The Building And Application Of Agricultural Non-point Source Pollution Database Based On Geodatabase

Point source pollution and non-point source pollution are always the two important problems of the water environmental quality. Point source pollution mainly includes industrial sullage and city's life sullage, which are drained from the certain outfall. While non-point source pollution has no certain outfall, it has some relation with some weather conditions. Non-point source pollution has some characteristics, such that its harm is heavy and it is difficult to prevent. It is reported that agricultural non-point source pollution influence 30%~50% of the world land and 12% of 2.1 billion hm2 land in the world is caused by agricultural non-point source pollution. In American, agricultural non-point source pollution is the main factor to environmental pollution. The Three-Gorge Reservoir is the biggest base of freshwater source and the water source supply base to realize middle schema of southern water to north after its establishment. The water environment of Three-Gorge Reservoir directly influences economy development of Yangtze River band and the sustainable development of china. With strengthening control of point source pollution, agricultural non-point source pollution will be the main pollution source to the Three-Gorge Reservoir area. So it is important to control and manage agricultural non-point source pollution to guarantee the water quality and realize the agricultural sustainable development.Now the study of the agricultural non-point source pollution is mainly to integrate GIS with environmental model. Building spatial database is the basement of using GIS to study non-point source pollution. Building non-point source pollution spatial database of the Three-Gorge Reservoir area can not only know about the background, status and rule of non-point source pollution and assessing Non-point source critical area and calculating pollution load but also provide the scientific dependent for bringing forward quantity control goal and establishing control stratagem of non-point source pollution of the Three-Gorge Reservoir area. It has an important effect on economy development of Yangtze River watershed and the water environment security and the zoology balance.This study has designed and built non-point source pollution spatial database of the Three-Gorge Reservoir area in chongqing based on Geodatabase and CASE tools. The study has also workout the corresponding metadata standard and built non-point source pollution metadata. At last.this study assessed the Non-point source critical area applying environmental model. The results of this dissertation include:(l)This study has designed and built an agricultural non-point source pollution spatial database of the Three-Gorge Reservoir area in Chongqing based on Geodatabase and CASE tools. Intradition, building spatial database always choose Coverage model, which has some shortages such as it has not special character about the expression of spatial object. With the development of oriented-object technology.Geodatabase has appeared representing oriented-object spatial model and stride forward to the objected spatial model. Geodatabase provide the better method to express spatial object. Many commercial and research units oversea have used Geodatabase as data model of spatial database, while it is not common in china. In this study, we discussed technologic system to build spatial database based on Geodatabase, and provided the valuable experience for other items.(2)According to the requirement of the item,the non-point source pollution metadata standard that is accorded with FGDC standard has been organized and non-point source pollution metadata has been built based on metadata standard. Non-point source pollution metadata of the Three-Gorge Reservoir area in Chongqing not can only help manage and maintain huge data,set up data document,know about data items of the non-point source pollution study in Three-Gorge Reservoir.provide data format,projection,scale,etc.,but also can provide effective way and technicle means for spare data and comm...