DETERMINATION OF REAERATION COEFFICIENTS - WHOLE-LAKE APPROACH

Onondaga Lake N.Y., experiences a marked annual dissolved oxygen deple tion over the entire water column at fall turnover. Depletion occurs a s a result of the entrainment of reduced substances that have accumula ted in the lake's hypolimnion over the summer. Recovery (return to nea r-saturated conditions) occurs over a period of 3-4 weeks. Observation s of dissolved oxygen (DO) levels during the recovery period of two ye ars are used to calculate the reaeration coefficient (K-a,K-20 = 0.22 d(-1)) in 1989, and 0.13 d(-1) in 1990) and the liquid film transfer c oefficient for oxygen (K-L,K-20 = 2.64 m . d(-1) in 1989, and 1.50 m . d(-1) in 1990). Local wind measurements are used to develop an empiri cal relationship between wind speed (U-10, m . s(-1)) and K-L,K-20: K- L,K-20 = alpha . U-10(beta), with alpha = 0.2; beta = 1.0 for U-10 les s than or equal to 3.5 m . s(-1) and alpha = 0.057; and beta = 2.0 for U-10 > 3.5 m . s(-1). Model output and field observations are compare d with estimates generated using other published relationships.