Assessment of the amount of sediment deposited behind dry wall and wire cage sills for the gully rehabilitation in a sub-watershed of the coruh river basin including uzundere, şenkaya and tortum north

The relevant study was implemented in Uzundere, Şenkaya and Tortum North sub-watershed that were also evaluated within the scope of the Coruh River Basin Rehabilitation Project. The goal of this study is to determine the potential effects of sills on sediment and erosion control by measuring how much sediment is stored with all dry stones and wire cage sills implemented within the scope of gully rehabilitation. To carry out the research, numbers of gully channels (at least 4-5) were identified from each sub-watershed. The numbers of dry walls and wire cage sills, sill's top length, length of post and the rates of sediment filling/occupancy in the gully channel of studied basins were determined. The soil bulk density was also measured in the sediment samples collected from these sills and the total stored sediment amounts were also assessed as a unit of ton. Based on the obtained data, the average sediment filling/occupancy rate of dry walls and wire cage sills installed on the gullies of the sub-watersheds was calculated as 60%. In terms of each sub-watershed, this rates for Uzundere, Tortum North and Şenkaya were calculated as 75%, 54% and 52%, respectively. Total stored sediment amounts based on the measured occupancy rate herein were found 235447 tons for Uzundere, 6652 tons for Tortum North and 14192 tons for Şenkaya sub-watershed. Unit sediment amounts determined for these three sub-watersheds (sediment stored behind 1 m long wire cage or dry wall sills) were ranged as 2.15 tons/m for Uzundere, 0.22 ton/m for Tortum North and 1.21 tons/m for Şenkaya sub-watershed. In this context, Uzundere and Şenkaya sub-watersheds created a significant difference compared to Tortum Kuzey sub-watershed (p < 0.05).