Effect of Micro-dams on Infiltration and Uniformity of Water Distribution Along the Furrow

There is a large amount of runoff water losses from the fields in the open-ended furrows. Therefore, it is necessary to provide a suitable solution for reducing runoff losses and subsequently, reducing soil erosion from the furrows. In this study, in order to control flow velocity as well as increase water infiltration along the furrows, several micro-dams with a height of 5 cm were constructed in the experimental furrows. Field studies and experiments were conducted at the research farm of the College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran, in summer 2018. The soil texture was clay loam, and the longitudinal farm’s slope was 0.96%. In this study, four different treatments were considered, which included: two erosive inflow discharges (0.6 and 0.9 L/s) and two barrier distances (10 and 20 m). Experimental furrows with a length of 100 m and a spacing of 0.75 m were created by the furrower machine. Eventually, the results were compared with control ones (furrow without micro-dams). Constructing micro-dams in the furrows increased distribution uniformity up to 99.3 percent. The results showed that micro-dams could improve the distribution uniformity of water and reduce water losses to about 45 percent. The results also depicted that the amount of infiltrated water in the first and second irrigation events was significantly higher than the third and fourth ones. The reason was because of lower soil moisture content and also higher surface roughness in the first and second irrigation events compared to subsequent irrigations. Among all irrigation events, the most amount of infiltration was observed in the treatment with a barrier of 10 m and an inflow discharge of 0.9 L/s.