Irrigation Science (IRRIGATION SCI)

Publications in this journal

• Article: The dual crop coefficient approach to estimate and partitioning evapotranspiration of the winter wheat–summer maize crop sequence in North China Plain

  Zhang B, Liu Y, Xu D, Zhao N, Lei B, Rosa RD, Paredes P, Paço T A, Pereira L S
  Irrigation Science 04/2013;
• Article: The contribution of shallow groundwater by safflower (Carthamus tinctorius L.) under high water table conditions, with and without supplementary irrigation

  Houshang Ghamarnia, Mohsen Golamian, Saloome Sepehri, Issa Arji, Samera Norozpour
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  ABSTRACT: Lysimetric experiments were conducted to determine the contribution made by groundwater to the overall water requirements of safflower (Carthamus tinctorius L.). The plants were grown in 24 columns, each having a diameter of 0.40 m and packed with silty clay soil. The four replicate randomized complete block factorial experiments were carried out using different treatment combinations. Six treatments were applied during each experiment by maintaining groundwater, with an EC of 1 dS m-1, at three different water table levels (0.6, 0.8 and 1.10 m) with and without supplementary irrigation. The uptake of groundwater as a part of crop evapotranspiration was measured by taking daily readings of the water levels found in Mariotte tubes. The supplementary irrigation requirement for each treatment was applied by adding water (EC of 1 dS m-1). The average percentage contribution from groundwater for the treatments (with and without supplementary irrigation under water table levels of 0.6, 0.8 and 1.10 m) were found to be 65, 59, 38% and 72, 70, 47% of the average annual safflower water requirement (6,466 m3 ha-1). The increase in groundwater depths under supplementary irrigation treatments from 0.6 to 0.80 and 1.10 m caused seed and oil yield reductions of (7, 23.10%) and (48.23, 65.40%), respectively
  Irrigation Science 04/2013; Irrig Sci(31):285–299.
• Article: Combining hydrological modeling and GIS approaches to determine the spatial distribution of groundwater recharge in an arid irrigation scheme

  Usman Khalid Awan, Bernhard Tischbein, Christopher Martius
  Irrigation Science 07/2012;
• Article: Evaluation on the potential of improving border irrigation performance through border dimensions optimization: a case study on the irrigation districts along the lower Yellow River

  Bo Chen, Zhu Ouyang, Zhigang Sun, Lanfang Wu, Fadong Li
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  ABSTRACT: In the Yucheng region along the lower reach of the Yellow River, current border irrigation systems in all three irrigation districts have low irrigation performances with the applied depth per irrigation event >150 mm, and application efficiency <65 %. It is often difficult to change irrigation practices, and rates of adoption are usually slow for China’s small-scale farmers. This study emphasizes the feasibility of optimizing border dimensions in border irrigation taking into consideration the existing irrigation conditions and farmers’ methods of irrigation practice. The performances of current border irrigation systems and improved systems were evaluated using agricultural irrigation survey data, field experimental data, and a simulation model. The irrigation conditions, that is, inflow rate, border dimensions, and relative cutoff distance, in the irrigation districts were found to be diverse. However, after border dimensions were optimized through simulation and field testing, it was determined that the applied depth per irrigation event could be decreased by an average of 49 mm, and the application efficiency could be increased on average by 26.7 % in the three irrigation districts. The annual potential amount of water savings among the three districts was calculated to be approximately 5,551 × 10 4 m 3 in the Yucheng region. Optimizing border dimensions is a practical technology for small-scale farming practices in the irrigation districts along the lower Yellow River.
  Irrigation Science 06/2012;
• Article: Production and oil quality in ‘Arbequina’ olive (Olea europaea, L.) trees under two deficit irrigation strategies

  J. M. García, M. V. Cuevas, J. E. Fernández
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  ABSTRACT: The effect of two deficit irrigation (DI) strategies on fruit and oil production and quality in a 12-year-old ‘Arbequina’ olive orchard with 238 treesha−1 was evaluated. The T1 treatment was a sustained DI regime (65% ETc, 2–3 irrigation events per week). The T2 treatment was a low-frequency DI (increasing stress/rewatering cycles, which consisted in withholding irrigation until fruit shrivelling and then applying a recovery irrigation providing the same amount of water that supplied in T1 for that period). As compared to full irrigation, both strategies reduced fruit production and increased the variability of fruit ripening, but favoured oil extraction. Free acidity, peroxide value, K232, K270 and sensory quality of oil were not affected by DI. Furthermore, carotenoid, chlorophyll, phenol, and oleic contents increased. The greatest phenol content and bitterness index were found in oil from T2 trees. Later harvesting caused sensory quality and tocopherol losses, although the oil synthesized in DI olives increased.
  Irrigation Science 05/2012;
• Article: The dual crop coefficient approach using a density factor to simulate the evapotranspiration of a peach orchard: SIMDualKc model versus eddy covariance measurements

