whole watershed.3. The driving forces of land use changes in the river Increasing population, which stimulate the increase of production and demand of livelihood, was the original driving force of irrigated land expanding. The Shiyang River watershed has been dominated by strong human activities, the agricultural, especially plantation dominated industrial structure determined extension-type development mode. Improvement of agricultural production techniques accelerated the expansion of irrigated land. Political and institutional factors played an important role in land use and land cover changes in the river.更多还原