Research On The Remote Sensing Monitoring System Of Chagan Lake Based On GIS

Water is the origin of life. Water quality status is directly related to the survival and developing of the human society. Therefore, developing countries and developed countries all pay much attention to the research and monitoring of water quality status. It has great significance for China which is water scarce and urgent to develop economy. With the appearance and development of remote sensing technology, we have put more and more attention to the research of water quality with remote sensing. We can build up the algorithm of each water quality parameter by analysing the relation between spectral reflectance properties of water and water quality parameters. Water quality with remote sensing has the advantages of large scale monitoring area and a low cost. More importantly, it can realize long term dynamic monitoring which traditional monitoring method cannot realize. Therefore, we should make a deep research and real-time monitoring on lakes based on remote sensing so as that related departments can take measures to the eutrophication and other pollution problems of lakes in time.Chagan Lake, located in the northwest of Jilin Province, is the largest inland lake in Jilin. In recent years, because of the exhaustion of the Chagan Lake resources, eutrophication and other problems have appeared, which makes us know that we must strengthen the real-time monitoring and eutrophication assessment of Chagan Lake while treating eutrophication. Therefore, based on the theory of water quality with remote sensing, the paper designed and realized remote sensing monitoring system of Chagan Lake with the support of techniques of the second development of GIS.1) The paper introduced the background, the purpose and significance of this research, revealed the trends of water quality with remote sensing research both domestic and abroad, and discussed how to realize this study.2) On the design of core functions, the paper used two methods to estimate major water quality parameters and evaluate the situation of eutrophication respectively. In other words, the paper did this research based on the data of high spectrum and remote sensing images both. Among these cases, the paper used MODIS which was free and could be easily obtained, and more importantly, MODIS could realized real-time monitoring with high temporal resolution (twice one day).3) Based on previous research, the paper selected the modules of major water quality parameters and the eutrophication assessment which were suitable for Chgan Lake. The modules of major water quality parameters included hyperspectral models of Chlorophyll a, transparency and total phosphorus, and model of Chlorophyll a based on MODIS.4) Using the second-round-exploitation groupware of GIS-ArcEngine and Visual C#, the paper designed remote sensing monitoring system of Chagan Lake. It contains four function modules: the basic function models of GIS, data management, the estimation of major water quality parameters and eutrophication assessment among which the estimation of major water quality parameters and eutrophication assessment are the core functions of this system. It can provide basic information and reference for building the system of remote sensing monitoring.5) For application proof-test, the paper selected data of high spectrum and MODIS on September, 2004 to estimate major water quality parameters (Chla, SDD, TP) and evaluate the situation of eutrophication of Chagn Lake. The results from the system are as follows: in main district of lake, the concentration of chlorophyll a in the northwest of Chagan Lake is lowest with the value of 20.8556ug/l while that in the southwest is highest with the value of 26.6677 ug/l. Transparency in the middle and southwest of Chagan Lake is lowest with the value of 24.2577cm while that in the westnorth is higher and northeast is the highest with the value of 25.9424cm. Total phosphorus in the northeast of Chagan Lake is lowest with the value of 0.107886mg/l while that in the southwest and middle is highest with the value of 0.127475mg/l. In the eutrophication assessment, two remote sensing monitoring methords all show that Chagan Lake has been in eutrophication.6) In the last of thesis, the paper summarized achievements, shortage and prospect.