Study On Modeling For Water Quality Parameters From Water-body In Rural Area

Water-body in rural area is closely related to people's lives in rural area,and it has a very important function in such aspects as economy,travels,amuses and bio-diversity protection,which features a large extent by the impact of water quality.Therefore,water quality monitoring may maintain the sustainability of the water-body functions,and facilitate a timely grasp of agricultural water resources and water environmental conditions, which is of great significance in our nation in relieving agricultural water shortage situation, improving the water environment quality in agriculture and promoting the sustainable development of agriculture.Water quality is usually about the description of physics, chemistry,heat and biological characteristic of water-body.Traditional water pollution monitoring in rural area usually adopts ground settled-points sampling method.This approach which is vulnerable to the restrictions of human,material and climate and hydrological conditions,can only understand the situation of water quality in monitoring sites,does not reflect the water quality difference of farmland throughout the region. Meanwhile ground settled-points sampling has a high cost and a slow speed.The remote sensing technology developed in the sixties of the 20th century,which is a process that the obtained electromagnetic radiation by measuring the land surface concludes earth surface parameters.This technology just made up for the shortcomings of traditional water quality monitoring,and its advantages of real-time,highly efficient,durable,the volume of data and the Wide scope of observation played an important role in water quality monitoring.At present this method has already become the important technological means of water pollution monitoring in regional farmland and space-time dynamic analysis,and has broken through the traditional settled-points monitoring and carried out a comprehensive regional agricultural water pollution monitoring.The remote sensing technology can clearly reflect that the current pollution situation and space distribution characteristic in the regional basin, and it can utilize the remote sensing data of many time phases to research and forecast water pollution history and pollution trends in the same basin,which may provide accurate information in programming for the protection of water resources.The remote sensing monitoring of the water pollution in agricultural district mainly utilizes remote sensing technology of visible light,reflecting infrared light,whose mechanism embodies a concentrated expression of the unique spectral reflectance character of the contaminated water-body different from clean water-body,and forming strong absorption or reflection on block of a certain particular wavelength.There are more aquatic living beings and impurity in the polluted water-body.These materials have different absorption and scattering function in different wave bands,which causes the prominent difference of reflecting rate from certain wavelength range.The water-bodies of different degree of pollutions demonstrate different spectrum characters.The pollution information with obvious characteristic can be gotten by quantitative speculating,combining the ground sampled point water quality monitoring data of particular time,may construct a speculating model of the water quality remote sensing in the regional range and appraise the water pollution state of regional farmland.This is main method to carry on the quantitative monitor of the water pollution using the remote sensing data.The content of the water-body pollution monitoring of agricultural district is numerous,only three water quality parameters of which is riper in studying and applying,that is chlorophyll-a,total suspended sediment and transparence.This research took water-body of rural area in Lishui County,Nanjing as research region,and took main water quality monitoring index with the remote sensing,including chlorophyll-a,total suspended substance and transparency as the research object.Analytic approaches of gray related degree connect organically the micro monitoring data on the ground with the macroscopically monitoring data of the remote sensing,which aimed at probing into the sensitive wave band or wave band association of typical water quality parameter in rural area from China and Brazil Earth Resource Satellite data(CBERS data), studied the establishment of remote sensing monitoring speculating model of water quality parameter from each water-body in rural district.At last the built three models separately applied to water-body in the rural area of Lishui County on July 30^th,2007.The obtaining result has objectively reflected the distribution situation of Chl-a,SS and transparence in water-body.The innovative point of this paper is that the theories,methods and techniques of water quality quantitative monitoring by remote sensing applied in the lake were applied to water-body in rural area,and studied remote sensing quantitative monitoring model of three water quality parameters for water-body in rural area,as well as the validity,precision and application effect of the built modeling.This paper reached the following conclusions by the study:1) The CCD data of CBERS images can be used in rural area to water quality quantitative monitoring by remote sensing of water-body;2) Chlorophyll-a of water-body in rural area had the best relativity with the sum of CBERS3 data and CBERS4 data;3) Total suspended sediment of water-body in rural area was in positive proportion to CBERS3 data,and was in negative proportion to CBERS1 data;4) Water transparency in rural area had the best correlation with CBERS1 data and CBERS3 data,that is,Water transparency in rural area was in positive proportion to CBERS3 data,and was in negative proportion to CBERS1 data;5) Water transparency in rural area was in inverse proportion to the total suspended sediment of water-body in rural area.Based on this paper's research, remote sensing monitoring model of each water quality parameter in rural region free of restraining from space-time can be further studied and be gotten,and the real-timely dynamically monitoring of water quality of water-body in the rural district can be realized as soon as possible,which has extensive realistic meaning and the applied prospect in preventing and curing the water pollution,floods to monitor,prevent and cure and so on.