基于GF-5的滇池蓝藻水华空间分布特征研究

Study on the spatial distribution characteristics of cyanobacteria bloom in Dianchi Lake based on GF-5

滇池水体富营养化严重导致蓝藻水华爆发,因此文章基于GF-5高光谱数据,运用归一化植被指数(Normalized Difference Vegetation Index,NDVI)识别滇池的蓝藻水华发生状况,并通过对NDVI值域进行分类,进一步对比分析草海、外海蓝藻水华的空间分布特征及差异。结论如下:①NDVI值域的一般数量统计分析表明,草海和外海NDVI均值分别是-0.350和-0.708,说明草海蓝藻水华覆盖情况较外海更严重;②NDVI值域的分级分类统计表明,草海以轻度蓝藻水华区域为主,占草海总面积的73.36%,重度蓝藻水华区域占比为1.12%;外海以无蓝藻水华区域为主,占外海总面积的95.42%,中度和重度蓝藻水华区域占比分别为0.52%和0.11%;总体上,滇池蓝藻水华空间分布呈“北重南轻”的格局,草海蓝藻水华覆盖密度为80.45%,草海较外海更易于蓝藻水华生长,水质更差。此研究方法可有效实时地监测识别高原湖泊蓝藻水华发生的空间分布状况,丰富了基于高光谱遥感进行湖泊水域水质监测的方法,为促进滇池水资源的治理和开发利用提供科学依据。

Cyanobacteria bloom because seriously eutrophication in Dianchi Lake.This paper bases on GF-5 hyperspectral data and uses NDVI to identify the occurrence of cyanobacteria bloom in Dianchi Lake,and classifies the range of NDVI to further compare and to analyze the spatial distribution characteristics and differences of cyanobacteria bloom in Caohai and Waihai.Conclusions are as follows:①From the general quantitative statistical analysis of the NDVI range,we can get the NDVI mean values of Caohai and Waihai are-0.350 and-0.708 respectively,which means the cyanobacteria bloom coverage in Caohai is much more seriously than that in the Waihai.②According to the classification statistics of the NDVI range,we can conclude that Caohai is dominated by the mild cyanobacteria bloom area,which accounts for 73.36%of the total area of Caohai.The proportion of severe cyanobacteria bloom area was 1.12%.Waihai is dominated by the area without cyanobacteria bloom,which accounts for 95.42%of the total area of Waihai.The proportion of moderate and severe cyanobacteria bloom are 0.52%and 0.11%respectively.In general,the spatial distribution of cyanobacteria bloom in Dianchi Lake is in the pattern of"north heavy south light",and the coverage density of cyanobacteria bloom is 80.45%,which indicates that Caohai is more prone to cyanobacteria bloom than Waihai,and the water quality of Caohai is relatively poor.This method can monitor and identify the spatial distribution of cyanobacteria bloom effectively in plateau lakes in real time,it made hyperspectral remote sensing of lake water quality monitoring methods more abundant,and provided scientific basis for promoting the management,development and utilization of water resources in Dianchi Lake.