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The Contaminant Model for Streams (CMS) was developed for studies where data and resources for model application are limited. CMS can be relatively easily and quickly applied, yet it is a versatile model that can be used for a variety of conditions ranging from short-term spill modeling to multi-year simulations of contaminant fate in stream water and bottom sediments. CMS was developed to fill a gap in the Adaptive Risk Assessment Modeling System (ARAMS™). Before the addition of CMS, ARAMS did not have a one-dimensional contaminant transport and fate model for streams that could simulate interactions between the water column and sediment bed.
CMS was developed such that it can be applied within the ARAMS framework and also can be run as a stand-alone application outside of ARAMS. The model can be used to simulate a wide range of conditions from spill simulations with time steps in seconds to long-term simulations with time steps of about a year. A variable time step is used with user options. It can be applied for both organic and inorganic contaminants, and the available fate and transport processes include advection and diffusion along the stream reach, settling, resuspension, burial, volatilization, decay or degradation, and diffusion between the water column and the sediment pore water. Suspended solids can be transported or a steady-state concentration may be input. However, the ARAMS version does not currently include solids transport. Steady-state, uniform hydraulic conditions are assumed within the modeled reach. Time-varying upstream loadings and flows can be applied, but flows are updated instantaneously throughout the reach, i.e., there is no hydraulic routing feature, thus greatly reducing model complexity.
The model user interface provides an easy-to-use method for quickly setting up the model and examining results. The interface also allows the user to select the methods and parameters used for the numerical solutions. The solution methods were selected to result in very short computer execution time for most applications. The model was verified against results from two other models developed by ERDC, RECOVERY, and PREWet, the latter of which uses an analytical solution method. The accompanying technical report describes the model and its verification.
Web Date: April 2008
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