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Description:
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Potential contamination from hazardous and solid waste landfills stemming from
population increase , rapid industrialization , and the proliferation of assembly plants
known as the maquiladoras , are of major concern in the U .S . -Mexican border area .
Additionally , historical , current , and future stresses on the Hueco Bolson alluvial aquifer
in the El Paso /Ciudad Juarez area due to excessive groundwater withdrawal can affect
contaminant migration in the area . In the current study , an updated and improved threedimensional
numerical groundwater flow and transport model is developed using a
current Hueco Bolson groundwater availability model as its basis . The model with
contaminant transport is required to access and characterize the extent of vulnerability of
the aquifer to potential contamination from landfills in the El Paso /Ciudad Juarez border
area . The model developed in this study is very capable of serving as the basis of future
studies for water availability , water quality , and contamination assessments in the Hueco
Bolson .
The implementation of fate and transport modeling and the incorporation of the
Visual MODFLOW® pre and post processor , requiring MODFLOW 2000 data conversion , enabled significant enhancements to the numerical modeling and computing
capabilities for the Hueco Bolson . The model in the current research was also developed
by employing MT3DMS© , ZONEBUDGET , and Visual PEST® for automated
calibrations .
Simulation results found that the Hueco Bolson released more water from storage
than the aquifer was being recharged in response to increased pumping to supply the
growing border area population . Hence , significant head drops and high levels of
drawdown were observed in the El Paso /Ciudad Juarez area . Predictive simulations were
completed representing scenarios of potential contamination from the border area sites .
Fate and transport results were most sensitive to hydraulic conductivities , flow
velocities , and directions at the sites . Sites that were located within the vicinity of the El
Paso Valley and the Rio Grande River , where head differences and permeabilities were
significant , exhibited the highest potentials for contaminant migration . |