CCHE2D and CCHE3D Pollutant Transport Model
Waters resources are polluted by release of excessive chemicals from industries and accidental chemical spill incidents. CCHE2D and CCHE3D pollutant transport models, CCHE2D-Chem and CCHE3D-Chem, are developed for pollutant transport simulations. Because the pollutants move with water and interact with sediment, pollutant transport is often simulated with the flow and sediment transport models.
Chemical fate and transport modeling in the current version of the CCHE pollutant transport models solve the total chemical concentrations both in the water column and bed. The partition between the dissolved and particulate form is based on linear equilibrium sorption/desorption assumption. Chemical decay processes are approximated as first-order reactions.
Processes of a chemical pollutant interacting with water, suspended sediment and bed sediments
Chemicals released in water resources generally exist in four phases, dissolved in water column, dissolved in pore water, adsorpted on suspended sediment and bed sediment. This figure shows a sketch of fate processes simulated by CCHE2D-Chem and CCHE3D-Chem models, including the four phases and chemical exchange between the water column and bed due to sedimentation and diffusion.
In June 2008, a 500-year flood occurred in the Mississippi River. A levee along the Iowa River just upstream of Oakville breached. A large inundation area, ~120 square kilometers, was formed and the high water level in this flooded zone remained for several weeks. It was observed that some oily pollutants were leached at multiple locations such as A, B1, B2, C, D, E and F, and transported on the water surface by wind driven flow. CCHE3D was applied to simulate the flow field and CCHE3D_Chem was applied to simulate the oily pollutant transport. The simulated main trend of pollution stripes are generally in good agreement with the satellite imaginary.
This is a simulation of pollutant transport in a large reservoir using CCHE2D-Chem model. The hypothetical incident was studied to estimate the impact of the released pollutants on the lake water quality and downstream. This is a two year simulation. The transport and mixing process showing in the video is faster than reality.