Christiansen Uniformity Coefficient Research Articles

Integrating water harvesting and gravity-fed micro-irrigation system for efficient water management in terraced land for growing vegetables

Enhancing and sustaining the productivity of hill agriculture in North-West Himalayan Region (NWHR) is a major challenge as it is practised under ecologically fragile environments which include altitudinal, climatic and topographical variations. The present study envisaged the scope for water resources development and its utilization in crop production through gravity-fed micro-irrigation enhancing water use in the terrace land of NW Himalaya. The water was harvested from a distantly located ultra low discharge water source to the lined tank and the micro-irrigation system (MIS) was integrated such that it could be operated by gravity. The system performance was found satisfactory as the flow rate variation, Christiansen uniformity coefficient and distribution uniformity were 26.5%, 86.3% and 87.5%, respectively. The system saved 41.1% and 33.3% irrigation water as compared to check basin irrigation in case of vegetable pea and French bean, respectively. The water use efficiency of the system was significantly higher than check basin irrigation. Economic indicators such as Net Present Value, Benefit Cost Ratio, Internal Rate of Return and payback period were used to evaluate the gravity-fed MIS and were INR 160,523 (1$ = 40.50 INR), 1.78, 12.2% and 3.38 years, respectively. It is recommended that the gravity-fed MIS must be integrated with the water harvesting system to effectively and economically utilize the water in vegetable cultivation in terraced land of the hill farming system.

Maize Growth and Yield under Daytime and Nighttime Solid‐Set Sprinkler Irrigation

Nighttime sprinkler irrigation usually results in lower wind drift and evaporation losses (WDELs) and better irrigation uniformity compared with daytime irrigation. However, daytime sprinkler irrigation modifies the microclimatic conditions within the crop canopy which could result in improved crop growth. We studied the effect of daytime and nighttime irrigation on the growth and yield of maize (Zea mays L.) irrigated with a solid‐set sprinkler system. Two irrigation treatments were tested: daytime irrigation (starting at 1000 Greenwich Mean Time, GMT) and nighttime irrigation (starting at 2200 GMT). The same irrigation amount was applied in both treatments. The irrigation amount was determined as the difference between the crop evapotranspiration (ETc) and the effective precipitation. The WDELs of daytime irrigation were twice the nighttime irrigation WDELs. Daytime irrigation decreased the mean Christiansen coefficient of uniformity (CU) by 5 to 7% and the seasonal CU by 4%. Daytime irrigation caused a 10% reduction in maize grain yield, mostly due to a reduction in biomass production. The lower soil matric potential found with daytime irrigation late in the season indicated that a progressive water stress occurred that was due to less water availability and was caused by the higher WDEL for daytime irrigation. Even though positive microclimatic changes have been reported with daytime sprinkler irrigation, the results of our study indicate that they cannot compensate the negative effects caused for the crop by less water reaching the soil root zone because of increased WDEL and by poorer irrigation uniformity.

Operational Analysis of Water Application of a Sprinkler Irrigation System Installed in a Golf Course: Case Study

Popup sprinkler irrigation systems are usually installed in golf courses, orchards, and lawns. Evaluation of these systems is considered essential to identifying any necessary improvements. To this end some performance indicators have evolved for comparison of the existing performance with established design criteria of the system. The irrigation uniformity and application efficiency of any irrigation system are important factors which are strongly affected by pressure and wind speed. In this study, the water application uniformity, system efficiency, water application rates, jet losses, and soil infiltration characteristics were considered as the basic performance indicators. The low quarter distribution uniformity of the system varied from 43 to 57% and the application efficiency was found to be only 34–47%. The Christiansen uniformity coefficient varied from 61.7 to 68.9% for different operating pressures. More losses were found for day time irrigation than for night time irrigation. Surface runoff was...

Determining Operating Inlet Pressure Head Incorporating Uniformity Parameters for Multioutlet Plastic Pipelines

An important objective of a microirrigation system is to determine the proper operating inlet pressure head, ensuring the desired level of water application uniformity as well as the allowable pressure head variation along the multioutlet pipeline. This paper offers, simple, direct, but sufficiently accurate, relationships incorporating different microirrigation uniformity parameters, such as Christiansen uniformity coefficient, coefficient of variation of emitter discharge, and allowable pressure head variation, to determine the operating inlet pressure head (i.e., pressure head and outflow profiles) for multioutlet plastic pipelines. In this analysis some mathematical expressions were deduced to relate three uniformity parameters; then the operating inlet pressure head is simply reformulated by taking into account a multiplying factor α to the required average outlet pressure head, in terms of three uniformity parameters. Resulting, the influence of different uniform pipe slopes on the water application uniformity and the operating inlet pressure head for various emitter discharge exponents, was evaluated. In addition, to cover various design combinations an extensive comparison between the proposed equations and those of the previous studies was also presented. Examination of the results from this research indicated that, the performance of the proposed technique is sufficient in comparison to those of the recent analytical and numerical procedures.

Rapid Evaluations of Anticlogging Performance of Drip Emitters by Laboratorial Short-Cycle Tests

Emitter clogging is the most annoying problem that restrains the development of drip irrigation technologies, but so far, there have been no effective evaluation methods for the anticlogging performance of drip emitters. In this study, a kind of short-cycle experiment was conducted in the laboratory by mixing sands with various concentrates and particle sizes in irrigation water. Through these tests, the clogging rates that quantitatively represent the clogging status of drip emitters in various experimental conditions were obtained, as well as the variation rules of emitter discharges. The statistical calculation results indicated that the anticlogging performance of predepositing drippers was better than round-flow drip tapes, but less than eddy drip arrows. The discharges of every emitter tested differed from each other and most were lower than nominal discharge rates. However, a few emitters had a contrary result. An important modification had been done for the Christiansen uniformity coefficient to accurately evaluate irrigation uniformity and the clogging status of drip emitters. As a result, a new method of rapid evaluation for the anticlogging performance of drip emitters was proposed.

From on-farm solid-set sprinkler irrigation design to collective irrigation network design in windy areas

In this paper, a contribution to the design of collective pressurised irrigation networks in solid-set sprinkler-irrigated windy areas is presented. The methodology is based on guaranteeing minimum on-farm performance, using a historical hourly wind speed database and a ballistic solid-set irrigation simulation model. The proposed method was applied to the Montesnegros Irrigation District (central Ebro basin, Spain). The district irrigates an area of 3493 ha using an on-demand schedule. The average wind speed in the area is 2.8 m s −1. An analysis of district water records showed that farmers often reduce water demand when the wind speed is high, but their irrigation decision making is limited by the capacity of the irrigation network and by the unpredictable character of local winds. Simulations were performed for 11 irrigation seasons, 2 triangular sprinkler spacings (18 m × 18 m and 18 m × 15 m), and 2 sprinkler models. The percentage of monthly suitable time for irrigation was determined for four management strategies. The first one was based on a wind speed threshold (3 m s −1), while the other three were based on three levels (standard, relaxed and restrictive) of two irrigation performance parameters: the Christiansen Uniformity Coefficient (CU) and the Wind Drift and Evaporation Losses (WDEL). The standard strategy classified the time as suitable for irrigation when CU ≥ 84% and WDEL ≤ 20%. The thresholds limits of the irrigation parameters for the relaxed strategy were CU ≥ 80% and WDEL ≤ 25%. Finally, the restrictive strategy used thresholds of CU ≥ 90% and WDEL ≤ 15%. The suitable time for the first strategy (56%) was always lower than for the standard and the relaxed strategies (with respective average values of 75 and 86%), and higher than for the restrictive strategy (30%). In order to design the collective network, the hydrant operating time was equalled to the suitable time for irrigation. The differences in the cost of the collective network plus the on-farm equipment were particularly relevant between the restrictive strategy and the other three. Differences in suitable operating time were clear between sprinkler spacings, and less evident between sprinkler models. The application of the proposed methodology may be limited by the availability of historical wind speed records and CU estimates for different combinations of sprinkler models, sprinkler spacings and wind speed.

