应用遥感数据评价蓝藻水华对太湖取水口的影响

Impact assessment of cyanobacteria bloom on water intakes in Taihu Lake using remote sensing data

为量化蓝藻水华对太湖饮用水取水口的影响,将太湖矢量图进行栅格化,根据权重函数计算像元的权重因子;再将权重因子图与由遥感影像得到的水华分布图进行叠加,对对应像元进行影响因子计算;最后根据像元的影响因子求出归一化影响指数（NII）,并以此进行影响评价.通过对2007年5月1-16日太湖MODISEVI影像进行的实例分析和验证,表明该方法能较好地反映太湖水华对取水口的影响程度,与实际情况符合;在提出的3种权重函数模型中,负指数模型和正态分布模型能较好地反映蓝藻水华对饮用水取水口的影响程度,可以作为影响评价的权重模型.

A new method based on remote sensing data was proposed to quantitate the impact of cyanobacteria bloom on drinking-water intakes in Taihu Lake. At first, the vector map of Taihu Lake was converted to grid map and the weight factor of each grid was calculated by weighting function. Secondly, the weighted grid map and the cyanobacteria distribution map based on remote sensing data were overlaid to calculate the impact factor of each grid. Finally, the normalized impact index （NII） was generated to assess the impact of cyanobacteria bloom on water intakes. According to the application of this method using MODIS EVI image on 1st to 16th May 2007 in Taihu Lake, the method performed well and was accorded with the distribution of cyanobacteria. It was also suggested that among the 3 weighting function models, the negative exponential model and normal distribution model were better than the linear one, and were suitable for impact assessment.