DynaRICE Modeling to Assess the Effect of the 1984 Ice Jam on Possible Bed Changes in the St. Clair River Tomasz Kolerski and Hung Tao Shen St. Clair River is not an ordinary, (normal), river Water level cannot exceed the level of Lake Michigan-Huron Beltaos (2009) Decline in Head Difference between Lake Michigan-Huron and Lake Erie The head difference, or lake-to-lake fall, between Lake Michigan-Huron and Lake Erie declined by about 62 cm between 1860 and 2006; St. Clair Rivers conveyance changed rapidly in the mid-1980s, Conveyance of St. Clair River Monthly Conveyance from Dunn Paper to Mouth of Black River Daly(2009) Conveyance of St. Clair River Monthly Conveyance from Mouth of Black River to Dry Dock Daly(2009) Conveyance of St. Clair River Monthly Conveyance from Dry Dock to St. Clair State Police Daly(2009) Conveyance of St. Clair River Monthly Conveyance from St. Clair State Police to Algonac Daly(2009) 1984 Ice Jam One of possible cause of the decline in the head difference between Lake Michigan-Huron and Lake Erie since 1962 is a major ice jam on the St. Clair River in April 1984 Available evidence is not sufficient to justify a conclusion that the 1984 jam was indeed the cause of the change 1984 Ice Jam Duration of 24 days Produced major impact on navigation (estimated losses $1.7M a day) Lake St. Clair water levels dropped about 0.6 m Flow reduced by approx. 65% Water velocity reduced by about 50% St. Clair River Gauges Station Name Latitude [m] Longitude [m] St. Clair Shores Algonac Port Lambton St. Clair State Police Dry Dock Mouth of the Black River Point Edward Dunn Paper Fort Gratiot Model Calibration Bed Manning's Coefficients St. Clair River Gauges HEC-RAS RMA2DynaRICE bathymetry bathymetry Ft. Gratiot -Dunn Paper Dunn Paper - Pt. Edward Pt. Edward - Mouth of Black River Mouth of Black River - Dry Dock Dry Dock - St. Clair S.P St. Clair S.P. - Pt. Lambton Pt. Lambton - Algonac Algonac - St. Clair Shores 1984 Ice Jam Water Level Data Ice Discharge Ice Formation in St. Clair Flats Ice Formation in St. Clair River Ice Jam Formation Ice Formation Animation Bed Shear Stress c f = friction coefficient; = water density; q x,y = components of unit width water discharge; H' = water depth beneath the ice layer. b = fraction of the total water flow depth affected by the bed friction); n b = bed Manning's coefficient; g = gravitational acceleration. Bed Shear Stress Ice Jam Release Water Level Data Ice Jam Release Animation Conclusions The results from DynaRICE simulations indicated that the ice jam in the river did not cause a significant increase in bed shear stress compared to pre- and post-jam open water conditions This is reasonable since the backwater effect of the jam was not significant as it is constrained by the limited level difference between Lake Huron and Lake St. Clair and the large depth of river flow relative to the jam thickness One possible indirect contribution of ice jams to the conveyance increase is the excess water stored in Lake Huron during a jam (Derecki and Quinn 1986). This increase in water storage increases the lake water level to produce larger discharge into the St. Clair River, which may have caused a gradual increase in conveyance Thanks!