Sediment concentration and hydraulic characteristics of rain-induced overland flows in arid land soils
- 356 Downloads
Rain-induced overland flow involves the detachment of soil particles by raindrop impact and the transportation by the resultant overland flow. The purpose of this study was to investigate the relationship between sediment concentration and different hydraulic parameters including flow depth, flow velocity, shear stress, stream power, and unit stream power. The effects of soil particle size distribution, rain intensity, and slope steepness on measured sediment concentration in rain-induced sheet flow were also examined.
Materials and methods
Two arid land soils with different particles size distributions (D2mm and D4.75mm) were subjected to simulated rains using a detachment tray under infiltration conditions. Two rain intensities of 57 and 80 mm h−1 were simulated on slope gradients ranging from 0.5 to 20 %, resulting in rain-induced overland flows. After pre-wetting each soil, the sediment-laden overland flow was sampled at several time intervals (2, 5, 15, 20, 30, and 40 min) and the sediment concentration was determined. Different hydraulic parameters including flow depth, flow velocity, shear stress, stream power, and unit stream power were measured. The hydraulic parameters were used to model the sediment concentration, and the model performance was evaluated.
Results and discussion
The result showed that the measured sediment concentration was greater in the higher rainfall intensity and at steeper slopes. With increasing slope steepness, sediment concentration increased from 4.3 to 15.5 kg m−3 and from 3.8 to 12.5 kg m−3 for soils D2mm and D4.75mm, respectively. There was a direct relationship between sediment concentration and the rain-induced flow velocity, shear stress, stream power, and unit stream power. Nevertheless, the values of sediment concentration increased as flow depth decreased on steeper slopes. Also, sediment concentration was lower in the soil containing larger aggregates than in the finer soil. The hydraulic parameters tended to overestimate low amounts of sediment concentration and underestimate high values.
In general, the accuracy of the hydraulic parameters in predicting sediment concentration was: flow velocity > stream power > shear stress > unit stream power > flow depth. Flow velocity was the best predictor of sediment concentration with a linear relationship, whereas the other parameters showed nonlinear relationships. This study revealed that rain-induced sediment concentration at small scales can be modeled precisely on the basis of the flow velocity parameter.
KeywordsArid land soils Detachment tray Flow velocity Rain-induced erosion Slope
- Assouline S (2004) Rainfall-induced soil surface sealing: a critical review of observations, conceptual models, and solutions. Vadose Zone J 3:570–591Google Scholar
- Gabet EJ, Dunne T (2003) Sediment detachment by rain power. Water Resour Res 39:1–12Google Scholar
- Kemper WD, Rosenau RC (1986) Aggregate stability and size distribution. In: Klute A (ed) Methods of soil analysis. ASA and SSSA, Madison, pp 425–442Google Scholar
- Le Bissonnais Y (1995) Soil characteristics and aggregate stability. In: Agassi M (ed) Soil erosion, conservation and rehabilitation. CRC Press, pp 41–60Google Scholar
- Leh M, Bajwa S, Chaubey I (2013) Impact of land use change on erosion risk: an integrated remote sensing geographic information system and modeling methodology. Land Degrad Dev 24:409–421Google Scholar
- Mahmoodabadi M, Ahmadbeygi B (2011) Effect of some physical and chemical properties of soil on aggregate stability in some cultivation systems. J Soil Manag Sustain Prod 1:61–79Google Scholar
- Mahmoodabadi M, Ahmadbeygi B (2013) Effect of primary particle size distribution on aggregate stability at different size classes. Water Soil Sci 23:207–219Google Scholar
- Mahmoodabadi M, Rouhipour H (2011) Study on process changes in some indices of soil erodibility and deposibility using rainfall simulator. J Water Soil Conserv 18:145–166Google Scholar
- Mahmoodabadi M, Rouhipour H, Arabkhedri M, Rafahi HG (2007) Intensity calibration of SCWMRI rainfall and erosion simulator. J Watershed Manag Sci Eng 1:39–50Google Scholar
- Mandal D, Sharda VN (2013) Appraisal of soil erosion risk in the Eastern Himalayan region of India for soil conservation planning. Land Degrad Dev 24:430–437Google Scholar
- Page AL, Miller RH, Jeeney DR (1992) Methods of soil analysis, Part 2, Chemical and mineralogical properties. SSSA. Pub., Madison, p 1159Google Scholar
- Sirjani E, Mahmoodabadi M (2012b) Study on flow erosivity indicators for predicting soil detachment rate at low slopes. Int J Agric Sci Res Technol 2:55–61Google Scholar
- Zhao G, Mu X, Wen Z, Wang F, Gao P (2013) Soil erosion, conservation, and eco-environment changes in the Loess Plateau of China. Land Degrad Dev 24:499–510Google Scholar