Numerical analysis of vertical water movement in a bounded profile

Soil Research ◽  
1975 ◽  
Vol 13 (1) ◽  
pp. 1 ◽  
Author(s):  
KK Watson ◽  
AA Curtis
Keyword(s):  
Water Movement ◽  
Sandy Loam ◽  
Air Pressure ◽  
Wetting Front ◽  
Flow Process ◽  
Compression Effect ◽  
Cumulative Infiltration ◽  
Computer Based ◽  
Air Compression ◽  
Made In

The usual assumption made in soil water studies that the effect of the air phase on the flow process is negligible is discussed in relation to certain profile configurations where such an assumption is not valid. A computer-based numerical solution of the equation describing water movement in an unsaturated soil is then modified by the inclusion of a time-dependent boundary condition, thus allowing the modelling of the air compression effect during infiltration. This analysis also satisfactorily models the drainage along primary draining scanning curves which occurs in the upper part of the profile as the air pressure increases. The analysis is limited to the Darcy flow regime which, for the system considered, terminates when the excess air pressure equals the air entry value of the porous material. Detailed results are presented for a sand and a sandy loam. Profile depths of 200 cm and 1000 cm have been analysed, and comparisons made of the effect of the air compression on the shape of the wetting front. The effect on cumulative infiltration is also noted.

scholarly journals Predicted Infiltration for Sodic/Saline Soils from Reclaimed Coastal Areas: Sensitivity to Model Parameters

2014 ◽  
Vol 2014 ◽  
pp. 1-12
Author(s):  
Dongdong Liu ◽  
Dongli She ◽  
Shuang’en Yu ◽  
Guangcheng Shao ◽  
Dan Chen
Keyword(s):  
Water Movement ◽  
Soil Surface ◽  
Coastal Areas ◽  
Model Parameters ◽  
Wetting Front ◽  
Sodic Soils ◽  
Infiltration Process ◽  
Infiltration Model ◽  
Soil Physical Quality ◽  
Cumulative Infiltration

This study was conducted to assess the influences of soil surface conditions and initial soil water content on water movement in unsaturated sodic soils of reclaimed coastal areas. Data was collected from column experiments in which two soils from a Chinese coastal area reclaimed in 2007 (Soil A, saline) and 1960 (Soil B, nonsaline) were used, with bulk densities of 1.4 or 1.5 g/cm3. A 1D-infiltration model was created using a finite difference method and its sensitivity to hydraulic related parameters was tested. The model well simulated the measured data. The results revealed that soil compaction notably affected the water retention of both soils. Model simulations showed that increasing the ponded water depth had little effect on the infiltration process, since the increases in cumulative infiltration and wetting front advancement rate were small. However, the wetting front advancement rate increased and the cumulative infiltration decreased to a greater extent whenθ0was increased. Soil physical quality was described better by theSparameter than by the saturated hydraulic conductivity since the latter was also affected by the physical chemical effects on clay swelling occurring in the presence of different levels of electrolytes in the soil solutions of the two soils.

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>

Influence of evaporation suppressants on water movement in soils

Soil Research ◽  
1968 ◽  
Vol 6 (1) ◽  
pp. 67 ◽  
Author(s):  
JW Kijne
Keyword(s):  
Soil Water ◽  
Capillary Flow ◽  
Water Movement ◽  
Sandy Loam ◽  
Cetyl Alcohol ◽  
Fatty Alcohols ◽  
Wetting Front ◽  
Treated Soil ◽  
Hydrophobic Character ◽  
Water Diffusivity

The soil-water diffusivity was determined as a function of water content for Urrbrae fine sandy loam treated with two fatty alcohols, two amines, Krilium, polyvinyl alcohol, and Carbowax. The fatty alcohols and dodecylamine had the strongest influence on soil-water diffusivity throughout the whole range of soil-water contents. Treatment with these amendments markedly reduced capillary flow of water to the soil surface. Dodecylamine reduced the rate of infiltration into the soil. Heats of wetting of the treated soil samples indicated that penetration rate and diffusivity near saturation were reduced in accordance with the hydrophobic character of the adsorbed compound. Cetyl alcohol was partly desorbed when water permeated through cetyl-alcohol-treated soil, forming a film on the advancing wetting front. This resulted in a slower rate of penetration than would have been expected from the hydrophobic character of the complex.