Assessing sprinkler irrigation uniformity using a ballistic simulation model

Experiments were performed in the Ebro Valley of Spain to provide the basis for the calibration and validation of a ballistic simulation model of sprinkler irrigation. The experiments included evaluations of isolated sprinklers and solid-sets. Two different sprinklers, two principal nozzle diameters and three operating pressures were considered in the experiments, which also covered the usual range of wind speeds in the study area. Model calibration served the objectives of predicting the Christiansen Coefficient of Uniformity (CU) and the water application pattern. The resulting standard error of CU estimation was 3.09%. Tables of simulated uniformity were produced for the two sprinklers using different nozzle diameters, sprinkler spacings, operating pressures and wind speeds. These tables can be used for design and management purposes, identifying options leading to adequate irrigation uniformity. A simple simulation software has been produced and disseminated to assist irrigation professionals and farmers in decision making.

Avaliação hidráulica de um sistema de irrigação localizada de baixa pressão, projetado pelo software "bubbler"

Conduziu-se este trabalho com o objetivo de avaliar o desempenho de um sistema de irrigação a baixa pressão, bubbler, em condições de campo. A avaliação consistiu de um estudo dividido em duas fases, em que, na primeira, foi elaborado o dimensionamento hidráulico do sistema de irrigação, com uso do programa computacional Bubbler versão 1.1, enquanto, na segunda fase, ocorreram a instalação e os testes de campo. Estabeleceram-se as alturas de 0,77; 0,71; 0,68 e 0,67 m na saída das mangueiras emissoras no campo, conforme recomendação do programa. Foram feitas as avaliações de vazão em cada mangueira emissora, para determinar o Coeficiente de Uniformidade de Christiansen (CUC), a Uniformidade de Distribuição (UD) e a Eficiência de Aplicação (EA). Os testes mostraram CUC igual a 96,64%, UD igual a 95,85% e EA igual a 86,98%. O sistema no campo proporcionou vazão média de 64,8 L h-1 contra os 79,2 L h-1 estabelecidos pelo programa. Os valores encontrados de vazão diferiram dos valores projetados pelo aplicativo, em conseqüência da variação dos diâmetros e das perdas de carga (linear e localizada) que apresentaram desvio-padrão de 0,23 m.

Performance of Rotating Spray Plate Sprinklers in Indoor Experiments

The use of rotating spray plate sprinklers (RSPS) can reduce the water and energy requirements in pressurized irrigation systems. Installation of RSPS in continuous move irrigation machines, such as traveling trailers (nozzle booms), presents relevant advantages compared to sprinkler-gun machines. The aim of this study is to develop design criteria for continuous-move irrigation machines using the RSPS Nelson Rotator R 3000 D-4. Water distribution by this RSPS was evaluated in an indoor facility under the following experimental conditions: 6.1, 7.0, and 7.8 mm nozzle diameters; 1.0 and 1.5 m nozzle height above the ground; and working pressures of 100, 150, and 200 kPa. The water distribution patterns were overlapped at 3 and 4 m distances, the simulated Christiansen uniformity coefficient averaged 91.8%, and the simulated average precipitation rate under the different experimental conditions ranged between 23 and 57mm⋅h-1. These values are acceptable for a wide range of irrigation-machine applications.

Wind effects on solid set sprinkler irrigation depth and yield of maize ( Zea mays )

A field experiment was performed to study the effect of the space and time variability of water application on maize (Zea mays) yield when irrigated by a solid set sprinkler system. A solid set sprinkler irrigation layout, typical of the new irrigation developments in the Ebro basin of Spain, was considered. Analyses were performed (1) to study the variability of the water application depth in each irrigation event and in the seasonal irrigation and (2) to relate the spatial variability in crop yield to the variability of the applied irrigation and to the soil physical properties. The results of this research showed that a significant part of the variability in the Christiansen coefficient of uniformity (CU), and wind drift and evaporation losses were explained by the wind speed alone. Seasonal irrigation uniformity (CU of 88%) was higher than the average uniformity of the individual irrigation events (CU of 80%). The uniformity of soil water recharge was lower than the irrigation uniformity, and the relationship between both variables was statistically significant. Results indicated that grain yield variability was partly dictated by the water deficit resulting from the non-uniformity of water distribution during the crop season. The spatial variability of irrigation water depth when the wind speed was higher than 2 m s−1 was correlated with the spatial variability of grain yield, indicating that a proper selection of the wind conditions is required in order to attain high yield in sprinkler-irrigated maize.

