Journal cover Journal topic
Natural Hazards and Earth System Sciences An interactive open-access journal of the European Geosciences Union
Nat. Hazards Earth Syst. Sci., 12, 2499-2505, 2012
https://doi.org/10.5194/nhess-12-2499-2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
10 Aug 2012
Basal interstitial water pressure in laboratory debris flows over a rigid bed in an open channel
N. Hotta Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 3058577, Japan
Abstract. Measuring the interstitial water pressure of debris flows under various conditions gives essential information on the flow stress structure. This study measured the basal interstitial water pressure during debris flow routing experiments in a laboratory flume. Because a sensitive pressure gauge is required to measure the interstitial water pressure in shallow laboratory debris flows, a differential gas pressure gauge with an attached diaphragm was used. Although this system required calibration before and after each experiment, it showed a linear behavior and a sufficiently high temporal resolution for measuring the interstitial water pressure of debris flows. The values of the interstitial water pressure were low. However, an excess of pressure beyond the hydrostatic pressure was observed with increasing sediment particle size. The measured excess pressure corresponded to the theoretical excess interstitial water pressure, derived as a Reynolds stress in the interstitial water of boulder debris flows. Turbulence was thought to induce a strong shear in the interstitial space of sediment particles. The interstitial water pressure in boulder debris flows should be affected by the fine sediment concentration and the phase transition from laminar to turbulent debris flow; this should be the subject of future studies.

Citation: Hotta, N.: Basal interstitial water pressure in laboratory debris flows over a rigid bed in an open channel, Nat. Hazards Earth Syst. Sci., 12, 2499-2505, https://doi.org/10.5194/nhess-12-2499-2012, 2012.
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