Experimental Study of Drainage Pipe's Openings Arrangement Effect on Drainage Water Salt Load

In this study, effect of three different openings arrangements of drainage pipes on the drainage water salt load was investigated using a physical model. The first arrangement of openings for drainage of the subsurface flow had four parallel rows on the upper and lower sides of the pipe (M4). In the second arrangement the pipes had three parallel rows of openings with 120 degrees apart between the rows (M3) and the third one had one row of holes on top of the pipe (M1). Drainage pipes were installed at 20 and 60 cm depths with spacing of 60 and 180 cm. The results showed that the M1 and M3 cases experienced a decline in the contribution of the groundwater in the drained water. The M4 case had the highest contribution of the groundwater, while the M1 had the lowest one of that. So, there was a significant difference between the drainage salt loads at M4 and M1cases. In all cases, deep drain installation led to increase the drainage water salt load.