Water Application Uniformity Research Articles

Treatment of Ferruginous Water in the Performance of Drip Irrigation Systems

One of the most important advantages of drip irrigation is the possibility of achieving a high uniformity of water distribution. However, this uniformity can be reduced when using water with high iron content, which can cause drippers to clog. This study aimed to verify the efficiency of the chlorination, aeration, decantation and filtration processes carried out to remove the iron from irrigation water and to investigate the effect of iron on water distribution uniformity. Four similar irrigation systems with five models of drippers were installed. The results showed that (i) there was a significant difference in the drippers’ behavior in relation to susceptibility to clogging when using water with a high iron content; (ii) the use of disk filters alone was not able to promote significant reductions in the iron quantity as a way to prevent the clogging of drippers; and (iii) the use of aerators followed by sedimentation tanks made it possible to achieve a considerable improvement in the water application uniformity for drippers that were more sensitive to clogging caused by the use of water with high iron content.

Research on pressure-regulating device based on different combination layouts, slopes and sprinkler interval distances

To improve the water application uniformity for sprinkler irrigation on sloping land, a new type of pressure-regulating device was designed. The pressure regulation device was installed between the pipe and the inlet of the sprinkler to regulate the pressure gradient. In this study, PIPENET software was used to simulate the installation of pressure regulation device on the corresponding PY10 sprinklers and analyze the working modes of each sprinkler in the irrigation system. The simulation considered factors such as sprinkler combination layout, ground slope and sprinkler interval distance, with average application rate and uniformity coefficient as evaluation criteria. The results showed that the installation of pressure regulation device reduced the pressure difference between each sprinkler. Under these conditions, irrigation uniformity was improved. The research results indicate that integrating different sprinkler layouts, ground slopes and sprinkler interval distances significantly improved the effectiveness of pressure-regulating device installation in hilly areas. This study provided a reference for addressing poor irrigation uniformity in sloping land in hilly areas.

Efeitos da lâmina de água aplicada e da uniformidade de armazenamento de água no solo na qualidade da irrigação e no rendimento da cultura

ABSTRACT The quality of water distribution and the coefficients that express water use efficiency are evaluated from the distribution of the irrigation depth (I). However, a hypothesis has been proposed that it may be more effective to base these analyses on the water depth stored in the soil profile (H), after irrigation. To evaluate this hypothesis, in a very clayey soil, bean was cultivated under irrigation by conventional sprinkling, with four scenarios of water application uniformity. During the crop cycle, irrigations were carried out, scheduled according to a lower limit of soil-water potential. The four scenarios were associated with 64, 144, 192 and 256 experimental points, which were characterized as having excellent (S1), adequate (S2), inadequate (S3) and unacceptable (S4) uniformity, according to obtained values of Christiansen’s uniformity coefficient (CUC) and distribution uniformity coefficient (DUC). At the end of the cycle, harvest was carried out in each grid, obtaining the crop yield. The uniformity of water distribution in the soil negatively impact crop yield only in S4, with an unacceptable water application pattern. The irrigation quality analysis based on values of H is more consistent with the results observed for the crop than the analysis based on the applied water depth.

Design of small gravity drip irrigation for smallholder farming in water scarce region of Indonesia

Many regions in Indonesia are suffering from a water crisis due to limited annual precipitation, especially in dry regions, which affects agricultural production. Climate change is becoming more severe, threatening global food and water security. Thus, the development of affordable irrigation for smallholder farms is crucial to increasing agricultural production. The study aims to provide a better design and management of a small gravity drip irrigation system for melon cultivation. Field experiments were conducted on a farmer’s field located in Sinjai Regency to analyze the performance of the small gravity drip irrigation system on melon cultivation. The technical design was determined by analyzing the water application uniformity and irrigation water productivity. The parameters of crop growth under small gravity drip irrigation were monitored during crop development stages, and the irrigation water productivity was calculated after the crop was harvested. As a result, the small gravity drip system performed well in crop performance, and the irrigation water productivity was 1.55 kg/m3. It can be concluded that a small gravity drip irrigation system is an effective strategy for irrigating melon cultivation on smallholder farms, minimizing water loss, and improving crop water productivity.

