HR: 1330h
AN: H42G-1156    [PDF]
TI: Simplicity from complexity: How lateral soil pipes define clear threshold relations at the hillslope scale
AU: Uchida, T
EM: uchida-t92rv@nilim.go.jp
AF: Research Center for Disaster Risk Management, National Institute for Land and Infrastructure Management, 1 Asahi, Tsukuba, 3050804 Japan
AU: * Tromp-van Meerveld, H J
EM: ilja.tromp@orst.edu
AF: Department of Forest Engineering, Oregon State University, Peavy 215, Corvallis, OR 97331 United States
AU: McDonnell, J J
EM: jeff.mcdonnell@orst.edu
AF: Department of Forest Engineering, Oregon State University, Peavy 215, Corvallis, OR 97331 United States
AB: The importance of lateral pipe flow on runoff generation in hillslopes has been described in many case studies from around the world. However, most pipe flow studies published to date have focused on only a few storms at any given site. Consequently, the overall controls on pipe flow response remain poorly understood. We present an intercomparison of pipe flow response to storm rainfall at four well instrumented sites: Panola (Georgia, USA), Toinotani (Kyoto, Japan), Jozankei (Hokkaido, Japan) and Hakyuchi (Tokyo, Japan). Our objective was to whittle down the complexities of lateral pipe flow on hillslopes by looking for commonality across different hillslopes. Despite the large differences between the study sites in topography, climate, soil type and soil matrix hydraulic conductivity, we found several common pipe flow responses to storm rainfall. Most evident was the highly threshold-like behavior of lateral subsurface stormflow and pipeflow, where despite differences in pedon scale soil properties, all of the hillslopes displayed a clear threshold-like response to storm rainfall. We used the results from the comparison to develop a decision tree to help define the conditions necessary for significant pipe flow (and hence, significant hillslope lateral flow generation) to occur. This decision tree is a useful organizational framework to summarize and organize comparative analyses and may provide a structure for defining the hierarchy of process controls. Our comparative analyses demonstrate the effectiveness of site inter-comparison for extracting common controls on complex hillslope processes.
DE: 1829 Groundwater hydrology
DE: 1860 Runoff and streamflow
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting