Evaluation of Distribution Uniformity and Water Saline Gradient for a Double Line- Source Sprinkler Irrigation System in Ahvaz Climate Condition

To study the effect of water salinity in sprinkler irrigation, the system should be improved for saline levels requirements and a uniform water distribution. In this research, the distribution uniformity and saline gradients were evaluated for a double line source sprinkler irrigation system in Ahvaz in dry and hot climate. During the spring and summer growing season of maize, the data were collected in three farms with similar conditions and different managements, so as daytime (D), nighttime (N) and daytime irrigation with a post short fresh water for foliage washing (F), in three replications. For the two growing seasons, distribution uniformity for each irrigation event in all treatments was defined between 59 to 89 % (mostly greater than 75 %). Cumulative distribution uniformity for D, F and N treatments were 91, 85 and 87 % in spring,93, 88 and 93 % in summer for saline treatments area, and 88, 82 and 88 % in spring for whole irrigation system and 91, 85 and 87 % in summer for whole irrigation system, respectively. The coefficient of variation for all treatments during the two growing seasons was less than 3%. Uniform and proper gradient of water salinity and parallel iso-saline lines were observed throughout the field, along with high regression coefficients for liner equations. The results showed that the experimental sprinkler irrigation system provided an appropriate condition for the system throughout the field with low cost and easily management. With avoiding irrigation in windy conditions, increasing wetted radius of sprinkles, increasing the side sprinkler numbers and regulation of them, the improvement of irrigation uniformity must be considered.