Specific processes during in situ infiltration into a sandy soil with low-level water repellency

authored by: Christina Ganz, Jörg Bachmann, Axel Lamparter, Susanne K. Woche, Wilhelmus H.M. Duijnisveld, Marc O. Göbel
Abstract: Despite growing knowledge about water repellent soils it is not well investigated how soil water repellency (SWR) of a lower level influences the in situ water infiltration into soils. Hence, we investigated a sandy soil where we found subcritical water repellency and unexpected stable (persistent) contact angles (CAs) in the subsoil characterized by CA measurements in the laboratory. To characterize the influence of this persistence on in situ water infiltration, a ponded tracer infiltration experiment was carried out. During the infiltration, hydraulic sensors revealed a slight saturation at the wetting front which is a sign for unstable flow. The excavated dye-stained infiltration zone was conical and its lateral extent decreased with increasing depth, showing characteristics of a macro-finger. We suggest the subsoil to exhibit a strong hysteretic water retention characteristic governing the infiltration process, but we could not verify this by standard laboratory measurements, as strongly persistent SWR prevented the fast wetting of the soil samples. Close to saturation the persistence of SWR led to a wetting period of soil samples of at least 56. days to overcome SWR and reaching an equilibrium state. There are three major conclusions of this study: 1. In contrast to many other studies we found persistent SWR also in the subsoil and not only in the humic topsoil, 2. The shape of the wetting front is contrary to common expectations for homogeneous sandy soils and 3. The wettability characteristics found might also be relevant for assessing infiltration dynamics at other sites regarding the fact that those observations are not obvious.
Organisation(s): Institute of Soil Science
Section Soil Physics
External Organisation(s): Federal Institute for Geosciences and Natural Resources (BGR)
Type: Article
Journal: Journal of hydrology
Volume: 484
Pages: 45-54
No. of pages: 10
ISSN: 0022-1694
Publication date: 25.03.2013
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Water Science and Technology
Electronic version(s): https://doi.org/10.1016/j.jhydrol.2013.01.009 (Access: Unknown)

BibTeX

@article{bde18da98ec046938757272200194dae,
title = "Specific processes during in situ infiltration into a sandy soil with low-level water repellency",
abstract = "Despite growing knowledge about water repellent soils it is not well investigated how soil water repellency (SWR) of a lower level influences the in situ water infiltration into soils. Hence, we investigated a sandy soil where we found subcritical water repellency and unexpected stable (persistent) contact angles (CAs) in the subsoil characterized by CA measurements in the laboratory. To characterize the influence of this persistence on in situ water infiltration, a ponded tracer infiltration experiment was carried out. During the infiltration, hydraulic sensors revealed a slight saturation at the wetting front which is a sign for unstable flow. The excavated dye-stained infiltration zone was conical and its lateral extent decreased with increasing depth, showing characteristics of a macro-finger. We suggest the subsoil to exhibit a strong hysteretic water retention characteristic governing the infiltration process, but we could not verify this by standard laboratory measurements, as strongly persistent SWR prevented the fast wetting of the soil samples. Close to saturation the persistence of SWR led to a wetting period of soil samples of at least 56. days to overcome SWR and reaching an equilibrium state. There are three major conclusions of this study: 1. In contrast to many other studies we found persistent SWR also in the subsoil and not only in the humic topsoil, 2. The shape of the wetting front is contrary to common expectations for homogeneous sandy soils and 3. The wettability characteristics found might also be relevant for assessing infiltration dynamics at other sites regarding the fact that those observations are not obvious.",
keywords = "Macro-finger, Ponded infiltration, Stable contact angles, Unstable flow, Water repellency",
author = "Christina Ganz and J{\"o}rg Bachmann and Axel Lamparter and Woche, {Susanne K.} and Duijnisveld, {Wilhelmus H.M.} and G{\"o}bel, {Marc O.}",
note = "Copyright: Copyright 2013 Elsevier B.V., All rights reserved.",
year = "2013",
month = mar,
day = "25",
doi = "10.1016/j.jhydrol.2013.01.009",
language = "English",
volume = "484",
pages = "45--54",
journal = "Journal of hydrology",
issn = "0022-1694",
publisher = "Elsevier",
}