Selected HYDRUS modules for modeling subsurface flow and contaminant transport as influenced by biological processes at various scales

Šimůnek, Jirka; Jacques, Diederik; Twarakavi, Navin K. C.; Genuchten, Martinus Th. van

doi:10.2478/s11756-009-0106-7

Cited by 16 publications

(8 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The aim of this theoretical approach provides the foundation to enhance our understanding of the ecohydrological function of peatland ecosystems and to direct further field and laboratory research. Model simulations were conducted using HYDRUS 1‐D which simulates the unsaturated water movement using Richard's equation (Simunek et al ., ). Water retention is characterized by the van Genuchten () model:

\begin{matrix} left \\ θ (h) = \{θ_{r} + \frac{θ_{s} - θ_{r}}{(1 + (a |h |)^{n}) m} h < 0 \\ θ_{s} h \geq 0 \end{matrix}

where

m = 1 - \frac{1}{n} n > 1

where θ ( h ) is the soil water retention as a function of pressure head, h (m), θ r and θ s are the residual water contents and saturated water contents respectively, n is the empirical parameter related to pore size distribution (dimensionless), and α is the empirical parameter related to the inverse of air entry pressure (m −1 ).…”

Section: Methodsmentioning

confidence: 99%

Moss and peat hydraulic properties are optimized to maximize peatland water use efficiency

et al. 2015

View full text Add to dashboard Cite

Peatland ecosystems are globally important carbon and terrestrial surface water stores that have formed over millennia. These ecosystems have likely optimized their ecohydrological function over the long‐term development of their soil hydraulic properties. The optimization of peat hydraulic properties is examined to determine which of the following conditions peatland ecosystems target during this development: (i) maximize carbon accumulation, (ii) maximize water storage, or (iii) balance carbon profit across hydrological disturbances. To identify this control, the short‐term hydrological response of a 0.5‐m‐deep peat profile was simulated during a 50‐day rain‐free period. A total of 5000 Monte‐Carlo model realizations were conducted, with peat hydraulic properties differing between each realization (values derived from known probability distributions). Saturated hydraulic conductivity (Ks) and empirical van Genuchten water retention parameter α were shown to provide a first order control on simulated water tensions. For hypothetical combinations of Ks and α, the probability that water tension exceeds the ecologically important threshold of 100 mb within 24 h showed a bimodal distribution. A peak at high probabilities was associated with profiles of high Ks and low α. Such a profile is optimized for water storage. A peak at low probabilities is associated with low Ks, high α, and is optimized for carbon accumulation. Actual hydraulic properties from five northern peatlands fall between this binominal distribution, balancing the competing demands of carbon accumulation and water storage. We argue that peat hydraulic properties are thus optimized to maximize water use efficiency and that this optimization occurs over a centennial to millennial timescale. Copyright © 2015 John Wiley & Sons, Ltd.

show abstract

\begin{matrix} left \\ θ (h) = \{θ_{r} + \frac{θ_{s} - θ_{r}}{(1 + (a |h |)^{n}) m} h < 0 \\ θ_{s} h \geq 0 \end{matrix}

where

m = 1 - \frac{1}{n} n > 1

Section: Methodsmentioning

confidence: 99%

Moss and peat hydraulic properties are optimized to maximize peatland water use efficiency

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Among the easier to implement models of biological and physical interactions in soil are extensions to HYDRUS to accommodate colloid transport (Simunek et al, 2006) and biologically mediated processes (Simunek et al, 2009). HYDRUS has been applied efectively to predict more rapid transport of E. coli following the physical weathering of soil cores resulting in the formation of macropores (Safadoust et al, 2012).…”

Section: Three-dimensional Numerical Models Of Soil Biological Processesmentioning

confidence: 99%

Biophysics of the Vadose Zone: From Reality to Model Systems and Back Again

Hallett

Karim

Bengough

et al. 2013

Vadose Zone Journal

View full text Add to dashboard Cite

Biological and physical interactions in unsaturated soil, the vadose zone, have received a surge of research interest over the past several years. This article reviews recent research, focusing on the limitations imposed by the complexity of soil, the use of model systems to understand processes, new technologies, and the understanding of how biology changes soil structure. Research using model systems to mimic natural structure, such as rough planar surfaces or packed columns, has made it possible to demonstrate and quantify microbial interactions at very small spatial scales, including the coexistence of competing microbes and the invasion of soil pores by organisms that should be too large to fit. It is now possible to see inside soil at micrometer resolution in three dimensions, either by the use of noninvasive imaging techniques on intact soils or a model transparent soil with the same refractive index as water. Soil biology also changes soil structure. Techniques from engineering such as fracture mechanics and rheology have measured enhanced particle bonding, dispersion, and aggregation caused by root and microbial derived exudates. Models of soil structure dynamics are beginning to use these data. Concurrent research on naturally structured soil is essential, but using model systems that allow for the application of material science approaches or the detection and modeling of specific processes will enable the building of complexity by piecing together simpler systems. A major challenge for future research is gaining a quantitative understanding of how soil biology changes structure and incorporating this knowledge with studies of soil biodiversity, microbial functions, and root–soil interactions. Upscaling from microbial processes at micrometer resolution to the whole plant, field or catchment presents an even greater challenge.

show abstract

“…The HP1 code (Jacques et al, , 2008a, 2009) was used as the simulator to solve the coupled flow, transport, and geochemical problem. HP1 (version 2.3) couples the water flow, multiple solute transport and heat transport code HYDRUS-1D (Šimůnek et al, 2008a) with the geochemical equilibrium and kinetic code PHREEQC (version 2.17.5) (Parkhurst and Appelo, 1999).…”

Section: Simulation Toolmentioning

confidence: 99%

Inverse optimization of hydraulic, solute transport, and cation exchange parameters using HP1 and UCODE to simulate cation exchange

Jacques

Smith

Šimůnek

et al. 2012

Journal of Contaminant Hydrology

Self Cite

View full text Add to dashboard Cite

Selected HYDRUS modules for modeling subsurface flow and contaminant transport as influenced by biological processes at various scales

Cited by 16 publications

References 25 publications

Moss and peat hydraulic properties are optimized to maximize peatland water use efficiency

Moss and peat hydraulic properties are optimized to maximize peatland water use efficiency

Biophysics of the Vadose Zone: From Reality to Model Systems and Back Again

Inverse optimization of hydraulic, solute transport, and cation exchange parameters using HP1 and UCODE to simulate cation exchange

Contact Info

Product

Resources

About