Simulation and Analyses of the Controlling Factors for the Eutrophic Condition of Shin-Shan Reservoir with CE-QUAL-W2
Date Issued
2012
Date
2012
Author(s)
Chuang, Chen-Wei
Abstract
Shin-Shan Reservoir located in Keelung city is an off-channel reservoir, which supplies water to Keelung and Taipei metropolitan area. In recent years, eutrophication occurred during summer time in Shin-Shan Reservoir. In this study, CE-QUAL-W2 model was used to simulate the effects of hypolimnetic aeration in Shin-Shan reservoir during summer and investigate the effects on the change of water quality under different intensity of hypolimnetic aeration. Model simulation was performed by using the data in 2010 as the basis of calibration for the model’s parameters, and used the measurement in 2009 for the verification of the model’s prediction.
The results of simulation showed good description of the hydrodynamic phenomena such as water levels and temperatures. In addition, the simulated results of the total phosphorus indicated overestimation of the total phosphorus during winter, while the model underestimation chlorophyll a during the summer (August to September). Overall, CE-QUAL-W2 modeling method provides a satisfactory closeness between simulated results and actual data in this reservoir.
Moreover, model analysis indicated a significant phosphorus concentration during summer with increase in hypolimnetic aeration. On the other hand, the concentration of nitrate in the water body increased slightly after a short period of hypolimnetic aeration due to the oxidation of ammonia to become nitrate, but reached a steady state once most of ammonia had been transformed. The concentration of chlorophyll a did not change significantly with the hypolimnetic aeration, presumably due to less direct impact of hypolimnetic aeration on the surface water quality.
Lastly, the simulation analyses show that by controlling the concentration of total phosphorus in the inflow, the concentration of total phosphorus and chlorophyll a would be significantly decreased in Shin-Shan Reservoir. In conclusion, controlling the quantity of nutrients in the inflow would be an effective way to improve reservoir’s water quality and preventing eutrophication from occuring.
The results of simulation showed good description of the hydrodynamic phenomena such as water levels and temperatures. In addition, the simulated results of the total phosphorus indicated overestimation of the total phosphorus during winter, while the model underestimation chlorophyll a during the summer (August to September). Overall, CE-QUAL-W2 modeling method provides a satisfactory closeness between simulated results and actual data in this reservoir.
Moreover, model analysis indicated a significant phosphorus concentration during summer with increase in hypolimnetic aeration. On the other hand, the concentration of nitrate in the water body increased slightly after a short period of hypolimnetic aeration due to the oxidation of ammonia to become nitrate, but reached a steady state once most of ammonia had been transformed. The concentration of chlorophyll a did not change significantly with the hypolimnetic aeration, presumably due to less direct impact of hypolimnetic aeration on the surface water quality.
Lastly, the simulation analyses show that by controlling the concentration of total phosphorus in the inflow, the concentration of total phosphorus and chlorophyll a would be significantly decreased in Shin-Shan Reservoir. In conclusion, controlling the quantity of nutrients in the inflow would be an effective way to improve reservoir’s water quality and preventing eutrophication from occuring.
Subjects
hypolimnetic aeration
water quality model
eutrophication
Type
thesis
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