|Shields jr, Fletcher|
Submitted to: Ecological Modeling
Publication Type: Peer reviewed journal
Publication Acceptance Date: 10/2/2006
Publication Date: 11/20/2006
Citation: Chao, X., Jia, Y., Shields Jr, F.D., Wang, S. 2006. Numerical modeling of water quality and sediment related processes. Ecological Modeling. 201(2007):385-397. doi:10.1016/j.ecolmodel.2006.10.003 Interpretive Summary: Lakes in agricultural watersheds sometimes experience water quality degradation linked to nonpoint source water pollution, which may be addressed using agricultural best management practices. However, predicting water quality changes in response to changing pollution loads is very complicated. A computer program to simulate lake water quality was developed and validated using data from Deep Hollow Lake, an oxbow lake surrounded by fields in the Mississippi Delta, and then used to test the sensitivity of lake chlorophyll concentration (an indicator of algal populations) to changes in concentrations of suspended sediment, inorganic nitrogen, and phosphorus. Chlorophyll concentration was most sensitive to changes in suspended sediments and least sensitive to phosphorus. These results provide a foundation for developing better tools for predicting the benefits of agricultural best management practices on receiving water body quality.
Technical Abstract: A three-dimensional water quality model was developed for simulating temporal and spatial variations of water quality with respect to phytoplankton, nutrients, and dissolved oxygen. Four major interacting systems were simulated, including phytoplankton dynamics, the nitrogen and phosphorus cycles, and the dissolved oxygen balance. The effects of suspended and bed sediment on the water quality processes were also considered. The model was verified using analytical solutions for the transport of non-conservative substances in open channel flow, and then calibrated and validated by applying to the study of the water quality of a natural shallow oxbow lake. The simulated time serial concentration of phytoplankton (as chlorophyll) and nutrients were generally in good agreement with field observations. Sensitivity studies were then conducted to demonstrate the impacts on water quality due to varying nutrients and suspended sediment loads to the chlorophyll concentration. Chlorophyll concentration was most sensitive to changes in suspended sediments and least sensitive to phosphorus.