Irrigation distribution uniformity analysis on a lateral-move irrigation system

• Published in: Irrigation science 2019-03, Vol.37 (2), p.195-206
• Main Authors: Faria, Lessandro Coll, Nörenberg, Bernardo Gomes, Colombo, Alberto, Dukes, Michael D., Timm, Luis Carlos, Beskow, Samuel, Caldeira, Tamara Leitzke
• Format: Article
• Language: English
• Subjects: Agriculture; Aquatic Pollution; Availability; Biomedical and Life Sciences; Climate Change; Coefficient of variation; Distribution; Distribution functions; Environment; Field study; Field tests; Goodness of fit; Irrigation; Irrigation systems; Irrigation water; Life Sciences; Normal distribution; Original Paper; Probability distribution; Probability distribution functions; Probability theory; Sprinklers; Statistical analysis; Sustainable Development; Waste Water Technology; Water depth; Water Industry/Water Technologies; Water Management; Water Pollution Control; Water storage; Wind effects; Wind speed
• ISSN: 0342-7188; 1432-1319
• DOI: 10.1007/s00271-019-00619-5

Probability distribution functions (PDF) have been used for decades to model the applied water depth by irrigation equipment; however, there are few studies that evaluate the PDF goodness-of-fit to mechanical lateral-move irrigation system water application, especially with oscillating plate sprinklers. The objectives of this study with a lateral-move irrigation system in the field were as follows: (1) to evaluate the normal, uniform, Weibull, gamma and logistic PDFs’ goodness-of-fit to represent the applied water depth ; (2) to evaluate the influence of wind on the coefficient of variation (CV) of the applied water depth; (3) to evaluate the relationship of the distribution coefficient ( H ), the availability factor ( F ), the average deficit (Da) and the water storage efficiency ( E ) as a function of wind speed. Twenty-nine in-field tests were carried out at the Empresa Brasileira de Pesquisa Agropecuaria (Embrapa). The PDFs’ goodness-of-fit to the applied water depths by the irrigation system was based on the Kolmogorov–Smirnov test at a 5% significance level. The normal, uniform, gamma, Weibull and logistic PDFs fitted 21, 8, 19, 26, and 25 of the 29 in-field tests, respectively; however, application of the Weibull PDF is complicated and the normal distribution is suggested instead. The logistic PDF had good fit and warrants further study. In addition, a negative linear relationship ( R 2  = 0.73) was observed between the wind speed and the coefficient of variation of the applied water depth by the irrigation system, as well as the distribution coefficient ( H ), the availability factor ( F ), and water storage efficiency ( E ), while the average deficit (Da) showed a positive linear relationship with the wind speed.