Coupled hydrodynamic and biogeochemical simulation of long-term trends in western Lake Erie HABs

Session: 37. - Harmful Algal Blooms (HABs) and their Toxicity: Remote Sensing and Modeling Approaches

Qi Wang, Queen's University, [email protected]
Leon Boegman, QUEENS UNIVERSITY, [email protected]

Abstract

During the 1970s, harmful algal blooms (HABs) were common occurrences in western Lake Erie. Remediation strategies reduced TP loads and bloom frequency; however, HABs have reoccurred since the mid-1990s, likely forced by climate change. Given these concurrent changes in nutrient loading and climate forcing, it’s necessary to develop management tools to understand historical changes in the lake and predict future water quality. Herein, we applied coupled one-dimensional hydrodynamic and biogeochemical models (GLM-AED) to reproduce water quality conditions of western Lake Erie from 1980 to 2015. The physical forcing is derived from surface meteorological buoys, airports and measurements of precipitation and inflow. Nutrient loads were reconstructed from historical monitoring data. The models were validated against observations of water levels, water temperature, DO, TP, PO4, NH4, NO3, total chlorophyll a, and cyanobacteria concentration. The results indicate GLM-AED has the capacity to simulate these parameters with adjustment from default values (e.g. to the longwave formulation). May-September mean TP concentrations were simulated to increase from 1999 – 2011, in agreement with observations. May-October mean cyanobacteria concentrations also increased from 1996 – 2010, concurrent with an increasing trend in bioavailable PO4. We conclude that GLM-AED can reproduce historical water quality conditions of western Lake Erie.

1. Keyword
Lake Erie

2. Keyword
harmful algal blooms

3. Keyword
modeling

4. Additional Keyword
long-term trends

5. Additional Keyword
nutrients