Incorporating Channel Spatial Variability into Two-Zone Transient Storage Modleing
Location
Eccles Conference Center
Event Website
http://water.usu.edu/
Start Date
3-29-2011 3:00 PM
End Date
3-29-2011 3:20 PM
Description
The two-zone.temperature and solute (TZTS) transport model separates transient storage into surface and subsurface (hyporheic) storage zones due to the potentially different residence time distributions and processes that individually influence each zone. Despite this approach to better represent individual transport processes and storage volumes, the effects of channel spatial heterogeneity on solute transport predictions are not well understood. Since constant channel geometry is often assumed among transient storage modeling efforts and numerical approximation methods are typically used, analytical solutions were developed for the solute component of the TZTS model to serve as verification of numerical results, aid in interpretation of results, and provide a more stable means to account for spatial variability in parameters. In a previous effort, the TZTS model was applied to a 6.5 km reach of the Virgin River, a low gradient desert river with sand to gravel substrate and negligible groundwater exchange, in southwestern Utah, United States. Parameters, including main channel and surface storage widths, were initially estimated using solute tracer data and assumed constant for the entire study reach. Although reasonable solute transport predictions were provided by the calibrated model, the significance of neglecting spatial variability in channel geometry on predictions was uncertain. We investigated the effects of these assumptions by using main channel and surface storage width parameters extracted from aerial high resolution multispectral and thermal infrared imagery. We then used the TZTS analytical solutions with a convolution approach to incorporate these spatially variable parameters into solute transport predictions. In comparing these results to the constant channel geometry predictions, we found significant spatial variability in solute residence times and, therefore, a requirement of further calibration resulting in different parameter sets.
Incorporating Channel Spatial Variability into Two-Zone Transient Storage Modleing
Eccles Conference Center
The two-zone.temperature and solute (TZTS) transport model separates transient storage into surface and subsurface (hyporheic) storage zones due to the potentially different residence time distributions and processes that individually influence each zone. Despite this approach to better represent individual transport processes and storage volumes, the effects of channel spatial heterogeneity on solute transport predictions are not well understood. Since constant channel geometry is often assumed among transient storage modeling efforts and numerical approximation methods are typically used, analytical solutions were developed for the solute component of the TZTS model to serve as verification of numerical results, aid in interpretation of results, and provide a more stable means to account for spatial variability in parameters. In a previous effort, the TZTS model was applied to a 6.5 km reach of the Virgin River, a low gradient desert river with sand to gravel substrate and negligible groundwater exchange, in southwestern Utah, United States. Parameters, including main channel and surface storage widths, were initially estimated using solute tracer data and assumed constant for the entire study reach. Although reasonable solute transport predictions were provided by the calibrated model, the significance of neglecting spatial variability in channel geometry on predictions was uncertain. We investigated the effects of these assumptions by using main channel and surface storage width parameters extracted from aerial high resolution multispectral and thermal infrared imagery. We then used the TZTS analytical solutions with a convolution approach to incorporate these spatially variable parameters into solute transport predictions. In comparing these results to the constant channel geometry predictions, we found significant spatial variability in solute residence times and, therefore, a requirement of further calibration resulting in different parameter sets.
https://digitalcommons.usu.edu/runoff/2011/AllAbstracts/25