Lateral water flux in the unsaturated zone: A mechanism for the formation of spatial soil heterogeneity in a headwater catchment

TitleLateral water flux in the unsaturated zone: A mechanism for the formation of spatial soil heterogeneity in a headwater catchment
Publication TypeJournal Article
Year of Publication2017
AuthorsGannon, JP, McGuire, KJ, Bailey, SW, Bourgault, RR, Ross, DS
JournalHydrological Processes
Volume31
Issue20
Pagination3568 - 3579
Date Published2017///
ISBN Number1099-1085
Accession NumberHBR.2017-55
Keywordshillslope hydrology, hydropedology, pedogenesis, soil science, stream chemistry, unsaturated flow
Abstract

Measurements of soil water potential and water table fluctuations suggest that morphologically distinct soils in a headwater catchment at the Hubbard Brook Experimental Forest in New Hampshire formed as a result of variations in saturated and unsaturated hydrologic fluxes in the mineral soil. Previous work showed that each group of these soils had distinct water table fluctuations in response to precipitation; however, observed variations in soil morphology also occurred above the maximum height of observed saturation. Variations in unsaturated fluxes have been hypothesized to explain differences in soil horizon thickness and presence/absence of specific horizons but have not been explicitly investigated. We examined tensiometer and shallow groundwater well records to identify differences in unsaturated water fluxes among podzols that show distinct morphological and chemical differences. The lack of vertical hydraulic gradients at the study sites suggests that lateral unsaturated flow occurs in several of the soil units. We propose that the variations in soil horizon thickness and presence/absence observed at the site are due in part to slope-parallel water flux in the unsaturated portion of the solum. In addition, unsaturated flow may be involved in the translocation of spodic material that primes those areas to contribute water with distinct chemistry to the stream network and represents a potential source/sink of organometallic compounds in the landscape.

URLhttps://onlinelibrary.wiley.com/doi/abs/10.1002/hyp.11279
DOI10.1002/hyp.11279
StartPage

3568

EndPage

3579