The water quality of the Beijing-Hangzhou Grand Canal in Yangzhou from 1986 to 2008 was detected with BP neutral network model.The simulated data of the water quality showed that in recent 20 years,the water quality varied between grade III and grade IV,and the main pollution item was eutrophication.The main pollution indicators became worse in these years,which showed that Yangzhou had made some progress in controlling the water pollution.Based on the data calculated by BP neutral network model,pollution i...