ساخت داخل كشور و بررسي مشكلات فني آن )center pivot( ارزيابي هيدروليكي سيستم آبياري باراني عقربه اي

Hydraulic Evaluation and Testing of Iranian Made Center Pivot Irrigation System

Center pivot irrigation system is used as a modern irrigation method in different parts of Iran. Unfortunately due to lack of proper design and hydraulic shortcomings of the system in several agricultural lands in Iran, the efficiency of the center pivot irrigation system is low or unacceptable. Low system efficiency results in non-uniformity of water distribution along the lateral and on the cultivated land. This non-uniformity also causes ponding of water on the cultivated land and run off from the field. Above problems and initially large investment required by the system would make the evaluation of the system during the operation a necessary task. The main objective of this research is the hydraulic evaluation of the center pivot irrigation system located in the agricultural land in the College of Agriculture of Shiraz University in Badjgah, and also determining the uniformity parameters such as CU, DU, AELQ, and PELQ. Field tests were conducted using ASAE standard procedure. The results show that the uniformity of water distribution obtained from the catch cans were not similar to the uniformity of the soil moisture content. It was also found that the average values of the distribution uniformity (DU), coefficient of uniformity (CU), actual efficiency of low quarter (AELQ), and potential application efficiency of low quarter (PELQ) were 0.63%, 0.75%, 0.55%, and 0.55% respectively. Based on these results and according to the ASAE standards, these values are low, indicating that the system is not properly designed or this system is not suitable for this area. Equal values of AELQ and PELQ show that in all cases during growing season the soil moisture deficit (SMD) was higher than the low quarter value (LQ). This means the irrigation depth was not sufficient and the crop was in stress during growing season. Electromotor damaged due to lack of metal cover and lack of proper design of electromotor adjacent hozzles were the main technical problems for the system.