  T. A. Paço, M. I. Ferreira, R. D. Rosa, P. Paredes, G. C. Rodrigues, N. Conceição, C. A. Pacheco, L. S. Pereira
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  ABSTRACT: The dual crop coefficient approach accounts separately for plant transpiration and soil evaporation by using the basal crop coefficient and the evaporation coefficient, respectively. The SIMDualKc model, which performs the soil water balance simulation with estimation of the actual crop evapotranspiration (ET) with the dual crop coefficient approach, was applied to a drip-irrigated peach orchard under Mediterranean conditions. Orchard ET was obtained with the eddy covariance technique, which was subsequently correlated with tree transpiration estimated from sap flow measurements and soil evaporation determined with microlysimeters, thus providing ET for the whole irrigation season. Twoyears of field observations were used for model calibration and validation using those ET measurements and taking into account the fraction of ground covered by trees through a density factor which adjusts the basal crop coefficient. Model fitting relative to ET observations during calibration and validation provided indices of agreement averaging 0.90, coefficients of regression close to 1.0, root mean square errors around 0.41mm and average absolute errors of 0.32mm. Model fitting relative to transpiration and to soil evaporation produced similar results, so showing the adequateness of modelling.
  Irrigation Science 05/2012; 30(2):115-126.
• Article: Hydraulics of microtube emitters: a dimensional analysis approach

  P. B. Vekariya, R. Subbaiah, H. H. Mashru
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  ABSTRACT: Dimensional analysis is a simple, clear and intuitive method for determining the functional dependence of physical quantities that are of importance to a certain process. Buckingham’s pi theorem is used to derive a dimensionally homogeneous equation for predicting the discharge of the microtube as a function of gravitational acceleration (g), microtube diameter (D), operating pressure head (H) and microtube length (L). Experimental investigations were conducted at College of Agricultural Engineering and Technology, Junagadh, to determine (a) the variation in Q with L, D and H and (b) the coefficients (K, y and z) of the developed model. The L and D of microtube were varied from 5 to 250 cm and 1.2 to 2mm. The operating pressure was varied from 0 to 1.5m. The L, H and D combinations selected in the study suit most of the manufacturer’s recommendations for microtube drip irrigation systems. The discharge of microtube decreased with increase in microtube length for particular microtube diameter and operating pressure. The discharge increased with increase in the microtube diameter for a particular operating pressure and microtube length. The values of K, y and z are 4.476, 1 and 0.5, respectively. Goodness of fit and efficiency coefficient reduced with increase in the microtube diameter. The dimensionally homogeneous equation (Eq.25) developed for all flow regimes can predict discharge with good accuracy for less than 2-mm microtube diameter. The microtube diameter was found to be 1.2mm based on the dominance of viscous forces over inertial forces.
  Irrigation Science 05/2012; 29(4):341-350.
• Article: Energy saving with variable speed pumps in on-demand irrigation systems

  Nicola Lamaddalena, Sami Khila
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  ABSTRACT: The present work analyzes energy saving in on-demand irrigation systems served by an upstream pumping station. The objective of this work is to identify the best pumping station operating mode to optimize energy consumption. This objective can be achieved by matching the discharge and the pressure head required by the network (characteristic curve of the network) during the whole irrigation season with the pumping station characteristic curves. The characteristic curve of the network can be obtained using an appropriate stochastic generation modeling, and COPAM software was used in the present work. The characteristic curves of the pumps can be adapted to the network characteristic curve by equipping the pumping station with variable speed devices. Several types of regulation based on variable speed techniques were identified and analyzed. The differences in energy consumption for each technique were quantified for two on-demand irrigation districts in Southern Italy and managed by the Water Users Organization “Consortium of Capitanata”. It was demonstrated that in comparison with the current pumping station regulation, energy savings of about 27 and 35% may be achieved for the two districts.
  Irrigation Science 05/2012; 30(2):157-166.
• Article: Use of CropSyst as a decision support system for scheduling regulated deficit irrigation in a pear orchard

