Preferential flow and spatial variation of water and contaminant transport through soil /
A field study was conducted on a Silawa variant in Brazos County, Texas, to evaluate spatial variability of water and contaminant fluxes through the soil profile. Two types of experiments were performed: interception of soil water flux and soil staining. A grid of 7 x 14 interceptor cells (each 2....
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1995.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=742745381&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | A field study was conducted on a Silawa variant in Brazos County, Texas, to evaluate spatial variability of water and contaminant fluxes through the soil profile. Two types of experiments were performed: interception of soil water flux and soil staining. A grid of 7 x 14 interceptor cells (each 2.5 x 2.5 cm) was built to collect potassium bromide and erioglaucine (blue dye) solutions at 0.3 m, 0.9 m, and 1.2 m depths in horizontal tunnels. The bromide and dye solutions were applied to the soil surface through a 1.2 x 1.2 m metal infiltration square while a positive head of about 5 cm was maintained inside the square. The spatial distributions of intercepted fluxes fitted lognormal probability functions well. Most preferential (non-matrix) flow was found at 0.9 and 1.2 m depths. Fluxes were most heterogeneous at 0.9 m in the Bt2 horizon where peds were largest and coated with clay films, and where the texture was finer than at 0.3 and 1.2 m in the E and Bt3 horizons, respectively. Convergence of flow paths from 0.3 to 0.9 m and divergence from 0.9 to 1.2 m was observed. Measurements of bromide concentrations at 0.3 m were used to calibrate a deterministic convection-dispersion and a stochastic-lognormal transfer function model. Neither model predicted travel time probability density distributions well at 0.9 or 1.2 m depth. Contrary to logical theoretical concepts, breakthrough curve peaks from deeper measurements sometimes occurred before breakthrough curve peaks from shallower measurements, possibly due to preferential flow and non representative measurement areas. Erioglaucine (blue dye) solution was applied under ponded as well as non-ponded conditions (through a spray system) to natural undisturbed soil and to soil above a tunnel. Plots were dug out after infiltration, and pictures of dye patterns were taken from horizontal and vertical cross-sections to show preferential flow paths. Analysis of pictures confirmed initial convergence and subsequent divergence of water and solute transport from the E to Bt3 horizon. |
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| Item Description: | Vita. "Major Subject: Soil Science". |
| Physical Description: | xi, 126 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references. |