Optimal moment to change pressure regulator and sprayer kit on center pivot irrigation machines: a theoretical proposal

A theoretical model was developed in order to determine the optimal moment for substituting the sprayer and pressure regulator kit on a center pivot irrigation machine. The model is based on the hypothesis that pressure regulator and sprayer deterioration decrease irrigation uniformity. To compensate the deficit that happens at under irrigated areas, an increase on irrigation depth is required. The model considers: additional water consumption and energy costs, maintenance and labor costs, as well as yield losses associated with under or over irrigated areas. The sum of all these components is compared to buying and installing a new spray kit cost, allowing the farmer to decide the best moment to renovate the sprayer and pressure regulator kits on a center pivot irrigation machine based on economic criteria.

低压条件下滴灌灌水均匀度试验研究

低压滴灌毛管进口工作压力、铺设长度、地面坡度及毛管管径是影响滴灌灌水均匀度的重要参数。试验研究结果表明,低压条件下毛管进口压力的变化对灌水均匀度的影响并不明显;灌水均匀度随着毛管铺设长度的增大呈降低趋势,管径越小,降低越显著,但在一定管长范围内,毛管铺设长度对灌水均匀度的影响并不明显;逆坡情况下,灌水均匀度随着坡度的增大而减小,顺坡情况下,灌水均匀度随着坡度的增大呈先增大而后减小的趋势,在2‰的坡度时达到峰值;灌水均匀度随着管径的增大而增大,当管径增大到一定程度后,灌水均匀度随管径增大的幅度减缓。

喷灌均匀系数的三次样条两次插值计算方法

为提高喷灌水量分布均匀性评价的准确性,当雨量筒径向布置时,为考虑所有测点数据对插值点降水深的影响,采用径向和周向两次的三次样条插值计算出未知点的降水深,从而计算喷灌均匀系数。以美国雨鸟30PSH型喷头雨量筒间隔为1m和2m的喷洒试验数据,计算网格点取1m和0.25m,分别采用三次样条两次插值法和邻近四点距离线性插值法计算了克里斯琴森均匀系数。结果表明,均匀系数由高至低的顺序依次为采样间隔为2m的线性插值、采样间隔为2m的三次样条两次插值、采样间隔为1m的线性插值和采样间隔为1m的三次样条两次插值。采样间隔2m比1m计算出的均匀系数总体高3~4个百分点,三次样条两次插值法比邻近点距离线性插值法略低1个百分点,2种计算网格点间距下的均匀系数差值小于1个百分点。结果证明,采样间距、插值方法、计算网格间距对均匀系数的影响依次降低,三次样条两次插值法可以用来评价喷灌组合均匀系数。

喷灌分布均匀系数研究

为突出局部灌溉不足或灌溉过量对均匀性的影响程度,提出了基于几何平均数分布均匀系数的概念,将其定义为部分测点水深几何平均值与所有测点算术平均值的比值。并根据部分测点水深数据的提取方法不同,分为1/4低值、1/4高值、1/2低值和1/2高值分布均匀系数。用MATLAB和VC~++语言编制了可以实现上述分布均匀系数计算的软件"SIUEW1.0"。结果初步证明:基于几何平均数的乘法模型要比基于算术平均数的加法模型更加突出了部分低(或高)于平均值的测点水深数据对均匀系数的影响程度,因此更适用于时局部灌溉不足或过量灌溉有严格控制要求地块的灌溉均匀性评价;无论高值和低值,取点数越少,均匀性的评价结果越差。

Perfil radial e uniformidade de precipitação do aspersor NaanDanJain 427, em função da regulagem do defletor

The study aimed to evaluate the radial profile and the uniformity of water distribution of sprinkler manufactured by the company NaanDanJain, model 427 1/2 '' M and nozzle with 2.8 mm of internal diameter, operating at pressures of 150, 200, 300 and 400 kPa and five positions of the deflector (0, 20, 50, 80 and 100%). For the determination of the parameters evaluated, the grid method was used and with the help of computer application CATCH 3D, overlapping layers of water depths was calculated with ten spacing. The results show that the deflector adjustment influences the radius of wetness and the distribution profile while the uniformity of water application showed as an important mechanism, since it permits different behavior for the sprinkler, ensuring wide track of utilization of the equipment.