Analysis of an irrigation district in northeastern Spain: II. Irrigation evaluation, simulation and scheduling

In the first paper of this series, the Loma de Quinto Irrigation District (LQD) was characterised, and water use was assessed. In this work, the analysis of the LQD is completed with field irrigation evaluations, solid-set sprinkler irrigation simulations and irrigation scheduling for optimal crop yield. The results of the irrigation evaluations indicated that the average Christiansen coefficient of uniformity (CU) for solid-sets, centre-pivots and linear-moves was 68.0, 75.5, and 80.0%, respectively. In solid-sets CU was severely reduced by wind speed. However, in centre-pivots and linear-moves CU was higher in evaluations with wind speeds between 2 and 6 m s −1 than under calm conditions. The evaluation data set was used to validate a ballistic solid-set sprinkler irrigation simulation model. The performance variables used for model validation were CU and the potential application efficiency of the low quarter (PAE lq). Both variables were adequately predicted in the range of the observed values. The model was used to extend the evaluation results to all the solid-set plots in the LQD. CU maps were produced for different wind speeds and operating pressures. These maps can be used to identify plots with low irrigation performance. The effect of irrigation scheduling on crop yield and net benefit was analysed using the CropWat simulation model. Simulations of the 1997 irrigation practices performed on a limited number of plots detected a 12% decrease in crop yield due to deficit irrigation and/or large irrigation intervals. The introduction of an optimal irrigation schedule (avoiding yield reductions) would imply increasing the alfalfa seasonal irrigation depth by 101 mm, and applying light, frequent irrigation events. Due to labour scarcity in the LQD, the implementation of the optimal schedule would require a high degree of irrigation automation, which is currently unavailable. Taking into consideration the value of the additional yield and the costs of the extra irrigation water depth and the automation devices, the resulting net benefit would be 50 ▪ ha −1. The purpose of this analysis of the LQD is to contribute to the diagnostic analysis phase of an incipient Management Improvement Program at the LQD. In order to complete this phase, an interdisciplinary committee will perform a study not just on irrigation but on a wide scope of irrigated agriculture in the LQD.

Hydraulic design and performance evaluation of landscape irrigation systems

Landscape irrigation systems serve the purpose of lifeline for urban agriculture and horticulture activities such as golf courses, theme parks, airport turfing, traffic islands, surface and rooftop gardening in commercial complexes. A Landscape irrigation system is essentially a pressure irrigation system comprising pop up sprinklers, micro sprinklers and hydrants. The hydraulics involved is very complex due to undulating nature of landscapes. The performance of the pop-up sprinkler used in irrigation of landscaping project (University Auditorium, TNAU) was evaluated. The main analysis examined the relationship between flow-pressure, profile of distribution of water and Christiansen's Uniformity Coefficient (CUC) related with flow pressure. The value of CUC was observed more than 94 percent.

Continuous Outflow Variation along Irrigation Laterals: Effect of the Number of Outlets

Previous continuous-uniform outlet discharge approaches for the hydraulic analysis of irrigation laterals are generally valid for large (theoretically) infinite number of outlets. For a finite number of outlets, however, these approaches may lead to errors in hydraulic computation. A new continuous-uniform outflow approach that takes into account the effect of the number of outlets on the lateral hydraulics is presented. A new analytical equation describing the energy line shape along uniform sprinkle and trickle irrigation laterals and manifolds is developed. The effect of ground slope and velocity head on hydraulic computation is also considered. The method is however restricted by the simplified assumption of equal outlet discharge. An alternate improved analytical method considering the effect of non-uniform outflow distribution along the lateral is also included. Analytical expressions for determining the inlet pressure head and global statistical parameters characterizing the outflow distribution (Christiansen uniformity coefficient, pressure head variation) are developed for design and evaluation purposes. Comparison tests with an accurate numerical stepwise method indicated that the proposed simplified approach is more accurate than other previous works particularly when the number of outlets is relatively small. The improved method is the most accurate method for all cases examined even for low levels of uniformity.

