Submitted as: model description paper 02 Sep 2021

Submitted as: model description paper | 02 Sep 2021

Review status: this preprint is currently under review for the journal GMD.

Tree Hydrodynamic Modelling of Soil Plant Atmosphere Continuum (SPAC-3Hpy)

Marcela Silva1, Ashley M. Matheny2, Valentijn R. N. Pauwels1, Dimetre Triadis3, Justine E. Missik4, Gil Bohrer4, and Edoardo Daly1 Marcela Silva et al.
  • 1Department of Civil Engineering, Monash University, Clayton, VIC, Australia
  • 2Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, TX, USA
  • 3Department of Mathematics and Statistics, La Trobe University, Bundoora, VIC, Australia
  • 4Department of Civil, Environmental and Geodetic Engineering, Ohio State University, OH, USA

Abstract. Modelling the water transport along the soil-plant-atmosphere continuum is fundamental to estimating and predicting transpiration fluxes. A tree-hydrodynamic model (SPAC-3Hpy) for the water fluxes across the soil-plant-atmosphere continuum is presented here. The model combines the water transport pathways to one vertical dimension, and assumes that the water flow through the soil, roots, and above-ground xylem can be approximated as a flow in porous media. This results in a system of three partial differential equations resembling the Richardson-Richards equation describing the transport of water through the plant system and with additional terms representing sinks and sources for the transfer of water from to the soil to the roots and from the leaves to the atmosphere. The numerical scheme, developed in Python 3, was tested against exact analytical solutions for steady state and transient conditions using simplified but realistic model parametrizations. The model was also used to simulate a previously published case study where observed transpiration rates were available in order to evaluate model performance. With the same model setup as the published case study, SPAC-3Hpy results were in agreement with observations. Through a rigorous coupling of soil, roots, and hydroactive xylem, SPAC-3Hpy can account for variable capacitance while conserving mass and the continuity of the water potential between these three layers. SPAC-3Hpy provides a ready-to-use open access numerical model for the simulation of water fluxes across the soil-plant-atmosphere continuum.

Marcela Silva et al.

Status: open (until 28 Oct 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Review on gmd-2021-270', Anonymous Referee #1, 23 Sep 2021 reply

Marcela Silva et al.

Data sets

Environmental variables and sap-flow derived transpiration data to replicate a published case study from Verma et al., 2014 Marcela Silva, Ashley M. Matheny, Valentijn R. N. Pauwels, Dimetre Triadis, Justine E. Missik, Gil Bohrer, and Edoardo Daly

Model code and software

SPAC-3Hpy scripts (Python 3) Marcela Silva, Ashley M. Matheny, Valentijn R. N. Pauwels, Dimetre Triadis, Justine E. Missik, Gil Bohrer, and Edoardo Daly

Marcela Silva et al.


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Short summary
Our study introduces the SPAC-3Hpy model, a ready-to-use open-access model that simulates the water fluxes across the soil, roots, and stem. To test the model capabilities, we tested it against exact solutions and a case study. The model presented considerably small errors when compared to the exact solutions and was able to correctly represent transpiration patterns when compared to experimental data. The results show that SPAC-3Hpy can correctly simulate above- and below-ground water transport.