  J. Marsal, C. O. Stöckle
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  ABSTRACT: Prediction of plant water status is necessary for the judicious application of regulated deficit irrigation. CropSyst, a generic crop growth model that is applicable to fruit trees, was used to forecast plant water potential for irrigation management recommendations in a pear orchard. Plant water potential is predicted along with tree transpiration using Ohm’s law analogy. The parameters of the model were adjusted by using field measured data on a lysimeter-grown pear tree. After adjustment, and using the same lysimeter data, a satisfactory agreement was found between simulated and measured tree transpiration, light interception, and stem water potential. Model simulations were also performed for other independent field data. These corresponded to eight different conditions of a deficit-irrigated field experiment in a pear orchard. Each condition differed in soil texture, time of irrigation cut-off, crop load, and tree leaf area. Deficit irrigation was managed first by withholding irrigation until reaching a threshold in midday stem water potential of −1.5MPa. Subsequently, irrigation was applied at fixed proportions of full irrigation requirements. Simulations with CropSyst were used as decision support system that could work independently of stem water potential measurements. Simulations in all eight sites were satisfactory at providing adequate time without irrigation during the first part of the deficit period. A highly significant relationship (r 2 =0.71) between predicted and measured stem water potentials was found for a simulation period of 40days. Simulations for longer periods (i.e. 74days) decreased the r 2 to 0.61, and for this reason after resuming irrigation, slight deviations were found for the average stem water potential in two out of five sites. In conclusion, CropSyst produced relevant information for managing deficit irrigation in simulation periods shorter than 40days.
  Irrigation Science 05/2012; 30(2):139-147.
• Article: A new approach for neutron moisture meter calibration: artificial neural network

  Eyüp Selim Köksal, Bilal Cemek, Cengiz Artık, Kadir Ersin Temizel, Mehmet Taşan
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  ABSTRACT: The neutron moisture meter (NMM) is a widely used device for sensing soil water content (SWC). Calibration accuracy and precision of the NMM are critical to obtain reliable results, and linear regression analysis of SWC against NMM count data is the most common method of calibration. In this study, artificial neural network (ANN) calibration models were developed and compared with linear regression. For this purposes, training and validation data were obtained from 2 calibration and 16 testing plots, respectively. Calibration plots consist of wet and dry soil water conditions separately. Data measured in dry beans and red pepper plots that have four different water levels were used to determine validity of regression and ANN-based calibration models. Volumetric SWC and NMM count ratio measurements were taken for depth intervals of 30cm throughout a 120-cm-deep soil profile. Several neural network architectures were explored in order to determine the optimal network architecture. Data analyses were conducted for each soil layer and for the whole profile, separately, based on both linear regression and ANN. Linear regression calibration equation coefficients of determination (r 2) for the 0–30, 30–60, 60–90 and 90–120cm depth ranges calculated by regression models were 0.85, 0.84, 0.72 and 0.82, respectively, and r 2 values were 0.94, 0.95, 0.87 and 0.88 based on ANN models, respectively. Using the data set from the entire 120-cm soil profile for calibration by ANN, the r 2 value was raised to 0.97.
  Irrigation Science 05/2012; 29(5):369-377.
• Article: Low energy consumption seasonal calendar for sectoring operation in pressurized irrigation networks

  M. T. Carrillo Cobo, J. A. Rodríguez Díaz, P. Montesinos, R. López Luque, E. Camacho Poyato
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  ABSTRACT: Pressurized irrigation networks and organized on-demand are usually constrained by the high amounts of energy required for their operation. In this line, sectoring, where farmers are organized in turns, is one of the most efficient measures to reduce their energy consumption. In this work, a methodology for optimal sectoring is developed. Initially it groups similar hydrants in homogeneous groups according to the distance to the pumping station and their elevation, using cluster analysis techniques and certain dimensionless coordinates. Second, an algorithm based on the EPANET engine is implemented to search for the best monthly sectoring strategy that accomplish supplying the actual irrigation demand under minimum energy consumption conditions. This methodology is applied to two Spanish irrigation districts (Fuente Palmera and El Villar). Results showed that organizing the networks in sectors, annual energy savings of 8 and 5% were achieved for Fuente Palmera and El Villar when the theoretic irrigation needs were considered. However, these savings rose up to 27 and 9%, respectively when the local practices, deficit irrigation, were taken into account. Thus, they confirm that water and energy efficiency cannot be optimized independently and need to be considered together.
  Irrigation Science 05/2012; 29(2):157-169.
• Article: Field evaluation of infiltration models in lawn soils

