Hydrologic influence on sediment transport of low-gradient, forested headwater streams in central LouisianaThis article is part of a larger document. View the larger document here.
Extensive research has been conducted on headwater streams in regions with high topographic variation. However, relatively few studies have examined low-gradient headwater stream systems, such as those existing in much of the southeastern Coastal Plain. The focus of this study is to investigate spatial and temporal variation of headwater stream hydrology in a low-gradient forested watershed and determine their effect on the transport of suspended and dissolved sediment. Stream discharge and sediment loads were monitored from December 2005 to April 2007 throughout a central Louisiana third-order watershed, with stream channel slopes of <1 percent. The study found that headwater streamflow in this low-gradient forested watershed was highly variable, from intermittent/no-flow conditions in the late summer, to high-volume overbank conditions in the winter. Transitioning from the headwater streams to the watershed outlet, stream hydrologic response and streamflow variability decreased. Suspended and dissolved solid concentrations during baseflow showed minimal seasonal variation, and loading was mainly controlled by discharge levels. Sediment yield from the watershed was low, due in part to the below normal precipitation and subsequent low storm runoff. As most of the land use in the watershed is commercial forest management, the low runoff decreases erosion susceptibility from harvesting activities. However, caution must also be taken and full implementation of forestry best management practices is recommended as harvest sites can become quickly saturated following precipitation events, creating the potential for unchecked surface runoff and sediment delivery to streams.