Wednesday, November 7, 2007 - 11:10 AM
303-7

Sediment Transport Characteristics of Low-Order Streams on the Gulf Coast Plain.

Philip Saksa1, Y.Jun Xu2, April Mason1, and Daniel L. Thomas3. (1) School of Renewable Natural Resources, Louisiana State University, Rm. 227, RNR Building, Baton Rouge, LA 70803, (2) School of Renewable Natural Resources, Louisiana State University Agricultural Center, 227 Renewable Natural Res Bldg, Baton Rouge, LA 70803, (3) Biological and Agricultural Engineering, LSU AgCenter, Baton Rouge, LA 70803

Headwater streams drain the majority of the landscape, and knowledge of sediment transport from these systems is therefore critical in protecting overall stream water quality.� While many sediment studies have been performed in topographically variable areas, such as the Pacific Northwest, little information exists on headwater streams draining the coastal plains, including streams on the Southeastern Gulf Coast Plain. A study on the hydrology and water quality of this region has been established in the Flat Creek Watershed, located within the Ouachita River Basin of North Central Louisiana.� Flat Creek is a flat, lowland watershed (369 km2) dominated by commercially forested loblolly pine plantations and bottomland hardwood.� Streams in the watershed have minimal slopes, low flow, and often become intermittent in the dry summer season.� Containing first, second, and third-order streams, this study aims to quantify both spatial and temporal variations and interactions in streamflow with suspended and dissolved solids (TSS & TDS) over the entire watershed, including responses to precipitation events.� Streams have a distinct seasonal variation, with higher flow and larger storm responses during the winter months, and low to no-flow with lesser storm responses in the summer season.� Additionally, beaver and debris dams are prevalent throughout the stream network, resulting in increased storage time with reductions in peak storm flows and sediment yields. Complicating the assessment of stream flow and sediment loading in this region, these dams further decrease the already low slopes and streamflow.� Variation in stream baseflow is much greater than variations in concentrations of TSS or TDS, and is the major factor in sediment loading for this area.� Results from this study can be used to help assess similar streams systems and improve land management in semi-tropical lowland regions.