JWSS - Journal of Water and Soil Science

The uniformity parameters in drip irrigation system are influenced by the slope of manifold and therefore, the evaluation of drip irrigation systems is important in slopping lands. In this research, different slopes of 0.2, 6, 11, 16, 20 and 25% were applied on the ground surface and manifold of drip irrigation system with diameters of 50, 63 and 75 mm and length of 70 m were installed on these uniform slopes. The lateral pipes with 16 mm diameter and 40 m length were placed on the contour lines and connected to manifold bilaterally. The results showed that in the normal emitters in above slopes, the qv(avg) values were 289, 6740, 46, 135, 38 and 27 percent, respectively, qv(max) values were 222, 48, 53, 90, 27 and 9 percent, respectively, and the CV values were 300, 114, 33, 140, 63 and 25 percent, respectively, higher than compensating emitters. However, in the normal emitters in above slopes, the EU values were 33, 34, 12, 25, 17 and 9 percent, respectively, EUa values were 26, 23, 6, 21, 15 and 13%, respectively, UC values were 17, 16, 4, 13, 14 and 9%, respectively, and US values were 10, 8, 2, 8, 5 and 4 percent, respectively, less than compensating emitters. Therefore, even in high slopes (20 and 25%), the irrigation efficiency in compensating emitters were better than normal emitters. The relationship between slope and discharge of emitters represented small changes in discharge of compensating emitters in sloping lands.