ASSESSMENT AND FORECAST OF WATER TROPHIC STATE FOR A LAKE IN CENTRAL CHINA

Eutrophication, which may influence the sustainability of the natural environment, is one of the notable water environment problems. This paper aims to estimate the water eutrophication of Moshui Lake in Hanyang District of Wuhan in central China as a case study with a Fuzzy Comprehensive-Quantifying Assessment (FCQA) method. The evaluation of changes of the water trophic state is based on the monitoring data of trophic indictors, TP and TN, between 2001 and 2010. The Scoring Method was applied to test the feasibility of using the FCQA method in the estimation of the water eutrophication state. Then, the Dynamic Gray Filling Model (GM (1, 1) model) was used to forecast trophic states of Moshui Lake between 2010 and 2016, while the forecasted value of 2010 was compared with that value calculated by the real monitoring data. The results indicated that the FCQA method had the advantages such as comparability and accuracy and is available for water eutrophication assessment. The average precision of the forecasted results by the Dynamic GM (1,1) is 95.91%. The improvement of the water trophic state of Moshui Lake from 2001 - 2016 can be defined in three stages: (1) Heavy eutropher in 2001-2005, (2) Moderate eutropher in 20062015, and (3) Light eutropher in 2016. The alleviation of the water trophic situation is mainly due to the human activities of environmental rescue. However, the still existing trophic problems in Moshui Lake indicate the importance of further environmental rescue work and people's awareness of keeping a sustainable water environment in the future.