30 Mar 2022
30 Mar 2022
Status: this preprint is currently under review for the journal HESS.

Subsurface flow paths in a chronosequence of calcareous soils: impact of soil age and rainfall intensities on preferential flow occurrence

Anne Hartmann1, Markus Weiler2, Konrad Greinwald2, and Theresa Blume1 Anne Hartmann et al.
  • 1Section Hydrology, GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 2Faculty of Environment and Natural Resources, Chair of Hydrology, University of Freiburg, Freiburg, Germany

Abstract. Soil hydrologic processes play an important role in the hydro-pedo-geomorphological feedback cycle of landscape evolution. Soil properties and subsurface flow paths both change over time, but due to lack of observations subsurface water flow paths are often not properly represented in soil and landscape evolution models. We investigated the evolution of subsurface flow paths across a soil chronosequence in the calcareous glacier forefield at the Griessfirn glacier in the Swiss Alps. Young soils developed from calcareous parent material usually have a high pH-value, which likely affects vegetation development and pedogenesis and thus the evolution of subsurface flow paths. We chose four glacial moraines of different ages (110, 160, 4900, and 13500 years) and conducted sprinkling experiments with the dye tracer Brilliant Blue on three plots at each moraine. Each plot was divided into three equal subplots and dyed water was applied with three different irrigation intensities (20, 40, and 60 mm h-1) and an irrigation amount of 40 mm. Subsequent excavation of soil profiles enabled the tracing of subsurface flow paths. A change in flow types with increasing moraine age was observed from a rather homogeneous matrix flow at 110 and 160 years to heterogeneous matrix and finger flow at 4900 and 13500 years. However, the proportion of preferential flow paths is not necessarily directly related to the moraine age, but rather to soil properties such as texture, soil layering, organic matter content and vegetation characteristics such as root length density and biomass. Irrigation intensity had an effect on the number of finger flow paths at the two old moraines. We also found that flow paths in this calcareous material evolved differently compared to a previous study in siliceous material, which emphasizes the importance of parent material for flow path evolution. Our study provides a rare systematic data set and observations on the evolution of vertical subsurface flow paths in calcareous soils, which is useful to improve their representation in the context of landscape evolution modeling.

Anne Hartmann et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2022-117', Anonymous Referee #1, 01 May 2022
  • RC2: 'Referee Comment on hess-2022-117', John R. Nimmo, 06 May 2022

Anne Hartmann et al.

Anne Hartmann et al.


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Short summary
The analysis of the age development of vertical subsurface flow paths in calcareous soils and the influence of rainfall intensity on this, with special focus on preferential flow occurrence, shows how water flow paths are linked to the organization of evolving landscapes. The observed transition to finger flow paths with increasing moraine age provides important but rare data for a proper representation of hydrologic processes within the feedback cycle of the hydro-pedo-geomorphological system.