中文摘要：

依据1999-2011年湘江出口樟树港站水质监测数据，选取溶解氧等10个水质指标，对数据优化后运用BP神经网络模型对其进行水质综合评价与分析，发现湘江出口水质具有明显的季节性与趋势性，近年来水质有所好转．同时对氨氮、溶解氧、总氮3个指标进行了季节性分析，并运用季节性水平模型计算了水质综合指数的季节比，将13年来的数据分3个年段对比分析，发现水质综合指数季节比与湘江降水量季节比、湘江出口水温季节比存在负相关性．

英文摘要：

Based on monitoring data of Xiangjiang estuary from 1999 to 2011 and selected 10 water quality indexes such as dissolved oxygen, BP neural network model was used to analyze and evaluate the water quality of Xiangjiang estuary after data optimization. The results showed that the water quality of Xiangjiang estuary, which has been improved in the latest years, possesses significant seasonality and tendency. The indexes of ammonia nitrogen, dissolved oxygen and total nitrogen were seasonally analyzed. And the seasonal ratio of comprehensive water quality index was calculated based on a seasonal level model. The data of 13 years were contrasted and analyzed bthree periods of 3-year time. The results indicated that there exists a negative correlation between the comprehensive water quality index seasonal ratio and the precipitation seasonal ratio or water temperature seasonal ratio.