Study on space-time variety of water environment quality based on gray relational model

On basis of average annual monitoring data of four monitoring sections in Quxian part of Qujiang river from 2006 to 2010,selecting TP,NH3-N,CODMn,BOD5 and DO as evaluation factors,water environment quality and space-time variety of the river was evaluated by using gray relational model.First,by way of normalizing the surface water environment quality classification standard and measured values of four monitoring sections,then calculating the correlation coefficient of the different water quality indexes of each section and year,finally calculating the relational grades of water quality indexes of each section and year.The results indicated that the water quality of four monitoring sections come up to functional classification standards.The water quality of A section retained Ⅰ level standard in five years,without obvious change.The water quality of B and C sections have some fluctuation in Ⅰ level and Ⅱ level standard.The class of water pollution of D section are on the rise from Ⅱ to Ⅲ level standard.The analysis suggested to improve the sewage treatment rate,optimize the treatment process,control the pollution of Industrial,agriculture,city life and rural life,plan the river ecosystem restoration.