  Runbin Duan, Clifford B. Fedler, John Borrelli
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  ABSTRACT: Water infiltration into soil is a critical process in designing irrigation systems, especially those used for the application of wastewater to land. Although some research was conducted to evaluate the performance of proposed infiltration models, few efforts were given to the study of infiltration models specifically in lawn soils. This paper was to compare five existing classic infiltration models with field data collected from lawn soils, to estimate and assess those models’ parameters, and to evaluate their prediction ability for lawn irrigation systems. A field study was conducted in three lawn soils using a double-ring infiltrometer. The performances of infiltration models proposed by Philip, Kostiakov, Mezencev, the United States Department of Agriculture Natural Resources Conservation Service (originally the United States Soil Conservation Service), and Horton were investigated with consideration of sum of squared error, root mean square error, coefficient of determination, adjusted coefficient of determination, mean error, absolute value of mean error, model efficiency, and Willmott’s index of agreement. Mezencev model and Horton model performed better than the other three infiltration models. The research indicated that three-parameter models had the best description of the relationship between cumulative infiltration and time in the researched lawn soils.
  Irrigation Science 05/2012; 29(5):379-389.
• Article: Influence of cross-regulator settings on the offtake discharge in a modern irrigation network

  Mohammad Ali Shahrokhnia, Mahmood Javan
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  ABSTRACT: The hydraulic performance of canals and related delivery structures is highly dependent on the management of cross-regulators. The HEC-RAS model was applied to Ordibehesht Canal at the Doroodzan irrigation network, northwest of Fars province in Iran for evaluation of water delivery performance due to operation of cross-regulators. Discharge deviations of offtakes due to cross-regulator gate position changes and deviations of water delivery equity were evaluated. Results showed that small changes in gate positions of check structures (cross-regulators) cause considerable changes in the offtake discharges and equity (spatial uniformity) of water delivery to the offtakes along the main canal. Results of the study led to the development of two sensitivity indicators. “Offtake sensitivity to check setting” that represents the changes in offtake discharges due to changes in cross-regulator setting, and “Sensitivity of the equity indicator to the gate position change” are the two developed indicators which can be used for better management of water delivery systems.
  Irrigation Science 05/2012; 27(2):165-173.
• Article: Deficit irrigation in a production setting: canopy temperature as an adjunct to ET estimates

  James R. Mahan, Andrew W. Young, Paxton Payton
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  ABSTRACT: Water available for agricultural use is declining worldwide as a result of both declining water resources and increasing application costs. Managing crop irrigation under conditions where the water need cannot be fully met represents the future of irrigation in many areas. On the southern high plains of Texas there is interest among producers to reduce the amount of water applied to cotton. In this study, a producer’s efforts to reduce water application to a cotton crop were assessed in terms of a comparison between evapotranspiration, rainfall, and irrigation that is widely used in the region. The producer was able to reduce water application to meet intended reductions relative to the evapotranspiration estimates but, depending on the method used for calculating the crop water need, he tended to over water the crop in two out of three intended deficit irrigation regimes. Analysis of continuously monitored canopy temperatures provided verification of over-irrigation. Continuously monitored canopy temperature is proposed as a useful adjunct to evapotranspiration approaches to deficit irrigation management.
  Irrigation Science 05/2012; 30(2):127-137.
• Article: Flow rate sprinkler development for site-specific irrigation

