Comprehensive assessment of water quality in Lanjiang River watershed based on fuzzy mathematics

A comprehensive water quality assessment model was developed based on fuzzy mathematics technique. The model adopted function of subjection to describe the boundary of water quality, was under the jurisdiction of subjection degree selecting nearly principles, reflect the mistiness, make the result closer the objective reality. The water quality data covering 6 parameters from 6 monitoring stations were collected from January 2005 to December 2010, and the model was used to assess the water quality of Lanjiang River watershed. The water quality of Lanjiang River from 2005 to 2010 is maintain Class III, and can basically satisfy its designated use. The major pollutants were ammonia nitrogen and total phosphorus. The water quality assessment model based on fuzzy mathematics is suitable for Lanjiang River watershed.