Kalamazoo River Hydrodynamic and Sediment Transport Modeling Supported by Fluvial Geomorphology

摘要

Background/Objectives. The mobility and transport of crude oil in a riverine system istypically influenced by oil physical properties. Submerged oil is often associated withorganic and/or fine-grained deposits in the near surface sediment profile. An estimated840,000 gallons of crude oil were released from a rupture in Enbridge Energy Line 6Bnear the Kalamazoo River at Marshall, Michigan on July 26, 2010. The transport of someoil was facilitated by 5.7 inches of rainfall from July 22 through July 25 that resulted in a25-year return frequency peak flow at the Marshall United States Geological Survey(USGS) Station on the day of the release. Submerged oil delineation and/or removal havecontinued through 2012. A model using the Environmental Fluid Dynamics Code wasused to support recovery decisions.Approach/Activities. Separate two-dimensional riverine and floodplain models were developed.Each model simulated flow and sediment transport for up to 40 miles of river.The riverine model domain included the channel and was designed with a curvilinearorthogonalgrid cell network to accommodate river sinuosity. The floodplain model domainincluded the riverine channel and floodplain and was designed with a finer-scaledCartesian grid. USGS station historical discharge data were used to establish flow boundaryconditions in the up and down river model domains. Tributary flow inputs were basedon data from USGS stations or a weighted method for ungaged watersheds that consideredgaged flow and gaged-ungaged drainage area ratios. Suspended sediment inputswere based on sediment concentration and flow using USGS station data. Model grid cellinputs included data to characterize bathymetry and topography, roughness, meteorologicalconditions, critical shear stress for deposition/erosion, and sediment physical conditions.The model calibrations were an iterative process and included boundary conditionor input value adjustments following comparisons of simulated and measured parametersincluding flow, velocity, and surface water elevation at locations for a specified flow timeseries. Mapped geomorphic surfaces throughout the model domains were used to supportmodel calibrations and ensure that simulations of erosional and depositional areas reasonablycorrelated with field conditions. The calibrated models were used to simulateflow and sediment transport for a range of flow scenarios including low flow, bankfull,and high flow (100-year return period). The simulations provided a basis for evaluatingthe potential for sediment and associated submerged oil transport and subsequent depositionwith flow events.