Modeling eutrophication in Lake Hamilton

Abstract

The problem of eutrophication or excess productivity in a lake has long been of interest to limnologist. In this thesis project, WASP4 eutrophication model was used to simulate the productivity of Lake Hamilton. The calibrated results then were compared with the measured data of 1987, and were found to be in close agreement for dissolved oxygen, soluble reactive phosphorus, organic phosphorus, chlorophyll a, and ammonia nitrogen. Modifications were suggested when it was felt that the capabilities of WASP4 model could be improved. The model also simulated the transformations and processes in the lake sediments. The response of the lake to long term reduction in external phosphorus loading was evaluated. Sensitivity analysis was performed on hypolimnetic dissolved oxygen and peak epilimnetic chlorophyll a for a range of values of sediment oxygen demand, settling rate of phytoplankton, phosphorus loading reduction, and decomposition rate. The model indicated that the hypolimnetic dissolved oxygen was most sensitive to the sediment oxygen demand. The productivity of Lake Hamilton was most dependent on the external phosphorus loadings. It was concluded that the WASP4 eutrophication model would be of great value in developing and implementing management decisions for improving the trophic status of lakes.