An experimental study on the responses of spring snowmelt erosion to driving factors in a Chinese Mollisol soil

Authors: WANG, LUN - Northwest A&f University; ZHENG, FENLI - Northwest A&f University; YANG, XINYUE - Northwest A&f University; LIANG, RUI - Northwest A&f University; WANG, XUESONG - Northwest A&f University; YANG, XIHUA - New South Wales Agriculture; WANG, BIN - Beijing Forestry University; Flanagan, Dennis

Submitted to: International Soil and Water Conservation Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/25/2025
Publication Date: 2/28/2025
Citation: Wang, L., Zheng, F., Yang, X., Liang, R., Wang, X., Yang, X., Wang, B., Flanagan, D.C. 2025. An experimental study on the responses of spring snowmelt erosion to driving factors in a Chinese Mollisol soil. International Soil and Water Conservation Research. https://doi.org/10.1016/j.iswcr.2025.02.008.
DOI: https://doi.org/10.1016/j.iswcr.2025.02.008

Interpretive Summary: Soil erosion by water is a serious problem around the world. While raindrop impacts and flowing water are the main driving factors which detach and transport soil from farm fields, other factors can also be important, especially in cold regions that experience snowfall, snowmelt, and freezing and thawing soils. Soils that experience freezing can become weakened when the temperatures rise, and melting snow on these soils can then more easily erode them. In this laboratory study, we used a silty clay soil with 2.4% organic matter from northeastern China, and prepared and packed it into small flume beds to a depth of 15 cm. These were then frozen, and subsequently allowed to thaw to two different depths (5 cm and 10 cm from the surface) then set to a slope of 8.75%. Half of the flumes were slowly saturated with water from below and allowed to drain, and the other half were saturated and then subjected to positive water pressure heads (seepage conditions), and then in the actual experiments three levels of inflow water were added to the top of the flumes to simulate snowmelt runoff. We found that the seepage conditions increased soil losses by 50% compared to the drainage conditions, and increasing water flows increased soil loss as expected. The depth of the thawed soil had only a minor impact on soil losses, but did affect how the rill erosion channels formed. These results will assist in understanding cold region erosion processes, and developing equations and model functions to predict them. This study impacts other scientists, university faculty, and students involved in soil erosion mechanics and prediction research, and conservation agency personnel and farmers and landowners seeking to reduce soil erosion on the land.

Technical Abstract: Snowmelt erosion, a major spring soil degradation process in the Mollisol region of China, is further exacerbated in the context of global warming. The mechanism of snowmelt erosion remains unclear due to the complex erosion process influenced by multiple factors during the melting period. In this laboratory study we examined the effects of three critical factors affecting soil erosion during thawing periods: thaw depth of the soil surface (5 and 10 cm), subsurface hydrologic condition (drainage or seepage), and snowmelt flow rates (1, 2, and 4 L min-1). The results indicated that seepage significantly aggravated slope sediment yield, with sediment yield increasing by 50% in comparison to the drainage treatments. Sediment yield was positively correlated with snowmelt flow rate, and as the flow rate increased from 1 L min-1 to 4 L min-1, the sediment yield increased by more than 4 times, due to the enhanced runoff energy and sediment transport capacity. Path analysis confirmed that snowmelt flow rate and near-surface soil hydrologic regime were the dominant factors for snowmelt erosion (explaining 0.917 and 0.308 of the path coefficients, respectively) while the effects of soil thaw depth were relatively low (explaining 0.032 of the path coefficients). However, soil thaw depth had a substantial impact on rill morphology evolution; rills tended to erode horizontally toward the sidewalls at shallow thaw depths, and evolved vertically downward at deeper thaw depths. Additionally, runoff energy consumption ('E) was a suitable indicator for characterizing soil erosion on partially thawed slopes with a high Coefficient of Determination (R2). In general, this study provides a scientific basis for a comprehensive understanding of snowmelt erosion dynamics, allowing development of more strategies for mitigating soil erosion in the spring and sustaining regional productivity in the Mollisol region of China.