雅砻江流域二滩水库周边植被变化

目的]定量研究二滩水库蓄水以后库区周边植被的变化规律,为水库蓄水对周围边植被生长变化的影响研究提供依据。方法]以遥感影像为试验数据,基于归一化植被指数的像元分解模型对研究区1999—2014年每年11月份的植被覆盖度进行估算,并依据土壤侵蚀强度分类分级标准对估算结果进行分级,通过波段运算结合阈值分割对植被覆盖状况变化较为明显的区域进行检测。结果]自1999—2014年,研究区整体植被覆盖状况逐年变好,主要表现为高覆盖度区域面积逐年增大;局部地区受到人类活动、土壤侵蚀、耕地以及滑坡的影响植被覆盖度降低,约占总面积的19.5%;植被覆盖状况显著变好的区域约占总面积的39.8%,主要集中在距离水库较近的区域。结论]二滩水库蓄水改善了库区周边植被的生长条件,植被覆盖状况整体逐年变好。

Vegetation Changes Around Ertan Reservoir in Yalongjiang River

Objective] To study the changes in vegetation coverage around Ertan reservoir when it is filled with water, in order to provide the basis for assessing the impact of reservoir filling on vegetation growth surround the reservoir.Methods] We used the dimidiate pixel model to predict the vegetation coverage of the study area in each November from 1999 to 2014 with the Landsat TM and environmental CCD images as the information sources. We then detected areas with obvious changes in vegetation cover through waveband operation and threshold segmentation.Results] From 1999 to 2014, the vegetation cover in the study area increased year after year, and the high coverage area expanded greatly. However, the vegetation cover decreased in some areas due to human activities, soil erosion, farmland and landslide, which accounted for 19.5% of the total area; the region with obvious increase in vegetation cover accounted for about 39.8% of the total area, mainly concentrated areas near to the reservoir.Conclusion] The Ertan reservoir had improved the growth of vegetation around, and the vegetation cover has increased year by year as a whole.