Turkey experiences most of its avalanches and debris flows in the northeast part of Anatolia, a region replete with mountains, valleys and rivers. These events of nature interrupt transportation and communication lines, let alone their potentially deadly impact on life and loss of property. Contributing to their frequency is land use in the forms of new roads and railways, new residential developments and the expansion of arable farming lands, in addition to the effects of climate, geology and hydrology. The denuding of forested areas for human purposes exposes soils to nature’s elements triggering sliding movements of soil pulled by gravity downward seeking equilibrium.
Particularly troublesome are steep slopes with high permeability and water volume discharge rates. Deposits form by debris particles moving down the slope. In some cases the speed of this movement can be so slow as to be almost imperceptible. Additionally, water seeping into the deposits freezes and thaws during winter months being finally released from this cycle in Spring. This freezing and thawing of water expands and contracts the deposits generating weathering particles that travel down the stream bed with the effect of gravity. The mass of the debris material in the flows can move from 8-10 cm to several meters per event.
Moreover, highways and railways in slope areas particularly prone to debris flows experience flooding, mudslides and wash outs.
Transverse structures constructed in creek beds against debris flows are proving very beneficial. These constructions prevent new flow events by capturing debris and reducing slope reduction. Transverse structures can be constructed using varied techniques. A debris flow barrier solution is a practical, flexible and economical use of an innovative engineering technology.
As debris flow barriers made of steel with an advanced energy disapation braking system are new to Turkey, a test site was chosen by the authorities in the Guneysu district of the Rize province in a tributary of the Potomya River In Bashkoy. Regarding calculations, the barrier was installed in a trapezoidal-shaped stream bed; the barrier has a height of 3 m, 9 m across the top and 3 m at the base with a resis-tance of 160 kPa. The test area was chosen after conside-ring many criteria such as geological conditions, optimum anchorage location and site accessibility.
The tributary runs seasonally through a culvert under a transversing footpath before joining a larger tributary downstream. The debris flow barrier is located 30 m upst-ream from this confluence where a main road is located. Thus, it prevents debris from crossing the road’s horizon to flood and block traffic.
Experience shows that barrier installation does not require heavy construction equipment and is quite fast. These barri-ers can be easily transported to difficult topographical envi-ronments due to their light weight and are compatible with varied channel geometries.
During a technical trip to the area on 27th of September, heavy rainfall with intensive flow rates were observed in the stream bed.
The barrier continues working having approached its upper limits and is ready for standard maintenance cleaning.