Water Distribution Uniformity Research Articles

Water management studies in PEM fuel cells, part IV: Effects of channel surface wettability, geometry and orientation on the two-phase flow in parallel gas channels

In this study, the effects of channel surface wettability, cross-sectional geometry and orientation on the two-phase flow in parallel gas channels of proton exchange membrane fuel cells (PEMFCs) are investigated. Ex situ experiments were conducted in flow channels with three different surface wettability (hydrophilically coated, uncoated, and hydrophobically coated), three cross-sectional geometries (rectangular, sinusoidal and trapezoidal), and two orientations (vertical and horizontal). Flow pattern map, individual channel flow variation due to maldistribution, pressure drop and flow visualization images were used to analyze the two-phase flow characteristics. It is found that hydrophilically coated gas channels are advantageous over uncoated or slightly hydrophobic channels regarding uniform water and gas flow distribution and favoring film flow, the most desirable two-phase flow pattern in PEMFC gas channels. Sinusoidal channels favor film flow and have lower pressure drop than rectangular and trapezoidal channels, while the rectangular and trapezoidal channels behave similarly to each other. Vertical channel orientation is advantageous over horizontal orientation because the latter is more prone to slug flow, nonuniform liquid water distribution and instable operation.

GIS user-interface based irrigation delivery performance assessment: a case study for Tanjung Karang rice irrigation scheme in Malaysia

Various indicators are used for evaluating the performance of different aspects of an irrigation system, and assessments also differ in terms of the types of performance indicators used. This paper describes a GIS-based assessment system which utilizes a new concept and evaluated the inadequacy of a widely used Relative Water Supply (RWS) concept to characterize the irrigation delivery performance for a rice irrigation system as the season advances. Development of this GIS-based assessment system resulted in the creation of new indicators, viz., the Rice Relative Water Supply (RRWS), Cumulative Rice Relative Water Supply (CRRWS) and Ponding Water Index (PWI). These indicators were determined from field tests and evaluated in a Malaysian Tanjung Karang Rice Irrigation Scheme (TAKRIS). The RWS concept was found to be inaccurate for characterizing the oversupply condition on irrigation deliveries for rice irrigation; and difficult to correctly quantify the oversupply condition for irrigation supplies. Besides, it was found that the RRWS indicator can distinctly characterize the oversupply condition for RRWS > 1.0 and undersupply condition for RRWS < 1.0 on irrigation delivery for any given period. A value of 1.0 for RRWS indicates an irrigation delivery that matches perfectly the actual field water demand. This study presents a cumulative RRWS plot that provides important information on irrigation supplies for any given time interval for management decisions. An increasing slope in the actual CRRWS curve with CRRWS = 1.0, means that irrigation supply can be slightly curtailed in the next period. On the other hand, if the slope is negative, supply has to be increased. If a computed CRRWS line follows the CRRWS = 1.0 line, it means that irrigation deliveries are perfectly matched with the field water demand. A graphical user-interface was developed for structuring the assessment tool within an ArcGIS platform. The system can instantly provide information on the uniformity of water distribution and the shortfall or excess, and provides vital information in terms of decisions that need to be made for the next period. The system helps to maintain continuous updating of input and output databases on real field conditions. Results are displayed on the computer screen together with color-coded maps, graphs and tables in a comprehensible form. The system is likely to be adopted for evaluating various water allocation scenarios and water management options. It can also be used as an analytical and operational tool for irrigation managers.

Design and Research on New Efficient Clarification Tank Treating Raw Water of Low-Temperature and High-Color

Based on advantages of plated sedimentation tank, mechanical stirring clarification tank, Densadge, design new efficient clarification tank treating raw water of low-temperature and high-color. Its functions of mixture, flocculation, precipitation and sludge concentration are gather in integral whole. This paper introduces mainly the tank structures, characteristics of technology, design principle, application parameters and operating conditions treating raw water of low-temperature and high-color, laboratory researches show that the tank possess the following characteristics: small occupation area, high load, uniform water distribution, reasonable flow trend, owning good adaptability and feasibility treating raw water of low-temperature and high-color, high removal rate of colour and turbidity has reached to high standards.

