Water Quality Satellite Remote Sensing Monitoring Model of Fujian Coastland Based on Fuzzy Evaluation

As the development of satellite remote sensing technology of the high resolution and multi-survey spectrum channel, it brings an obvious advantage for ocean monitoring of water quality situation for continuous, real-time, large scale. With the observed samples of 12 marine water quality monitoring sites in the marine sector in Fujian coastal water, the remote sensing satellite standard algorithm and semi-analysis algorithm model is adopted, and marine ecological parameters are retrieved such as chlorophyll-a, particulate organic carbon, yellow substance and transparency. Evaluation factors of sea water closely related to the marine pollution degree in Fujian coastland are selected as dissolved oxygen, chemical oxygen demand, inorganic nitrogen and active phosphate, the statistical relationship model is established between marine ecology parameters and the evaluation factor of marine water quality. The evaluation of sea water quality is conducted by the fuzzy comprehensive evaluation method, and finally a set of marine water quality monitoring model is finished based on the satellite remote sensing and fuzzy evaluation model. The inversion precision of the model is verified by the synchronization acquisition field measurement of the marine water quality of Fujian coastal water in 2009-2013. Results show that, for the computed yellow substance by semi-analytical algorithm, the average relative error is 34%, the root mean square error is 0.179; for the computed transparency the average relative error is 26%, the root mean square error is 0.332, so the inversion result is ideal. For dissolved oxygen, the average relative error of the statistical model is the minimum, while the active phosphate model is the maximum, all four models have good agreement with measured values, and the correlation coefficient of the regression equation is more than 0.58. Results of the satellite remote sensing monitoring show that in most of the harbor and rivers into the sea along the coast of Fujian, the water quality barely meets class Ⅳ standard, the ocean water quality gradually improves with the offshore distance, and the harbor pollution trend is greater inside bay than that of the outside. From 304 samples of marine water quality monitoring, the satellite monitoring results of 245 samples are consistent with the ground observations, and the accurate rate of monitoring is 81%. The use of the monitoring model is feasible for the satellite remote sensing monitoring of sea water quality in Fujian coastland, so the prospect of business application is better. Because the accurate rate of the model is obviously higher to the marine water quality monitoring of Ⅳ than that of Ⅱ and Ⅲ , the marine water quality monitoring model is more suitable for the offshore sea area in Fujian.