Measurement of rill and ephemeral gully flow velocities and their model expression affected by flow rate and slope gradient

Evaluating the effects of stream power on rill flow resistance

“…On the other hand, the s exponent into Equations (18) (0.94 for Q ≤ 0.133 L s −1 , and 0.97 for Q > 0.133 L s −1 ) for fixed beds, is close to 1. However, this result cannot be explained by the feedback mechanism, and could be affected by uncertainties on the velocity measurement due to the flow instability and self‐aeration phenomena that characterize supercritical flows with high Froude numbers (Montuori, 1984), as those used in the investigation by Ban et al (2020) (3.8 ≤ F ≤ 10.8) (Figure 1b).…”

“…In this paper, the rill flow hydraulic variables (flow depth h , channel slope s , mean flow velocity V , Reynolds number Re , Froude number F , and Darcy–Weisbach friction factor f ) corresponding to fixed and mobile bed rills investigated by Ban et al (2020) and Ban (2023) are used to test the applicability of a theoretically deduced rill flow resistance equation (Ferro, 2018) based on a power‐velocity profile. The main aims of this article are (i) testing the theoretical approach using fixed and mobile bed rill data available in the literature, (ii) discussing the effects of flow discharge and slope, governing the stream power, on sediment transport capacity, and (iii) testing the occurrence of the feedback mechanism presented by Govers (1992).…”

“…Recently, experimental runs on fixed bed rills and clear flow were carried out by Ban et al (2020) while experiments on mobile bed rills were performed by Ban (2023). Ban et al (2020) found that the flow velocity fitted well with unit width flow discharge and slope gradient by a power function, leading to a more reliable model as compared to that predicting flow velocity as a function of only flow discharge. For flow discharge less than 0.133 L s −1 , Ban (2023) obtained that flow velocity does not depend on the slope while slope gradient combined with a higher flow discharge contributes to better velocity prediction.…”

“…In this paper, the rill flow hydraulic variables (flow depth h, channel slope s, mean flow velocity V, Reynolds number Re, Froude number F, and Darcy-Weisbach friction factor f ) corresponding to fixed and mobile bed rills investigated by Ban et al (2020) and Ban (2023) are used to test the applicability of a theoretically deduced rill flow resistance equation (Ferro, 2018) based on a power-velocity profile.…”

Gully Recognition and Spatial-temporal Evolution Law of Gully Based on SegNet Model

“…Gully erosion is a linear erosion pattern occurring on steep slope cultivated land, formed by the combined action of runoff erosion and human cultivation, and plays a connecting role in the slope gully erosion system (Liu et al , 1988;Poesen et al , 2003;Wang et al , 2003). At present, studies on gully erosion have focused on critical topographical conditions (Daggupati et al , 2014;Feng, 2022;Maugnard et al , 2014;Torri and Poesen, 2014), factors influencing gully formation (Feng, 2022;Gong et al , 2011;Xu, 2018), mechanical processes and control measures of gully development (Guo, 2019;Xiao, 2017), flow dynamics and sediment transport (Ban et al , 2020;Kang et al , 2021a;Xuet al , 2021), and gully erosion models (Douglas-Mankin et al , 2020;Luquin et al , 2021;Tekwaet al , 2021). However, large-area field surveys are needed to accurately grasp the morphological features and spatial distribution characteristics of widely and densely distributed gullies, requiring a large workload and low efficiency.…”