|CHAO, XIAOBO - University Of Mississippi|
|JIA, YAFEI - University Of Mississippi|
|ZHU, TINGTING - University Of Mississippi|
Submitted to: Advances in Environmental Research
Publication Type: Book / Chapter
Publication Acceptance Date: 6/1/2015
Publication Date: 9/1/2015
Citation: Chao, X., Jia, Y., Zhu, T. 2015. Numerical modeling of chemical spills and assessment of their environmental impacts. In: Daniels, J.A. editor. Advances in Environmental Research. Nova Science Publishers. 44:1-28.
Interpretive Summary: The CCHE2D model was applied to simulate the fate and transport of chemical spill in water bodies. The model was verified using analytical solutions and validated using a real chemical spill accident occurred in the Rhine River, Switzerland, in Nov. 1986. The model was then applied to simulate the chemical concentration distributions of two hypothetical chemical incident in Ross Barnett Reservoir in Mississippi. The environmental information of National Pollutant Discharge Elimination System (NPDES) Facilities and Toxics Release Inventory (TRI) Facilities in the watersheds of the reservoir and upstream Pearl River were collected. Some field observation data, including water discharge, water surface elevation, wind direction and speed, and water quality data, were obtained from USGS and National Climatic Data Center. The time series of flow velocities and chemical concentrations in the reservoir were simulated. Based on numerical results and EPA’s drinking water standard, polluted areas in the reservoir due to the chemical incident were estimated. In order to provide information for emergency management and response planning, the numerical model was applied to simulate lots of cases by changing flow discharges, wind directions and speeds statistically. Based on the simulation results of those multiple model runs, the following statistical results were produced for environmental risk assessment: 1) The probability at each location that chemical concentration is higher than the MCL; 2) The possible maximum chemical concentration at each location; 3) The earliest time that the concentration may exceed MCL at each location; 4) The maximum exposure time that the concentration may exceed MCL at each location. This model provides useful information for developing and implementing an emergency response plan, and they are also valuable for environmental impact assessment.
Technical Abstract: Chemical spills in surface water bodies often occur in modern societies, which cause significant impacts on water quality, eco-environment and drinking water safety. In this paper, chemical spill contamination in water resources was studied using a depth-integrated computational model, CCHE2D, for predicting fate and transport processes of chemical contaminants in surface waters. The processes of volatilization, photolysis, hydrolysis, sorption, desorption, degradation, etc. were included, and the interaction between sediment bed and water column were also considered. In addition, the model can also simulate the processes in bed sediment layers. This model was first validated using a real chemical spill accident occurred in Rhine River, Switzerland, in Nov. 1986. The simulated results were generally in agreement with the field observations. The validated model was then applied to simulate the flow fields as well as the processes of fate and transport chemical spills in Ross Barnett Reservoir in Mississippi with unsteady flows driven by wind and hydrograph. Based on numerical results and EPA’s drinking water standard, polluted areas due to the chemical incident in the reservoir can be estimated. In order to provide information for emergency management and response planning, the chemical spill model was applied to simulate lots of cases by changing flow discharges, wind directions and speeds statistically. Using statistical analysis, the probability of each location that chemical concentration was higher than the Maximum Contaminate Level (MCL) was calculated, and the worst condition for some important facilities, such as water intake, recreation places, and reservoir outlet were studied. The computed results provide useful information for chemical incident response and environmental impact analysis.