Effects of rainfall, overland flow and their interactions on peatland interrill erosion processes. Issue 7 (7th February 2018)

• Record Type: Journal Article
• Authors: Li, Changjia; Holden, Joseph; Grayson, Richard
• Is Part Of: Earth surface processes and landforms. Volume 43:Issue 7(2018)
• Page Start: 1451
• Page End: 1464
• Publication Date: 2018-02-07
• Subjects: overland flow -- erosion -- flow hydraulics -- raindrop impact -- peat; Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.4328
• Languages: English
• ISSNs: 0197-9337

Abstract

Abstract: Interrill erosion processes on gentle slopes are affected by mechanisms of raindrop impact, overland flow and their interaction. However, limited experimental work has been conducted to understand how important each of the mechanisms are and how they interact, in particular for peat soil. Laboratory simulation experiments were conducted on peat blocks under two slopes (2.5° and 7.5°) and three treatments: Rainfall, where rainfall with an intensity of 12 mm h −1 was simulated; Inflow, where upslope overland flow at a rate of 12 mm h −1 was applied; and Rainfall + Inflow which combined both Rainfall and Inflow. Overland flow, sediment loss and overland flow velocity data were collected and splash cups were used to measure the mass of sediment detached by raindrops. Raindrop impact was found to reduce overland flow by 10 to 13%, due to increased infiltration, and reduce erosion by 47% on average for both slope gradients. Raindrop impact also reduced flow velocity (80–92%) and increased roughness (72–78%). The interaction between rainfall and flow was found to significantly reduce sediment concentrations (73–85%). Slope gradient had only a minor effect on overland flow and sediment yield. Significantly higher flow velocities and sediment yields were observed under the Rainfall + Inflow treatment compared to the Rainfall treatment. On average, upslope inflow was found to increase erosion by 36%. These results indicate that overland flow and erosion processes on peat hillslopes are affected by upslope inflow. There was no significant relationship between interrill erosion and overland flow, whereas stream power had a strong relationship with erosion. These findings help improve our understanding of the importance of interrill erosion processes on peat. Copyright © 2017 John Wiley & Sons, Ltd. Abstract : Raindrop impact increased peat surface erosion rate by 47%. Raindrop impact increased flow resistance which reduced overland flow velocities by 80–92%. Interaction between rainfall and flow reduced erosion by 73–85% through increasing flow resistance and reducing stream power.