The impact of slit and detention dams on debris flow control using GSTARS 3.0

Debris flows, often the result of environmental degradation in mountainous areas, can be an extreme geological catastrophe. The concept of building detention dams to control debris flows has emerged after numerous deaths and huge economic losses have accumulated due to the destruction of infrastructure. Detention dams are well known for their efficient flow control and relatively low installation cost. However, their efficiency in decreasing peak flow is adversely affected by sedimentation, which not only decreases the effective lifetime of dams but also causes obstruction of outlets. In this research, the capability of GSTARS3.0 (Generalized Sediment Transport model for Alluvial River Simulation) was evaluated for a semi-three-dimensional simulation of sedimentation and flow routing in the reservoirs of two different kinds of detention dams: a classic detention dam and a slit dam. Sediment transport, scour, and deposition processes were simulated and calibrated along an experimental flume that represented the reservoirs of the detention dams to give a semi-three-dimensional variation of the bed geometry after debris flow events. Finally, models were applied to the Mojen River, Iran, as a real case. The model results convincingly show the capability of the GSTARS3.0 model to simulate sedimentation in reservoirs and the superiority of slit dams in controlling debris flow.