IMPLEMENTASI METODE VIKOR DALAM PENERIMAAN JURNALIS PADA KORAN WASPADA MEDAN

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
Soraya Rahma Hayati ◽  
Mesran Mesran ◽  
Taronisokhi Zebua ◽  
Heri Nurdiyanto ◽  
Khasanah Khasanah
Keyword(s):  
Decision Making ◽  
Decision Support ◽  
Decision Support System ◽  
Decision Support Systems ◽  
Support System ◽  
Support Systems ◽  
Knowledge Based ◽  
Computer Based ◽  
Support Decision Making ◽  
Made In

The reception of journalists at the Waspada Daily Medan always went through several rigorous selections before being determined to be accepted as journalists at the Waspada Medan Daily. There are several criteria that must be possessed by each participant as a condition for becoming a journalist in the Daily Alert Medan. To get the best participants, the Waspada Medan Daily needed a decision support system. Decision Support Systems (SPK) are part of computer-based information systems (including knowledge-based systems (knowledge management)) that are used to support decision making within an organization or company. Decision support systems provide a semitructured decision, where no one knows exactly how the decision should be made. In this study the authors applied the VlseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR) as the method to be applied in the decision support system application. The VIKOR method is part of the Multi-Attibut Decision Making (MADM) Concept, which requires normalization in its calculations. The expected results in this study can obtain maximum decisions.Keywords: Journalist Acceptance, Decision Support System, VIKOR

scholarly journals Characterizing water fingering phenomena in soils using magnetic resonance imaging and multifractal theory

2009 ◽  
Vol 16 (1) ◽  
pp. 159-168 ◽  
Author(s):  
A. Posadas ◽  
R. Quiroz ◽  
A. Tannús ◽  
S. Crestana ◽  
C. M. Vaz
Keyword(s):  
Magnetic Resonance Imaging ◽  
Steady State ◽  
Magnetic Resonance ◽  
Preferential Flow ◽  
Water Movement ◽  
Three Dimensions ◽  
Water Infiltration ◽  
Resonance Imaging ◽  
Flow Process ◽  
Multifractal Theory

Abstract. The study of water movement in soils is of fundamental importance in hydrologic science. It is generally accepted that in most soils, water and solutes flow through unsaturated zones via preferential paths or fingers. This paper combines magnetic resonance imaging (MRI) with both fractal and multifractal theory to characterize preferential flow in three dimensions. A cubic double-layer column filled with fine and coarse textured sand was placed into a 500 gauss MRI system. Water infiltration through the column (0.15×0.15×0.15 m3) was recorded in steady state conditions. Twelve sections with a voxel volume of 0.1×0.1×10 mm3 each were obtained and characterized using fractal and multifractal theory. The MRI system provided a detailed description of the preferential flow under steady state conditions and was also useful in understanding the dynamics of the formation of the fingers. The f(α) multifractal spectrum was very sensitive to the variation encountered at each horizontally-oriented slice of the column and provided a suitable characterization of the dynamics of the process identifying four spatial domains. In conclusion, MRI and fractal and multifractal analysis were able to characterize and describe the preferential flow process in soils. Used together, the two methods provide a good alternative to study flow transport phenomena in soils and in porous media.

scholarly journals Blurring of the Human and the Artificial: A Conceptual Clarification

Proceedings ◽  
2020 ◽  
Vol 47 (1) ◽  
pp. 7
Author(s):  
Wolfgang Hofkirchner
Keyword(s):  
Artificial Intelligence ◽  
Conceptual Clarification ◽  
Computer Based ◽  
Made In

Due to certain progress made in Artificial Intelligence (AI) and related fields, there is a common agreement that we are facing a blurring of the human and the artificial. This presentation will argue that this agreement is rather one that pertains to anthropomorphic notations when dealing with computers and computer-based devices, as opposed to one that is justified by engineering results. In fact, the language used to describe mechanic functions hides what ontologically occurs, and how the autonomy of humans can be endangered. The clarification intended here uses the philosophical distinction between agents and patients and translates it into the systems theoretical distinction between self-organising systems and non-self-organising entities.

