Hydrologic and sediment transport response to forestry; southwest Georgia headwater streams
Summer, W. B.
Jackson, C. Rhett
Golladay, Stephen W.
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Properly established streamside management zones (SMZs) reduce potential impacts of timber harvesting on stream sediment fluxes. However, effects of partial harvesting within SMZs on water quality are not well documented. The objectives of this study are to examine the effects of forestry activities on hydrology and sediment export in undisturbed first-order streams as part of a long-term paired watershed study. The study design includes two reference (no harvest) and two treatment watersheds (all are between 26 – 48 hectares in size). The entire treatment watersheds were harvested except for SMZs, which were divided into upper and lower sections. The upper sections had an intact SMZ, while the lower sections were thinned according to Georgia best management practices (BMP) guidelines. Flow and sediment concentrations were monitored at the outlet of each treatment and reference watershed for two years prior to and one year following harvest. Though peak flow rates have not significantly increased in treatment watersheds as a result of harvest, cumulative flows have doubled. Observations of variable source areas indicate water tables have risen in treatment watersheds.