In order to completely realize the water environmental quality in the Weihe River of Shaanxi reach,this paper carried out the comprehensie evaluation for the water environmental quality by employing the grey decision making-comprehensive index method,according to the data collected over the period from 2000 to 2008.Selected COD,NH3-N,BOD5 and DO index were concerned in the assessment.The analysis results showed:(1) The comprehensive index of water quality in Weihe River of Shaanxi reach was from 1.967 to 5,...