Abstract

Over the past several hundred years, agriculture has significantly changed both the magnitude and pattern of sediment transport on a global scale. In order to make informed management decisions, it is necessary to understand how landscapes respond to anthropogenic perturbations across geologic and topographic settings. In the Atlantic Piedmont, accumulations of sediment trapped behind colonial mill dams document impact of widespread land use change. However, an anthropogenic signature of valley floor sedimentation is less obvious in upland landscapes within the nearby Valley and Ridge Province, where Quaternary climate fluctuations and periglacial hillslope processes have driven headwater valley sedimentation over timescales ranging from 103-105 years.
Here, we focus on the 0.66 km2 Cole Farm study watershed, a calcareous shale and limestone catchment within the Susquehanna Shale Hills Critical Zone Observatory that has been continuously farmed since the early 1800's with a transition to no-till practices in the early 1970's. We aim to characterize the geometry and spatial patterns in soil thickness on hillslopes of a >4 m-thick colluvial valley fill. To quantify spatial patterns in decadal soil transport and erosion, we are currently analyzing samples from two soil pit catenas for 137Cs. We will constrain longer-term sedimentation history in the valley fill through radiocarbon dating of valley cores. Together, the spatial patterns of soil thickness, topography, and the timing of erosion and sedimentation will help constrain the relative influence of climate versus land use controls on hillslope erosion and valley sedimentation.

Citation

Perri Silverhart*, Roman A DiBiase (2018): Investigating climate change versus land use controls on hillslope erosion and valley sedimentation at the Cole Farm study watershed, central Pennsylvania. Abstract H53N-1775 presented at 2018 AGU Fall Meeting, Washington, D.C., 10-14 Dec.

This Paper/Book acknowledges NSF CZO grant support.