Remote Sensing Based Water Monitoring And Spatial-temporal Analysis

With more and more serious problem on water pollution, it is significant to monitor the water quality and get to know the trend of the water quality change for water resource management and water environment protection. As an essential technology besides conventional water monitoring method, remote sensing based water monitoring, which has the advantages of large scale monitoring area, fast and dynamic processing, economical and easy operation for a long monitoring period, can discover the water quality migratory trend while the conventional method can not disvover.This paper studies the theories and methods for monitoring water quality using remote sensing and analyzing spatial-temporal features of water quality change. The historical water quality data in the area of HuangPu River up stream is first analyzed and the water quality change trend is obtained based on these data, the empirical and semi-analysis methods are then presented for monitoring water quality using remote sensing in this area.The results of the regression model base on the empirical algorithms indicate that in Lake Tai, the concentration of suspended sediments has a strong relationship with TM band 3, and the ratio between TM bands 3 and 1 can further improve the relationship with the concentration of suspended sediments;and Chl-a has a strong relationship with the ratio between TM bands 5 and 2;while the the concentration of dissolved oxygen in River Huangpu up stream has a high correlation with the ratio of TM bands 3 and 4. The dissolved oxygen regression model is a reliable and generic model with a high estimation accuray in River Huangpu up stream, while the effect on the model by the atmosphere condition needs further studying.The semi-analysis method for remote sensing based water quality monitoring is thus further proposed. The water sampling and data processing methods through the spectrometer instrument are presented. The results show that the water spectra obtained can describe the scatter and absorb features of water quality elements through the proposed method in the paper. The ratio of the reflectance between702nm and 675nm is the best for estimating the concentrations of Chl-a in inland waters.The model is then implemented to estimate dissolved oxygen concentration of the whole River Huangpu up stream, and the result demonstrates that the rule of the dissolved oxygen distribution is consistent with that of the real distribution of River Huangpu up stream, i.e., the water quality of Lake Dianshan is the best, the better are the main flows while the worst are the anabranches. The analysis of the nutrient enrichments of Lake Dianshan shows that the degree of nutrient enrichments has greatly increased since 2000, and the north part of the lake like Lake Zhaotian is apt to algal bloom, and the seasons like the winter and autumn have a higher frequency of algal boom.