Modeling Near-surface Water Redistribution in a Desert Soil

Luo, Yuan and Ghezzehei, Teamrat A. and Yu, Zhongbo and Berli, Markus

Vadose Zone Journal, volume 19(1), pp. e20081 , 2020.

Abstract

Despite the vast extent of desert soils on the Earth’s surface, our understanding of the moisture dynamics of near-surface desert soils (top centimeters to a few meters) remains limited. A recent study introduced a HYDRUS-1D model to simulate water redistribution in a bare, sandy desert soil as a function of infiltration and evaporation. For soil conditions drier than pF 2, the model consistently underestimated evaporative fluxes and subsequently overestimated moisture content in the near-surface soil. The goal of this study was to explore the use of the Peters-Durner-Iden (or PDI) instead of the original bimodal van Genuchten (or BVG) water retention and hydraulic conductivity functions to improve water redistribution simulations for drier soils in desert environments. By comparing measured and simulated moisture redistribution data, we found that the simulations of moisture redistribution were improved by employing PDI soil water retention functions instead of BVG soil water retention functions. In particular, simulations for volumetric moisture contents ranging between 6% and 10% (suction heads between pF 2 and pF 3.8 and saturation degrees between 19% and 32%, respectively) improved using PDI. Interestingly, using PDI instead of BVG hydraulic conductivity functions had no noticeable effect on the simulation results. This study also emphasized the importance of good-quality soil water retention data for the relevant soil moisture content range. In conclusion, the HYDRUS-1D model using PDI hydraulic functions can accurately predict moisture redistribution for bare, sandy soil at volumetric moisture contents as low as 6% (pF 3.8 or 19% saturation, respectively).

Citations

Cite as:

Luo, Yuan and Ghezzehei, Teamrat A. and Yu, Zhongbo and Berli, Markus, Modeling Near-surface Water Redistribution in a Desert Soil, Vadose Zone Journal, 19(1):e20081, 2020.

BibTex

@article{2020-Luo-et-al-b,
  title = {Modeling Near-surface Water Redistribution in a Desert Soil},
  author = {Luo, Yuan and Ghezzehei, Teamrat A. and Yu, Zhongbo and Berli, Markus},
  journal = {Vadose Zone Journal},
  status = {published},
  year = {2020},
  volume = {19},
  number = {1},
  pages = {e20081},
  doi = {10.1002/vzj2.20081}
}