Hydraulic Evaluation of two Sprinkler Irrigation Systems (Linear) During the Growing Season in Qazvin Plain

Restrictions on water resources in the country prevent agricultural development. Pressurized irrigation systems are one of the management strategies to improve productivity and use of water resources. However, by improperly using these systems, these systems themselves cause irrigation losses and water loss. Evaluation of irrigation systems during operation and resolving its defects can prevent such incidents. Therefore, the aim of this study was to evaluate two pressurized irrigation systems (Linier) in a field located in the research station so that the effects of tendency to an efficient irrigation system in increasing water use efficiency index or reducing water losses have been investigated. For this purpose, Kristiansen uniformity coefficient (CU), low quadrant distribution uniformity (DU), low quadrant application potential efficiency (PELQ) and low quadrant real efficiency (AELQ) have been used. The results of field evaluation based on CU and DU showed that the mean of these indices in wheat irrigation system was 89.38% and 83.92% and in rapeseed irrigation system was 76.85% and 70.31%, respectively. Also, from the perspective of potential efficiency (PELQ) and real (AELQ), the average water application of wheat irrigation system was 62.89% and in canola irrigation system was 49.33%, respectively. In a general view, both systems are in an acceptable range based on CU and DU evaluation indicators, while based on the computational values of PELQ and AELQ indices, they are outside the acceptable range, indicating the lack of proper management of the exploiter of the studied systems. The low evaluation indicators of the mentioned pressure irrigation systems indicate that in the absence of attention to the factors affecting during the operation period, it is not possible to expect the improvement of irrigation efficiency to mechanize the perceived irrigation. The operation of pressurized irrigation systems is dependent on several factors, each of which can be effective in the efficiency of an irrigation system. In such a way that cases such as inappropriate design of an irrigation system, disproportionate operation conditions and climatic conditions governing the region, lack of pressure management and other effective parameters during the operation period can affect the efficiency of an irrigation system. On the other hand, an irrigation system is a set of independent components that the proper or inappropriate function of each of these components can affect the efficiency of an irrigation system. In this regard, considering the location of agricultural meteorological station in the vicinity of the fields, some of the factors affecting the efficiency of an irrigation system in two crops were investigated, and the results of hydraulic evaluation of irrigation systems showed that the low evaluation indicators during the operation period were based on factors such as the constant of the average speed of movement of the irrigation system during the whole growth period (which caused deep penetration). The lack of the same height for sprinklers in the irrigation system, the presence of relatively high wind speeds in the region (which causes evaporation and wind blowing of water droplets), not following the proper diameter of sprinkler nozzles during the irrigation system spans (which causes the non-identical distribution of water at the farm level) and the old sprinklers of the irrigation system noted. Evaluation and analysis of field information obtained from the mentioned farms showed that one of the best and most effective factors in improving the performance of the system is recording and analyzing field information during the operation period. In such a way that by monitoring the effective factors such as the function of the system, optimal irrigation management can be applied at the irrigation system level and consequently at the farm level. In addition, inflexibility in irrigation management program and adaptation to operation conditions have also been one of the factors reducing the efficiency of the studied irrigation system. However, in case of more flexibility of irrigation management and compliance with the conditions of the operation period, we can expect improvement in irrigation system performance. However, there are mainly several problems in the field of system management and promotion of technical knowledge of operation. In a general approach, the low evaluation indicators of the irrigation systems under the mentioned pressure indicate that in the absence of attention to the factors affecting during the operation period, it is not possible to expect the improvement of irrigation efficiency to mechanize the perceived irrigation. This means that the efficiency of mechanized irrigation systems such as Linier irrigation system and other irrigation systems (drip and sprinkler) varies in a wide range, which in case of not paying attention to the factors affecting during the operation and design of the system, in some cases, the expected efficiency of these mechanized irrigation systems will not be obtained.