Remote Sensing Retrieval Of Chlorophyll-a Concentration And Monitoring Of Cyanobacteria Bloom In Chaohu Lake

With the rapid development of urban construction in China,factors such as industrial pollution and human activities have severely affected the natural ecological environment of inland lakes.Taking Chaohu Lake as an example,in the context of the rapid economic development of Hefei City and Chaohu City,the water quality of Chaohu Lake has serious eutrophication problems.Water pollution can affect the production,life and economic development of nearby cities and towns.Therefore,efficient monitoring of lake water quality can prevent and reduce serious lake pollution incidents and provide scientific basis for lake pollution prevention,control and treatment.The monitoring technology combined with space and ground,remote sensing retrieval technology of chlorophyll-a concentration,the extraction technology of cyanobacteria blooms proposed in this paper can quickly and accurately obtain a wide range of water quality conditions,monitor the migration process of water pollutants,and make up for the low efficiency of traditional monitoring technologies,low precision and other shortcomings.The main research contents and conclusions are as follows:(1)Based on the data of multispectral,the buoy automatic detection station monitoring technology and satellite remote sensing monitoring technology are used to realize the combined space and ground chlorophyll-a concentration monitoring in Chaohu Lake.Although the buoy automatic detection station has a high monitoring frequency,it can only reflect the water quality at a certain point.Although the satellite remote sensing technology can be used for large-area dynamic monitoring,the satellite revisit cycle is long and is easily affected by the weather.Therefore,The two monitoring methods can achieve complementary advantages and effectively capture the spatiotemporal dynamic changes of the chlorophyll-a concentration in Chaohu Lake.(2)Based on OHS hyperspectral data,670 nm,686nm,700 nm and 716 nm are the sensitive bands of chlorophyll-a concentration,and the corresponding band combinations are carried out.The introduction of Ordinary Kriging method,Inverse Distance Weighting method,BP neural network and set model,broaden the chlorophyll-a concentration retrieval method,and improve the chlorophyll-a concentration retrieval and prediction accuracy.(3)Based on the data of GF-1 WFV and HJ-1 CCD,the slope analysis technology is used to determine the NDVI extraction threshold and grading threshold of cyanobacteria blooms,extract the cyanobacteria blooms in Chaohu Lake,and analyze the dynamic change characteristics of the cyanobacteria blooms in Chaohu Lake;based on the Landsat8 OLI data,determine cyanobacteria blooms NDVI and FAI extraction thresholds and grading thresholds,have compared the accuracy of NDVI and FAI extraction methods.The FAI method can suppress cloud interference and its accuracy is better than the NDVI method.It also analyzes the eutrophication trend of Chaohu Lake.