scholarly journals Laboratory Experiments on the Effect of Microtopography on Soil-Water Movement: Spatial Variability in Wetting Front Movement

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
Leif Sande ◽  
Xuefeng Chu
Keyword(s):  
Soil Water ◽  
Smooth Surface ◽  
Laboratory Experiments ◽  
Unsaturated Flow ◽  
Water Movement ◽  
Experimental Studies ◽  
Soil Profiles ◽  
Wetting Front ◽  
Front Movement ◽  
Soil Water Movement

The effect of microtopography on soil-water movement is a topic of interest for a range of disciplines, with experimental studies investigating the relationship between the two lacking. Laboratory experiments were conducted by simulating rainfall across packed soil surfaces to investigate the effect of microtopography on wetting front movement within experimental soil profiles. In small soil box experiments, the observed wetting fronts for soil profiles showed considerably deeper movement beneath a smooth surface than depressions for 12–60 min rainfalls. For large soil box experiments, the wetting front reached moisture sensors installed at 5 and 10 cm depths and corresponding to various rough and smooth surface features at significantly different times, with movement being most rapid beneath the smooth surface. Wetting front movement was “quicker” beneath surface peaks than depressions for the rough surface as attributed to 2D/3D unsaturated flow. This study provides valuable experimentally based insight into the effect of microtopography on soil-water movement.

Using HYDRUS 2D/3D to Evaluate Soil Water Movement in Drip-irrigated Young Populus tomentosa Plantations on Sandy Loam Soil

2020 ◽  
Author(s):  
Doudou Li ◽  
Benye Xi ◽  
Liming Jia
Keyword(s):  
Soil Water ◽  
Drip Irrigation ◽  
Water Movement ◽  
Sandy Loam ◽  
Vertical Movement ◽  
Populus Tomentosa ◽  
Sandy Loam Soil ◽  
Wetting Front ◽  
Loam Soil ◽  
Soil Water Movement

<p>     Understanding the rules of soil water movement under drip irrigation can provide data support and theoretical basis for developing precise drip irrigation strategies. In this study, a two-years-old <em>Populus tomentosa </em>plantation under surface drip irrigation on sandy loam soil was selected to measure the dynamics of soil water potential (<span><em>ψ</em></span><em><sub>s</sub></em>), wetting front and soil water content (<span><em>θ</em></span>) during irrigation and water redistribution periods were investigated in field experiments. Then, the observed data in the field were used to evaluate the accuracy and feasibility of the HYDRUS-2D/3D model for simulating the short-term soil water movement. Besides, the validated model was used to simulate the dynamics of wetting front under different initial soil water content (<span><em>θ</em></span><em><sub>i</sub></em>). During irrigation, the variation of <span><em>ψ</em></span><em><sub>s</sub></em>, horizontal and vertical movement distances of the wetting front, and <span><em>θ</em></span> within the wetting volume with irrigation duration could be described by the logistic function (<em>R<sup>2</sup></em> = 0.99), the logarithm function (<em>R<sup>2</sup></em> = 0.99), the power function (<em>R<sup>2</sup></em> = 0.82), and the polynomial function (<em>R<sup>2</sup></em> = 0.99), respectively. At the end of irrigation, the horizontal and vertical movement distances of the wetting front reached 22.9 cm and 37.3 cm, respectively. The <span><em>ψ</em></span><em><sub>s</sub></em> and <span><em>θ</em></span> within the soil wetting volume were 61.6% and 30.9% higher than those at the start of the irrigation, respectively, but the <span><em>ψ</em></span><em><sub>s </sub></em>decreased to its initial level about 120 hours later after the stop of irrigation. The average deviations of the horizontal and vertical wetting radius between the simulated and measured values were 1.3 and 4.5 cm, respectively. The mean RMSE and RMAE of HYDRUS-2D/3D for simulating <span><em>θ</em></span> at the end of irrigation and during water redistribution were 0.021 cm<sup>3</sup>∙cm<sup>-3</sup> and 9.7%, respectively. The movement distances of wetting front in the experimental plantation under various soil drought degrees (soil water availabilities were 40%, 60%, 73% and 80%) were obtained through scenarios simulations using HYDRUS-2D/3D. And it was found that the wetting front could move further under higher <span><em>θ</em></span><em><sub>i</sub></em>, and the movement distance of the wetting front was always smaller in the horizontal direction than in the vertical direction under different <span><em>θ</em></span><em><sub>i </sub></em>conditions. Consequently, HYDRUS-2D/3D can be used to well simulate the short-term soil water movement in drip-irrigated young <em>P. tomentosa</em> plantations on sandy loam soil. In addition, the constructed figure (describes the variations of the horizontal and vertical soil wetting distances with the irrigation duration) can be used to determine the reasonable irrigation duration for the plantations of <em>P. tomentosa</em> and other tree species on sandy loam soil.</p>

