Sediment dynamics following active management of a stream buffer zone: A case study

Abstract

In this case study, change in sediment yield over a one year period was examined on paired watersheds (treated vs. reference) located in east Alabama. The effect of a partial cutting within a stream buffer zone (SBZ) on sediment yield was explored as well as the relative effects of pastoral, forested, and clearcut areas. During the no-harvest (calibration) period, upstream pastoral area generated much more sediment load per unit area than downstream forested sections during rainfall events. A partial cut within an SBZ changed the sediment pattern of downstream sections of the treatment watershed. On the treated sections, the observed sediment yield was higher than expected while there was no significant change in sediment yield from the pastoral area. Some of this increase was attributed to seasonal effects due to reduction in evapotranspiration. There was no change in the sediment yield pattern of the control watershed. The partial cut within the SBZ played a much more critical role than the stream road crossing as the sediment source. This study further shows that a holistic approach is needed to control sediment yield in mixed land use watersheds.