Effect of plot size on measured runoff and sediment yield from natural rain-storms

Subject Areas : Farm water management with the aim of improving irrigation management indicators

Farrokh  Asadzadeh ¹ (Assistant Professor, Department of Soil Sciences, Faculty of Agriculture, Urmia University, Urmia, Iran)
Manoochehr  Gorji ² (Associate Professors, Department of Soil Sciences, College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran)
Alireza  Vaezi ³ (Assistant Professor, Department of Soil Sciences, Faculty of Agriculture, Zanjan University, Zanjan, Iran)
Reza  Sokouti ⁴ (Assistant Professor, West Azerbaijan Agricultural and Natural Research Center, West Azerbaijan, Iran)
Salman  Mirzaee ⁵ (PhD student of Soil Science, ShahreKord University, Shahrekord, Iran)

Received: 2012-12-14 Accepted : 2013-08-21 Published : 2013-09-22

Keywords: natural rainfall storm, Runoff, Sediment,

Abstract :

Erosion Plots are widely used to evaluate the main factors affecting soil erosion. Therefore, understanding the effects of different variables such as spatial scale on their performance is needed. This study was carried out to assess the effect of plot scale on measured runoff and sediment yield at event scale. To represent different spatial scales, plots with seven sizes differing in length (2, 5, 10, 15, 22.1, 25, and 30 m) and width (1, 1, 1.2, 1.6, 1.8, 2, and 2.4 m, respectively) were constructed in Poldasht region, west Azarbayjan province, northwest Iran. For each size of plots, specific runoff and sediment yield were separately measured for 11 runoff producing natural storms during the study period from September, 2010 to September, 2011. The results indicated that the unit area runoff and sediment yield decreases with power form relation as plot area or length increases. Statistical analysis of runoff and sediment yield data showed that, in most cases, there is a significant difference between the results of 10 m or shorter in length, plots and longer plots (p<0.05). However, there was no significant difference between the results of 15 m and longer plots. Based on these results, plots with 10 to 15 m in length were able to produce comparable results with large plots.