Effect of infiltration head on soil water movement of small-diameter tube outflow furrow irrigation under mulch film

2019 ◽  
Vol 16 (2) ◽  
pp. 232-237 ◽  
Author(s):  
H.X. Wu ◽  
Yunxin Zhang ◽  
Lishu Wang ◽  
Dongjuan Chen ◽  
Chao Ma
Keyword(s):  
Soil Water ◽  
Water Movement ◽  
Small Diameter ◽  
Scientific Basis ◽  
Furrow Irrigation ◽  
Wetting Front ◽  
Migration Distance ◽  
Content Type ◽  
Mulch Film ◽  
Soil Water Movement

PurposeThe purpose of this study is to investigate the effect of different infiltration heads on soil water movement using a free infiltration test for small-diameter tube outflow furrow irrigation under mulch film.Design/methodology/approachThe test consisted of small-diameter tube outflow furrow irrigation under mulch film with three different infiltration heads (3, 4 and 5 cm) and furrow drip irrigation under mulch film using an infiltration head of 4 cm (CK).FindingsDuring irrigation, the accumulated infiltration and migration distance of the wetting front increased with time. During the same infiltration time, both the accumulated infiltration and horizontal migration distance of the wetting front increased with the larger infiltration head, whereas the vertical migration distance of the wetting front gradually decreased. With increasing distance from the furrow center, soil moisture content declined, but the uniformity of its distribution increased as the infiltration head increased.Originality/valueThis study can provide scientific basis for the use of small-diameter tube outflow furrow irrigation under mulch film.

Quantification of wetting front movement under the influence of surface topography

Soil Research ◽  
2018 ◽  
Vol 56 (4) ◽  
pp. 382
Author(s):  
Xuefeng Chu ◽  
Xinhua Jia ◽  
Yang Liu
Keyword(s):  
Surface Topography ◽  
Soil Water ◽  
Overland Flow ◽  
Unsaturated Flow ◽  
Soil Surface ◽  
Transport Processes ◽  
Soil Conditions ◽  
Wetting Front ◽  
Dimensional Flow ◽  
Front Movement

Soil surface topography affects fundamental hydrologic processes, such as infiltration and soil water percolation. Topographic variations potentially alter both the magnitude and directions of unsaturated flow. The objective of this study is to evaluate the effects of surface topography on wetting front moving patterns under different rainfall and soil conditions through combined experimental and numerical modelling studies. Specifically, laboratory-scale infiltration and unsaturated flow experiments and HYDRUS-2D modelling were conducted for different topographic surfaces, rainfall intensities, and soil types. The simulated and observed wetting front distributions were compared and evaluated. Two different stages were observed: topography-dominated two-dimensional flow and uniform one-dimensional flow. A uniformly distributed wetting front was eventually achieved although soil surfaces had dissimilar topographic characteristics. However, the timing or duration to reach such a uniform flat wetting front varied, mainly depending on surface topography, rainfall characteristics, and soil hydraulic properties. The findings from this study are important to better understand the mechanism of topography-controlled unsaturated flow, wetting front movement, and overland flow generation, and to further improve modelling of soil water flow and transport processes under such complex conditions across different scales.

