HR: 1340h
AN: H23G-1692    [Abstracts]
TI: Water Flow and Solute Transport in Heterogeneous Soils: A new Multicompartment Sampler and a Theoretical Toolkit for Data Analysis
AU: * de Rooij, G H
EM: ger.derooij@wur.nl
AF: Wageningen Univ., Center for Water and Climate, Soil Physics, Ecohydrology, and Groundwater Management, P.O. Box 47, Wageningen, 6717 KS, Netherlands
AU: Hogervorst, F A
EM: franck.hogervorst@wur.nl
AF: Wageningen Univ., Center for Water and Climate, Soil Physics, Ecohydrology, and Groundwater Management, P.O. Box 47, Wageningen, 6717 KS, Netherlands
AU: Bloem, E
EM: esther.bloem@wur.nl
AF: Wageningen Univ., Center for Water and Climate, Soil Physics, Ecohydrology, and Groundwater Management, P.O. Box 47, Wageningen, 6717 KS, Netherlands
AU: Stagnitti, F
EM: frank.stagnitti@deakin.edu.au
AF: Deakin Univ., School of Life and Environmental Science, P.O. Box 423, Warrnambool, Vic 3280, Australia
AU: Cirpka, O A
EM: olaf.cirpka@eawag.ch
AF: Swiss Federal Institute of Aquatic Science and Technology (EAWAG), Dept. Water Resources and Drinking Water, Uberlandstrasse 133, Dubendorf, 8600, Switzerland
AB: Water flow and solute transport in soils are invariably affected by heterogeneity and often by preferential flow, both typically occurring within 1 square meter. Paradoxically, we need to understand flow and transport at this small scale to quantify them at the field and regional scales. This paradox arises from the geometry of soils: the scale in the direction of the flow is orders of magnitude smaller than the scales perpendicular to it. We present a coherent package of experimental and theoretical tools to observe and analyze small-scale variations (within 0.1- 1 square meter) of water and solute fluxes. Multicompartment samplers can measure small-scale water and solute movement in space and time, particularly in temperate climates. The latest generation of samplers allows repeated extraction of percolate samples in situ under controlled suction to minimize disturbance of the unsaturated flow field. After discussing the general principle of such samplers, a method will be presented to estimate the required total sampling area of a sampler from the degree of flow convergence in a soil. In recent years, we improved our ability to analyze the data produced by multicompartment samplers. The spatial solute distribution curve as the spatial equivalent of the travel time distribution was parameterized and physically interpreted. Both distributions were unified in the leaching surface, which has tremendous potential for detailed interpretation and model evaluation. Multicompartment samplers can also help identify the nature of the solute transport process. Recently, we expanded the theory of solute dilution to make it applicable to multicompartment sampler data. We will demonstrate how dilution theory can be used to determine the predominance of a convective-dispersive or a stochastic-convective transport regime during a tracer experiment.
DE: 1838 Infiltration
DE: 1866 Soil moisture
DE: 1875 Vadose zone
DE: 1895 Instruments and techniques: monitoring
SC: Hydrology [H]
MN: 2007 Fall Meeting