Perfil radial e uniformidade de precipitação do aspersor NaanDanJain 427, em função do defletor de ajuste

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relação entre uniformidade da produtividade e indicadores de uniformidade da irrigação em sistema de irrigação por microaspersão em citros

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Dinâmica de entupimento de gotejadores em função da aplicação de água rica em ferro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Uniformidade de distribuição de água em irrigação localizada com sistema de aeração, decantação e filtragem

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Riego por goteo en Mendoza, Argentina : : evaluación de la uniformidad del riego y del incremento de salinidad, sodicidad e iones cloruro en el suelo

El presente trabajo tiene por objeto evaluar la uniformidad del riego por goteo en las zonas de regadío de las cuencas de los ríos Mendoza y Tunuyán (zonas Alta y Baja), de la provincia de Mendoza, Argentina. Las evaluaciones -en 17 propiedades- permitieron determinar: coeficientes de uniformidad, salinidad del agua de riego y del suelo en cabeza, medio y pie de la subunidad de riego, y en el bulbo húmedo e interfilar en dos estratos del perfil del suelo (0,10‑0,30 m y 0,30-0,50 m). Se determinó, además, la textura del suelo y su posible relación con los niveles de salinidad de la rizósfera. Se estimó que el 18% de las subunidades de riego evaluadas presentan un coeficiente de uniformidad por debajo del rango recomendable y que en el 94% de las propiedades existen diferencias significativas entre caudales medios registrados entre subunidades y entre sectores de operación de riego. Se encontraron diferencias significativas en la salinidad del extracto de saturación, en la sodicidad y en la concentración del anión cloruro, al comparar el suelo extraído del bulbo de mojado respecto del interfilar. Asimismo, los resultados muestran que no existen diferencias significativas de esas variables en las distintas profundidades de suelo analizadas. El aumento de la salinidad resultó en función del lugar de muestreo (bulbo o interfilar), la calidad del agua de riego y la textura del suelo. La variación de sodicidad, en cambio, dependió del lugar de muestreo (bulbo o interfilar) y del contenido de bicarbonatos en el suelo. Los resultados indican la importancia de realizar evaluaciones rutinarias del comportamiento de los sistemas de riego en términos de uniformidad y salinización inducida.

Relationship between citrus productivity and indicators of uniformity in trickle irrigation system

In trickle irrigation systems, the design is based on the pre-established emission uniformity (EU) which is the combined result of the equipment characteristics and its hydraulic configuration. However, this desired value of the EU may not be confirmed by the final project (in field conditions) and neither by the yield uniformity. The hypotheses of this research were: a) the EU of a trickle irrigation system at field conditions is equal to the emission uniformity pre-established in the its design; b) EU has always the lowest value when compared with other indicators of uniformity; c) the discharge variation coefficient (VC) is not equal to production variation coefficient in the operational unit; d) the difference between the discharge variation coefficient and the productivity variation coefficient depends on the water depth applied. This study aimed to evaluate the relationship between EU used in the irrigation system design and the final yield uniformity. The uniformity indicators evaluated were: EU, distribution uniformity (UD) and the index proposed by Barragan & Wu (2005). They were compared estimating the performance of a trickle irrigation system applied in a citrus orchard with dimensions of 400m x 600m. The design of the irrigation system was optimized by a Linear Programming model. The tree rows were leveled in the larger direction and the spacing adopted in the orchard was 7m x 4m. The manifold line was always operating on a slope condition. The sensitivity analysis involved different slopes, 0, 3, 6, 9 and 12%, and different values of emission uniformity, 60, 70, 75, 80, 85, 90 and 94%. The citrus yield uniformity was evaluated by the variation coefficient. The emission uniformity (EU) after design differed from the EU pre-established, more sharply in the initial values lower than 90%. Comparing the uniformity indexes, the EU always generated lower values when compared with the UD and with the index proposed by Barragan. The emitter variation coefficient was always lower than the productivity variation coefficient. To obtain uniformity of production, it is necessary to consider the irrigation system uniformity and mainly the water depth to be applied.

