Water Movement Characteristics Research Articles

Approximate analytical solution of a soil water movement equation under different ponding radii on the basis of numerical simulation

AbstractThis study addresses the problem of 2D soil water movement under ponding radii of 1, 2, and 3 cm. The soil water movement characteristics (shape parameters of the water content profile, ratio of horizontal wetting front to vertical wetting front, relationship between infiltration time and horizontal wetting front, and relationship between infiltration time and cumulative infiltration) under the above three kinds of water ponding radius were analyzed. On the basis of the assumption that the soil wetting body is a semi‐ellipse and the analytical solution of the 1D soil water movement equation at any angle, the approximate analytical solution of the 2D soil water movement equation under ponding conditions is optimized. The function relationships between infiltration time, wetting front, and cumulative infiltration are established. We applied the numerical data simulated by HYDRUS‐3D to validate the parameters in proposed analytical solutions and evaluated the relationships between the wetting front and hydraulic parameters. The results indicate that as the water ponding radius increases, the wetting body and 2D water content distribution becomes larger. When the water ponding radius was 2 cm, the numerical and analytical solution of 1D soil water distribution showed the best comparison results, and the model error was the smallest. The ratio of wetting fronts was linearly increased with the increase of air‐entry suction with R2 = 0.9969.

Influence of Long-Term Mulched Drip Irrigation on Upward Capillary Water Movement Characteristics in the Saline–Sodic Region of Northwest China

Capillary water, serving as a crucial intermediary between groundwater and crop root layer moisture, is important for both soil retention and crop utilization. To investigate the effect of mulched drip irrigation (MDI) on upward capillary water in cotton fields with different application years (0, 10, 14, 18, 20, and 24 years) in the saline–sodic region of Northwest China, an indoor soil column test (one-dimensional capillary water rise experiment) was conducted. The results showed that the wetting front transport law, capillary water recharge, and wetting front transport rate over time exhibited an increasing trend in the early stages of MDI application (10 and 14 years), peaking at 18 years of application, followed by a decreasing trend. The relationship between the capillary water recharge and rising height was fitted based on the Green–Ampt model, and their slopes reveal that 14 and 18 years of MDI application required the largest amount of water per unit distance, indicating an excellent water-holding capacity beneficial for plant growth. Conversely, 0 years required the smallest amount of water per unit distance. Based on the movement characteristics of upper capillary water, we confirmed that the MDI application years (0–18 years) improves soil infiltration capacity, while the long-term application years (18–24 years) reduces groundwater replenishment to the soil. Furthermore, the HYDRUS-1D model was employed to simulate the capillary water rise process and soil moisture distribution under different MDl application years. The results showed an excellent consistency with the soil column experiments, confirming the accuracy of HYDRUS-1D in simulating the capillary water dynamics in saline–sodic areas. The results would provide suggestions to achieve the sustainable development of long-term drip-irrigated cotton fields.

Some physical properties of a sandy clay loam humic soil under native forest and sugarcane in northern KwaZulu-Natal, South Africa

The conversion of native forest land to commercial farming can have profound effects on soil physical properties. This study compared bulk density (BD), saturated hydraulic conductivity (Ks) and other physical properties of a sandy loam humic soil under native forest and sugarcane fields in northern KwaZulu-Natal. Three plots (approximately 0.1 to 0.3 ha) were demarcated at each site. Ten composite soil and core samples were collected in each plot at intervals of 0.05 m in the 0–0.2 m, 0.1 m in the 0.2–0.6 m and 0.2 m in the 0.6–1.0 m depths and analysed using standard methods. In total, 60 composite and core samples were collected from both sites. Overall, BD was higher under forest (1 410 kg m−3) than sugarcane (1360 kg m−3) while the Ks was higher under sugarcane (310 mm h−1) than forest (260 mm h−1). The Ks correlated positively with sand at 0–0.3 and 0–1.0 m depths. The results suggest that long term (30 years) sugarcane cultivation has the capacity to decrease BD while improving Ks of the studied soils, making the crop more beneficial on water movement characteristics especially in the drought-prone Zululand region of South Africa.

