基于遥感影像的黄土高原沟壑区生态效应评价

水土流失和生态退化是当今黄土高原面临的主要生态问题,已严重制约区域经济发展。该文基于Landsat TM和OLI数据,估算了黄土高原沟壑区的遥感生态指数(remote sensing ecological index, RSEI),定量分析了2002、2009、2017年甘肃、陕西、山西3个主要塬区的生态安全特征,并指出了需要重点治理的区域。研究结果表明:与2002年相比,2017年甘肃塬区的遥感生态指数呈微弱增长(增加0.04),陕西塬区总体呈现改善的趋势,遥感生态指数由0.45(2002)增加至0.56(2017),山西塬区遥感生态指数由0.54(2002)减少至0.46(2017)。与2002年相比,2017年甘肃塬区中生态条件差、较差区域减少,良好、优秀的区域增加;陕西塬区中生态条件差、较差区域减少,中等、良好的区域增加,优秀的区域保持稳定;山西塬区中生态条件差、较差和中等的区域增加,良好、优秀的区域减少。甘肃塬区的蒲河和洪河流域,陕西塬区的沮河、三水河、泔河和漆水河流域以及山西塬区的州川河和鄂河流域目前的生态环境仍呈现退化趋势。3个塬区中,甘肃、陕西塬区生态条件得到不同程度的改善,山西塬区生态条件虽有下降,但生态条件改善趋势已初现端倪,随着各项水土保持和生态恢复措施不断实施深入,3个塬区生态环境将会有效改善。该研究结果对黄土高原塬面地区生态恢复、水土流失综合治理具有重要指导意义。

Evaluation of ecological effect of gully region of loess plateau based on remote sensing image

Abstract: Soil erosion and ecological degradation are the most important ecological environment problems for the Chinese Loess Plateau in recent years, which have seriously hindered the sustainable development of the economy of the Chinese Loess Plateau. Based on the remote sensing image data of the Landsat TM and OLI, the remote sensing ecological index (RSEI) of the tableland protected regions of the Gansu, Shaanxi and Shanxi in the Chinese Loess Plateau were estimated during the period of 2002, 2009 and 2017 in this paper, and the influences of the change of the ecological restoration were also quantitatively evaluated. Besides, the locations of the regions of main ecological degradation were also screened out in this study. The results show that: (1) compared with the results of 2002, the remote sensing ecological index of the Gansu tableland region in 2017 showed a slightly increasing trend (increased by 0.04). Besides, the RSEI of the Shaanxi tableland region in 2017 also showed an obviously increasing trend, and the RSEI increased from 0.45 (in 2002) to 0.56 (in 2017), which indicated that the ecological environment of the Shaanxi tableland region has been improved. The RSEI of the Shanxi tableland region decreased from 0.54 (in 2002) to 0.46 (in 2017), which indicated that the ecological environment of this region has been degraded. (2) Compared the results of 2017 with 2002, the areas of the poor ecological conditions and relatively poor ecological conditions in the Gansu tableland region reduced obviously, while the areas of the good and excellent ecological conditions showed an increasing trend. In the Shaanxi tableland region, the areas of the poor ecological conditions and the relatively poor ecological conditions also demonstrated a decreasing trend, while the areas of the medium ecological conditions and the good ecological conditions increased significantly, the excellent areas presented a fairly stable status. In the Shanxi tableland region, the areas of the poor ecological conditions, the relatively poor ecological conditions and the medium ecological conditions presented increasing trend, while the areas of the good ecological conditions and the excellent ecological conditions showed a decreasing trend. (3) In the Gansu tableland region, the degradation of ecological environment mainly located in the Puhe and the Honghe river basins. In the Shaanxi tableland region, the degradation of ecological environment mainly distributed in the Juhe, Sanshuihe, Ganhe and Qishuihe river basins. In the Shanxi tableland region, the ecological environment degradation areas concentrically located in the Zhouchuanhe and Ehe river basin. (4) Compared the three tableland regions, the ecological conditions in the Gansu tableland regions and the Shaanxi tableland region have been remarkable improved during the period of 2002-2017. Although the ecological conditions in the Shanxi tableland region have declined, the improvement trend of ecological conditions has emerged in this study area. With the continuous implementation of various soil and water conservation and ecological restoration measures, the ecological environment in these three tableland regions of the Chinese Loess Plateau will be effectively improved. The research results of remote sensing ecological security in this paper have a far-reaching significance for the ecological restoration of the tableland regions of the Chinese Loess Plateau, and it is informative for the comprehensive control of regional soil erosion.