System Performance Evaluation for Tea Plants Replacing Sprinkler with Drip Irrigation using Water Uniformities in Dooars, India

Tea gardens are facing water scarcity; moreover, their irrigation utilises overhead sprinklers, which lack uniformities and controlled irrigation methods. Evaluating the performance of drip irrigation is an important research area for better water resources management. To address these issues different drip irrigation methods have been experimented with having different combinations of drippers. Two plots are online drip systems while the other two are inline systems operated at the same pressure on water application uniformity while other conditions remain similar. Earlier studies witnessed experimentation of drip irrigation with only the same emitter flow. While in this research, the uniformity coefficient, emission uniformity and performance index are calculated. It is found that due to various dripper discharges and systems the water application significantly changes. Extreme values of discharge variation of the emitters were observed during field operations under the same pressure and length of laterals. From the evaluation of the uniformities and investment cost, the performance of an inline system with a 4 lph dripper at 60 cm with 1-m lateral spacing is found to be the best model for tea irrigation under the specified conditions. Later stage and further research efforts should be aimed at the findings of the efficiencies and yield response of tea under the four drip systems.

Influence of Irrigation Systems on the Plant Growth and Leaf Ratio Analyses of Rubber (Hevea brasiliensis) Seedlings

The sprinkler irrigation system is the most widely used system for rubber irrigation in a nursery. However, the method is associated with high water loss during irrigation. In view of this, an experiment was conducted to assess the effect of different irrigation systems on the growth dynamics, leaf ratio analyses, water productivity, and water use efficiency of rubber seedlings. The treatments were the irrigation systems; soil + overhead sprinkler (CON), growing media (GM) + drip irrigation (DRP), GM + capillary wick system (WCK), and GM + overhead sprinkler (SPR). Each treatment was replicated three times, and the experiment was laid out in a randomized complete block design. The results showed that the DRP and WCK had significantly (p<0.05) higher seedlings’ growth parameters by 15–39% than obtained in the SPR and CON. However, the DRP, WCK, and SPR had statistically comparable seedlings’ root length and volume by 14–43% higher relative to the CON. Similar trends of plant growth dynamics, such as crop growth rate (CGR), leaf area index (LAI), and leaf ratio analyses, were observed for all treatments. However, the CON had lower CGR and LAI, which could be attributed to the lower water retention of the soil used in the treatment. The DRP and WCK had comparable water productivity with 56–60% higher than the SPR and CON treatments. The sprinkler irrigation treatments (SPR and CON) had 84% lower water use efficiency than the DRP and WCK. The DRP and WCK are the best treatments in this study because their higher water application uniformity led to higher seedlings’ growth dynamics and water productivity. The sprinkler system had higher water loss due to the lack of application uniformity, leading to lower plant growth than other irrigations. However, the SPR shows the potential to be more cost-effective due to its lower recurrent cost of labor than drip and wick irrigation.

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

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

Towards improving the global water application uniformity of centre pivots through lateral speed adjustment

An initial step is made towards improving the global water application uniformity of centre pivots by adjusting the lateral speed based on diurnal changes of wind drift and evaporation losses (WDEL). A large WDEL dataset was used to construct an artificial neural network (ANN) model capable of predicting the above ground application efficiency (AGAE ≈ 1- WDEL) from input weather data. Given its reasonably good accuracy (RMSE = 1.5%), the ANN model was then applied in heuristic, simple and dynamic algorithms that used forecasted or real-time weather parameters corresponding to the hourly time intervals of the pivot's revolution time. For each timing interval, the final output of the algorithms is a coefficient ( λ ), that when multiplied by the lateral speed, can ensure a more consistent water delivery depth across the field. The proposed algorithms were theoretically tested for extremely hot, dry, humid, and windy days. These efforts indicated that under the climatic conditions of the study, λ could potentially vary between 0.92% and 1.06% if the revolution time is about 24 h. The λ coefficient typically increased from 1:00 AM to 9:00 AM, then decreased until the sunset, between 19:00 to 21:00, and then increased again until midnight. This general trend for λ could however, be disrupted by sudden changes in the wind speed. Future studies should conduct extensive field work to test the efficacy of the proposed algorithms and quantify the improvement of centre pivot global water application uniformity through the lateral speed adjustment. • Centre pivot lateral speed can be adjusted to account for a changing application efficiency. • Two theoretical algorithms were developed to improve the global water application uniformity. • The first algorithm uses forecasted weather data while the second uses real time data. • The lateral speed adjustment factor varied within ±6% during a 24-hr cycle. • Centre pivot lateral speed adjustment is easy to implement.