Hydraulically most advantageous pipe diameters for supplying water to reclaimed land

Recently, some countries have been using treated wastewater to irrigate crops. In the administrative district of Kerbela, they also decided to borrow the experience of these countries, but on the condition that the treated wastewater would be environmentally safe in terms of sanitary and hygienic terms. It is necessary to comply with the requirements for the quality of water for irrigation of crops, and also not cause damage to the environment, soil and plants. From the treatment facilities of Kerbela 1000000 m3/day (1.16 m3/s) of water are formed, but the project provides for an increase to 400000 m3/day (4.63 m3/s) therefore, the selection of the diameter of the pipes for supplying water to the irrigation fields is provided for two flow rates. For preliminary calculation, the WaterCAD V8i simulation model was used, with the help of which the optimal pipe diameter and hydraulic characteristics of the flow were selected. Based on the results of the model, the optimal dimensions of the pipe diameter, modes of fluid movement and head loss are determined. The choice of pipe material was made from four types (ductile iron, GRP, concrete and plastic). The novelty of the work lies in the fact that for the first time a main scheme is being laid for transporting treated wastewater in this region and the hydraulic characteristics of water movement are being studied.

ANALYSIS AND ASSESSMENT OF THE HYDROMORPHOLOGICAL SITUATION AT THE CONSTRUCTION SITE OF A BRIDGE CROSSING OVER THE ZEYA RIVER IN BLAGOVESHCHENSK USING MATHEMATICAL MODELING OF WATER MOVEMENT CHARACTERISTICS

The hydromorphological situation at the site of bridge construction is analyzed in the paper; the analysis results are presented. The issues of ensuring the channel geometry stability are considered. The impact of a temporary construction embankment on the f low kinematics is estimated. The level regime of the river and the channel reformations in the alignment of the bridge crossing and on the upstream section of the river are studied at the calculated level and water flow. The results obtained make it possible to determine and establish the values of the permissible degree of impact of the designed hydraulic structures and measures on the channel regime of the near-mouth section of the Zeya River in the area of the projected bridge crossing over the river in Blagoveshchensk, within which the natural and anthropogenic-induced conditions of the statistical stability of the “flow-moving channel” system are realized by the river flow. The studies were carried out in 2 stages: the first one, a test stage, was carried out for the initial everyday state of the riverbed in the section of the Zeya River in the area of the bridge crossing, according to which the model was calibrated in accordance with the specified boundary conditions in the area under study; the second one, on the model, was carried out for three options of the construction dam length, erected from the left bank to the 15th pillar of the bridge, to the middle of the span between the 15th and 16th pillars and up to the 16th pillar of the bridge crossing, which made it possible to assess the impact of the structure with different options of its length on the flow hydraulics in the area of the bridge crossing. The research method applied is the mathematical 2-D modeling of the water movement characteristics, for which the “FLOOD” software package is used.

Experimental study and three-dimensional modeling of moisture transport in wood by means of near-infrared hyperspectral imaging coupled with a heat and mass transfer simulation method

Abstract Substantial efforts have been undertaken for visualizing and simulating the characteristics of water movement in wood. However, three-dimensional (3D) thermo-hygric simulations still pose challenges, not only because wood has a heterogeneous microstructure that results in complex computational models but also because there is a lack of proper experimental techniques to support and validate the model constructions. In this study, the moisture distribution in wood during the water adsorption and desorption processes was first visualized using a near-infrared hyperspectral imaging (NIR–HSI) method that has high resolution, sensibility, and stability. Then, based on the moisture visualization results, the main parameters of a mass transfer simulation code were varied. The visualization and simulation results were confirmed to match well with the main characteristics; e.g., drying speed was slower in the wood parts with higher densities. Additionally, there was a relatively large gradient over the surface layer of the wood samples as the drying progressed, whereas this was not an obvious feature in the water adsorption process. Hence, this study proposes that the NIR–HSI method can be combined with thermo-hygric and 3D simulation model construction. Such an approach provides the basis for optimizing drying conditions and providing high-quality wood products.

Study on the effect of morphological changes of bridge piers on water movement properties

Abstract The different shapes of bridge piers across rivers have a great influence on the river water movement, and the study of the influence of pier morphology changes on the water movement characteristics is of great value for bridge design and river flooding. The hydrodynamic model can effectively simulate and predict the changes of river flow patterns, which can provide scientific data support for river management. This paper constructs a hydrodynamic model based on MIKE21 and applies it to the numerical simulation of river hydrodynamics in the lower reaches of the Yellow River, taking elliptical piers as an example, and simulates the effect of the change of pier morphology on the flow velocity, water level and flow field of the river. The results show that the effect of elliptical pier morphology on the flow characteristics of the river channel is significant; under the same flow rate, the congestion value of the pier at the maximum axis ratio is 1.65 times the minimum axis ratio, and the larger the axis ratio, the more serious the congestion; the difference in flow velocity at the maximum axis ratio can reach 2.33 times the minimum axis ratio.