Influência do tempo de uso sobre as características hidráulicas do microaspersor do grupo modular

O desenvolvimento de novos equipamentos de irrigação e o aprimoramento dos já existentes, como dos microaspersores, devem considerar a avaliação das características hidráulicas, disposição adequada dos mesmos em condições de campo e interferência devido ao tempo de uso, garantindo índices de desempenho satisfatório. Nesse contexto, este trabalho teve o objetivo de determinar a equação vazão x pressão, o coeficiente de variação de fabricação - CVf e de vazão - CVq, a uniformidade de distribuição de água para diferentes graus de sobreposição do microaspersor do grupo modular de bocal laranja, novo e usado, sob funcionamento na posição invertida. O aumento do espaçamento entre microaspersores e entre laterais reduziu os índices de uniformidade em todas as pressões estudadas, tanto do microaspersor novo como do usado. A maior precipitação do jato de água ocorreu na distância de 0,0 a 1,0 m da haste de sustentação dos microaspersores novo e usado. O alcance do jato de água do microaspersor usado foi menor em relação ao bocal novo.

Evaluation of uniformity coefficients for sprinkler irrigation systems under different field conditions in Kurdistan Province (Northwest of Iran)

In the past few decades, several coefficients of uniformity were developed to express the uniformity of water distribution for different sprinkler irrigation systems. Christiansen's uniformity coefficient seems to be the most popular uniformity coefficient used by researchers on the global scale. However, more coefficients have also been proposed by other researchers. Therefore, this study focused on evaluating different uniformity coefficients proposed and on investigating the effects of field conditions on the results obtained by means of those coefficients. In doing so, sprinkler uniformity tests were conducted by using rain-gauge in order to measure the uniformity coefficients of ten fields irrigated by solid set sprinkler irrigation systems in Dehgolan Plain located in the Kurdistan Province, northwest of Iran. All fields selected differed in prevailing conditions such as the wind speed, size and type of nozzle, raiser height, operating pressure and sprinklers spacing. The coefficient of uniformity for each field was computed using the equations proposed by Christiansen (1942), Hawaiian Cane Society Specialists Hart and Reynolds (1965), Wilcox and Swailes (1947), Karmeli (1978), Criddle et al. (1956), Benami and Hore (1964), and Beale (1966). Data analysis was performed using the general linear model procedure of Statistical Analysis System Software. The results indicated that should not the field effect be considered in the statistical model, significant differences (P &amp;lt; 0.05) would be observed between the aforesaid coefficients; however, by considering the field effect in the statistical model, no significant differences (P &amp;gt; 0.05) would be observed. The results of this study conclusively indicated that the application of various coefficients of uniformity depends on the field conditions and as any specific coefficient of uniformity is suitable only for specific field conditions.

Water distribution uniformity and scheduling in micro-irrigation systems for water saving and environmental protection

Micro-irrigation can apply water with high uniformity. However, uniformity alone is not sufficient to achieve the goal of irrigation. Irrigation scheduling is equally important in micro-irrigation systems. The significance of various irrigation schedules and emitter flow uniformities were examined in a system design. Several irrigation schedules were compared with an optimal irrigation schedule. The optimal irrigation schedule can achieve optimal return and also provide water saving compared with the conventional irrigation schedule in which the whole field is fully irrigated at the same time. Deep seepage can be eliminated or minimised by scheduling deficit irrigation. An environmental protection irrigation schedule, where the whole field is in deficit, can save more water but will cause some reduction in total return compared to the optimal irrigation schedule. A simple irrigation schedule, in which the total amount of water applied is the same as the amount required, cannot only produce nearly optimal yield but also achieve increased water saving when high uniformity is also applied in the design. It is important to specify that the differences in total return and water saving between different schedules are reduced when high uniformity is applied in the design. For high uniformity the effects of crop sensitivity to deficit irrigation are not important and result in only limited (or acceptable) yield reduction and over-irrigation. Since a high proportion of water resources are used for agricultural production, micro-irrigation systems designed with high uniformity can be scheduled to achieve water conservation as well as environmental protection.

