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Modelling the sediment transport capacity of flows in steep nonerodible rills
Author(s) -
Jiang Fangshi,
Gao Pengyu,
Si Xiaojing,
Zhan Zhenzhi,
Zhang Haidong,
Lin Jinshi,
Ji Xiang,
Wang Ming Kuang,
Huang Yanhe
Publication year - 2018
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.13294
Subject(s) - stream power , colluvium , flume , geology , sediment transport , rill , power function , hydrology (agriculture) , sediment , flow (mathematics) , debris flow , soil science , geotechnical engineering , geomorphology , geometry , mathematics , debris , soil water , mathematical analysis , oceanography
A precise estimation of sediment transport capacity ( T c ) is key to establishing process‐based erosion models. However, few data are available for estimating transport capacity on steep slopes and test materials sorted at high coarse grain values of >2 mm. Colluvial deposits with loose, coarse material and steep slopes make up the packed materials underlying the collapsing walls in benggang , which collapse due to hydraulic pressure and gravity. The objectives of this study were to investigate how flow discharge and slope steepness affect T c and to examine relationships between T c and flow velocity, shear stress, stream power, and unit stream power for colluvial deposits found on steep slopes. A nonerodible rill flume of 4 m long and 0.12 m wide was used. Slope steepness values ranged from 18% to 84%, and unit flow discharge values ranged from 0.56 × 10 −3 to 4.44 × 10 −3 m 2 s −1 . T c increased as a power function with flow discharge and slope steepness with a Nash–Sutcliffe model efficiency ( NSE ) value of 0.99, and the effects of flow discharge were stronger than those of slope steepness. T c was overestimated for a colluvial deposit when the equations of the ANSWERS, Zhang et al. and Wu et al. models were considered and when T c exceeded 5 kg m −1 s −1 , as the slope steepness used in our study was much higher than those used (<47%) in the other models. Regression analyses show that T c can be predicted from linear equations of flow velocity, stream power, and unit stream power, and T c can be fit to shear stress with power function equation. Flow velocity optimizes to predict T c with NSE = 0.97, and stream power and shear stress can also be successfully related to T c ( NSE = 0.91 and NSE = 0.81, respectively); however, unit stream power performs poorly ( NSE = 0.67). These results provide a basis for establishing process‐based erosion models on steep colluvial slopes.