Performance of Linear Move Irrigation System under Egyptian Conditions

The efficiency of irrigation as a standard engineering measure has been traditionally used to assess water use management. The objective of this study was to evaluate the technical performance of linear move sprinkler irrigation such as operating speeds for different specifications. Catch cans method was conducted to evaluate the distribution uniformity (DUlq) and the Christiansen coefficient uniformity (CU), evaluation was done at a private farm for two linear move irrigation systems: LM1 (linear move, 6 diameter number of the nozzle orifice 17 attached with 10 L min⁻ˡ flow) and LM2 (linear move, 8 diameter number of the nozzle orifice 25 attached with 20 L min⁻ˡ flow) under three different system speeds. The collected water after the irrigation system full passing over the can’s lines was measured using the graduated funnel to calculate the DUlq and CU. Ideal operating LM1 at the intermediate system speed (75% of the standard irrigation system speed equivalent to 22.5 m h⁻ˡ), operating LM2 at the lowest system speed (50% of the standard irrigation system speed equivalent to 15 m h⁻ˡ) recommended for the uniform irrigation water distribution. The results will improve the selection of travel speed when the water application uniformity of linear move irrigation system is evaluated.

IRRIGATION UNIFORMITY OPTIMISATION OF A MINI-CENTRE PIVOT SYSTEM

In El Oued, southern Algeria, the traditional Mini-Centre Pivot System (MCPS) is widely used for the irrigation of agricultural crops, and its use has been growing continuously. However, these systems have a constant nozzle diameter along the lateral pipe, which affects productivity directly, besides decreasing both the quantity and quality of agricultural products by irrigation heterogeneity. Therefore, optimising the design of the MCPS nozzles is linked strongly to the desired uniform irrigation. This study aims to determine the optimal configuration of nozzles for high irrigation uniformity. To achieve this goal, a genetic algorithm was used for maximising the uniformity of MCPS-mediated irrigation. The optimisation is carried out according to water distribution modelling, calculation of the Heermann and Hein uniformity coefficient (CUH), and existing nozzle diameters. To verify the accuracy of the proposed model, three existing MCPS (60 m, 50 m, and 46 m in length) are investigated experimentally. The developed code findings in terms of CUH are in agreement with those obtained by experimental tests. The analysis indicated that the nozzle diameter should vary from 5 to 15 mm along the lateral pipe. In these optimal conditions, the CUH was improved by 29.77%, 33.99%, and 19.36%, respectively, for the existing 60, 50, and 46 m irrigation systems. The most obvious findings to emerge from this study is that using a genetic algorithm to optimise the design based on the nozzle size improves water application uniformity by more than 19% in terms of the CUH.

A Comparative Study of Standard Center Pivot and Growers-Based Modified Center Pivot for Evaluating Uniformity Coefficient and Water Distribution

The center pivot irrigation system is a type of irrigation technology used to apply water effectively and uniformly over a wide variety of areas and topographies. These irrigation systems’ uniformity of water application greatly affects water use, energy consumption, and crop production. Performance tests of the standard lateral galvanized and modified polyethylene plastic pipes in the center pivot irrigation systems were conducted in different regions of Saudi Arabia. Water distribution depths along the laterals, coefficient of uniformity (CU), and distribution uniformity of the low quarter (DU) were determined. The results revealed that profiles of water distribution ranged from 4 to 14 mm for the standard-center pivot irrigation systems, while those for the modified-center pivot irrigation systems ranged from 6.5 to 50 mm. Standard-center pivot irrigation systems’ CU values ranged from 74 to 90%, with an average of 86%. In comparison, the modified-center pivot irrigation systems’ CU values ranged from 62 to 83%, with an average of 78%. The DU values ranged from 60 to 82% for the standard-center pivot irrigation systems, with an overall average of 77%. For the modified-center pivot irrigation systems, the DU values, in contrast, ranged from 31 to 75%, with an average of 65%. Thus, the accuracy and uniformity of the standard-center pivot irrigation systems are superior to those that have been modified. Additionally, a statistical model was developed to investigate the relationship between the water losses and the main climatic factors under field operating conditions. Therefore, the study results are expected to draw attention to standard lateral pipes’ value on the one hand and demonstrate the detrimental consequences of growers’ incorrect practices in pivot irrigation systems, motivating them to take strong action against these activities, on the other hand.