GIS-based irrigation water management for precision farming of rice

Precision farming aims to manage production inputs over many small management zones rather than on large zones. It is difficult to manage inputs at extremely fine scales, especially in the case of the rice irrigation system. However, site-specific irrigation management can potentially improve the overall water management in comparison to irrigated areas of hundreds of hectares. A critical element of the irrigation scheduling and management is the accurate estimation of irrigation supplies and its proper allocation for the irrigation offtake structures based on the actual planted areas. All irrigation scheduling procedures consist of monitoring indicators that determine the need for irrigation. The final decision depends on the irrigation criterion, strategy and goal. Irrigation scheduling is the decision of when and how much water to apply to a field. The amount of water applied is determined by using a criterion to determine irrigation need and a strategy to prescribe how much water to apply in any situation. The right amount of daily irrigation supply and monitoring at the right time within the discrete irrigation unit is essential to improve the irrigation water management of a scheme. This paper presents the GIS capability to achieve the goal in the view of irrigation strategy and goal with special reference to precision farming of rice. The GIS-based water management model was developed for the scheduling daily irrigation water deliveries and regular monitoring of irrigation delivery performance. The “Scheduling” program computes the right amount of irrigation deliveries based on crop water requirements. The “Monitoring” program gives information on the uniformity of water distribution and the shortfall or excess. The displayed results allow the manager to view maps, tables and graphs in a comprehensible form to ease decision making that where the irrigation amount will be delivered as the season progresses. GIS was used as a useful tool to assist the irrigation water management program in the context of precision farming. Keywords: i rrigation, monitoring, precision , farming, rice , GIS DOI: 10.3965/j.issn.1934-6344.20 1 0.0 1 .0 27 -0 35 Citation: Rowshon M K , Amin M S M . GIS-based i rrigation w ater m anagement for p recision f arming of r ice. Int J Agric & Biol Eng, 20 1 0; 3 ( 3 ): 27 <span style=line-height: 130%; font-family:

Effect of Application Uniformity on Production under Deficit Sprinkler Irrigation

The study aims to develop a computer model for assessing the effect of uniformity and deficit irrigation on farm crop production. The formulation of the model is based on the concept of field water balance. The model was applied for a selected autumn crop (maize). Ready to use values of evapotranspiration in the selected site (Al-Jazeera irrigation project-Nenawah) were used. Also, a published field data for sprinkler water distribution uniformity was adopted in the study. The study revealed that the yield ratio deficit increases with the increase in soil moisture depletion but decreases with the increase in irrigation uniformity. The actual crop evapotranspiration increases with uniformity. The results of the study also showed that the relative water use efficiency under deficit irrigation increases with the increase in soil moisture percent depletion and irrigation deficit ratio. Keywords: Sprinkler irrigation, Irrigation uniformity, Deficit irrigation, Evapo-transpiration, Water use efficiency.

Application of design theory for restoring the black beach degraded rangeland at the headwater areas of the Qinghai-Tibetan Plateau

Emitter clogging is one of the most important factors that affect the performances on drip irrigation systems. Emitter clogging, which is formed in a short time due to irrigation systems’ running under an inadequate pressure or owing to water quality, not only negatively influences uniformity of water distribution but also causes inadequate irrigation. In this survey, the clogging level determination of the emitters used in drip irrigation systems of some agricultural farms situated in Canakkale and their effects on irrigation performances were observed. The emitters were obtained from different farms in the investigated area, and were tested under the pressures of 50, 100, 150, 200, 250, 300 kPa in hydraulic laboratories. The clogging extend of emitters, flushing of clogging increased pressure and also performance values as coefficient of variation (Cv) under 100 kPa pressure, statistical uniformity (Us), emission uniformity (Eu) and Christiansen’s uniformity coefficient (Cu) were established through the tests. Acquired performance values must be matched with emitter performances that have not been used in irrigation. As a result of the study it was determined that some emitters are plugged on laterals used for 2 or 3 years in consequence of the tests. It as also determined that emitter coefficient of variation varied in the ranges of 0.43 and 0.63, 0.43 and 0.69, 0.48 and 0.58, 0.56 and 0.73 for unused emitters, for one year, for two years and for three years used emitters. Coefficient of variation between emitter flows remained within the limit of 5% in all laterals, except for one of the laterals used for one year. Coefficient of variation of emitters along two of the laterals used two years and all of those used three years remained out of 5% limitation. Similar results to CVm (manufacturing variation coefficient) were determined for performance parameters in respect of statistical uniformity (Us), emission uniformity (Eu) and Christiansen’s uniformity coefficient (Cu). Key words: Drip irrigation, emitter clogging, drip irrigation performance.