On the Necessity of Unsteady Flow in Fluid Machines

1959 ◽  
Vol 81 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Robert C. Dean
Keyword(s):  
Unsteady Flow ◽  
Fluid Machinery ◽  
Flow Process ◽  
Made In

It is shown that work can be done on, or by, a fluid in a frictionless flow process only if the flow is unsteady. The implications of this conclusion in the analysis of fluid machinery, and provisions which must be made in analysis to account for unsteady flow, are discussed.

scholarly journals Blurring of the Human and the Artificial: A Conceptual Clarification

Proceedings ◽  
2020 ◽  
Vol 47 (1) ◽  
pp. 7
Author(s):  
Wolfgang Hofkirchner
Keyword(s):  
Artificial Intelligence ◽  
Conceptual Clarification ◽  
Computer Based ◽  
Made In

Due to certain progress made in Artificial Intelligence (AI) and related fields, there is a common agreement that we are facing a blurring of the human and the artificial. This presentation will argue that this agreement is rather one that pertains to anthropomorphic notations when dealing with computers and computer-based devices, as opposed to one that is justified by engineering results. In fact, the language used to describe mechanic functions hides what ontologically occurs, and how the autonomy of humans can be endangered. The clarification intended here uses the philosophical distinction between agents and patients and translates it into the systems theoretical distinction between self-organising systems and non-self-organising entities.

A LABORATORY STUDY ON THE EFFECTS OF SOIL MOISTURE CONTENT, TEXTURE, AND TIMING OF LEACHING ON N LOSS FROM TWO SOUTHERN ALBERTA SOILS

1982 ◽  
Vol 62 (2) ◽  
pp. 407-413 ◽  
Author(s):  
T. G. SOMMERFELDT ◽  
C. CHANG ◽  
J. M. CAREFOOT
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Soil Moisture Content ◽  
Sandy Loam ◽  
Wetting Front ◽  
N Losses ◽  
Initial Soil Moisture ◽  
N Removal ◽  
Southern Alberta ◽  
Initial Soil

A column study was conducted to determine the effects of soil texture, initial soil moisture content and timing of leaching on N removal from two irrigated soils of southern Alberta. Pelleted NH4NO3 fertilizer (0.639 g N per column = 336 kg∙ha−1) was applied to Lethbridge loam (Leth L) and Cavendish fine sandy loam (CV FSL) at three initial levels of soil moisture: air dry (AD), 0.5 field capacity (0.5 FC), and wet (W, 25 cm suction). Leaching began immediately after the fertilizer application or was delayed 1 wk. Water was applied in 1400-mL (7.6 cm depth) increments every 2nd day for a total of 33 600 mL (175 cm depth). The leachate was collected, measured, and analyzed for NH4-N and NO3-N. The soil was analyzed for N content before and after leaching. More N was leached from CV FSL (0.600 g) than from Leth L (0.521 g). Responses to initial soil moisture were similar for both soils; the NO3-N concentration peak followed the advancing wetting front more closely in the AD than in the W systems and leaching losses were greatest from the 0.5 FC treatment. Delayed leaching did not significantly affect the amount of N leached. N losses, other than from leaching, were greatest in the W and AD treatments, in the AD treatment these losses were attributed to volatilization and, in the W soils, to denitrification.

Inland and coastal flooding: developments in prediction and prevention

2005 ◽  
Vol 363 (1831) ◽  
pp. 1475-1491 ◽  
Author(s):  
J.C.R Hunt
Keyword(s):  
Extreme Events ◽  
Urban Areas ◽  
Water Movement ◽  
Computational Modelling ◽  
Coastal Flooding ◽  
Remotely Sensed Data ◽  
Flood Prevention ◽  
Prediction And Prevention ◽  
Analyse Time ◽  
Made In

We review the scientific and engineering understanding of various types of inland and coastal flooding by considering the different causes and dynamic processes involved, especially in extreme events. Clear progress has been made in the accuracy of numerical modelling of meteorological causes of floods, hydraulics of flood water movement and coastal wind–wave-surge. Probabilistic estimates from ensemble predictions and the simultaneous use of several models are recent techniques in meteorological prediction that could be considered for hydraulic and oceanographic modelling. The contribution of remotely sensed data from aircraft and satellites is also considered. The need to compare and combine statistical and computational modelling methodologies for long range forecasts and extreme events is emphasized, because this has become possible with the aid of kilometre scale computations and network grid facilities to simulate and analyse time-series and extreme events. It is noted that despite the adverse effects of climatic trends on flooding, appropriate planning of rapidly growing urban areas could mitigate some of the worst effects. However, resources for flood prevention, including research, have to be considered in relation to those for other natural disasters. Policies have to be relevant to the differing geology, meteorology and cultures of the countries affected.

Sign in / Sign up

Export Citation Format

Share Document