Effect of allowable flow-rate variation and local head loss on maximum length of non-pressure compensated drip tape

A challenge for the design of drip irrigation systems with non-pressure compensated emitters is to increase the maximum length of the lateral lines without significantly reducing water application uniformity. This work evaluated the effect of the flow-rate variation and the local head loss in the maximum length of drip tape with a non-pressure compensated flat emitter. The tests were carried out in a laboratory, using a collapsible drip tape non-pressure compensated in three 50-meter segments. The production line was configured to generate drip tapes without insertion of emitters and with closed emitters (0.30 m spacing). The experimental local head loss was compared with the Darcy-Weisbach equation's estimates using the Blasius friction factor. In the sequence, simulations were generated for the flow-rate variations of 10 and 20% for the emitter spacings of 0.30, 0.40, and 0.50m. The results showed that the local head loss had little influence on the lateral line's maximum length, generating variations of 2.5% on average. However, increasing the allowable flow rate variation from 10 to 20% resulted in a 34% increase in the lateral line maximum length. Also, the reduction in uniformity coefficients was less than 5%, enabling the indexes to remain above 90%. The adoption of higher flow rate variation values allowed gains in the lateral line length with a small decrease in uniformity, making it an alternative to reduce design and operational costs.

Testing Novel New Drip Emitter with Variable Diameters for a Variable Rate Drip Irrigation

This research presents a new variable rate drip irrigation (VRDI) emitter design that can monitor individual water drops. Conventional drip systems cannot monitor the individual water flow rate per emitter. Application uniformity for conventional drip emitters can be decreased by clogged emitters, irregular emitter orifices, and decreases in pressure. A VRDI emitter can overcome the irrigation challenges in the field by increasing water application uniformity for each plant and reducing water losses. Flow rate is affected by the diameter of the delivery pipe and the pressure of the irrigation delivery system. This study compares the volumetric water flow rate for conventional drip emitters and new VRDI emitters with variable diameters inner (1 mm, 1.2 mm, 1.4 mm, and 1.6 mm) and outside (3 mm, 3.5 mm, 4 mm, and 4.5 mm) with three pressures (34 kPa, 69 kPa, and 103 kPa). The tests revealed that the new VRDI emitter had flow rates that increased as the operating pressure increased similar to a conventional drip tube. The flow rate was slightly increased in the VRDI with pressure, but even this increase did not show large changes in the flow rate. The flow rate of the conventional drip tube was 88% larger than the VRDI emitter for all pressures (p < 0.05). However, operating pressure did not affect the drop sizes at the VRDI emitter, but the generalized linear mixed models (GLM) results show that volume per drop was impacted by the outside diameter of the VRDI outlet (p < 0.05). The interaction between the inner and outside diameter was also significant at p < 0.01, and the interaction between outside diameter and pressure was statistically significant at p < 0.01. The electronic components used to control our VRDI emitter are readily compatible with off-the-shelf data telemetry solutions; thus, each emitter could be controlled remotely and relay data to a centralized data repository or decision-maker, and a plurality of these emitters could be used to enable full-field scale VRDI.

Field Performance Evaluation of a Small-Scale Drip Irrigation System Installed in the Upper West Region of Ghana

This study was conducted to evaluate the water application uniformity for a drip irrigation system, considering the water quality and the duration of usage. The uniformity parameters, Emission Uniformity (EU %) and Uniformity Coefficient (UC %) were determined for the drip irrigation system installed over a year of performance. The procedures are based on taking measurements of emitter discharge along selected driplines on a sub-main. The catch can be identified as L1A, L1B, L1C, L1D, same for L2A to L2D, L3A to L3D and L4A to L4D. This gave a total of sixteen (16) measurement positions as there were 4 driplines. Results indicated that the uniformity of water application was 90% indicating that the emitter was still good after a year of installation. The average discharge rate was 0.57 l/h. The uniformity coefficient (UC %) for the gravity-fed drip irrigation system was 78%, indicating good water application and was quite significant for the evaluation of the uniform distribution of water for the design. The expansion of this irrigation method in rural communities could contribute to relevant water savings in most areas of the Upper West Region of Ghana.

