This work was funded by LOICZ project 014.27.013 (Land Ocean Interaction in the Coastal Zone), and administered by NWO-ALW, the Netherlands Organization for Scientific Research.
Water -- Dissolved oxygen, Estuaries -- Water quality, Estuaries -- Turbidity -- Mathematical models
The sensitivity of oxygen depletion in turbid estuaries to parameters like freshwater discharge, depth, and sediment availability is investigated using an idealized model. The model describes tidally averaged circulation and suspended sediment concentration (SSC), which are input into an advection–diffusion sink module of dissolved oxygen (DO). Based on the analysis of field data collected in the Ems estuary, the modeled oxygen depletion rates are proportional to SSC. The model is calibrated to the observed variation of DO with SSC and temperature. Modeled DO closely tracks changes to the estuarine turbidity zone (ETZ): increased channel depth, decreased freshwater discharge, and decreased mixing move the ETZ upstream, amplify SSCs, and decrease DO. Summertime temperatures produce lower DO than cooler periods. Model results are consistent with historical measurements in the Ems, which indicate that hypoxic events (DO concentrations < 2 mg l−1) have occurred more frequently after deepening from 5 to 7 m.
Talke, Stefan A.; de Swart, Huib E.; and de Jonge, Victor, "An Idealized Model and Systematic Process Study of Oxygen Depletion in Highly Turbid Estuaries" (2009). Civil and Environmental Engineering Faculty Publications and Presentations. 86.