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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVING COMPUTATIONAL MODELING IN SUPPORT OF BETTER EROSION AND SEDIMENT MOVEMENT CONTROL IN AGRICULTURAL WATERSHEDS

Location: Watershed Physical Processes Research Unit

Title: Three dimensional numerical modeling of flow and pollutant transport in a flooding area of 2008 US Midwest Flood

Authors
item Chao, Xiaobo -
item Jia, Yafei -
item Hossain, Azad -

Submitted to: American Journal of Climate Change
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 7, 2013
Publication Date: June 26, 2013
Citation: Chao, X., Jia, Y., Hossain, A. 2013. Three dimensional numerical modeling of flow and pollutant transport in a flooding area of 2008 US Midwest Flood. American Journal of Climate Change. 2:116-127.

Interpretive Summary: A three dimensional model was developed and applied to simulate the wind-driven flow and pollutant transport in natural waters. The model was first validated against measured velocity profile of wind-driven flow obtained in an experimental open channel. Then it was applied to simulate the wind-driven flow and pollutant transport over flood plains along the Mississippi River during the 2008 US Midwest flooding event. The remote sensing technology was used to provide the locations of residential house and farmer’s facility, and the length of the broken levee. It was also used to identify the pollutant distributions in the computational domain and extract pollution source locations. Based on the field observation and satellite imagery, the pollutants in the studied flood zone was considered as oily material. It was floating on the water surface and mainly driven by the wind-induced surface velocity. The simulation of wind driven flow was tested using several meshes with different vertical uniform and non-uniform distributions, and the mesh with thinner surface and bottom layers (4% of total depth) was selected for the simulating the flow and pollutant transport in the flood zone. The simulated pollutant distributions were generally in good agreement with observations obtained from satellite imagery. This model provides useful information to understand the flow circulation and pollutant transport in the flooding zone. It may help for evaluating pollutant spill impact on flood plain soil and crops during a flood.

Technical Abstract: This paper presents the development and application of a three-dimensional numerical model for simulating the flow field and pollutant transport in a flood zone near the confluence of the Mississippi River and Iowa River in Oakville, Iowa. Due to a levee breaching along the Iowa River during the US Midwest Flood in 2008, this small town was completely flooded for a couple of weeks. During this period, the high water level reached about 2.5 meter above the ground, and wind was the major force for the flow circulation. It was observed that some pollutants were leaked from the residential and farming facilities and transported into the flood zone. Leaking of pollutants from these facilities were reported by different news media during the flood and were identified using high resolution satellite imagery. The developed 3D numerical model was validated using experimental measurements, and then applied to the flood inundated zone in Oakville for simulating the unsteady hydrodynamics and pollutant transport. The simulation results of pollutant distributions had good general agreement with the observed data obtained from satellite imagery.

Last Modified: 10/20/2014
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