Pressure Head Variation Research Articles

Development of a web-based simulation application for efficient drip irrigation submain design

Drip simulation software is essential for accurately optimizing and maximizing the efficiency of drip irrigation systems, enabling precise water management and resource conservation. The present study developed a powerful web-based application to assist irrigation system designers in evaluating the effectiveness of the submain design on uniform or non-uniform slope conditions. The software facilitates the simulation and optimisation of submain design by incorporating modern drip design approaches and state-of-the-art software development methodologies. With its intuitive user interface, the software allows users to effortlessly enter important design parameters, including slope specifications, lateral discharge rates, submain length, lateral spacing and submain inlet pressure head. The software calculates to determine the pressure head values at each outlet and the relative variation in pressure head (vh), allowing for comprehensive design evaluation. Extensive testing using various typical sample data ensured the high accuracy and reliability of the developed web application. It empowers users to explore multiple design alternatives and determine the most suitable option. Rigorous testing, employing various typical sample data, has further enhanced the accuracy and reliability of the developed application. Live demonstrations were conducted to evaluate its user-friendliness, yielding overwhelmingly positive feedback from designers. The software can be accessed conveniently via the website https://www.dripdesigncheck.in/telescopic/submain, ensuring easy availability to users.

A study of the water quality parameter and its impact using HYDRUS-1D in Deepor Beel, Guwahati, Assam

This study focuses on knowing the status of 12 water quality parameters with their variation and soil-solute interaction due to dumping of wastes at six different locations of Deepor Beel (a Ramsar site), finding their necessary correlations and development of a solute transport model using HYDRUS-1D software. HYDRUS-1D model used in this study will show the movement of iron through the soil profile in the area selected near the Municipal dumping yard at Boragaon. The results indicated that certain parameters are higher than their standard permissible limits with its extreme values obtained at the dumping location at Boragaon. The water near the dumping site is acidic (pH= 5.92), with high iron concentrations (3.68 mg/l), increasing hardness and turbidity as well as lower D.O level (3.67 mg/l). HYDRUS-1D solute transport model gives a distinct and clear picture of the solute movement, water flow, water content, pressure head and concentration profile variation along the soil profile with respect to time and depth. The results of this model showed that continuous influx of harmful solutes on the surface of the Deepor Beel could lead to break through of this solute through the soil column into the groundwater storage. Hence the present study showed that water quality is deteriorating at various locations of the beel and necessary steps are immediately required for sustaining the ecological balance of the wetland.

The effects of capillary fringe on solitary wave induced groundwater dynamics

The capillary fringe is an important factor influencing the groundwater hydrodynamics in the coastal aquifer. The mechanism of the water table changes with the effect of capillary fringe under the wave action is still unclear. In this study, laboratory wave flume experiments were conducted to investigate the groundwater hydrodynamic features, paying particular attention to the capillary effects, in different areas of the beach under the solitary wave action. In the present experiments, medium sands were used to form the beach, resulting in a large capillary fringe height. Accordingly, the entire swash process occurred within the capillary truncated area. Based on the experiment measurements, three mechanisms are confirmed with respect to the coastal water table fluctuations, i.e., the flux mechanism, the gradient mechanism and the newly-proposed meniscus mechanism. The meniscus mechanism in the capillary truncated zone and the gradient mechanism in the capillary untruncated zone contribute to the non-hysteresis of the pressure head variation in the beach landward of the swash zone. The capillary truncated zone can be deemed as an extent of the swash zone since the effect of the swash process plays roles beyond the swash zone through a truncated capillary fringe. In addition, detailed observation of the evolution of the meniscus profile among the beach surface particles suggests that both vertical and horizontal seepage flows are important in the capillary truncated zone. In the swash zone, temporal variation of the hydraulic head can be classified into four/five stages in the case that the measuring position is near to/far from the uprush limit, and the effects of shoreline, water surface elevation, seepage face and exit point on the groundwater dynamics are discussed. Findings from the present study provide useful insights into the wave-induced coastal groundwater dynamics. • Capillary fringe effects on solitary wave induced groundwater dynamics are investigated through wave flume experiments. • Observation of the meniscus dynamics among beach surface particles provides new insights into the capillary fringe behaviors. • Flux mechanism, gradient mechanism and the newly-proposed meniscus mechanism for groundwater fluctuations are confirmed. • Meniscus mechanism dominates the hydrodynamic process in the capillary truncated zone. • Hydrodynamic process in swash zone can be divided into four or five stages with different dominant influencing factors.

Sampling patterns may influence the evaluation of irrigation uniformity of Center Pivot systems

Abstract The evaluation of irrigation uniformity can be affected by the sampling pattern in the field. Thus, this work aimed to compare the water application uniformities of a Center Pivot using three sampling patterns: along the equipment radius (radial), in the direction of movement of the pivot (circular) and in a two-dimensional way (meshed). For this, samplers were positioned under the spans of a Center Pivot system, being evaluated the effects of the sampling pattern and of the span, in a 3×3 statistical factorial design, with three replications. The results showed that circular and meshed arrangements were statistically equal and had higher values of Christiansen's and Distribution Uniformity Coefficients. The mesh type arrangement represented a more uniform distribution profile of irrigation depths on the surface. For areas of flat or slightly undulating topography and when using pressure regulating valves for the emitters, sampling in a radial pattern is sufficient, but for terrains with irregular topography or when pressure head variations along the lateral line are important for the operation of the emitters, the combination of the radial and circular pattern is interesting. The meshed sampling detects the stoppage effect of the towers and drift, however, in a reduced area.

The impact of diurnal surface water fluctuations on groundwater diffusion: assessment through Fick's second law.

This article reports the interaction between groundwater and surface water sources based on diurnal head fluctuations. The model uses the well-known Fick's second law to numerically estimate the pressure head variations in heterogeneous aquifers. The developed numerical model can examine the effects of both stream level sudden diurnal and gradual variations on the pressure heads in a confined heterogeneous aquifer. Calculations of pressure heads as a result of the interaction indicated that independent of the sequence of diffusion coefficient in the two similar confined aquifers, variations in pressure head will be the same at considerable amount of distances from the interaction region, unless when the total effective diffusion lengths are different. In the investigated cases, through time, the significant difference in the pressure heads between the gradual and sudden increase in stream water levels vanished, and the pressure head variations between the two cases became negligible.

Effect of Nozzle Angel & Cyclic Pressure Head Variation on Water Distribution Uniformity for Stationary Sprinkler Systems

The present research included studying the effect of the sprinkler nozzle angle and cyclic variation of the operating pressure head on the uniformity of water distribution for many sprinkler heads spacing with rectangular and triangular sprinkler heads arrangement for different sprinkler heads. The research conducted 40 tests to measure a single sprinkler water distribution pattern under similar climatic operating conditions by adopting the water distribution pattern along a beam that represents the radius of the wetting circle which its center is a sprinkler head for different sprinkler nozzle angles (Ɵ + 5 °, Ɵ + 3.5 °, Ɵ, Ɵ -3.5 °, Ɵ -5 °) and the constant-cyclic operating pressure head conditions for different sprinkler heads. 320 patterns were found for field water distribution pattern and uniformity coefficient for four different spacing with a rectangular and triangular sprinkler heads arrangement for the sprinkler heads and the measured water distribution patterns. The research revealed that 70% of the uniformity coefficients in the rectangular arrangement are greater or equal to its value in a triangular arrangement. The increase in the nozzle angle results in increasing the uniformity coefficient of 1.4% for each degree, an increase in the nozzle angle, and can reach 2.4% for each degree for a specific spacing, arrangement, and sprinkler head. Also, the difference between the two water distribution patterns in the case of operating with constant pressure head and variable pressure head is slight, but it shows in the values of the uniformity coefficient, where the maximum difference reaches 10%, and in general, the best in the values of the uniformity coefficient requires determining the nozzle angle, the spacing and the arrangement of sprinkler head as well as the case of operating pressure head constant or variable.

Influence of hydraulic properties on physically modelling slope stability and the definition of rainfall thresholds for shallow landslides

Physically-based models are recognized as a good tool for slope stability analysis and have been implemented for the definition of rainfall thresholds for landslides. In this study, a methodology for estimating rainfall intensity and duration thresholds for shallow sliding failure, using the physical model TRIGRS, was implemented in a tropical mountainous basin of the Valle de Aburrá (Colombia). The variation of pressure head and factor of safety during different rainfall events and hydraulic conditions is studied for specific grid cells. Steady state and a maximum pressure head were reached for each grid cell regardless of the different rainfall intensities and hydraulic conductivities simulated, but the time in which this condition is reached depends on these variables and occurs faster for steeper slopes. The influence of hydraulic properties on the stability results and the position of the rainfall intensity and duration thresholds were studied with parametric analysis. Very low values of saturated hydraulic conductivity do not allow rainfall intensity and duration thresholds to be developed. The rainfall threshold position also has a greater variation with respect to the parameters of the soil water retention curve and the initial infiltration rate (or long-term background rainfall rate) for low values of saturated hydraulic conductivity.

Linear model of water movements for large-scale inverted siphon in water distribution system

Abstract This paper proposes a linear model that relates the pressure head variations at the downstream end of an inverted siphon to the flow rate variations at two ends. It divides the pressure head variations in the inverted siphon into low-frequency part and high-frequency part. The two parts are caused by the deformation of the siphon wall and the reflection of acoustic wave, respectively. In order to build a simplified relation between wall deformation and low-frequency pressure head variations, the Preissmann slot method (PSM) is adopted in this paper. The linear model can also be used in other forms of structures, such as pipes and tunnels, where a pressurized flow condition is present. In comparison with simulation results using the finite volume method, the linear model shows an L2 norm of 0.177 for a large-scale inverted siphon and 0.044 for a PVC pipe. To this end, the linear model is adopted to model a large-scale inverted siphon in a virtual water delivery system. Simulation results show that the inverted siphon can reduce water fluctuations. An equation to quantify this effect is proposed based on the linear model.

DEVELOPMENT AND PERFORMANCE EVALUATION OF PRESSURIZED IRRIGATION SYSTEM

The purpose of the present study is to develop and evaluate a sprinkler irrigationsystem based on its design criteria to minimize friction loss, pressure head variation, and specificenergy and maximize water uniformity distribution. The system was developed from single inlet openlateral (SIOL) to double inlet closed lateral (DICL). Experiments were conducted to study twodifferent parameters (lateral length and irrigation water inlet method to lateral line) affecting theperformance of the developed system. The system performance was evaluated in terms of waterdistribution uniformity, coefficient of uniformity, pressure head variation and specific energy. It wasconcluded that pressure head variation and specific energy were significantly decreased while waterdistribution uniformity was improved with DICL compared to SIOL at all lateral lengths. The laterallength of 165m with DICL was recommended to be used as they achieved acceptable distributionuniformity, coefficient of uniformity and pressure head variation values which were 75%, 81% and18%, respectively.

Idioblasts formation and essential oil production in irrigated Piper aduncum

ABSTRACT The growing of Piper aduncum for essential oil extraction has increased, but there is a lack of basic information about its management and cultivation, which allows the productivity and quality of the oil, in order to attend the market demands. This study aimed to evaluate the relation between the production of essential oils from P. aduncum and soil water pressure heads (20 kPa, 40 kPa, 60 kPa, 100 kPa and non-irrigated). The assessment comprised the quantification of idioblasts and the production of essential oil extracted from leaves of cultivated plants. The variation in the soil water pressure head alters the amount of idioblasts in P. aduncum leaves, with impacts on the essential oil production. A soil water pressure head range of 20-60 kPa is sufficient for this species to express the highest amount of idioblasts and the highest level of essential oil production. The species adapts itself to different water availability conditions in the soil. Under stress conditions, due to water deficit or excess, the production of essential oil is reduced.

Effects of capillary fringe and truncation factor on pore-water pressure and water table variation in dewatering and watering sand column experiments

Abstract Spatiotemporal variations of the pore-water pressure and water table response to small amounts of water exchange were measured in a sand column. In the dewatering experiment, the pressure head variation can be divided into three stages: the initial pressure head declining phase when water table is above the sand surface, a sudden drop in accordance with the capillary fringe when water level passes through the sand surface, and a slow declining phase with respect to the specific yield of the sand. As for the watering experiment of the shallow groundwater with different initial truncation factors (TF), the addition of a minute amount of water results in a rapid rise of the pressure head initially, then a gradually increase to its equilibrium. When the upper extent of the fully saturated capillary fringe coincides with the sand surface (TF ≤ 1), a thin film of water addition produces nearly instantaneous increase in pore-water pressure, corresponding to a rapid rise of groundwater table to the sand surface. Pressure head increment increases linearly with the TF value and reaches its maximum when TF value approaches unity. Considering the vertical distribution of the pressure head, its gradient becomes larger right after the water addition, then decreases to its initial value of hydrostatic condition in the end. In the case of TF > 1, there is an unsaturated layer above the groundwater table, the pressure head increases after the water addition, whose magnitude however decreases as the increase of TF value. Nevertheless, the final position of the groundwater table is still below the sand surface, and the gradient of the pressure head vertical distribution dose not vary significantly throughout the entire process. In consideration of hydrostatic pressure assumption, temporal variation of the water table was also quantitatively obtained based on the measured instantaneous pore-water pressure data, which is consistent with time-varying process of the pressure head during both the dewatering and watering experiments.

Impact of Climate Change on Hydraulic Performance in Water Distribution Networks

The Intergovernmental Panel on Climate Change (IPCC) has forecast higher mean air temperatures for the mid-latitude region of North America. Studies have shown a strong positive correlation between temperature and municipal water demand. Warmer air temperatures in the future have the potential to increase municipal water demand above levels forecast without climate change considerations. The predicted increase in mean temperature and the onset of hotter and dryer summer weather may create challenges for water providers in the future. Without appropriate network upgrades, higher water demands may degrade the hydraulic performance of existing systems. This creates a need to characterize the impact of higher temperatures on peak water demands and on the hydraulic performance in water distribution networks. The aim of the research is to begin to understand the impact of higher temperatures on nodal demands and pressures in water distribution networks. The sensitivity of municipal water demand to an increase in air temperature is established through previous climate adaptation research completed for the geographical region of central Canada. Results indicate that without adaptation, a 2-4 °C temperature increase causes mean pressure head to fall below the acceptable minimum and produces large uncertainties in pressure head under maximum hour demand (MHD) and maximum day demand (MDD) + fire design conditions in the Anytown network. The combination of low mean pressure head and a high coefficient of variation of pressure head increases the probability of hydraulic failure in the Anytown network. Adaptation strategies are presented as ways to hedge the effects of a warming climate in the Anytown network

THE DESIGN OF ECONOMIC MICRO-IRRIGATION LATERALS BY COMPUTER AID

To design micro-irrigation laterals, by an accurate, simple and quick method, The OPT-LAT model was created. The model calculates the maximum lateral length with field length in x-axis or y-axis at different lateral diameters. It can also estimate the optimal diameter that meets least cost irrigation system. Not only that, but also it can compare between optimal lateral diameter in x-axis or y-axis. The validity of OPT-LAT model was proved through the comparison between the lateral lengths calculated by the model and the corresponding ones calculated by Osama (2). The model has been applied on 160 m × 120 m plot area as a case study. At the x-axis direction, the lateral lengths were 58 m for different lateral diameters, the optimal internal diameter was 13.6 mm at annual least cost of 0.229 L.E/m/year and less percent of pressure head variation of 12 % at lateral diameter of 36 mm. The corresponding values at y-axis were 78 m lateral lengths, the optimal internal diameter was 13.6 mm at annual least cost of 0.239 L.E/m/year and less percent of pressure head variation of 12.04 % at lateral diameter of 36 mm. These results indicate that as the diameters of the laterals increased, the percent of the pressure head variation decreased, annual fixed cost increased and repair plus energy annual costs increased. The above results depend on energy price and pipe price according to its material type.

IRRIGATION EFFICIENCIES OF SUGAR CANE YIELD UNDER DIFFERENT FURROWS LENGTHS IN UPPER EGYPT

The research field experimental work was conducted at the farm of El-Mattana Research Station of the Agricultural Research Center, Luxor Governorate, Upper Egypt during growing season 2012&2013 in clay soil on sugarcane crop. The objective of the herein research trial are to study surface irrigation system performance through using gated pipe system technique under different furrows irrigation lengths treatments L125 (125m) L100 (100m). L75 (75m) and land slope 0.1 % comparing with the traditional irrigation methods under the same condition and treatments. The consequent effects of applying such methods on advance, recession and opportunity time, total water applied, yield, water application efficiency and water use efficiency for sugar cane was considered. The Results showed that the total head losses due to friction was increased gradually until reached 8.4% of the original pumping pressure head measured. The flow variation through 18 meters apart of the gated pipe system was about 13.9 %. Therefore the uniformity distribution of flow through outlets along the gated pipe system was about 86.1 %. On the other hand pressure head variation was about 9.42 %. The result revealed that the traditional methods received more amounts of irrigation water than gated pipe system in the three cases of furrow lengths. The highest values water saving were achieved by using irrigation gated pipe technique with leveling by laser technique 0.1% slope. The traditional irrigation (T1) gave lower water application efficiency than irrigation using gated pipe system (T2) The maximum value of sugar cane yield was achieved in case of using irrigation gated pipe at L100 with 0.1 % slope treatment. On the other hand, the minimum value of sugar cane was achieved in case of irrigation traditional method at L 75 treatment. The average values of sugar cane yield were 55 and 42 ten/fedan under gated pipe and traditional irrigation method respectively. The irrigation with gated pipe improved yield WUE for sugarcane crop under three treatments furrows lengths compared to traditional irrigation.

Predicting soil moisture distribution, dry matter, water productivity and potato yield under a modified ‎gated pipe irrigation system: SALTMED model application using field experimental data

The use of gated pipes in surface irrigation helps to reduce water losses commonly associated with the use of the traditional furrows. This study focused on predicting soil moisture content‎, total dry matter, crop yield and water productivity of potato crop using traditional and modified, self-compensating gate outlet (SCGO) gated pipe using the SALTMED model to explore the model suitability to identify the optimum and economic gate spacings. The traditional gated pipes are known to exhibit a range of pressure head variations along the pipeline causing a non-uniform discharge from orifices while the modified gate pipe system, known as compensating gated pipes (SCGO) stabilizes the pressure heads and produce more uniform water discharge along the pipe line. The effect of three gate spacings (0.7, 1.0 and 1.5m) was studied in a field experiment that has been conducted for two successive seasons, 2011–2012 and 2012–2013. The SALTMED model has been applied and showed excellent agreement between the simulated and observed soil moisture, dry matter, yield and water productivity. Similar to the field results, the simulated values indicated that the modified (SCGO), with the 1.5m gate spacing, gave the highest yield and water productivity. The modified gated pipe received less water than the traditional gated pipe, due to its high application efficiency. In addition to water saving, there is an economic benefit for using 1.5m gate spacings as its cost is low (14 gates per 21m pipe length) in comparison with 1.0m and 0.7m spacings. The results confirmed SALTMED ability to simulate with high precision, soil moisture, dry matter, water productivity and yield for potato under gated pipe irrigation. Therefore, the model can be used for design purposes to identify the optimum and economic gate spacings without the need to conduct expensive, costly and labor intensive field trials.

On the Use of the Water Hammer Equations with Time Dependent Friction during a Valve Closure, for Discharge Estimation

The paper presents a new method for in site discharge estimation in pressured pipes. The method consists in using the water hammer equations solved with the method of characteristics with an unsteady friction factor model. The differential pressure head variation measured during a complete valve closure is used to derive the initial flow rate, similarly to the pressure-time (Gibson) method. The method is validated with a numerical experiment, and tested with experimental laboratory measurements. The results show that the proposed method can reduce the discharge estimation error by 0.6% compared to the standard pressure-time (Gibson) method for the flow rate investigation.

