Simulations on soil water variation in arid regions

Dong, Weiquan; Yu, Zhongbo; Weber, Dennis

doi:10.1016/s0022-1694(03)00041-6

Cited by 14 publications

(10 citation statements)

References 44 publications

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“…Numerical models simulating water flow in the arid southwestern United States indicate that thermally driven vapor fluxes are dominant throughout most of the unsaturated zone (Scanlon et al, 2003; Walvoord et al, 2004). Shallow water flow simulations evaluating vegetative controls on water movement within natural and engineered soil in arid regions typically focus on liquid water flow (Dong et al, 2003; Scanlon et al, 2005b; Young et al, 2006), however, neglecting the potential for water vapor transport. Yin et al (2008) incorporated thermal vapor flow when simulating shallow paleowater fluxes, but their results documented total water fluxes rather than isothermal and thermal liquid water and water vapor components.…”

mentioning

confidence: 99%

Interacting Vegetative and Thermal Contributions to Water Movement in Desert Soil

Garcia

Andraski

Stonestrom

et al. 2011

Vadose Zone Journal

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Thermally driven water‐vapor flow can be an important component of total water movement in bare soil and in deep unsaturated zones, but this process is often neglected when considering the effects of soil–plant–atmosphere interactions on shallow water movement. The objectives of this study were to evaluate the coupled and separate effects of vegetative and thermal‐gradient contributions to soil water movement in desert environments. The evaluation was done by comparing a series of simulations with and without vegetation and thermal forcing during a 4.7‐yr period (May 2001–December 2005). For vegetated soil, evapotranspiration alone reduced root‐zone (upper 1 m) moisture to a minimum value (25 mm) each year under both isothermal and nonisothermal conditions. Variations in the leaf area index altered the minimum storage values by up to 10 mm. For unvegetated isothermal and nonisothermal simulations, root‐zone water storage nearly doubled during the simulation period and created a persistent driving force for downward liquid fluxes below the root zone (total net flux ∼1 mm). Total soil water movement during the study period was dominated by thermally driven vapor fluxes. Thermally driven vapor flow and condensation supplemented moisture supplies to plant roots during the driest times of each year. The results show how nonisothermal flow is coupled with plant water uptake, potentially influencing ecohydrologic relations in desert environments.

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mentioning

confidence: 99%

Interacting Vegetative and Thermal Contributions to Water Movement in Desert Soil

Garcia

Andraski

Stonestrom

et al. 2011

Vadose Zone Journal

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“…parallel vs. orthogonal to the slope), and (4) how the bulk root-induced hydraulic conductivity is quantitatively related to the observed root distribution. Dong et al (2003) estimated macropore contribution to the bulk soil hydraulic conductivity based on bulk soil water potential and macropore size distribution, which addresses issue (2) quite well. It was developed for one-dimension vertical flow, and not appropriate for simulating water movement on hillslope.…”

Section: Root Macropore Modellingmentioning

confidence: 89%

“…Rasse et al (2000) demonstrate that Alfalfa root-induced macropores increase saturated soil hydraulic conductivity by 57%, and facilitate deep percolation. Whether the roots impede (by root water uptake) or facilitate (by root-induced macropores) deep percolation depends on various conditions including climate, soil, and vegetation characteristics (Newman et al, 2006), particularly the frequency and duration at which macropores are saturated or nearly saturated (Dong et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Modelling investigation of water partitioning at a semiarid ponderosa pine hillslope

Guan¹,

Šimůnek²,

Newman³

et al. 2010

Hydrological Processes

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Abstract:The effects of vegetation root distribution on near-surface water partitioning can be two-fold. On the one hand, the roots facilitate deep percolation by root-induced macropore flow; on the other hand, they reduce the potential for deep percolation by root-water-uptake processes. Whether the roots impede or facilitate deep percolation depends on various conditions, including climate, soil, and vegetation characteristics. This paper examines the effects of root distribution on deep percolation into the underlying permeable bedrock for a given soil profile and climate condition using HYDRUS modelling. The simulations were based on previously field experiments on a semiarid ponderosa pine (Pinus ponderosa) hillslope. An equivalent single continuum model for simulating root macropore flow on hillslopes is presented, with root macropore hydraulic parameterization estimated based on observed root distribution. The sensitivity analysis results indicate that the root macropore effect dominates saturated soil water flow in low conductivity soils (K matrix below 10 7 m/s), while it is insignificant in soils with a K matrix larger than 10 5 m/s, consistent with observations in this and other studies. At the ponderosa pine site, the model with simple rootmacropore parameterization reasonably well reproduces soil moisture distribution and some major runoff events. The results indicate that the clay-rich soil layer without root-induced macropores acts as an impeding layer for potential groundwater recharge. This impeding layer results in a bedrock percolation of less than 1% of the annual precipitation. Without this impeding layer, percolation into the underlying permeable bedrock could be as much as 20% of the annual precipitation. This suggests that at a surface with low-permeability soil overlying permeable bedrock, the root penetration depth in the soil is critical condition for whether or not significant percolation occurs.

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“…Recently, efforts have been made to better understand and quantify processes within the vadose zone that determine water fluxes by improved measurement techniques of water content (e.g., Dahan et al 2003;Jones et al 2005), observation of different scale phenomena (e.g., Hendrickx and Flury 2001;Mattson et al 2004;Hopmans and Schoups 2005) and enhanced numerical modeling (e.g., Dong et al 2003;Saito et al 2006;Sakai et al 2009). Benchscale laboratory experiments can greatly support these efforts by simulating and investigating processes that occur in the field under controlled initial and boundary conditions (Oostrom et al 2005).…”

Section: Introductionmentioning

confidence: 99%

Soil column experiments to quantify vadose zone water fluxes in arid settings

et al. 2011

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For the determination of groundwater recharge processes in arid environments, vadose zone water fluxes and water storage should be considered. To better understand and quantify vadose zone processes influencing groundwater recharge, a soil column experimental setup has been developed that mimics arid atmospheric conditions and measures water and temperature fluxes in high temporal and spatial resolution. The focus of the experiment was on the determination of water infiltration, redistribution, evaporation and percolation under non-isothermal conditions. TDR rod sensors and a specific TDR ''Taupe'' cable sensor were used for water content measurements and allowed the infiltration fronts to be traced over the whole column length. Applying single irrigations of different amount and intensity showed the applicability of the experimental setup for the measurement of water movement in the unsaturated soil column.

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Simulations on soil water variation in arid regions

Cited by 14 publications

References 44 publications

Interacting Vegetative and Thermal Contributions to Water Movement in Desert Soil

Interacting Vegetative and Thermal Contributions to Water Movement in Desert Soil

Modelling investigation of water partitioning at a semiarid ponderosa pine hillslope

Soil column experiments to quantify vadose zone water fluxes in arid settings

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