HR: 1340h
AN: H33B-0460    [Abstracts]
TI: How Lateral Preferential Flow Influences the Infiltration Behaviour
AU: * Kienzler, P M
EM: kienzler@ihw.baug.ethz.ch
AF: ETH Zurich, IHW, ETH Hoenggerberg Schafmattstrasse 8, Zurich, 8093 Switzerland
AU: Naef, F
EM: naef@ihw.baug.ethz.ch
AF: ETH Zurich, IHW, ETH Hoenggerberg Schafmattstrasse 8, Zurich, 8093 Switzerland
AB: Fast subsurface flow (SSF) in the vadose zone can play a key role in draining a hillslope. Even relatively small amounts of lateral preferential flow occurring continually can prevent total saturation of the soil profile and the generation of overland flow. In the presented project, the factors controlling this preferential flow were studied to define the soil parameters that control the rate of SSF on a hillslope. To this purpose, flows were closely monitored during sprinkling experiments and natural rainfall events on a hill slope where SSF occurs. Highly resolved measurements of soil moisture and surface and subsurface runoff in different depths were made. Event and pre-event water fractions as well as flow velocities in the different flow components were determined using artificial tracers. In addition, the naturally occurring 222Rn was measured continuously in a new approach to determine flow velocities and residence times. Together with detailed soil investigations and geophysical measurements it was possible to identify and quantify the relevant parameters and soil structures for the occurrence of SSF and for the infiltration behaviour at the test site. The results enabled us to assess the rate of lateral preferential flow, the soil water storage volumes and the infiltration capability between different soil horizons. The well-defined boundary conditions in this relatively simple system allowed insight into the mechanisms of pre-event water mobilization and the dependence of subsurface flow on the rainfall intensity.
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting