Modeling of Hypolymnetic Water Quality in Deep Pits Created by Sand Dredging in the Lake Ijssel Area

摘要

Water quality modeling techniques were developed and used to simulate the oxygen budget in the hypolymnetic region of pits with a depth up to 45m created in the Lake IJssel area (Netherlands) as a result of sand dredging. The settling of organic matter originating from phytoplankton growth and the related decomposition can create a high demand for oxygen in the hypolymnetic region of the pit. During the summer period when the pit is thermally stratified this can result in anaerobic conditions. Based on the models, a better understanding of the dominant processes and the influence of pit geometry and water quality of the lake is established. Such information is of special interest for the development of design criteria for new pits or the extension of existing pits in relation to water quality management in the area.