Comparison studies of unsaturated flow below annual and perennial plants

2012 ◽  
Vol 65 (12) ◽  
pp. 2162-2168
Author(s):  
Bill Scott ◽  
Ross Lantzke ◽  
Dave Nicholson ◽  
Paul Findlater
Keyword(s):  
Plant Growth ◽  
Water Content ◽  
Soil Water ◽  
Vertical Profile ◽  
Unsaturated Flow ◽  
Water Movement ◽  
Sandy Soils ◽  
Lambert W Function ◽  
Neutron Moisture ◽  
Soil Water Movement

Values of unsaturated water content determined with neutron moisture measurements (NMM) reveal different water profiles below different plantings. In the extremes, calibration requires a linear and logarithmic response (using the Lambert-W function) along with the normal submersion in a drum of water. Nevertheless a post-calibration with a hydraulic push sampler was used for confirmation. Data were collected at six pastures near the Western Australia coast near Geraldton, with four replicates through the profile. The sites have mostly sandy soils and receive 300–500 mm of rainfall annually. Findings generally showed that, if there was sufficient water, as in 2006, the perennials were able to use the water evenly throughout the vertical profile. Otherwise, with low rainfall, as in 2009, perennials struggle to survive and use less water than the annuals. Modelling of the soil water movement, plant growth and calibration/recalibration is and will be used to get a maximum likehood fit. Clearly, in desert conditions and little or no vegetation, rainfall tends to build up deep in the profile, increase salinity in groundwater, and create waterlogging. Any vegetation is helpful; perennials more so; provided they have sufficient water and are not significantly harvested.

Modeling Soil Water Movement in Pedostructure

2006 ◽  
Author(s):  
Rabi H. Mohtar ◽  
Erik Braudeau
Keyword(s):  
Soil Water ◽  
Water Movement ◽  
Soil Water Movement

Simulating soil-water movement under a hedgerow surrounding a bottomland reveals the importance of transpiration in water balance

2008 ◽  
Vol 22 (5) ◽  
pp. 577-585 ◽  
Author(s):  
Z. Thomas ◽  
J. Molénat ◽  
V. Caubel ◽  
C. Grimaldi ◽  
P. Mérot
Keyword(s):  
Water Balance ◽  
Soil Water ◽  
Water Movement ◽  
Soil Water Movement

scholarly journals Discontinuous finite volume element method of two-dimensional unsaturated soil water movement problem

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Fan Chen ◽  
Zhixiao Xu
Keyword(s):  
Soil Water ◽  
Finite Volume ◽  
Unsaturated Soil ◽  
Water Movement ◽  
Optimal Error Estimate ◽  
Two Dimensional ◽  
Fully Discrete ◽  
Volume Method ◽  
Movement Problem ◽  
Soil Water Movement

AbstractIn this paper, a numerical approximation method for the two-dimensional unsaturated soil water movement problem is established by using the discontinuous finite volume method. We prove the optimal error estimate for the fully discrete format. Finally, the reliability of the method is verified by numerical experiments. This method is not only simple to calculate, but also stable and reliable.

Unsaturated soil water movement in hysteretic and water repellent field soils

1996 ◽  
Vol 184 (3-4) ◽  
pp. 153-173 ◽  
Author(s):  
J.C. van Dam ◽  
J.H.M. Wösten ◽  
A. Nemes
Keyword(s):  
Soil Water ◽  
Unsaturated Soil ◽  
Water Movement ◽  
Water Repellent ◽  
Field Soils ◽  
Soil Water Movement

Unsaturated zone tritium and chlorine 36 profiles from southern Australia: Their use as tracers of soil water movement

1994 ◽  
Vol 30 (6) ◽  
pp. 1709-1719 ◽  
Author(s):  
P. G. Cook ◽  
I. D. Jolly ◽  
F. W. Leaney ◽  
G. R. Walker ◽  
G. L. Allan ◽  
...  
Keyword(s):  
Soil Water ◽  
Unsaturated Zone ◽  
Water Movement ◽  
Chlorine 36 ◽  
Soil Water Movement
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