Use of multiple model grids in aquatic ecosystem modeling

Session: Applications of Simulation Models in Watershed Science and Lake Ecology (2)

Derek Schlea, LimnoTech, [email protected]
Todd Redder, LimnoTech, [email protected]
Renn Lambert, LimnoTech, [email protected]
Yuan Hui, University at Buffalo, SUNY, [email protected]
Joseph Atkinson, University of Buffalo, Dept. of Civil , Struct. & Env Eng., [email protected]

Abstract

A whole-lake, linked hydrodynamic-eutrophication model is being developed for Lake Ontario to support future decision making and adaptive management strategies. A relatively fine grid (100 m in nearshore) was constructed to support a modeling evaluation that simultaneously addresses the issues of nearshore eutrophication and oligotrophication of the offshore waters. The detailed spatial resolution grid can result in prohibitive simulation runtimes, however, which limits the efficiency and robustness of calibration activities and sensitivity testing. To address the need for more efficient water quality simulations, we developed an algorithm that collapses the hydrodynamic model grid into a coarser grid, while preserving water balance and hydraulic information at the coarser scale. The resulting “coarse” version of the water quality grid has significantly lower runtimes, allowing for more rapid testing of key input coefficients, forcing functions, and initial conditions, as well as providing a screening tool for potential nutrient load reduction and other scenarios. This presentation will show comparative evaluations of results generated for both grids and discuss the advantages of leveraging a coarser grid to improve the efficiency and robustness of applying a fine grid that preserves the greater detail needed for final versions of the baseline and future scenario simulations.