Optimizing Artificial Aeration for Lake Winterkill Prevention

ABSTRACT

Optimizing winter lake aeration equipment has never been quantified in situ with regard to air or water flow, polynya size (the open water area created by the aerators), or energy required to maintain adequate dissolved oxygen (DO) concentrations. We conducted experiments using different combinations of compressors, air diffusers and mechanical surface aerators in winterkill lakes in northwest Alberta in order to determine a simplified approach to aeration equipment sizing. A hyperbolic relationship existed between energy use and polynya size. The largest polynya sizes were created using 0.15 kW ha⁻¹ with both submersed air injection and surface aerators. However, adequate DO concentrations were maintained with surface aeration using one-third to one-half of the energy used for air injection. Optimal sizing occurred with 0.15–0.23 kW ha⁻¹ for air injection and 0.06–0.1 kW ha⁻¹ for surface aeration.

Key Words:

• winter lake aeration
• winterkill prevention
• equipment sizing
• energy use
• mechanical surface aeration
• air injection