甘肃省民勤县土地利用/土地覆盖变化遥感分析

Remote Sensing on the Changes of Land Use and Land Cover in Minqin County of Gansu Province

以西北干旱典型分布区-甘肃省民勤县为例,采用2000年和2010年两期Landsat TM遥感影像,应用决策树分类法进行土地利用/土地覆盖类型划分,特别细分了未利用地类型。在此基础上,从各种土地利用/土地覆盖类型的面积变化、土地利用/土地覆盖类型间的转移以及土地利用动态度等角度分析西北干旱区土地利用/土地覆盖类型的变化规律。结果表明:实验区土地利用/土地覆盖类型以未利用地占研究区的面积最大,而未利用地中又以戈壁、流动沙地、风蚀劣地三者为主;10 a间,土地利用动态度变化明显,林地、草地面积大幅减少,耕地面积增加,耕地增加面积主要来源于林地、草地转换,说明这期间,人类毁林、垦植现象明显,生态环境有所恶化;未利用地中盐碱地面积减少,流动沙地、干沟面积增大,风蚀劣地面积变化不大,盐碱地部分转化草地,干沟与流动沙地由风蚀劣地部分转化得来,草地、耕地部分转化成风蚀劣地,流动沙地与风蚀劣地之间相互转化,这些变化既有人为因素的影响,也有自然因素的影响,说明人类活动及自然因素同时影响着研究区内未利用地类型的变化。

With the data obtained from two composite Landsat5 TM images of 2000 and 2010 in a typical arid region of Minqin County, Gansu Province, we classified the arid land, especially unused land by using the decision tree classification method, and explored the changes of land use, land cover type area, change degree and transition. The unused land takes up the largest area in Minqin County, mainly containing gobi, desert and Aeolian barren lands. Land use dynamic changed dramatically in ten years, while forestland and glassland area decreased, cropland area increased, and the increased cropland area mainly came from forestland and grassland, which indicated that deforestation and reclamation were distinct during the study period, and the ecological environment became worse. In unused land, saline alkali land area decreased, and the mobile sand land and hondo area increased. Aeolian barren land area changed little. Part of saline alkali area convetted to grassland, the mobile sand land and hondo were converted from aeolian barren land, which were converted from glassland and cropland. There was also mutual transformation between mobile sand land and aeolian barren land. The unused land use changes were simuhaneously influenced by artificial factors and natural factors.