  Robson André Armindo, Tarlei Arriel Botrel, Tiago Capello Garzella
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  ABSTRACT: Due to the rapid depletion of water resources, water must be used more efficiently in agriculture to maintain current levels of yield in irrigated areas. The efficiency of irrigation systems can be increased by adjusting the amount of water applied to specific conditions of soil and crop, which may vary in a field. Taking into account spatial and temporal variability, it is evident that an equipment capable of providing different irrigation levels is necessary to meet the water requirement of the soil. This work aims to develop and evaluate a flow rate sprinkler to be used in center pivots or linear moving irrigation systems, with potential for utilization in irrigation scheduling. A prototype was developed by duplicating its calibrations, and discharge coefficient adjustment was carried out in the laboratory. To predict the flow rate, a successful model that represented the operation of the flow rate sprinkler was established. The calibration of the flow rate sprinkler prototype showed satisfactory statistical and technical results. Automation of the prototype was achieved by driving a step motor using communication from the parallel port of a microcomputer, which was controlled by a software developed for this purpose. The results were satisfactory and technically feasible.
  Irrigation Science 05/2012; 29(3):233-240.
• Article: Reference evapotranspiration estimation without local climatic data

  Pau Martí, Pablo González-Altozano, María Gasque
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  ABSTRACT: The Penman–Monteith equation for reference evapotranspiration (ETo) estimation cannot be applied in many situations, because climatic records are totally or partially not available or reliable. In these cases, empirical equations that rely on few climatic variables are necessary. Nevertheless, the uncertainty associated with empirical model estimations is often high. Thus, the improvement of methods relying on few climatic inputs as well as the development of emergency estimation tools that demand no local climatic records turns into a task of great relevance. The present study describes different approaches based on multiple linear regression, simple regression and artificial neural networks (ANNs) to deal with ETo estimation exclusively from exogenous records from secondary stations. This cross-station approach is based on a continental characterization of the study region, which enables the selection and hierarchization of the most suitable ancillary data supplier stations. This procedure is compared with different traditional and cross-station approaches, including methodologies that also consider local temperature inputs. The proposed methods are also evaluated as gap infilling procedures and compared with a simple methodology, the window averaging. The artificial neural network and the multiple linear regression approaches present very similar performance accuracies, considerably higher than simple regression and traditional temperature-based approaches. The proposed input combinations allow similar performance accuracies as ANN models relying on exogenous ETo records and local temperature measurements. The cross-station multiple linear regression procedure is recommended due to its higher simplicity.
  Irrigation Science 05/2012; 29(6):479-495.
• Article: Surface velocity coefficients for application of the float method in rectangular and compound open channels

  N. Marjang, G. P. Merkley
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  ABSTRACT: A three-dimensional mathematical hydraulic model was applied to calculate velocity profiles and discharge under steady, uniform flow conditions in rectangular and compound open-channel cross sections. The velocity profiles were used to calculate surface velocity coefficients for use with the float method for discharge estimation in the field. Surface velocity coefficients were calculated at increments of one-eighth of the base width from the vertical walls to the center of the cross section, and submergence of the float object from 0 to 30cm, with a 5-cm depth increment. Model results were summarized to show the relationship between surface velocity coefficient and channel characteristics compared to values published by the US Bureau of Reclamation (USBR). For rectangular cross sections, the coefficients from the model are generally higher than the published USBR values. But the coefficients from the model and USBR are in very close agreement for the tested compound cross sections. The published coefficients by the USBR are a function of only average water depth. However, the model results show that the coefficient is also related to channel size, cross-sectional aspect ratio, surface roughness height, float submergence and lateral location of the float object. These factors should be included in the determination of the surface velocity coefficient to improve the discharge estimations from the application of the float method.
  Irrigation Science 05/2012; 27(6):457-470.
• Article: A one-dimensional complete hydrodynamic model of border irrigation based on a hybrid numerical method

  Shaohui Zhang, Di Xu, Yinong Li
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  ABSTRACT: A numerical model of border irrigation flow is a useful tool in the design and evaluation of surface irrigation systems. A one-dimensional complete hydrodynamic numerical model of border irrigation was established by using the time–space hybrid numerical method. Differences in stability, convergence, precision, and efficiency of the one-dimensional model were analyzed and compared between the hybrid numerical method proposed here and the Roe finite-volume method. At the same time, the computational performance and simulation effects were validated based on the results of typical border irrigation tests. The results show that the hybrid numerical method provides better numerical stability and convergence with little water quantity-balance and average relative errors than does the Roe finite-volume method. The computational efficiency is about two times higher under the same measurement circumstances. The proposed model of border irrigation can increase computational stability and convergence, can improve computational precision and efficiency, and can provide a good numerical simulation tool for the design and evaluation of border irrigation systems.
  Irrigation Science 05/2012; 29(2):93-102.