基于MODIS植被指数估算青海湖流域植被覆盖度研究

将MODIS数据合成的4种植被指数作为输入参数,采用像元二分模型对研究区的植被覆盖度进行估算,利用2006年的TM数据解译结果和2011年8月的野外实测数据对反演结果进行验证。结果显示:采用ND-VI估算的植被覆盖度比较符合研究区实地状况,样点估算精度达到87.13%;其他3种植被指数估算的植被覆盖度值比实际值低,尤其是对该区域典型植被草原草甸的覆盖度估算结果明显偏低。研究表明:2011年8月青海湖流域植被覆盖度以中高覆盖度为主,占整个流域面积的57%以上;植被覆盖度在空间上呈中部高、西北低的分布特点。

Estimation Vegetation Coverage Based on Vegetation Index of MODIS Data in Qinghai Lake Watershed

The Qinghai Lake watershed is the natural barrier which controls the desertification spreading for west to the east.Because of the simple structure of the grassland ecological system here,the area is fragile.Vegetation coverage is a effective index that measure the vegetation and ecological environment of the watershed.A dimidiate pixel model was adopted to estimate the vegetation coverage of the study area,and four different vegetation index form MODIS data were used as the input parameters.The vegetation coverage result precision was validated with the reference of 2006 TM data interpretation results and the field investigation data in August 2011.The results show that:the vegetation coverage based NDVI estimation is consistent with the study area condition,sample estimate precision is 87.13%;the vegetation coverage of other three vegetation index estimation value is lower than the actual value,especially the estimation results of the typical grassland meadow coverage is apparent on the low side.The results show the vegetation coverage is high in Qinghai Lake watershed,more than 57% with high and middle vegetation coverage in 2011 August.And the distribution characteristic is middle part high and northwest part low.