PERFORMANCE OF ROTATING SPRAY PLATE SPRINKLERS

Understanding the distribution characteristics of an individual irrigation sprinkler or spray nozzle is necessary to improve the uniformity of any sprinkler system.Relevant factors affecting the improvement of the irrigation performance of sprinkler systems are the engineering factors (i.e. operating pressure, riser height of sprinkler / nozzle, sprinkler type, deflector plates, and nozzle diameter), and the climatic factors (i.e. wind speed, air humidity and air temperature). It is important to highlight that this study has been focused on center pivot sprinkler irrigation system as it is the widely used sprinkler irrigation system in new lands of Egypt ( Toshka, Sinai and Nobaria).Therefore, five different types of spray nozzles, used on center pivot irrigation system, have been tested and evaluated. Several outdoor single-sprinklers and overlapped - sprinklers irrigation tests have been conducted for determining: water application rate, uniformity of water distribution, and application efficiency, under different engineering and climatic conditions. Various sprinkler types - pressure -riser height combinations were used and the variation of application rate and weather conditions (i.e. air temperature, relative humidity, and wind speed) were measured during the test. A statistical approach has been used with these data to estimate water distribution uniformity coefficient CU, and water application efficiency AE, using a linear model. CU, and AE as sprinkler irrigation performance parameters, were estimated as functions of the sprinkler type, nozzle characteristics, riser height, operating pressure, and wind speed. Other climatic and engineering factors were not of significant effect on the CU or AE in this study. The model can be a useful tool to select the operational conditions (e.g. working pressure, riser height, nozzle type) that can be suitable for certain environmental conditions ( air temperature, relative humidity, etc.) to improve water distribution uniformity CU and water application efficiency AE.

Índice de capacidade do processo na avaliação da irrigação por aspersão

Analisar a qualidade da irrigação, além de avaliar seu bom funcionamento, é uma forma de verificar a viabilidade de sua implantação e operação. Como a uniformidade de distribuição é um dos parâmetros mais utilizados para essa avaliação, este trabalho objetivou utilizar técnicas de engenharia de qualidade, usando o índice de capacidade do processo (Cpl) para avaliar a uniformidade de distribuição de água em um sistema de irrigação por aspersão convencional. Os ensaios foram conduzidos no Núcleo Experimental de Engenharia Agrícola, UNIOESTE, com dois aspersores modelo Super10, marca NAANDAN, espaçados 9 m entre si, durante 25 irrigações de 1 h cada. Os dados climáticos foram coletados a cada 10 min, por uma estação meteorológica sem fio. Encontraram-se um CUC médio de 79,72% e velocidade do vento média de 1,85 m s-1. Foram aplicados os testes de controle de qualidade, elaborando os gráficos de controle de Shewhart e calculado o índice de capacidade do processo (Cpl), sendo que os resultados obtidos permitem afirmar que a utilização do índice de capacidade do processo torna-se uma ferramenta poderosa para classificar sistemas de irrigação em função de sua uniformidade de distribuição.

Effect of irrigation uniformity on evapotranspiration and onion yield

SUMMARYThe main objective of the current study was to analyse how water application through a sprinkler irrigation system influences yield of onion (Allium cepaL.), taking into account water application heterogeneity and the effects on theoretical crop evapotranspiration (ETc). Field experiments were conducted on commercial onion plots, irrigated with a permanent sprinkler irrigation system, located in Albacete, Spain, over two irrigation seasons. Two experimental plots were selected each study year: plot A (PA), in which water was applied heterogeneously by using sprinklers with different nozzle combinations, and plot B (PB, used as the reference plot) in which the four sprinklers were maintained with the same nozzle combinations. Both experimental plots were divided into 25 subplots with the aim of studying the water distribution (measured as Christiansen uniformity coefficient (CU)), the impact on the actual evapotranspiration (ETa) and the yield obtained. Irrigation was scheduled using a daily simplified water balance method within the root area following the approach of the Food and Agriculture Organization. In the present study, sprinkler irrigation in PAresulted in lower CU (65–82% lower in 2002 and 59–79% lower in 2005) compared with PB(78–92% lower in 2002 and 79–93% lower in 2005). Between 30 May and 18 August 2002, the estimated crop water requirements in PAin the absence of water deficit was 22 mm over the accumulated value of ETc (491v.469 mm), while estimated crop water requirements under water deficit were 187 mm below ETc (282v.469 mm). In 2005, between 29 May and 25 August, ETa without water deficit was more similar to ETc (458v.444 mm) but Eta under water deficit was 242 mm. The greater uniformity of water distribution in PBwas translated into a greater uniformity of yield distribution. A smaller range in yield was observed in PBwhen compared with PA. No statistically significant differences were observed between PAand PBin the crop quality parameters bulb moisture content, total soluble solids, pH and total acidity.