Effects of Oil Pollution on Water Movement in Soils with Different Textures

Exploring water movement characteristics in oil-polluted soils could facilitate the understanding of soil stress resistance. The aim of the present study was to evaluate the effects of oil pollution on water movement in soils with different textures and explore the underlying mechanisms. A heavy loam (Earth-cumuli-Orthic Anthrosols, EOA), a light loam (Hapli-Ustic Cambosols, HUC), and a sandy loam (Usti-Sandic Primosols, USP) were spiked with different levels of crude oil (0, 0.5, 1, 2, and 4%, w/w). Soil water movement parameters, including saturated hydraulic conductivity, unsaturated hydraulic conductivity, and specific water capacity were measured. Soil water availability under different levels of oil pollution was also analyzed. According to the results, saturated hydraulic conductivity of all three soils decreased with an increase in the level of oil pollution, as did the unsaturated hydraulic conductivity of HUC and USP. Under 4% oil pollution, the saturated hydraulic conductivity of the EOA, HUC, and USP decreased by 52.8%, 81.7%, and 39.6%, compared with their respective unpolluted soils, while the unsaturated hydraulic conductivity of HUC and USP decreased by 78.0% and 39.9% at 20% soil water content. In addition, the unsaturated hydraulic conductivity of EOA decreased with an increase in oil pollution level when the soil water content was >25%; however, a reverse trend was observed at soil water content <25%. The specific water capacity of all soils increased first and then decreased with an increase in water suction, while it decreased with an increase in the level of oil pollution. The suction ranges corresponding to the available water content in the three soils were reduced by oil pollution, and the corresponding water-holding capacities were weakened. Oil pollution had major negative impacts on water movement in the soils with different textures, causing a decline in water infiltration and supply capacities, which could hamper soil drought resistance. However, the effects of soil texture on water movement were greater than the effects of oil pollution under the experimental conditions.

Effects of biochar on water movement characteristics in sandy soil under drip irrigation

Biochar addition can improve the physical and hydraulic characteristics of sandy soil. This study investigated the effects of biochar on water holding capacity and water movement in sandy soil under drip irrigation. By indoor simulation experiments, the effects of biochar application at five levels (0%, 1%, 2%, 4% and 6%) on the soil water retention curve, infiltration characteristics of drip irrigation and water distribution were tested and analyzed. The results showed that biochar addition rate was positively correlated with water holding capacity of sandy soil and soil available water. Within the same infiltration time, with an increasing amount of added biochar, the diffusion distance of the horizontal wetting front (HWF) tended to decrease, while the infiltration distance of vertical wetting front (VWF) initially declined and then rose. The features of wetted bodies changed from “broad-shallow” to “narrow-deep” type. The relationship between the transport distances of HWF and VWF and the infiltration time was described by a power function. At the same distance from the point source, the larger the amount of added biochar, the higher the soil water content. Biochar had a great influence on the water content of the layer with biochar (0–200 mm) and had some effects at 200–250 mm without biochar; but it had less influence on the soil water content deeper than 250 mm. For the application rate of biochar of 4%, most water was retained within 0–250 mm soil layer. However, when biochar application amount was high (6%), it would be helpful for water infiltration. During the improvement of sandy soil, biochar application rate of 4% in the plow layer had the best effect.

Analysis of the changes in medium moisture content according to a crop irrigation strategy and the medium properties for precise moisture content control in rock wool

The substrate moisture content affects crop absorption, microorganisms, oxygen concentration, water stress, and the ultimate evaporation amount. The moisture content in the rhizosphere can be controlled by the amount of water, the frequency of water supply, the time of water supply, and the rate of water supply provided to the crops. The purpose of this study was to investigate the physical properties of a rock wool medium and to investigate the water movement characteristics of the medium according to different watering conditions. To measure the moisture content of the substrate and the drainage amount, load cells were used as weight sensors, and the total irrigation capacity was 99 and 198 mL/min, respectively. The moisture content at each irrigation starting point was set from 30 to 80% of the substrate moisture content at each 5%. The relationship of the starting point of drainage, the 30% drainage rate, the point of the first saturation according to the two different irrigation rates, and the point of moisture content at the start of irrigation showed a sigmoidal relationship. When reviewing the irrigation to the first saturation point, the substrate moisture content got higher as the moisture content at the irrigation start increased. Also, it was shown that the higher the irrigation rate, the higher the saturated moisture content seen in the substrate. The high irrigation rate is useful for the saturation of the substrate, but a large amount of water was needed to adjust the drainage rate. For this reason, we analyzed the irrigation rate under various cultivation conditions.

