Significance of Mesh Density in Aquifer Storage and ...

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XVI International Conference on Computational Methods in Water Resources (CMWR-XVI) Ingeniørhuset

Significance of Mesh Density in Aquifer Storage and Recovery Modeling
Author:Hwai-Ping Cheng <> (US Army Engineer Research and Development Center)
Steven England <> (US Army Corps of Engineers, the Philadelphia District)
Christopher Brown <> (US Army Corps of Engineers, the Jacksonville District)
Presenter:Steven England <> (US Army Corps of Engineers, the Philadelphia District)
Date: 2006-06-18     Track: General Sessions     Session: General

Aquifer Storage and Recovery (ASR) is means to store fresh water deep underground in brackish water aquifers. This stored water can be recovered at a later date during emergencies or times of water shortage. ASR is expected to provide a cost- effective solution to many of the world’s water management needs. However, the quality of the stored water may degrade over time due to mixing and buoyancy stratification. Water quality may further be reduced during extraction due to upconing of saline water underlying the ASR well. This water quality degradation may reduce the volume of the available fresh water during recovery to the point that the ASR well is no longer cost effective. Because flow and concentration gradients may be high in the vicinity of an ASR well, the vertical and horizontal resolution of the 3D mesh in the vicinity of the ASR well is important. Meshes that do not have sufficient resolution in the area of interest may not accurately simulate observed conditions in these high gradient areas. On the other hand, meshes that contain too much resolution will require more computational resources, resulting in extended simulation times. A preliminary study has shown that the ASR simulation became more computationally stable as the vertical resolution was increased in the geologic units above, below, and containing the ASR well when the WASH123D model was used as the computational tool. In this paper, a sensitivity study of how various vertical and horizontal mesh resolutions may impact computational accuracy and efficiency is presented. For this paper a sensitivity analysis will be performed to evaluate the effect of various mesh resolutions on computational speed and accuracy.