Study on the Dynamic Spatio-Temporal Change Monitoring of the Tai Lake Chlorophyll-a Concentration Based on TM/ETM+ Images

Lakes are very important in freshwater supply. At present, most of the lakes in the world are suffering from eutrophication with industrialization, economic growth, and human activities. Frequent monitoring and integrated management are necessary for lakes. Chlorophyll-a (chl-a) is the important indicator of phytoplankton and water quality. However, conventional methods for monitoring chl-a in lakes will waste more manpower and material resources and can´t provide water quality information of the whole lake. Remote sensing technique is suitable to obtain spatial and temporal information quickly and frequently, and it will be widely applied in water quality monitoring for lakes in future because of its advantage of efficiency and long-term dynamic monitoring. The images covering the Tai Lake for the study are TM of 1991-07-23 and ETM+ of 2001-07-26.The chlorophyll-a concentration has been extracted from the two-period images of the Tai Lake based on a statistical model and the spatial distribution maps with three levels based on chlorophyll-a concentration have been made to display the distribution regularity of concentration.