HR: 12:05h
AN: H52B-08    [Abstracts]
TI: Velocities of Water Pulses are the Key to Up-Scaling Subsurface Storm Flow
AU: * Germann, P F
EM: germann@giub.unibe.ch
AF: Dept. Geography, University of Bern, Hallerstrasse 12, Bern, 3012, Switzerland
AU: Retter, M
EM: retter@giub.unibe.ch
AF: Dept. Geography, University of Bern, Hallerstrasse 12, Bern, 3012, Switzerland
AB: The velocity of laminar flow in soils is dynamically related to the thickness of water rivulets while the lateral extent of all the rivulets is proportional to the mobile component of volumetric soil moisture. The geometry of the pores thus constrains flow as it is expressed with the hydraulic conductivity at saturation. Flowing rivulets can be superimposed under the two conditions of (i) gravity being the only flow-driving force (i.e. hydraulic pressure and capillary potential become negligible at the hill-slope scale) and (ii) gravity being immediately balanced by viscosity. The rivulet approach is positioned between the realm of Darcy's law, where all the pores are filled with water, and the realm of the Richards' equation, where the diffusion of capillary potential increasingly dominates flow as soil moisture decreases. The rivulet approach to flow provides for a framework for dealing with fast flow that is usually associated with preferential flow. Measured vertical and lateral flow velocities will be presented. The resulting spectrum of time and length scales of subsurface storm flow will be discussed.
DE: 1838 Infiltration
DE: 1839 Hydrologic scaling
DE: 1865 Soils (0486)
DE: 1866 Soil moisture
DE: 1872 Time series analysis (3270, 4277, 4475)
SC: Hydrology [H]
MN: 2007 Joint Assembly