The Application Of GIS To Water Quality Modeling In Chengdu Water System

Taking the water system and water quality in Chengdu as example, this thesis summarizes the basic method of combining the water quality simulating and geographical information system (GIS) technology, especially researches the analysis and management of the simulated results by the means of GIS technology.This thesis analyzes present situation of organic compounds pollution and elaborated the transfer and biodegradation mechanism of organic compounds in water and emphasized it's necessary to forecast organic compounds pollution in river by means of water quality mathematic model. At the same time, the thesis analyzes and summarizes water quality models and their usage in water quality modeling. Though water quality models have strong calculating function when modeling water quality, it's difficult to show their modeling results, however, using GIS can solve this difficulty. So this thesis introduces its developing process, constitution, function and the trend of development, and explained its superiority of spatial analysis and data management. According to the present research situation of domestic and foreign environmental information system, it's necessary to integrate GIS and water quality models to analyze water quality.Using the advanced program language of Visual Basic, the calculating program simulating water quality in Chengdu water system is gotten. Using this program and selecting proper water quality models and parameters, this thesis simulates the waterquality in Cheng water system when the initial and boundary conditions are given.After introducing the basic function of GIS software (Maplnfo Professional 5.5), the digitalized maps of Chengdu river system are gotten, the Maplnfo table of simulated results and inspected data are built and geocoded, then their thematic map are created by the means of this software, so the visualization of simulated and inspected results comes true. By the common user interface of water quality simulating and geographical information management and using GIS to manage the simulated results of water quality and the inspected results orderly, this method not only makes up for the shortcomings of water quality models, but also exerts sufficiently GIS's advantages of spatial analysis and data management.This research of combining water quality modeling and GIS technology is just a primary try and exploration, it has some significance for some work in this field and can influence the further research of combining more complicated water quality models with GIS technology.