Investigation of Tape Line Drip Irrigation Systems in the Eastern Faryab Plain: Technical Assessment and Solutions

Abstract Today, by field evaluating modern irrigation systems and monitoring their status, we can identify their strengths and weaknesses, thereby facilitating better utilization through amendments and the adoption of new management practices. In this study, 30 experimental farms managed by farmers in 2024, equipped with tape drip irrigation systems, were selected in the Faryab region, where potatoes and onions were cultivated. To evaluate the irrigation systems, a main pipe was randomly selected, and four lateral pipes located at the beginning, one-third, two-thirds, and the end of the main pipe were considered. The flow rate from the emitters and the pressure at the beginning and end of the tested pipes were measured. The system's performance was evaluated based on the Christiansen’s Uniformity Coefficient (CU), Distribution Uniformity (DU), Coefficient of Variation (Cv), Emitter Uniformity (EU), flow variation (qvar), application efficiency (Ea), Actual Lower Quartile Distribution Efficiency (AELQ) (AELQ), and Potential Lower Quartile Application Efficiency (PELQ). The results showed that the average CU, DU, Cv, and EU in the evaluated designs were 77.6%, 69.8%, 0.29, and 59.5%, respectively. Furthermore, the average flow variation (qvar), application efficiency (Ea), actual lower quartile application efficiency (AELQ), and potential lower quartile application efficiency (PELQ) were 58.2%, 61.5%, 59.8%, and 53.8%, respectively. The results indicated that the average volume of water consumed, yield, and water productivity index (WPI) for onions were 8340 m³ ha⁻¹, 41 t ha⁻¹, and 5.86 kg m⁻³, respectively, while these values for potatoes were 7710 m³ ha⁻¹, 39.5 t ha⁻¹, and 5.98 kg m⁻³.