Çoruh Nehri̇ Havzasina Bağli Oltu Mi̇krohavzasinda Kanal Ve Oyuntu Erozyonuyla Gerçekleşen Toprak Kaybinin “Erozyon Çubuk Yöntemi̇yle” Beli̇rlenmesi̇

Abstract

Water erosion is an important erosion type that erodes and transports the most. With the effects of stream water, both streambank and gully erosions cause even more soil transport and debris accumulation resulting more flood events and associated loss of life and properties, as well as increasing the deposition of sediment in dam reservoirs that shorten the economic lifespan of these dams. This study was carried out in 14 different bank erosion sites (stream reach) in the Oltu Micro Catchment (OMC), one of the sub-watershed of the Coruh River Basin, to measure gully and streambank erosions over five-year long study period using "erosion pin method". Oltu Micro Catchment has arid and semi-arid climate and has a 37% slope degree with a rugged structure. Over the five-year study period, the annual gully and streambank erosion rates were ranged from 1.25 to 8.79 cm/yr and the five-year average was measured as 4.43 cm/yr. The five-year soil losses were ranged from 30.5 to 190.8 tons/km/yr, and the five-year average was measured as 83.9 tons/km/yr. Compared to 1 st and 2 nd order streams, most of these measured soil losses were due to gully erosion (78%). In addition, it was determined that very large increase in bank erosion was occurred due to increase in rainfall in this semi-arid region showing that these types of watersheds are sensitive to bank erosions. As a conclusion, streambank and gully erosions are dynamic processes effected by the spatial and temporal scale differences under varying climate settings. Additionally, this study is a pioneer one in the region that identifies a need for the conservation practices (particularly for the gullies) to reduce the soil losses and deposited sediment in the whole channel system and eventually in dam reservoirs.