Effects of the land use/cover on the surface runoff and soil loss in the Niğde-Akkaya Dam Watershed, Turkey

Erosion, flood, and overflow events are frequently experienced due to changes in the land use in watersheds where human impacts are intensive. It is important to understand the effects of land use types on erosion at a watershed scale. This knowledge can then be used to manage soil and water resources in watersheds better. The aim of this study is to determine the effects of different land uses/covers on the surface runoff and soil loss by using a rainfall simulator in natural land conditions in the Niğde Akkaya Dam watershed with semi-arid conditions. For this purpose, 5 cultivated lands with different product patterns with similar conditions (apple orchard (A), potato cultivation area (P), bean cultivation area (B), clover cultivated land (CL), abandoned cultivated land (AB), plantation areas (cedar (C) and almond (AL)), and pasturelands covered with Thymus sp. (T), Agropyron sp. (AG) and Stipa sp. (S) were selected for the applications. The applications were carried out in two repetitions on circular test parcels of 0.28 m2 established in these lands. During the land applications, the characteristics of surface runoff (ponding time, surface runoff start time, average surface runoff rate, runoff coefficient) and the average sediment concentration in the surface runoff water were determined. The data obtained were evaluated by using the ANOVA, Duncan's test, and Pearson correlation analysis test and SPSS statistical program. The results of the study revealed that the surface runoff occurred in the abandoned cultivation area, bean cultivation area, potato cultivation area, and thyme-covered pastureland in a short time. The runoff coefficient values by the land cover are sorted from high to low as B > T > P > A > AB > AL > C > CL > S > AG. The sediment concentration in the runoff water is sorted from high to low as T > P > B > AB > AL > A > C > S. When the situation was evaluated in terms of the soil loss (erosion), it was concluded that the sorting is as P > T > A > AB > B > AL > C > S > CL.