太湖水体Chl-a预测模型ARIMA在引排水方案优化中的应用

APPLICATION OF CHL-A PREDICTION MODEL ARIMA IN OPTIMIZATION OF WATER DIVERSION AND DRAINAGE SCHEME IN LAKE TAIHU

我国东部大型浅水湖泊太湖的富营养化和藻华暴发一直是困扰该地区社会经济高质量发展的重要水问题之一,其中水资源分配不均及部分营养盐浓度较高,严重制约了太湖水体生态环境的健康发展。基于1999—2019年太湖水质、气象等逐月观测资料,构建了基于协变量(TN、TP、COD_(Mn)、降水量和引排水量)的叶绿素a(Chl-a)预测模型ARIMA(1,1,1)(0,1,1)_(12),并结合2007—2019年历史引排水方案经验和效果,提出了未来平水年情景下降低太湖藻华大面积暴发风险的引排水方案优化策略。结果表明:所构建的ARIMA(1,1,1)(0,1,1)_(12)模型能有效预测太湖水体Chl-a浓度;且在预设未来情景下,通过同步增加引、排水量可有效降低水体营养盐含量。引排水方案的优化关键在于季节性水资源的合理调配,在满足水安全的基础上适当加大冬春季节引排水,可达到改善水动力和排出营养盐的效果。

The eutrophication and algal blooms of Lake Taihu,a large shallow lake in eastern China,have always been one of the important water problems that troubled the high-quality development of this region.The uneven distribution of water resources and relatively high concentration of some nutrients have seriously restricted the healthy development of the ecological environment of Lake Taihu.Based on the monthly observation data of water quality and meteorology of Lake Taihu from 1999 to 2019,a Chl-a prediction model ARIMA(1,1,1)(0,1,1)_(12) based on covariates(total nitrogen,total phosphorus,permanganate index,precipitation,water diversion and drainage volume) was established in this paper.An optimization strategy of water diversion and drainage schemes was proposed to decline the risk of algal blooms outbreak in Lake Taihu under the future normal year scenario.Results showed that the ARIMA(1,1,1)(0,1,1)_(12) model could effectively predict the monthly Chl-a concen trations of Lake Taihu.In the preset future scenario,the nutrient content of water can be effectively reduced by synchronously increasing both water diversion and drainage.The key to the optimization of water diversion and drainage scheme is rational allocation of seasonal water resources,and based on meeting water safety,adeptly enhancing both diversion and drainage in winter and spring could improve the water dynamic and nutritional salt discharge.