Research on the Influence of Reclamation on Water and Sediment Environment Offshore

Reclamation changes the characteristics of water movement, then affects the marine environment system, and may even lead to environmental disasters. The influence on the 4 aspects of the current field, wave field, suspended sediment field and topography were summarized. Impacts of large area of reclamation project on the marine environment are found very few, and to expand the study scope and make up for the current lack of a wide range of studies on multiple reclamation impacts on the marine environment is an important research direction in the future; In the long time scale, it is a lack of long-term cumulative effects on coastal reclamation and whether the influence can restore; the present study focuses only on the impact evaluation of scope, type, and degree from lack of exploring the potential mechanism; It is a lack of interdisciplinary research, and the analysis of comprehensive influence of reclamation projects on land, sea and biological and ecological environment.

Water Controlling Research of Complex Fault Structures in Wugou Mine

Once the lead abutment pressure influence the fault structure, its internal rock mass is damaged easily while the fault structures are the most vulnerable of mining influence weak link. If the fault structures conduct the aquifer, the mine water inrush will occur. This paper researchs water level of Taiyuan limestone aquifer with three-dimensional form simulation and analyzes mine water movement characteristics and the change of water level and hydraulic contact of each aquifer combining with complex geological conditions of Wugou mine, aiming at tectonic evolution and tectonic combination characteristic of the mine, according to the long observation hole material. Combining with water pressure test results and drilling and geophysical prospecting achievement, using daubing coefficient method to analyze sealing of fault structure, we conclude that faults are pressure-torsional normal faults which their fault zone is compact and has high strength so we can narrow even do not leave set fault waterproof pillar in Wugou mine.

Clarification of water movement properties in a multi-soil-layering system

In multi-soil-layering (MSL) systems, the effect of the materials and structural differences on the wastewater treatment performance and clogging mechanisms are not fully understood because of insufficient quantitative evaluations of water movement properties inside the system. In the present study, water movement properties were examined using laboratory-scale MSL systems consisting of one to six soil mixture layers (SML). The aims were to determine (1) changes in water movement characteristics inside the systems by varying the hydraulic loading rate (HLR), (2) the relationship between the number of inflow points and water movement characteristics, and (3) water movement characteristics and clogging mechanisms under wastewater treatment conditions.As the HLR increased, the flow rates in the SML increased linearly, followed by a slight decline in the rate of increase, whereas flow rates in the permeable layers (PL) between the SML (PLb) increased exponentially except in the system with one layer. Water movement inside the systems with one inflow point inclined toward the central part of the system compared to that with three inflow points. Under wastewater treatment conditions, flow rates in the first SML decreased to 437 L m−2 day−1 from 1433 L m−2 day−1 in three days after applying wastewater. However, as the number of layers increased, high flow rates in the SML were maintained for longer periods. In the first to third SML, a decreasing trend of oxidation–reduction potential (Eh) values was correlated with a decrease in flow rates. Partial clogging in the first PLb was associated with Eh values in the PL of the upper part beginning to decrease. The study indicated that establishment of an optimum structure, materials, and aeration was required to maintain a proper level of permeability and anaerobic conditions inside the SML, which would facilitate simultaneous removal of organic matter, nitrogen and phosphorus.

Subsurface Drip Irrigation Placement and Cotton Irrigation Water Requirement in the Tennessee Valley

Fluctuations in dryland cotton yield in the Tennessee Valley region of northern Alabama are common and are usually related to irregular drought periods during the growing season. Subsurface drip irrigation (SDI) has gained popularity as a water delivery system for small, irregular-shaped cotton fields. A seven-year study was conducted with the objective to determine the response of seed cotton yield to SDI tape orientation relative to crop row direction and different irrigation rates under dryland conditions of the Tennessee Valley. Seven treatments were tested in a randomized incomplete block design which consisted of three irrigation treatments (33%, 66%, and 99% pan evaporation), two SDI tape orientations (parallel and perpendicular), and a dryland control. All SDI treatments produced yields significantly higher than non-irrigated, dryland cotton in four out of seven years. Maximum yield was obtained at a median pan evaporation water replacement value of 74%. No statistical differences were observed between SDI tape orientations on seed cotton yield in all years except in 1999 when parallel out yielded perpendicular at lower irrigation rates. Results confirm the long-term efficacy of supplemental irrigation to increase seed cotton yield irrespective of SDI tape placement during sporadic periods of drought. These results are applicable only for fields with the same soil type or with similar water movement characteristics.

