Study on the effect of river flow on subsurface water diversion without cutoff wall in the alluvial rivers

Water shortages in arid and semi-arid regions necessitate new methods for supplying water from available resources. Underground dams and subsurface intakes have recently attracted the attentions for water exploiting in these regions. A couple of this type of intake has been constructed in a few seasonal rivers, but their performances for different river discharges and porous media have not been evaluated. In this study, the effect of river subsurface flow rate and cut-off on subsurface water diversion was experimentally investigated. The results showed that with increasing the upstream flow rate, the diverted flow rate (through drains) increased at first and then tended to a constant value gradually. The particle size of the porous medium had a significant effect on the rate of flow through drains, so that the increase of particle size caused to increase diverted flow rate, significantly. It was also shown that without the cut-off, the water diversion efficiency decreased about 40%. Furthermore, an equation was developed for determining the diverted flow rate based on the experimental observations and dimensional analyses.