50年来东北黑土区土地利用变化对沟蚀的影响——以克东地区为例

Effect of land use change on gully erosion in black soil region of Northeast China in the past 50 years: A case study in Kedong county

以位于东北典型黑土区的克东地区作为研究区,以1965年的Corona、2005年的SPOT5和2015年高分一号影像作为数据源,通过目视解译获取研究区对应年份的侵蚀沟分布状况;以1954年地形图和1975年的Landsat/MSS、2005年和2015年的Landsat/TM影像为数据源分别获取1965年、2005年和2015年土地利用数据;以侵蚀沟裂度为指标从土地利用变化角度分析研究区近50年来沟蚀变化状况。结果表明:黑土区沟壑侵蚀状况日益严重,耕地中侵蚀沟面积最大、侵蚀沟裂度增长速度最快;耕地、草地和建设用地上沟蚀状况的加剧伴随着林地和未利用地的开垦;耕地和草地相互转换裂度变化最大,退耕还林还草短期内侵蚀沟裂度仍然很高,但随着近10年来"退耕还林"的推行和用地状况的改善,沟蚀虽仍在发展但速度趋于缓慢。

The black soil region of Northeast China is one of the most important grain producing areas in China. However, increasingly severe gully erosion has destroyed much farmland and reduced grain production. In this paper, a typical black soil region, located in Kedong county, Heilongjiang province of Northeast China, was chosen as the study area. Based on Corona imagery in 1965, SPOT 5 imagery in 2005 and Gaofen-1 imagery in 2015, the distributions of gullies in 1965, 2005 and 2015 were obtained by visual interpretation. Based on relief maps in 1954, MSS imagery in 1975 and Corona imagery in 1965, the land use data in1965 were obtained. Based on TM imagery in 2005 and 2015, the land use data in 2005 and2015 were obtained. Then by using erosion density as the main indicator, the change of erosion gully was analyzed from the perspective of land use change. The results revealed that the gully erosion in the study area deteriorated in the past 50 years. The area of severe erosion greatly increased and showed a contiguous development trend. The cultivated land was the most important type of land use in the study area, and gully erosion on the cultivated land was the most serious. With the increased gully erosion on cultivated land, grassland and construction land, forest land and unused land were constantly reclaimed. The gully density increased the most during the interchange between cultivated land and grassland. The gully density was still very high and changed greatly after cultivated land was returned to forest land and grassland in the short term. However, with the implementation of"returning farmland to forest"and the improvement of land use, the gully erosion is still developing, but it changed slower over the ten years. By analyzing gully density change in the process of land use conversion on different slopes from 2005 to 2015, we found that the development of gully erosion is prone to occur after the forest land, grassland and unused land are cultivated on higher slopes, and it is more difficult to manage gullies with higher slopes.