Study of River Flow Effects on Subsurface Water Diversion Using Porous Media in Seasonal Rivers

In arid and semi-arid regions، collection of surface and subsurface waters in small seasonal rivers is very crucial، particularly in dry seasons. The cost of construction and maintenance of classical water intakes makes them inappropriate for these rivers. In this study a rather new method to divert surface and subsurface water is experimentally evaluated. In this kind of intakes، a couple of trenches are excavated and the drain pipes are installed in them and then filled with very porous materials. Indeed the system acts as a river drainage network. This method not only reduces the construction and maintenance costs but also minimize the disturbance of river topology and morphology. Therefore this intake is also suitable for rivers with high sedimentary loads. In a few small rivers in Khorasan Razavi province، Islamic republic of Iran، such systems have been installed but their design and applicability have not been evaluated. In this research، experimental model of the intake to collect flow was built for flow diversion and flow rate deviation examined. Results showed a direct relationship between flow diversion with water level and with increasing distance between the drainages، the drainage flow increases. Drainage flow in the porous medium is initially decreased and then increased and drainage flow is the lowest in the middle drainage. In the review drainage arrange، the drainage of two deep with shorter porous medium is more suitable. Finally، regression mathematical model for the structural design of the intake subsurface with porous medium and drainage system were presented.