Modelling Dissolved Oxygen/Sediment Oxygen Demand under Ice in a Shallow Eutrophic Prairie Reservoir

Abstract

Dissolved oxygen is an influential factor of aquatic ecosystem health. Future predictions of oxygen deficits are paramount for maintaining water quality. Oxygen demands depend greatly on a waterbody's attributes. A large sediment-water interface relative to volume means sediment oxygen demand has greater influence in shallow systems. In shallow, ice-covered waterbodies the potential for winter anoxia is high. Water quality models offer two options for modelling sediment oxygen demand: a zero-order constant rate, or a sediment diagenesis model. The constant rate is unrepresentative of a real system, yet a diagenesis model is difficult to parameterise and calibrate without data. We use the water quality model CE-QUAL-W2 to increase the complexity of a zero-order sediment compartment with limited data. We model summer and winter conditions individually to capture decay rates under-ice. Using a semi-automated calibration method, we find an annual pattern in sediment oxygen demand that follows the trend of chlorophyll-a concentrations in a shallow, eutrophic Prairie reservoir. We use chlorophyll-a as a proxy for estimation of summer oxygen demand and winter decay. We show that winter sediment oxygen demand is dependent on the previous summer's maximum chlorophyll-a concentrations.

Impact of Alluvial Diamond Mining on Macroinvertebrate Community Structure in the Lower Vaal River, Northern Cape Province in South Africa

“…Dissolved oxygen (DO) is important for all forms of life (Terry et al, 2017). Low DO in the water can cause physiological stress for fish and macroinvertebrates.…”

River and Lake Ice Processes—Impacts of Freshwater Ice on Aquatic Ecosystems in a Changing Globe

“…Akomeah et al [52] and Terry et al [53] both used surface water quality models to investigate the water quality of ice-covered water bodies, the former concentrating on a river and the latter on a lake within the Qu'Appelle river-lake system on the Canadian Prairies. Both studies are initial steps in larger projects to investigate the dynamics of dissolved oxygen concentrations and sediment oxygen demand during the winter seasons.…”

Seasonal Variation in Sediment Oxygen Demand in a Northern Chained River-Lake System

“…This rate was selected based on similar studies at nearby catchments and reported values which ranged from 0.1/day to 0.2/day [32,38].…”

“…At a low water quality model complexity, like the Streeter and Phelps dissolved oxygen balance, other process parameters are constrained, allowing models to be properly calibrated to few parameters. Building a model by gradually adding complexity is a strategy adopted by some modelers [32]. Complex models increase the number of processes being modeled, the output variables, and parameters [32].…”

“…Building a model by gradually adding complexity is a strategy adopted by some modelers [32]. Complex models increase the number of processes being modeled, the output variables, and parameters [32]. Apart from the uncertainties associated with the model structure (as not all physical processes might be adequately represented, or even included) and forcings in a complex model, calibrating to optimum parameters, is often difficult in the face of sparse input data, as is common at most sites.…”