Abstract: Taking the Aozhou section of Xiangjiang River as a case, the total nitrogen concentration in water body and related affecting factors were characterized with triangular fuzzy number, and the triangular fuzzy parameters were introduced into the existing fuzzy linear regression model to predict the total nitrogen concentration in water body. The relative errors between the predicted and measured values of total nitrogen concentration in the section in 2002-2005 were less than 20%, with a qualified prediction rate being 100%, which suggested that the modified fuzzy linear regression model had definite practicability in predicting the total nitrogen concentration in river water.

Key words: Ecological and environmental water requirement, Conception, Classification, Calculation method