Importance of stormflow sediment loading for tmdl development in low-gradient forested headwaters

Document Type

Conference Proceeding

Publication Date

12-1-2010

Abstract

The impacts of intensive forest management to streamflow and sediment loading have not been well established in low-gradient headwaters that are highly intermittent during the summer, like those existing throughout the Gulf Coastal Plain. In addition, many studies regarding forestry operations and sediment have been conducted at the plot-scale, leaving a knowledge gap between plot- and watershed-scale benefits of forestry best management practices (BMPs). Paired-watershed and Before-After-Control-Impact (BACI) designs were utilized to assess plot- and watershed-scale changes in sediment loading for 27 months after clearcut harvesting with and without BMPs in a low-gradient, headwater-dominated watershed draining 369 km of north-central Louisiana. Assessment of BMP effectiveness was complicated by poor stage-discharge relationships and an abundance of beaver and debris dams, which complicate the stage-discharge relationship, but also act as settling ponds for sediment. Baseflow and stormfiow Total Suspended Solids (TSS) concentrations were not different between treatment periods. TSS loading increased post-harvest due to differences in the abilities of rating curves to predict high flows (p < 0.05), but was comparable to undisturbed forested watersheds of the Southeast. High flow events represent a substantial portion of annual and study period sediment loads, highlighting the need for load reduction strategies for peakflow conditions. This paper is a companion to Brown et al., 2010.

Publication Source (Journal or Book title)

ASABE - TMDL 2010: Watershed Management to Improve Water Quality

First Page

183

Last Page

192

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