Application of a process-based shallow landslide hazard model over a broad area in Central Italy

Process-based models are widely used for rainfall-induced shallow landslide forecasting. Previous studies have successfully applied the U.S. Geological Survey’s Transient Rainfall Infiltration and Grid-Based Regional Slope-Stability (TRIGRS) model (Baum et al. 2002) to compute infiltration-driven changes in the hillslopes’ factor of safety on small scales (i.e., tens of square kilometers). Soil data input for such models are difficult to obtain across larger regions. This work describes a novel methodology for the application of TRIGRS over broad areas with relatively uniform hydrogeological properties. The study area is a 550-km2 region in Central Italy covered by post-orogenic Quaternary sediments. Due to the lack of field data, we assigned mechanical and hydrological property values through a statistical analysis based on literature review of soils matching the local lithologies. We calibrated the model using rainfall data from 25 historical rainfall events that triggered landslides. We compared the variation of pressure head and factor of safety with the landslide occurrence to identify the best fitting input conditions. Using calibrated inputs and a soil depth model, we ran TRIGRS for the study area. Receiver operating characteristic (ROC) analysis, comparing the model’s output with a shallow landslide inventory, shows that TRIGRS effectively simulated the instability conditions in the post-orogenic complex during historical rainfall scenarios. The implication of this work is that rainfall-induced landslides over large regions may be predicted by a deterministic model, even where data on geotechnical and hydraulic properties as well as temporal changes in topography or subsurface conditions are not available.

Mesoscopic aspects of root water uptake modeling – Hydraulic resistances and root geometry interpretations in plant transpiration analysis

In the context of soil water flow modeling, root water uptake is often evaluated based on water potential difference between the soil and the plant (the water potential gradient approach). Root water uptake rate is modulated by hydraulic resistance of both the root itself, and the soil in the root vicinity. The soil hydraulic resistance is a function of actual soil water content and can be assessed assuming radial axisymmetric water flow toward a single root (at the mesoscopic scale). In the present study, three approximate solutions of mesoscopic root water uptake − finite difference approximation, steady-state solution, and steady-rate solution − are examined regarding their ability to capture the pressure head variations in the root vicinity. Insignificance of their differences when implemented in the macroscopic soil water flow model is demonstrated using the critical root water uptake concept. Subsequently, macroscopic simulations of coupled soil water flow and root water uptake are presented for a forest site under temperate humid climate. Predicted soil water pressure heads and actual transpiration rates are compared with observed data. Scenario simulations illustrate uncertainties associated with estimates of root geometrical and hydraulic properties. Regarding the actual transpiration prediction, the correct characterization of active root system geometry and hydraulic properties seems far more important than the choice of a particular mesoscopic model.

Design of Zero Slope Microirrigation Laterals: Effect of the Friction Factor Variation

AbstractMicroirrigation has become quite a common practice in agricultural production in various parts of the world. To achieve the optimum (hydraulic and economic) system performance, designers are often faced with the problem of designing a maximum lateral length which results in a desired coefficient of uniformity (CU) or an allowable pressure head variation (δH). Previous theoretical design approaches are usually based on a constant Darcy–Weisbach (DW) friction factor along the lateral and this assumption can lead to substantial errors. In the research reported in this paper, a new analytical design approach does not require the constant DW assumption for zero-slope laterals while it still takes into account the emitter exponent and the effect of minor friction losses caused by emitters. Assuming a constant friction factor along the lateral might result in errors up to 14% in the calculation of the maximum lateral length. Conversely, the maximum relative error caused by the application of the proposed...

Diagnosis of a Pipeline System for Transient Flow in Low Reynolds Number with Impedance Method

This study explores the comprehensive calibration potential of impedance-based methods implementing several unsteady friction models for a pipeline system with or without leakage. The corresponding response functions in the frequency domain approach have been derived by the impulse response method and incorporated into the genetic algorithm-based calibration method. Unsteady models addressed either frequency-dependent friction or acceleration-based frictions. Parameter calibration exercises with experimental data have shown that the impedance-based approach provides a versatile and feasible optimization framework via the fitting of an objective function based on the predicted and measured pressure head variation. To check the impact of pressure pulsation and noise, extended calibration tests were performed using oscillated and disturbed pressure data bounded by the frequency and amplitude of a pump system and the measurement error of a conventional pressure transducer. The performance of the integrated optimization examples demonstrates the robustness of the impedance-based approach, both in the representation of a real-life system and the configuration of various system characteristics.