Original Article
Pressurized Irrigation Systems
Mustafa Goodarzi; Saber Zolfaghari
Abstract
Extended AbstractIntroductionPressurized irrigation systems are increasingly used to improve water management and reduce water losses in agricultural production, particularly in regions facing water scarcity. However, the expected benefits of these systems cannot be achieved solely through appropriate ...
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Extended AbstractIntroductionPressurized irrigation systems are increasingly used to improve water management and reduce water losses in agricultural production, particularly in regions facing water scarcity. However, the expected benefits of these systems cannot be achieved solely through appropriate design and installation. Their long-term performance also depends on proper operation, preventive maintenance, timely technical support, and continuous monitoring during the service life of the system. Inadequate operation and maintenance may gradually alter hydraulic conditions, reduce the effectiveness of water application, and lead to deterioration in the overall condition of irrigation systems. In addition, farmers and system operators need adequate technical knowledge and continued access to professional support to maintain the systems under field conditions. The objective of this study was to evaluate changes in selected technical indicators of pressurized irrigation systems following the implementation of an operation and maintenance monitoring program and to assess farmers’ perceptions of the factors contributing to successful long-term operation and maintenance of these systems.MethodologyThe study was conducted in Arak and Shazand counties of Markazi Province, Iran. A total of 30 pressurized irrigation systems were selected for field evaluation, including 20 systems in Arak and 10 systems in Shazand. The systems were evaluated repeatedly at four measurement stages consisting of the initial technical supervision stage and three subsequent follow-up stages during the cropping season. Two field-based technical indicators were used to assess the condition of the irrigation systems: operating pressure and soil water content. Operating pressure was measured using a pressure gauge and expressed as meters of water head. These two indicators were selected because operating pressure provides an important indication of the hydraulic operating condition of pressurized irrigation systems, while soil water content provides information about the resulting moisture condition of the root-zone soil following irrigation. In addition to the field measurements, a structured questionnaire was administered to the operators of the evaluated irrigation systems. The questionnaire consisted of 24 items and was designed to assess farmers’ perceptions of factors affecting the successful operation and maintenance of pressurized irrigation systems. Responses were recorded using a five-point Likert scale. The content of the questionnaire was reviewed by experts in irrigation and operation and maintenance of pressurized irrigation systems. Field data were analyzed using descriptive statistics and repeated-measures analysis of variance. Measurement stage was considered the within-system factor, whereas county was considered the between-system factor. Where appropriate, pairwise comparisons were conducted using Bonferroni adjustment to control the probability of Type I error associated with multiple comparisons.Results and Discussion The results showed that the mean operating pressure of the evaluated irrigation systems was 42.33 m of water head at the initial technical supervision stage. The corresponding values at the first, second, and third follow-up stages were 39.73, 40.30, and 39.97 m, respectively. Thus, operating pressure showed an overall decline after the initial supervision stage, although the values remained relatively stable across the three subsequent follow-up stages. Repeated-measures analysis indicated a statistically significant effect of measurement stage on operating pressure, demonstrating that operating pressure changed over the monitoring period. However, the overall difference between Arak and Shazand counties was not statistically significant. Bonferroni-adjusted pairwise comparisons showed that the pressure at the initial supervision stage was significantly higher than the pressure recorded at the second and third follow-up stages. In contrast, the difference between the initial supervision stage and the first follow-up stage was not statistically significant. Furthermore, none of the differences among the three follow-up stages was statistically significant. These results suggest that although some reduction in operating pressure occurred following the initial supervision, the pressure conditions were comparatively stable during the subsequent monitoring stages.Soil water content also showed an overall declining tendency. The mean soil water content decreased from 27.51% at the initial supervision stage to 26.47%, 26.83%, and 25.72% at the first, second, and third follow-up stages, respectively. The repeated-measures analysis showed no statistically significant overall difference between Arak and Shazand counties. The results therefore indicate that the general temporal pattern of soil water content was similar in the two counties. Bonferroni-adjusted pairwise comparisons indicated that the significant difference was primarily observed between the initial supervision stage and the first follow-up stage, whereas the subsequent pairwise differences were not statistically significant. An important finding was the increase in variability in soil water content toward the third follow-up stage. This increase may indicate greater heterogeneity among irrigation systems or differences in management conditions among operators. However, because spatial variability, irrigation discharge, application uniformity, and detailed soil characteristics were not independently evaluated, the underlying causes of this variability cannot be determined from the present data.The questionnaire results provided complementary information concerning farmers’ perceptions of operation and maintenance. The highest percentage score was obtained for operation management (83.33%), followed by technical recommendations (70.33%). The scores for operator training, increased productivity, and water saving were 56.67%, 46.67%, and 41.33%, respectively. These results indicate relatively high perceived performance in operation management and technical recommendations, while training, productivity, and water saving received comparatively lower scores.ConclusionsThe findings indicate that the operation and maintenance monitoring program was associated with relatively stable hydraulic and soil-moisture conditions during the follow-up period, although both operating pressure and soil water content showed an overall declining tendency after the initial supervision stage. The results support the importance of moving from a one-time supervision approach toward a continuous operation and maintenance support system. Periodic technical inspections, follow-up visits, preventive maintenance, operator training, and routine monitoring of key indicators such as operating pressure and soil water content can help identify potential changes in system condition at an early stage. Nevertheless, because the study did not include an independent control group and did not directly measure indicators such as discharge, distribution uniformity, application efficiency, or water productivity, the findings should be interpreted as evidence of changes in selected technical indicators rather than direct proof of improvements in overall irrigation efficiency. Future studies should incorporate a broader range of hydraulic, agronomic, and economic indicators and, where possible, include control systems to provide stronger evidence regarding the causal effectiveness of continuous monitoring and technical supervision programs. Conflict of InterestThe authors declared no potential conflicts of interest concerning the research, authorship, and publication of this article. FundingThe authors received no financial support for the research, authorship, and publication of this article. Data Availability StatementsAll relevant data and results supporting the findings of this study are presented within the article. The datasets generated and/or analyzed during the current study are available from the corresponding author upon reasonable request. Author ContributionAll authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by all authors. All authors contributed equally to the conceptualization of the article and writing of the original and subsequent drafts.AcknowledgementThe authors sincerely appreciate the cooperation and assistance of the farmers and irrigation-system operators who participated in this study, the technical experts and supervisors of the pressurized irrigation systems, and the management and technical staff of Arak and Shazand agricultural jihad centers for their valuable support during the fieldwork and data collection.
