Response of Wetland Soils to Flow Alterations in the Sabine River below Toledo Bend Dam for the Texas Instream Flows Program.
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Hydric soils are a key component to the development of wetland ecosystems. It is well documented that dams change the hydrology and sediment deposition of regulated rivers which can alter hydric soil properties on the riparian wetlands. This research looks at four different techniques to establish if hydric conditions have changed below the Toledo Bend Dam: pH, redoximorphic features (“redox”), presence of Ferrous Iron (Fe 2), and the chroma of soil colors. Three riparian wetland sampling sites were identified below the dam using high radar LIDAR digital elevation modeling. Soils were collected from each stratum to a depth of 50 cm using a stratified random approach. Distinct patterns were observed in regards to the pH, redox, Ferrous Iron, and color of soils at the three research sites. In general, soils had a lower pH and more redox potential with decreasing elevation and with increasing distance from Toledo Bend Dam suggesting only the lowest elevations were hydric soils. Reduced conditions detected by ferrous iron also indicated that sites farthest from the dam were retaining hydric properties. Chroma color, although less consistent, also supported the reduced effect on sites downstream. The results are to be presented to the Texas Instream Flow program to help assess the conditions of the Lower Sabine River.
Toledo Bend Dam
Lower Sabine River
Nally, Deseri 1975- (2011). Response of Wetland Soils to Flow Alterations in the Sabine River below Toledo Bend Dam for the Texas Instream Flows Program.. Honors and Undergraduate Research. Available electronically from