HR: 0800h
AN: H51C-0649    [Abstracts]
TI: Rivulets Link the Hydrology of Soils to Hill-Slopes
AU: * Germann, P F
EM: germann@giub.unibe.ch
AF: Dept. of Geography, University of Berne, Hallerstrasse 12, Bern, 3012, Switzerland
AB: Hydrologists dealing with run-off formation in small catchments often complain about much faster responses to precipitation at the catchment scale than what was predicted with soil hydrological approaches to infiltration and drainage. Constant velocity of the wetting front was observed, for instance, over a depth of 2 m and lasting more than 14 hours during an infiltration-drainage experiment in a tank that was homogeneously filled with sand. Constant velocity means neither acceleration nor deceleration of the moving water. This is only possible if the flow-driving and the flow-impeding forces continuously balance behind the wetting front. Rivulets are the conceptual units that dynamically balance forces during flow. They are considered thin streaks of flow that can be superimposed to rivulet ensembles and to water-content waves. Rivulets keep moving under the impact of gravity unless one of the following processes decelerates them: (i) increase of momentum dissipation due to reduced widths of the flow paths, (ii) capillarity-induced water sorption from the rivulets, and (iii) reduction of the rivulets' momentum due to the cessation of input. The velocities of the rivulets' wetting fronts collected so far in various systems like soils, unconsolidated sediments, fissured granites, and formations of chalk and karst, that extend over distances between 0.1 to 2000 m vary within about a factor of 50, thus offering a way of up-scaling soil hydrological processes to hill-slopes and small catchments that is based on rivulets.
DE: 1804 Catchment
DE: 1838 Infiltration
DE: 1839 Hydrologic scaling
DE: 1865 Soils (0486)
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting