Verification of the detachment-transport coupling relationship of rill erosion using colluvium material in steep nonerodible slopes

Libo Chen; Pengyu Gao; Xiaolin Li; Qin Zhu; Zumei Wang; Fang Shuai; Yue Zhang; Jinshi Lin; Yanhe Huang; Fangshi Jiang

doi:10.7717/peerj.14766

Verification of the detachment-transport coupling relationship of rill erosion using colluvium material in steep nonerodible slopes

PeerJ. 2023 Jan 24:11:e14766. doi: 10.7717/peerj.14766. eCollection 2023.

Authors

Libo Chen¹, Pengyu Gao¹, Xiaolin Li¹, Qin Zhu¹, Zumei Wang¹, Fang Shuai¹, Yue Zhang¹, Jinshi Lin¹, Yanhe Huang¹, Fangshi Jiang¹

Affiliation

¹ Jinshan Soil and Water Conservation Research Center, Fujian Agriculture and Forestry University, Fuzhou, China.

Abstract

The detachment-transport coupling equation by Foster and Meyer is a classical equation that describes the relationship between detachment and transport. The equation quantifies the relationship between sediment loads and soil detachment rates, deepens the understanding of soil erosion and provides a reliable basis for the establishment of an erosion model. However, the applicability of this equation to slopes with gradients greater than 47% is limited. In this work, the detachment-transport coupling relationship is investigated using the colluvium material of Benggang. A nonerodible rill flume 4 m long and 0.12 m wide was adopted. The slope gradient ranged from 27% to 70%, the unit flow discharge ranged from 0.56 × 10^-3 to 3.33 × 10^-3 m² s^-1, and the sediment transport capacity (T_c ) was measured under each slope and discharge combination. The sediment was inputted into the flume according to the predetermined sediment addition rate (from 0% to 100% of T_c ), and the detachment rate (D_r ) under each combination of the slope and discharge was measured. D_r linearly decreased with increasing sediment loads, which is consistent with the detachment-transport coupling equation by Foster and Meyer. The linear equations can predict the detachment capacity (D_c ) and T_c well (Nash-Sutcliffe efficiency coefficient (NSE) = 0.98 for D_c , and NSE = 0.99 for T_c ). The detachment-transport coupling equation can adequately predict the D_r (NSE = 0.89). However, its applicability to slopes of <47% (NSE: 0.92-0.96) was greater than that to slopes of ≥47% (NSE: 0.81-0.89), and the predicted D_r under T_c levels of 20% and 40% were higher than the measured values, while the predicted value under a T_c level of 80% was lower than the measured value. In summary, the detachment-transport coupling equation by Foster and Meyer can accurately reflect the negative feedback relationship between detachments and transports along steep-slope fixed beds and is suitable for colluvial deposit research. The results provide a basis for the construction of steep-slope colluvial deposit erosion models. In the future, the study of the hydrodynamic characteristics of sediment transport processes should be strengthened to clarify the detachment-transport effect of flows through hydrodynamics.

Keywords: Colluvium deposit; Flume test; Rill flow; Steep slope; Water erosion.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Biological Transport
Hydrodynamics
Soil Erosion*
Soil*

Substances

Soil

Grants and funding

This work was supported by the National Natural Science Foundation of China (41977071), the Natural Science Foundation of Fu-jian Province of China (2021J01120), and the Forestry Peak Discipline Construction Project of Fujian Agriculture and Forestry University (72202200205). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.