Water Movement Characteristics in a Multi-Soil-Layering System

The Multi-Soil-Layering (MSL) system consists of soil units arranged in a brick-like pattern that are surrounded by layers of zeolite or alternating particles with a homogeneous size that allow a high hydraulic loading rate. Characteristics of the changes in the water movement, hydraulic retention time (HRT) and system weight during the wastewater treatment in the MSL system were investigated using a laboratory-scale MSL system (D10 × W50 × H73 cm). As the loading rate increased from 1,000 to 5,500 L m−2 d−1, wastewater preferentially flowed into the permeable layers in the MSL, which decreased the contact of the wastewater with the soil mixture layers. HRT was inversely related to the loading rate. HRT decreased from 20 to 1 h, as the loading rate increased from 250 to 6,000 L m−2 d−1. As an indicator of the system condition, the weight variation of the system was determined during the wastewater treatment. When the weight was stable, input and output of wastewater and decomposition of organic matter appeared to be equilibrated. When the weight increased, the system started to clog. Due to clogging, the efficiency of COD and phosphorus removal decreased, while the efficiency of nitrate removal increased.

Structural phase changes of the liquid water component in Alpine snow

The arrangement of free water in the complex texture of Alpine snow was measured by different methods: broadband electro-magnetic measurements ranging from radio frequencies up to the microwave K-Band regime directly allow the detection of the geometrical structure of the water bodies; hydraulic measurements—measurements of water percolation through or water drainage off an Alpine snow cover—show a significant change of water movement characteristics which are caused by changes in the water geometrical configuration (structural phase changes) due to the natural variation in the free water saturation. Structural characteristics of water bodies included in snow are reflected by the dielectric depolarization factors. The special case of ring-shaped water inclusions is reflected by the magnetic permeability. Field measurements were carried out in the Stubai Alps, Austria. Metamorphism of these Alpine snow covers was characterized by several melt–freeze cycles. Four main regimes of water saturation existed, each characterized by different structural properties of the free water bodies: the pendular zone with closed isolated water bodies, a funicular zone with confluent water bodies, a transitional zone where isolated water bodies begin to merge and a sub-regime included in the pendular zone characterized by the existence of ring-shaped water bodies. Experimental results of a 12-year field study are presented.

Determining differential water movement through ion exchange resin for nitrate leaching measurements

Abstract The fate of fertilizer N applied to agricultural soils is of growing concern due to the potential for groundwater contamination. The recent development of an exchange resin that specifically absorbs NO3 has led to the potential for a new technique to measure cumulative NO3 leaching. The main limitation to the application of the resin technique is the matching of water movement through the resin with that of soil. A soil water movement device was developed to compare water movement through the resin to that of soil. A study was initiated to develop a resin/soil pack with water movement characteristics that closely matches those of natural soils. Three different soil types were used in this study: a Cahaba sandy loam (fine‐loamy, siliceous, thermic Typic Hapludult), a Congaree clay loam (fine loamy, mixed, nonacid, thermic Typic Udifluvent), and a Hiwassee clay (clayey, kaolinitic, thermic Typic Rhodudult). Both pure resin and resin mixed with soil were found to have higher water movement characteristics compared to bulk soil. A resin pack method was found which had water movement characteristics that were not significantly different from that of bulk soil for the three different soil types. The resin pack method is described.

Some Concepts Concerning Soil Site Assessment for Water Quality

Soil site assessment for potential surface water and groundwater contamination involves predicting water movement through the soil profile and across the soil surface. Knowledge of the effect of local and regional soil landscapes and geomorphic surfaces on the hydrogeology is needed to determine the likelihood for contaminated waters to reach a stream, pond, lake, or other kind of surface water, or to move through the vadose zone to groundwater aquifers. Lateral movement of water in the soil or vadose zone is an important water-quality consideration in some areas. Site assessment must evaluate characteristics such as the local and regional watershed relationships, stream delivery systems, known areas that are sensitive to groundwater pollution, sediment delivery, local landscape and slope characteristics, lateral and vertical water movement characteristics of the soil and vadose zones, crop management systems, and attenuation properties of the soil such as cation exchange capacity (CEC) and surface area properties. Soil genesis processes provide important clues as to the lateral and vertical movement of water through the soil.

Characteristics of Water Movement in a Surface Soil and Effects of Vegetation on them

Characteristics of Water Movement in a Surface Soil and Effects of Vegetation on them