Desenvolvimento de um infiltrômetro de aspersão portátil

Desenvolveu-se, neste trabalho, um infiltrômetro de aspersão portátil, cujas características de precipitação relativas a diâmetro de gotas e energia cinética de impacto das gotas produzidas sobre solo, são semelhantes àquelas da chuva natural. Os resultados dos testes efetuados permitiram concluir-se que: o infiltrômetro desenvolvido permite aplicar-se água de forma não intermitente, numa área útil de 0,70 m²; a uniformidade de distribuição de água, expressa pelo coeficiente de uniformidade de Christiansen, apresentou valores entre 82 a 87%; a relação entre a energia cinética da chuva produzida pelo infiltrômetro e a energia cinética da chuva natural, situou-se acima de 90% para intensidades de precipitação de até 100 mm h-1.

Sprinkler water distributions as affected by winter wheat canopy

Sprinkler uniformity is often used to evaluate irrigation system performance. The measurement of uniformity is generally made from one test when no crop is present. However, a developing crop canopy has significant potential to modify the distribution of water applied during irrigation. This study was conducted to evaluate the influence of a winter wheat canopy on sprinkler uniformity and on canopy-intercepted water by measuring water distributions above and below the canopy. The Christiansen uniformity coefficient (CU) was calculated on both a daily and a cumulative basis. The CU was higher below the canopy than above the canopy. Canopy-intercepted water, which is here defined as the sum of canopy storage and stemflow, increased with increasing water application depth. Sprinkler uniformity had no significant effect on the mean amount of water interception by the canopy. The ratio of water interception to total water application depth for the whole irrigation season was between 0.24 and 0.28. The CUs calculated from the cumulative depth caught above and below the canopy are larger than the averages of individual CU values during the irrigation season. Measurement of individual CUs during the irrigation season therefore underestimates the cumulative CU. Experimental results also demonstrated that sprinkler uniformity in this study had little effect on crop yield.

Soil water distribution, uniformity and water-use efficiency under alternate furrow irrigation in arid areas

Soil water distribution, irrigation water advance and uniformity, yield production and water-use efficiency (WUE) were tested with a new irrigation method for irrigated maize in an arid area with seasonal rainfall of 77.5–88.0 mm for 2 years (1997 and 1998). Irrigation was applied through furrows in three ways: alternate furrow irrigation (AFI), fixed furrow irrigation (FFI) and conventional furrow irrigation (CFI). AFI means that one of the two neighboring furrows was alternately irrigated during consecutive watering. FFI means that irrigation was fixed to one of the two neighboring furrows. CFI was the conventional method where every furrow was irrigated during each watering. Each irrigation method was further divided into three treatments using different irrigation amounts: i.e. 45, 30, and 22.5 mm water for each watering. Results showed that the soil water contents in the two neighboring furrows of AFI remained different until the next irrigation with a higher water content in the previously irrigated furrow. Infiltration in CFI was deeper than that in AFI and FFI. The time of water advance did not differ between AFI, FFI and CFI at all distances monitored, and water advanced at a similar rate in all the treatments. The Christiansen uniformity coefficient of water content in the soil (CUs) was used to evaluate the uniformity of irrigated water distribution and showed no decrease in AFI and FFI, although irrigation water use was smaller than in CFI. Root development was significantly enhanced by AFI treatment. Primary root numbers, total root dry weight and root density were all higher in AFI than in the FFI and CFI treatments. Less irrigation significantly reduced the total root dry weight and plant height in both the FFI and CFI treatments but this was less substantial with AFI treatments. The most surprising result was that AFI maintained high grain yield with up to a 50% reduction in irrigation amount, while the FFI and CFI treatments all showed a substantial decrease of yield with reduced irrigation. As a result, WUE for irrigated water was substantially increased. We conclude that AFI is an effective water-saving irrigation method in arid areas where maize production relies heavily on repeated irrigation.

Influência de fatores climáticos e operacionais sobre a uniformidade de distribuição de água, em um sistema de irrigação por aspersão de alta pressão

Realizou-se um estudo para se avaliar a uniformidade de distribuição de água em um sistema de irrigação por aspersão de alta pressão, na região norte-fluminense, RJ. Por meio da metodologia descrita pela ASAE (1990) foi avaliada a uniformidade de distribuição de água utilizando-se, para isso, o coeficiente de uniformidade de Christiansen (CUC) com aspersores em disposição retangular e triangular. Para cada uma das situações, o CUC foi analisado em função das seguintes variáveis independentes: velocidade e direção do vento, pressão de operação do aspersor, espaçamento entre aspersores na linha lateral, espaçamento entre linhas laterais e velocidade de rotação do aspersor. A análise dos dados foi feita por meio de regressão múltipla, gerando-se modelos estatísticos para a estimativa do CUC. Observou-se que o aumento da velocidade do vento e do espaçamento entre aspersores diminui o CUC, enquanto o aumento da pressão de operação do aspersor o elevou nos intervalos estudados.