EFICIÊNCIA DE IRRIGAÇÃO EM LAVOURAS DE CAFEEIROS CONILON NA REGIÃO CENTRO SERRANA DO ESPÍRITO SANTO

O café representa a principal fonte de renda dos produtores rurais de São Roque do Canaã, porém o município apresenta restrição hídrica ao cafeeiro devido à baixa e irregular distribuição de chuvas. Fato que implica na adoção de sistemas de irrigação para suprir as exigências hídricas do cafeeiro, onde é utilizado principalmente do tipo localizada por gotejamento. Porém, identifica-se a ausência de limpeza, manutenção e avaliações nestes sistemas de irrigação, o que reduz a eficiência e uniformidade de aplicação de água. Diante do exposto, objetivou-se com a realização deste trabalho, avaliar o desempenho de sistemas de irrigação localizada por gotejamento no município de São Roque do Canaã, visando determinação da uniformidade e eficiência de aplicação de água. Foram avaliados sistemas de irrigação em dez propriedades no município. Com base nos resultados obtidos, foram determinados e classificados o Coeficiente de Uniformidade de Christiansen (CUC), o Coeficiente de Uniformidade de Distribuição (CUD), Coeficiente de Uniformidade Estatística (Us) e Eficiência de aplicação (Ea). Os sistemas de irrigação localizada por gotejamento apresentaram baixa uniformidade de aplicação de água, sendo necessário que algumas práticas de manutenção preventiva e corretiva sejam adotadas para que os sistemas operem com maior uniformidade, e em consequência, com maior eficiência no uso da água.

A simplified method to improve water distribution and application uniformity for sprinkler irrigation on sloping land: adjustment of riser orientation

Abstract To improve the water application uniformity for sprinkler irrigation on sloping land, indoor tests were conducted on an artificial slope (slopes of 0, 0.05, 0.10 and 0.15) to evaluate the effects of two riser orientations, vertical (VO) and perpendicular (PO) to the slope, on the uniformity of sprinkler rotation, radius of throw, water distribution of an individual sprinkler and the overlapped water application uniformity (WAU). Compared with the VO, the PO could effectively improve the water distribution on sloping land and minimize the risk of soil erosion. Additionally, the PO was superior in the WAU, and a rectangular arrangement could dramatically enhance the WAU at smaller sprinkler spacing, while larger acceptable sprinkler spacing was accepted in a triangular arrangement. The riser orientation and sprinkler spacing had the most significant effect on the WAU, followed by the slope and sprinkler arrangement, suggesting that the adjustment of riser orientation or sprinkler spacing was helpful in improving the WAU. However, from the aspects of investment cost and installation convenience for irrigation projects, the method of PO was recommended. Therefore, when designing the sprinkler irrigation systems on the slope, choosing PO is the simplest and most effective way to achieve good irrigation uniformity.

Effects of water application uniformity using a center pivot on winter wheat yield, water and nitrogen use efficiency in the North China Plain

In recent years, the use of fertigation technology with center pivot irrigation systems has increased rapidly in the North China Plain (NCP). The combined effects of water and nitrogen application uniformity on the grain yield, water use efficiency (WUE) and nitrogen use efficiency (NUE) have become a research hotspot. In this study, a two-year field experiment was conducted during the winter wheat growing season in 2016–2018 to evaluate the water application uniformity of a center pivot with two low pressure sprinklers (the R3000 sprinklers were installed in the first span, the corresponding treatment was RS; the D3000 sprinklers were installed in the second span, the corresponding treatment was DS) and a P85A impact sprinkler as the end gun (the corresponding treatment was EG), and to analyze its effects on grain yield, WUE and NUE. The results showed that the water application uniformity coefficients of R3000, D3000 and P85A along the radial direction of the pivot (CUH) were 87.5, 79.5 and 65%, respectively. While the uniformity coefficients along the traveling direction of the pivot (CUC) were all higher than 85%. The effects of water application uniformity of the R3000 and D3000 sprinklers on grain yield were not significant (P>0.05); however, the average grain yield of EG was significantly lower (P<0.05) than those of RS and DS, by 9.4 and 11.1% during two growing seasons, respectively. The coefficients of variation (CV) of the grain yield had a negative correlation with the uniformity coefficient. The CV of WUE was more strongly affected by the water application uniformity, compared with the WUE value, among the three treatments. The NUE of RS was higher than those of DS and EG by about 6.1 and 4.8%, respectively, but there were no significant differences in NUE among the three treatments during the two growing seasons. Although the CUH of the D3000 sprinklers was lower than that of the R3000, it had only limited effects on the grain yield, WUE and NUE. However, the cost of D3000 sprinklers is lower than that of R3000 sprinklers. Therefore, the D3000 sprinklers are recommended for winter wheat irrigation and fertigation in the NCP.

