Author(s): Akihiko Hirayama; Akio Wake; Michio Kumagai
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Keywords: No Keywords
Abstract: Eutrophication of waters embayed by cities has been causing various problems for water-use. Though enhanced sewage treatment has decreased nutrient loadings, the remaining input and sediment nutrient release result in a continuation of the same problem. The nutrient release rate is regulated both by physical and chemical conditions at the bottom. Current and wave stresses at the bottom are the major physical factors. Wave stress in particular becomes more significant in shallow waters, but its effects have been given little consideration in previous water quality studies. Further, previous model applications are primarily concerned with long term predictions, with time steps of a day or longer. In the present study, a two-dimensional hydrodynamic and water quality model incorporating sediment resuspension and algal dynamics is developed to simulate short-term variations of suspended solids and chlorophyll a. Sediment resuspension is estimated using stresses from both currents and waves. Calculations are compared with comprehensive field data obtained at the shallow south basin of Lake Biwa in the spring of 1991.
Year: 1995