Aplicação de cloro orgânico no tratamento de tubogotejador utilizado na irrigação com água ferruginosa

To evaluate the effect of the organic chlorination in the uniformity of water distribution and in the outflow of a tubedripper with 2,2 L h-1, had been tested four levels of concentrations of dicloroisocianurato of sodium (N1 = 0, N2 = 15, N3 = 30 e N4 = 45 mg L-1 of free chlorine). The evaluations had been carried through in the beginning of the experiment and to each 100 hours of functioning of the system, totalizing 8 evaluations. In the calculation of the uniformity of water application had been used the coefficients of uniformity of Christiansen (CUC), of distribution (CUD) and emission (Us). Also the study of the discharge and the coefficient of variation of the discharge (CVq). It was verified that in the level N1, reductions of 23; 30.2 and 8.35%, for the CUC, CUD and US, respectively. The discharge presented a 6.13% reduction, reflecting in an increase of the CVq. The treatment with dicloro was efficient to prevent against clogging for all the used concentrations and the system was classified with excellent uniformity in practically all the evaluations.

A Simplified Method for Field Evaluation of Solid Set Sprinkler Irrigation Systems

Solid-set sprinkler irrigation has been widely used around the world because it can improve water application efficiency, increase crop production, and reduce environmental impact of irrigation. The uniformity of water distribution is a very important factor in the design and management of these sprinkler irrigation systems. In this article, a statistical method based on the coefficient of variation (CV) is evaluated using existing data to verify the rationale of this method. Two data sets of the water depths measured from different sprinkler systems were obtained. Eighteen randomly selected points from each data set were proved to be satisfactorily significant to evaluate the distribution of the intensity with 95% confidence limits compared with the results from the actual data points. A significant amount of labors and time can be saved with the application of this method when compared with the other traditional methods. This is a simple method that can provide irrigators, turf managers, and farmers a useful tool to evaluate the water distribution from their sprinkler irrigation systems.

DEVELOPMENT OF A PLANTING MACHINE USED UNDER SUB SURFACE IRRIGATION SYSTEM

A Self-propelled planting machine was developed to be suitable for lands in which sub surface drip irrigation system is applied. The developed machine was investigated during planting corn seeds as a function of change in both sub surface irrigation parameters ( two different lateral line depths and two distances between emitters in the lateral line) and machine operating parameters( three different forward speeds and two distances between plants in the row). The sub surface drip irrigation system was evaluated in terms of soil moisture content and water distribution uniformity. The developed planting machine was evaluated comparing with the manual method in terms of emergence ratio, longitudinal dispersion, energy requirements, crop yield and planting cost. The experimental results reveal to the following: - for sub surface irrigation parameters: Lateral line depth of 30 cm with three emitters per meter were considered optimum values to achieve high uniformity of water distribution and high water use efficiency. - for machine parameters: - Machine forward speed of 3.2 km/h with 30 cm distance between plants in the row were prefered to achieve high crop yield and low planting cost.

Use of the frequency inverter on center pivot irrigation system and its effects on water depth and water distribution uniformity

Este trabalho teve o objetivo de avaliar a uniformidade de distribuicao e lâmina de agua aplicada por um equipamento de irrigacao do tipo pivo central em funcao da variacao da velocidade de rotacao no conjunto motobomba com o uso de um inversor de frequencia e o efeito da posicao da linha lateral nesses parâmetros. Foram testadas tres posicoes de linhas coletoras de agua: aclive de 3,45%, nivel e declive de 11,78%. O delineamento experimental foi inteiramente casualizado, sendo feitas tres repeticoes em cada posicao testada. Aplicou-se a analise de variância seguida do teste de Tukey. O valor medio do coeficiente de uniformidade de Heermann e Hein foi de 88,85%, qualificando a uniformidade de distribuicao de agua como boa. A lâmina media ponderada de irrigacao aplicada foi 5,71 mm, variando dentro de cada ensaio significativamente (5%) entre as posicoes de declive versus aclive e nivel. Concluiu-se que a posicao da linha lateral influenciou significativamente na rotacao do conjunto motobomba, lâmina de agua aplicada e consumo de energia, porem nao foram verificadas diferencas nos valores de uniformidade de distribuicao de agua.

