Impacts of Evaporation-Induced Groundwater Upwelling on Mixing Dynamics in Shallow Wetlands

Xiaolong Geng, Michel C. Boufadel, Hailong Li, Viravid Na Nagara, Kenneth Lee

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

Groundwater mixing dynamics play a crucial role in the biogeochemical cycling of shallow wetlands. In this paper, we conducted groundwater simulations to investigate the combined effects of evaporation and local heterogeneity on mixing dynamics in shallow wetland sediments. The results show that evaporation causes groundwater and solutes to upwell from deep sediments to the surface. As the solute reaches the surface, evaporation enhances the accumulation of the solute near the surface, resulting in a higher solute concentration than in deep sediments. Mapping of flow topology reveals that local heterogeneity generates spatially varied mixing patterns mainly along preferential flow pathways. The upwelling of groundwater induced by surface evaporation through heterogeneous sediments is likely to create distinct mixing hotspots that differ spatially from those generated by lateral preferential flows driven by large-scale hydraulic gradients, which enhances the overall mixing in the subsurface. These findings have strong implications for biogeochemical processing in wetlands.

Original languageEnglish (US)
Article numbere2023GL104642
JournalGeophysical Research Letters
Volume50
Issue number15
DOIs
StatePublished - Aug 16 2023

All Science Journal Classification (ASJC) codes

  • Geophysics
  • General Earth and Planetary Sciences

Keywords

  • contaminant transport
  • evaporation
  • groundwater flow
  • heterogeneity
  • numerical modeling
  • preferential flow

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