Understanding Hillslope Hydrology by Cobbling Together a Variety of Measurement and Sampling Schemes at the Panola Mountain Research Watershed, Georgia, USA
Abstract
The Panola Mountain Research Watershed (PMRW), which is one of five research sites of the U.S. Geological Survey's Water, Energy and Biogeochemical Budgets Program, is a 41-hectare forested watershed in the southern Piedmont physiographic province, 25 km southeast of Atlanta, Georgia. The watershed contains a naturally regenerated second-growth forest on abandoned agricultural land. One research focus at PMRW is to better understand processes that control the movement and solute composition of water along hydrologic pathways at the hillslope scale. Some of the research questions include: When does saturated flow occur on the hillslope? What are the primary hydrologic pathways? How do the soil depth and distribution, and hydrologic properties vary on the hillslope and how do they affect soil moisture and saturated flow? Is hillslope flow controlled by surface or subsurface (impermeable layer) topography? Does vegetation, trees in particular, control hillslope soil moisture, and subsurface flow; and conversely, does the soil distribution and related moisture content affect vegetation? The answers to these questions require specific types of data, for which there generally is no prescribed framework of instrumentation. This poster describes the suite of data and measuring devices, including the judicious application of duct tape, used at PMRW to address some of these questions. The measurements include saturated flow generated at the base of a soil section from the bedrock surface in 2-m sections of a 20-m trench excavated across the hillslope, using homemade tipping bucket gauges and some additional gauges added for excess flow from individual macropores. Also, soil-moisture content and tension were monitored across the hillslope using various capacitance, electromagnetic, and tensiometric approaches. The soil depths were determined from a 2-m grid of knocking pole measurements, which left a suite of ~2-cm diameter holes in which 2-cm PVC homemade wells were installed as maximum-rise or crest-stage gauges or for ground-water sampling. To investigate the linkage between transpiration from the dominant trees and soil moisture, several trees, instrumented with homemade sap flow sensors, were monitored. The techniques used to address the research questions and the lessons learned are reported.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2004
- Bibcode:
- 2004AGUSM.H33B..01P
- Keywords:
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- 1829 Groundwater hydrology;
- 1836 Hydrologic budget (1655);
- 1860 Runoff and streamflow;
- 1866 Soil moisture;
- 1894 Instruments and techniques