Application of IGM(0,N) Model to Simulate Trends in Estuarine Water Quality

The water quality of rivers flowing into lakes is a reflection of the regional environment and significantly contributes to the nutrient levels of the lake. Based on multi-year monitoring data of the estuarine water quality of the Zi River which flows into the Dongting Lake, single factor analysis was performed for the dissolved oxygen, nitrogen ammonia(NH_3-N), chemical oxygen demand, total phosphorus, permanganate index, and biochemical oxygen demand. The analysis indicated that the estuarine water quality class was dependent on the NH_3-N level. The NH_3-N trend of the Zi River was then simulated using an improved grey model IGM(0, N) based on a grey correlation analysis. The IGM(0, N) model produced a smaller average relative error and a more accurate prediction compared with a multiple regression model, thus validating the use of the IGM(0, N) model as a suitable method to simulate the estuarine water quality with a complex multi-factor system.