Performance Evaluation of Drip Irrigation System and Water Productivity (WP) of Rock Melon Grown inside Netted Rain House Shelter

The yield of the crops may be subject to the distribution of water directly to the plant root zone using drippers or emitters. To date, there has not been adequate work to evaluate irrigation system performance and water productivity (WP) specifically for rock melon inside a netted rain house shelter in tropical area. Amongst the problem of this system is the non-functional irrigation components after been used for specific of time, thus reducing the irrigation efficiencies and distribution uniformity. This study evaluates irrigation performance of drip irrigation system and estimates WP of rock melon cultivation in the netted rain house shelter. The results indicate that the operating pressure of the drip irrigation system tested varied from 0.8 to 3.0 psi with a discharge rate between 0.14 and 0.25 Lmin−1. Water application uniformity between laterals varied from 66.06 to 89.72%. The WP of rock melon was around 7.93 kg/m3, which is considerably high and in similar range as demonstrated in previous literature. The field evaluation also reveals that the manipulation of valve controller at lateral based on a few selected scenarios did not provide a significant difference in pressure and discharge at the head, middle, and tail section of the drip irrigation system. Such findings would be a very useful information for a precision water management particularly for rock melon cultivation grown under rain house shelter system.

Effects of Travel Speed and Collector on Evaluation of the Water Application Uniformity of a Center Pivot Irrigation System

Water application uniformity is an important performance parameter when designing and operating an irrigation system. Performance tests of a center pivot irrigation system equipped with fixed and rotated spray plate sprinklers (FSPS and RSPS, respectively) were conducted at five travel speeds. The effects of travel speed, collector size, and setting height on water application uniformity were evaluated using Heermann and Hein’s coefficient of uniformity (CUH). The CUH was 12.7% higher for the RSPS than the FSPS and decreased as the travel speed increased. Collector size and setting height affected CUH, and CUH was higher when the collector had a large opening cross-section compared to the collector with a small opening cross-section. CUH was higher when the collector with a low setting height compared to when it a high setting height for the FSPS. However, collector setting height had no effect on CUH for the RSPS. The weighted average water application depth (Dw) decreased as the travel speed increased. Collector size had no significant effect on Dw, but Dw with a low collector setting height was larger than the values with a high collector setting height. The water application rate increased as distance from the pivot point increased and was higher for the FSPS than the RSPS. The results will improve the selection of travel speed and collector when the water application uniformity of a center pivot irrigation system is evaluated.

Dynamic Adjustment of Center Pivot Nozzle Height: An Evaluation of Center Pivot Water Application Pattern and the Coefficient of Uniformity

Abstract.This study assesses the potential of dynamic nozzle height adjustment for overhead irrigation systems. This system would maintain the nozzle or emitter a constant distance above the crop canopy throughout the growing season and would dynamically respond to variability in canopy height across the field. Within such systems, nozzle height would no longer be fixed in space and time. Nozzle heights would instead vary across space and time. This dynamic system response may therefore have adverse impacts on water application uniformity. The impact of DESA on application uniformity was assessed in three steps. First, changes in individual sprinkler patterns for pressure, nozzle type, flow rate, and nozzle height were measured in controlled experiments. Next, parametrized equations of the individual sprinkler patterns and how they are altered by nozzle height are developed. Next, the Center Pivot Evaluation and Design software was used to simulate theoretical uniformity, and these simulations were tested against field measurements of the coefficient of uniformity. Finally, we use the parameterized equations within the Center Pivot Evaluation and Design software to simulate the coefficient of uniformity for pivots with constant nozzle heights with a random distribution of nozzle heights, which simulate a dynamic elevation system. It was found that the uniformity coefficient decreased by 4-6% as the distribution of heights throughout the pivot become more variable, due to localized dynamic height adjustment. Systems equipped with nozzles with triangular spray patterns were less impacted than systems equipped with nozzles with elliptical spray patterns. Keywords: Keyword. Center pivot, Center Pivot Elevation and Design (CPED), Nozzle height, Sensor, Sprinkler pattern, Uniformity coefficient.