城市水源地植被覆盖度遥感估算与时空变化动态分析

Remote Sensing Estimation and Temporal-spatial Variation Dynamic Analysis of Vegetation Coverage in Urban Water Source

选取云南省昭通市渔洞水库流域1996-2012年6期TM/ETM影像数据提取归一化植被指数(NDVI),根据像元二分模型利用不同时期NDVI计算了流域植被覆盖度,得到渔洞水库流域植被覆盖度分级图。结果表明:该区域1996-2012年间植被覆盖度变化明显,平均植被覆盖度从1996年0.306增加到2012年0.356,增加值为0.05,植被覆盖度增加区域的面积达到412.44km2,约占流域总面积的58.17%。其中2000-2008年间为植被恢复期,植被覆盖度呈现持续增长趋势,2008-2012年间为植被退化期,植被覆盖度持续减小。1996-2012年间,高植被覆盖度区域增加显著,主要分布在流域东部、中偏西部以及东南部地区,而2008-2012年间流域西北部地区植被覆盖度等级有明显下降情况,且历年来高植被覆盖度集中的东部地区也呈现植被覆盖度等级明显下降的情况。

This paper selects 6 TM/ETM image data of Yudong Reservoir Watershed in Zhaotong City of Yunnan Province from 1996 to 2012,and calculates normalized vegetation index （NDVI） of different periods.It estimates the vegetation coverage of Yudong Reservoir Watershed between 1996 and 2012 based on the pixel binary model,and then obtains the classification map of vegetation coverage in Yudong Reservoir Watershed.The results show that：vegetation coverage changes greatly between 1996 and 2012,the vegetation coverage increased from 0.306 in 1996 to 0.356 in 2012,increased by 0.05,the increased area of vegetation coverage reached 412.440 km2,accounting for about 58.17％ of the total area of the watershed.The recovery period of vegetation was 2000 to 2008,vegetation coverage showed a trend of sustained growth,and the period of 2008 to 2012 was the vegetation degradation,vegetation coverage continued to decrease.On the other hand,the high quality of vegetation coverage area increased significantly between 1996 and 2012,especially in the east,middle west and southeast regions of the watershed,but the level of vegetation coverage obviously decreased in the northwest between 2008 and 2012.Actually the high quality of vegetation coverage also decreased in the east.