HR: 0800h
AN: H51F-0426    [Abstracts]
TI: Literature review of dispersivity lengths for transport in soils.
AU: Vanderborght, J
EM: j.vanderborght@fz-juelich.de
AF: Agrosphere Institute, Forschungszentrum Julich GmbH, Juelich, 52425 Germany
AU: * Vereecken, H
EM: h.vereecken@fz-juelich.de
AF: Agrosphere Institute, Forschungszentrum Julich GmbH, Juelich, 52425 Germany
AB: The one-dimensional convection-dispersion equation is often used in practice to estimate the risk of non-point source groundwater contamination by widespread surface applied chemicals. The dispersivity length is known to be a sensitive parameter for the prediction of the mass that leaches from soil towards the groundwater. Dispersivity lengths are commonly derived from leaching experiments with inert tracers in soil cores or field plots. In this contribution, we present a database of dispersivity lengths that were derived from leaching studies in naturally structured soils. The database contains more than 600 entries derived from 57 publications. One database entry contains a dispersivity length and information about the experimental conditions: transport distance, flow rate, boundary conditions, soil texture class, pore water velocity, transport velocity, and measurement method. An analysis of the database illustrated that dispersivity lengths strongly depend on experimental factors. Correlations between experimental factors complicate the identification of single factor effects on dispersivity. Saturated flow conditions and high flow rates in naturally structured soils clearly led to larger dispersivities. However relatively more lab scale experiments and experiments in heavier soil textures were carried out under these conditions. Since saturated conditions and high flow rates are less relevant for transport under natural climatic boundary conditions, experiments under these conditions were excluded for further analyses. A further analysis confirmed that dispersivities in soils scale in general with travel distance. Dispersivities were on average larger in finer than in coarser textured soils. But, the variability of dispersivities is large and the number of samples is small so that a relation between soil texture and dispersivity remains uncertain.
DE: 1832 Groundwater transport
DE: 1865 Soils (0486)
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: Fall Meeting 2005