Groundwater

Oral

395097 - Quantifying the impact of preferential flow to shallow groundwater in riparian buffers: Mesoscale laboratory experiments

Thursday, June 7
8:30 AM - 10:00 AM
Location: Lakeshore B
Co-Authors: Garey Fox, Raleigh, NC – North Carolina State University; Rafael Munoz Carpena, Gainesville, FL – University of Florida; Bin Gao, Gainesville, FL – university of Florida; Derek Heeren, Lincoln, NE – University of Nebraska-Lincoln

Riparian buffers are management practices used to remove pollutants from surface runoff prior to discharge into a stream. Floodplains and riparian areas are uniquely susceptible to macroporous soil conditions due to their geomorphic depositions, abundant root network, biological activities. Macroporous soils can result in significant subsurface preferential leaching of water and pollutants to the shallow groundwater, bypassing surface pathways and therefore limiting the effectiveness of riparian buffers. Currently, the design of buffers or vegetative filter strips focuses on surface runoff and uniform infiltration but neglects preferential flow to shallow groundwater. To improve the performance of riparian buffers, the effect of macropores and preferential pathways needs to be incorporated into design tools. The objective of this study was to generate experimental data to evaluate the ability of theoretical models such as the dual porosity, dual permeability, and source-responsive models ability to simulate preferential flow in riparian areas.
Experiments were conducted on a riparian-buffer-scale model consisting of a 150-cm long, 70-cm wide and 40-cm deep soil box, a rainfall simulator, and a runoff collector. The box was filled with soil and artificial macropores were generated to create preferential flow paths. Small-volume soil moisture sensors were placed at various positions and depths in the soil box. Prior to each experiment, soil properties, bed topography, macropore arrangement and initial soil moisture were measured. Then a constant rainfall intensity was simulated and infiltration rate, soil water content and runoff outflow were recorded throughout the experiment to quantify surface and subsurface transport mechanisms. Several scenarios simulating various macropore arrangements, rainfall intensities and initial soil moisture conditions were performed. Individual scenarios were used to test the different preferential flow models.

Lucie Guertault, NC

Postdoctoral Research Associate
North Carolina State University

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395097 - Quantifying the impact of preferential flow to shallow groundwater in riparian buffers: Mesoscale laboratory experiments



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