Response of Tall Fescue to Saline Water as Influenced by Leaching Fractions and Irrigation Uniformity Distributions

AbstractThe use of poor quality water for irrigation purposes in the urban landscape has the potential to save significant quantities of good quality water for higher priority uses. Research was conducted to determine the impact leaching fractions (LF = drainage volume/irrigation volume) and irrigation‐uniformity distributions have on the spatial distribution of water and salts and plant response when irrigating with saline water. Tall fescue (Festuca arundinacea Schreb. ‘Monarch’) was grown in 18 plots, each with a centrally located lysimeter that enabled estimates of evapotranspiration and irrigation requirements. Imposed treatments included setting LF at 0.05, 0.15, or 0.25 and manipulating plot irrigation systems such that the Christiansen uniformity coefficient (CUC) was set at 0.65, 0.75, or 0.85. Saline irrigation water (2.5 dS m−1) was applied for an 18‐mo period. Significant LF × CUC interactions were observed for depth‐weighted soil salinity, yield, evapotranspiration (ET), tissue moisture content, and canopy temperatures. Although the coefficient of variation increased with each measured parameter as the CUC decreased, only the depth‐weighted electrical conductivity (ECc) showed a coefficient of variation > 20%. A 14% savings in irrigation water was obtained when the high CUC, low LF treatment was compared with the high LF, low CUC treatment. Ninety‐one percent of the variability in the average plot ECc could be accounted for if the actual LF, lysimeter ET, and average plot canopy temperatures at the end of the experiment were taken into consideration. Under the conditions of this experiment, irrigating tall fescue with 2.5 dS m−1 water would be an acceptable practice even at LFs as low as 0.05 if the CUC is optimized.

AVALIAÇÃO TÉCNICA DO SISTEMA DE IRRIGAÇÃO POR ASPERSÃO DO PERÍMETRO IRRIGADO BARREIRAS

RESUMO Este trabalho foi realizado no sistema de irrigação por aspersão do Perímetro Irrigado Barreiras, Petrolândia, PE. As avaliações compreenderam duas modalidades distintas, tendo a primeira abrangido três lotes convencionais em pontos distintos da tubulação principal e a segunda o uso de um aspersor adicional tipo "drag line". Na primeira modalidade, constatou-se que a pressão de serviço apresentou variação de 44,80% em relação à recomendada (250kPa). A velocidade média do vento foi da ordem de 1,88 + 1,31m.s-1, o Coeficiente de Uniformidade de Christiansen situou-se em torno de 86,0% e a eficiência média de irrigação foi de 54,27% + 18,23%, sendo o melhor resultado (68,68%) obtido sob pressão de 293kPa. Na segunda modalidade, constatou-se melhoria acentuada do seu desempenho, sob pressão de 250kPa.

Desempenho e uniformidade da distribuição de água de um pivô central

O objetivo deste experimento foi avaliar as características de desempenho de um equipamento de irrigação pivô central, de baixa pressão, bem como determinar a uniformidade de distribuição de água, tanto abaixo como acima da superfície do solo. Para a avaliação do desempenho do sistema utilizaram-se os coeficientes de uniformidade de Christiansen (CUC) e de distribuição (CUD), calculados a partir de dados da precipitação dos aspersores. O pivô central foi ensaiado nas velocidades de 25%, 50%, 75% e 100% da velocidade máxima de deslocamento do equipamento. Utilizou-se quatro linhas de coletores, uniformemente espaçados. Os valores encontrados do CUC e o CUD foram superiores ao mínimo recomendado para a cultura do milho, confirmando o bom desempenho do pivô central. Em todas as profundidades do solo estudadas os coeficientes de uniformidade foram superiores aos obtidos acima do solo, ocorrendo um aumento nos valores dos coeficientes de uniformidade abaixo da superfície do solo com o tempo.