Simulation Study On Effect Of Nutrients Input (Nitrogen And Phosphorus) On Algal Growth In Dianshan Lake Based On ELCOM-CAEDYM Model

Dianshan lake is one of main water source in Shanghai's, Meanwhile Dianshan lake has transportation, irrigation and drainage, aquaculture, flood regulation and storage functions. Dianshan basin's economic has developed rapidly, but the water quality of Dianshan lake has significantly decreased,which has transformed severe eutrophication lake. In this paper, the application and results of a three-dimensional model of physical and biogeochemical interactions in the lake Dianshan is presented. ELCOM (Estuary, Lake and Coastal Ocean Model) is a 3D hydrodynamic model used for predicting the velocity, temperature and salinity distributionin natural water bodies. CAEDYM (Computational Aquatic Ecosystem Dynamics Model) is a process-based ecological model which simulates up to five phytoplankton groups as well as nitrogen, phosphorus and oxygen dynamics and transport and silica transport.The coupled model is validated against available water quality data after in-depth investigation in lake Dianshan, and subsequently used to investigate the hypothesis that the effect of different amount of nutrients input (Nitrogen and Phosphorus) on algal growth in lake Dianshan.The numerical model results are integrated to provide research abasis for warning of the algal bloom outbreak and comprehensive management of eutrophication.Secondly, through the establishment of ELCOM-CAEDYM three-dimensional model of eco logical dynamics in Dianshan lake, considering the load into the lake, light, temperature, h umidity, wind direction, wind speed, rainfall and other hydro-meteorological conditions and plankton growth of algae in the lake, then,using the ensemble prediction uncertainty analy sis method combines experimental and reference to calibrate the water quality model para meters,and makes the simulation results agree well with the measured values,which more accurately reflects the actual situation of eutrophication Dianshan lake.Finally, basing on ELCOM-CAEDYM,Simulation study on Effect of Nutrients input(Ni trogen and Phosphorus)on Algal Growth in Dianshan Lake has been implemented. To so me extent,Dianshan phosphorus content of the lake determine the level of eutrophication D ianshan. Therefore, controlling phosphorus loading into the lake are Dianshan key measures for prevention and treatment of eutrophication and algal blooms. Although effect of the i ncrease of nitrogen input on chlorophyll-a content is not obvious, but if we can reduce th e total nitrogen content to a critical value between 3.7mg/L～4.31mg/L, the chlorophyll-a content is significantly reduced, which will effectively control the eutrophication in Diansha n lake.Regulating nitrogen, and phosphorus have a synergistic effect on the control of chlo rophyll-a in Dianshan lake. When the total nitrogen input reducting 10% to 15%, the amo unt of chlorophyll-a concentration (percentage content) and total nitrogen input reduction (p ercentage content) to achieve the maximum effective and economical benefit ratio.When th e total phosphorus input reducting 7% to 10%, the amount of chlorophyll-a concentration (percentage content) and total phosphorus input reductions (percentage content) to achieve t he maximum effective and economical benefit ratio.