Evaluation method of soil water distribution uniformity under conditions of field subsurface drip irrigation.

Evaluation method of soil water distribution uniformity under conditions of field subsurface drip irrigation.

Surfactant Use to Improve Soil Water Distribution and Reduce Nitrate Leaching in Potatoes

Recent evaluations of soil water use by potato (Solanum tuberosum L.) plants have confirmed that a dry zone develops mid to late in the growing season when potatoes were grown in a ridge and furrow system under sprinkler irrigation on some sandy soils. Although trickle irrigation has been shown to reduce the dry zone in potato hills, a more cost- and labor-effective solution could be the use of a surfactant to change soil water surface tension and thereby promote more uniform water distribution into hills. Water content in surfactant-treated potato hills was compared with no-surfactant―treated hills using data from time domain reflectometry probes collected at 15-minute intervals. In addition, nitrate-nitrogen (NO 3 ― N) concentration in soil water collected 1 m below the crop row with porous cup samplers was evaluated to assess NO 3 ― N leaching below the root zone of potatoes. Data from surfactant applications at 9.35 L ha ―1 at planting with the seed piece in 1998, 1999, and 2003 through 2005 generally resulted in significantly increased movement of water into the dry portion of potato hills and in many cases decreased soil water NO 3 ― concentrations at a depth of 1 m beneath potato hills. Comparison of several surfactants suggested that water movement into the dry zone can be accomplished with a number of different products. Some trends of increased potato yield with surfactant applications as compared with no surfactant were noted in a few cases; but in all cases (P = 0.16―0.24), these were not statistically significant at the 95% level.

Estimation of In Vivo Water Content of the Stratum Corneum from Electrical Measurements

In vivo water content in the epidermal stratum corneum can be estimated by means of low frequency susceptance measurements. In the in vitro calibration necessary to find the in vivo water content, the stratum corneum will have a uniform distribution of water across its thickness. However, in vivo stratum corneum has an increasing water concentration profile from the outermost towards the innermost parts. This paper will investigate the possibility of estimating the equilibrium water content in the in vivo stratum corneum non-invasively from electrical susceptance measurements. Given a known shape of the water concentration profile in the in vivo stratum corneum and the dependence of susceptance on the water content, it is possible to calculate the water content in vivo based on analytically derived expressions for the water concentration profile. A correspondence between in vivo and in vitro water content needed for this purpose is also established.

EFFECT OF SOIL SURFACE COMPACTION PRESSURE AND COMPACTING CYLINDER SURFACE SHAPES ON BORDER IRRIGATION EFFICIENCY

A field experiment was carried out at the Experimental Station Farm, Faculty of Agriculture, Cairo University. The purpose of this study is to investigate the effect of different levels of soil surface compaction pressure (P) (15, 22.5, 30, 37.5 kPa) and compacting cylinder surface shapes (C) with protrusion spaces (5, 10, 15 and 20 cm) on: the infiltration rate (IR), percentage of water losses by deep percolation (DPP), percentage of soil moisture defect (SMD), total advance time (AT), water distribution uniformity (Du), water application efficiency (Ea), the corn crop yield (Cy) and the water use efficiency (WUE). All data were collected during the summer seasons of 2004 and 2005 for corn crop. For the compacted soil surface, the values of IR, DPP, SMD and AT decreased by increasing the soil surface compacting to 22.5 kPa and by increasing protrusion space to 15 cm. The values of Du and Ea increased by increasing the soil surface compacting to 22.5 kPa and by increasing protrusion space to 15 cm. The best Cy and WUE were obtained at soil surface compacting (P2) 22.5 kPa, with any compaction cylinder surface shape.