TY - JOUR

T1 - The role of bedrock topography on subsurface storm flow

AU - Freer, Jim

AU - McDonnell, J. J.

AU - Beven, K. J.

AU - Peters, N. E.

AU - Burns, D. A.

AU - Hooper, R. P.

AU - Aulenbach, B.

AU - Kendall, C.

PY - 2002/12/1

Y1 - 2002/12/1

N2 - We conducted a detailed study of subsurface flow and water table response coupled with digital terrain analysis (DTA) of surface and subsurface features at the hillslope scale in Panola Mountain Research Watershed (PMRW), Georgia. Subsurface storm flow contributions of macropore and matrix flow in different sections along an artificial trench face were highly variable in terms of timing, peak flow, recession characteristics, and total flow volume. The trench flow characteristics showed linkages with the spatial tensiometer response defining water table development upslope. DTA of the ground surface did not capture the observed spatial patterns of trench flow or tensiometric response. However, bedrock surface topographic indices significantly improved the estimation of spatial variation of flow at the trench. Point-scale tensiometric data were also more highly correlated with the bedrock surface-based indices. These relationships were further assessed for temporal changes throughout a rainstorm. Linkages between the bedrock indices and the trench flow and spatial water table responses improved during the wetter periods of the rainstorm, when the hillslope became more hydrologically connected. Our results clearly demonstrate that in developing a conceptual framework for understanding the mechanisms of runoff generation, local bedrock topography may be highly significant at the hillslope scale in some catchments where the bedrock surface acts as a relatively impermeable boundary.

AB - We conducted a detailed study of subsurface flow and water table response coupled with digital terrain analysis (DTA) of surface and subsurface features at the hillslope scale in Panola Mountain Research Watershed (PMRW), Georgia. Subsurface storm flow contributions of macropore and matrix flow in different sections along an artificial trench face were highly variable in terms of timing, peak flow, recession characteristics, and total flow volume. The trench flow characteristics showed linkages with the spatial tensiometer response defining water table development upslope. DTA of the ground surface did not capture the observed spatial patterns of trench flow or tensiometric response. However, bedrock surface topographic indices significantly improved the estimation of spatial variation of flow at the trench. Point-scale tensiometric data were also more highly correlated with the bedrock surface-based indices. These relationships were further assessed for temporal changes throughout a rainstorm. Linkages between the bedrock indices and the trench flow and spatial water table responses improved during the wetter periods of the rainstorm, when the hillslope became more hydrologically connected. Our results clearly demonstrate that in developing a conceptual framework for understanding the mechanisms of runoff generation, local bedrock topography may be highly significant at the hillslope scale in some catchments where the bedrock surface acts as a relatively impermeable boundary.

KW - Bedrock topography

KW - Macropores

KW - Soil moisture

KW - Subsurface storm flow

KW - Topographic index

KW - Trench flow

U2 - 10.1029/2001WR000872

DO - 10.1029/2001WR000872

M3 - Journal article

AN - SCOPUS:0037001330

VL - 38

SP - 5-1-5-16

JO - Water Resources Research

JF - Water Resources Research

SN - 0043-1397

IS - 12

M1 - 1269

ER -