Dissertation/Thesis Abstract

Sediment and phosphorus dynamics behind weirs in agricultural drainage ditches
by Usborne, Elizabeth Louise, M.S., Mississippi State University, 2012, 115; 1516405
Abstract (Summary)

Low grade rip rap weirs installed in agricultural surface drainage ditches manage downstream eutrophication by slowing water flow, allowing sediments time to settle out of the water column and phosphorus (P) to sorb to soil. A laboratory experiment was conducted in microcosm chambers to simulate increased hydraulic residence time caused by weirs and two field studies were conducted to compare experimental data with field data and determine sediment deposition rates. One field study monitored weirs monthly after installation and the other measured weirs of varying ages. Weirs retained significantly more water and sediment than controls. Longer inundation times led to abiotic factors known to release P during hydrologic flux, but did not translate to reduced P storage. By converting intermittently inundated sediments into more consistently saturated sediments, weirs function as a viable conservation practice for about a year until temporary P retention mechanisms and sediment retention capacities are reached.

Indexing (document details)
Advisor: Kroeger, Robert
Commitee: Boyd, Christopher, Cox, Michael, Moore, Matthew
School: Mississippi State University
Department: Wildlife and Fisheries
School Location: United States -- Mississippi
Source: MAI 51/02M(E), Masters Abstracts International
Source Type: DISSERTATION
Subjects: Ecology, Soil sciences, Water Resource Management
Keywords: Agricultural drainage ditches, Lower Mississippi River alluvial valley, Phosphorus, Sediment, Weirs, pH
Publication Number: 1516405
ISBN: 9781267541970
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