Modeling the Transport, Transformation, and Fate of Distributed Contaminants across the Land Surface

CTT&F was developed as a physically-based, spatially distributed watershed contaminant transport, transformation and fate sub-model for existing hydrological modeling systems. To better predict the ultimate fate of contaminants through the various landscape media, physical transport and transformation processes in CTT&F are simulated for each cell and routed to the watershed outlet. This permits the contamination mass and concentration at any cell in the watershed to be examined. For uplands, CTT&F simulates contaminant erosion and the 2D transport process of the eroded material. For channels the sub-model simulates the erosion of bed contaminants and the 1D downstream transport of this material together with washload supplied by the overland flow. The CTT&F sub-model in conjunction with distributed hydrologic transport models may be used to simulate solid contaminant and partitioning among truly dissolved phase, dissolved organic carbon (DOC) bound phase and sediment (multiple grain sizes) sorbed phase of the contaminant. In this study, CTT&F was coupled with a distributed hydrologic model to simulate RDX and TNT using an experimental test plot. Compared with measured data from the plot experiment, the results show that the model simulations agree well with the measured data set.