Slope shape effect on runoff and soil erosion under natural rainfall conditions


Creative Commons License

Sensoy H., KARA Ö.

IFOREST-BIOGEOSCIENCES AND FORESTRY, cilt.7, ss.110-114, 2013 (SCI İndekslerine Giren Dergi) identifier identifier

  • Cilt numarası: 7
  • Basım Tarihi: 2013
  • Doi Numarası: 10.3832/ifor0845-007
  • Dergi Adı: IFOREST-BIOGEOSCIENCES AND FORESTRY
  • Sayfa Sayıları: ss.110-114

Özet

Slope is often non-uniform along the hillslope, with variations describing concave and convex shapes associated with natural hillslopes. This is because runoff generations vary significantly over short distances, with changes in surface alteration during or between flow events on different slope shapes. The aim of this research is to determine the effects of slope shapes on runoff and soil erosion. A field experiment was conducted from September 2007 to September 2009 on hillside field plots located in the northern part of the city of Bartin in northwestern Turkey. The experiment focused on complex topography including uniform, concave, and convex slopes. Nine experimental field plots were established on a 30 per cent slope, including three replications of field plots per different shape treatment. Runoff and soil loss by water erosion were measured in these plots under natural rainfall conditions. A total of 158 rainy days and 69 runoff events were registered over the period of investigation. Runoff and soil loss were greater in uniform plots than in concave and convex plots. The greatest amount of runoff was measured between September 2007 and August 2008 (Period1: P1), with 211.53 mm from uniform plot1 and during September 2008 and August 2009 (Period2: P2) with 430.06 mm from uniform plot3. The lowest runoff quantities with 157.44 and 371.63 mm from concave plot3 and concave plot1, respectively, were measured at P1 and P2. The highest soil loss was recorded at 2.97 kg m(-2) and 6.16 kg m(-2) during P1 and P2 from uniform plot2 and uniform plot3, respectively, and soil loss was lowest from concave plot3 and concave plot1, with a total of 0.23 kg m(-2) and 0.67 kg m(-2), respectively. The distribution of eroded soil was separated into >2 mm (coarse) and <= 2 mm (fine) size classes, and suspended quantity in runoff was also determined. Results indicated that the majority of soil lost from the uniform plots is composed of fine particles rather than coarse and suspended material. On the other hand, both concave and convex slopes demonstrated larger variability in the size distribution of eroded particles from individual plots.