Irrigation performance and gross water productivity in furrow-irrigated ornamental tree production

In the ornamental plant production region of Girona (Spain), which is one of the largest of its kind in southern Europe, most of the surface is irrigated using wide blocked-end furrows. The objectives of this paper were: (1) to evaluate the irrigation scheduling methods used by ornamental plant producers; (2) to analyse different scenarios in order to assess how they affect irrigation performance; (3) to evaluate the risk of deep percolation; and (4) to calculate gross water productivity. A two-year study in a representative commercial field, planted with Prunus cerasifera ‘Nigra’, was carried out. The irrigation dose applied by the farmers was slightly smaller than the required water dose estimated by the use of two different methods: the first based on soil water content, and the second based on evapotranspiration. Distribution uniformity and application efficiency were high, with mean values above 87%. Soil water content measurements revealed that even at the end of the furrow, where the infiltrated water depth was greatest, more than 90% of the infiltrated water was retained in the shallowest 40 cm of the soil; accordingly, the risk of water loss due to deep percolation was minimal. Gross water productivity for ornamental tree production was € 11.70 m–3, approximately 20 times higher than that obtained with maize in the same region

Regulated deficit irrigation - a means to control growth in woody ornamentals

Improving plant quality and the uniformity of a crop are major objectives for growers of ornamental nursery stock. The potential to control excess vigour and to improve quality through regulated deficit irrigation (RDI) was investigated using a range of woody ornamental species. RDI regimes reduced vegetative growth consistently across different species and growing seasons. Plants adapted to reduced water supplies primarily via stomatal control, but also by osmotic adjustment when grown under the most severe RDI regimes. Only plants exposed to <= 25% of potential evapo-transpiration demonstrated any evidence of leaf injury, and the extent was slight. Growth inhibition increased as the severity of RDI increased. Improvements in quality were attained through a combination of shorter internodes and final shoot lengths, yet the number of 'formative' primary shoots remained unaffected. Compact, well-branched plants could be formed without a requirement for mid-season pruning. In addition to severity, the timing of RDI also influenced growth responses. Applying 50% ETp for 8 weeks during July-August resulted in the formation of good quality plants, which retained their shape until the following Spring. Re-positioning irrigation drippers within the pots of well-watered plants, in an attempt to induce a partial root drying (PRD) treatment, reduced growth, but not significantly. The adoption of irrigation scheduling, based on 50-100% ETp, has the potential to improve commercial crop quality across a range of ornamental species.

Optimal moment to change pressure regulator and sprayer kit on center pivot irrigation machines: application to a study case

A theoretical model developed by the authors for determining the optimal moment to substitute sprayer and pressure regulator kit on a center pivot irrigating potatoes and beans has been applied. The methodology compares the sum of the costs due to additional consumption of water and energy, maintenance and labor, as well as yield losses associated to areas with deficit or over irrigation to the costs due to buy and install a new sprinkling set on the pivot. The results showed that for a reduction of 3.07% of the Hermann and Hein’s Uniformity Coefficient (UCh), the substitution of the sprinkling module on the pivot is justified when potatoes and beans are cultivated.

Model to increase the lateral line length of drip irrigation systems

Non-pressure compensating drip hose is widely used for irrigation of vegetables and orchards. One limitation is that the lateral line length must be short to maintain uniformity due to head loss and slope. Any procedure to increase the length is appropriate because it represents low initial cost of the irrigation system. The hypothesis of this research is that it is possible to increase the lateral line length combining two points: using a larger spacing between emitters at the beginning of the lateral line and a smaller one after a certain distance; and allowing a higher pressure variation along the lateral line under an acceptable value of distribution uniformity. To evaluate this hypothesis, a nonlinear programming model (NLP) was developed. The input data are: diameter, roughness coefficient, pressure variation, emitter operational pressure, relationship between emitter discharge and pressure. The output data are: line length, discharge and length of the each section with different spacing between drippers, total discharge in the lateral line, multiple outlet adjustment coefficient, head losses, localized head loss, pressure variation, number of emitters, spacing between emitters, discharge in each emitter, and discharge per linear meter. The mathematical model developed was compared with the lateral line length obtained with the algebraic solution generated by the Darcy-Weisbach equation. The NLP model showed the best results since it generated the greater gain in the lateral line length, maintaining the uniformity and the flow variation under acceptable standards. It had also the lower flow variation, so its adoption is feasible and recommended.