Inferring Sediment Transport Capacity from Soil Microtopography Changes on a Laboratory Hillslope

Abstract

In hillslope erosion modeling, the Transport Capacity (Tc) concept describes an upper limit to the flux of sediment transportable by a flow of given hydraulic characteristics. This widely used concept in process-based erosion modeling faces challenges due to scarcity of experimental data to strengthen its validity. In this paper, we test a methodology that infers the exceedance of transport capacity by concentrated flow from changes to soil surface microtopography sustained during rainfall-runoff events. Digital Elevation Models (DEMs) corresponding to pre- and post-rainfall events were used to compute elevation change maps and estimate spatially-varying flow hydraulics ω taken as the product of flow accumulation and local slope. These spatial data were used to calculate a probability of erosion PE at regular flow hydraulics intervals. The exceedance of Tc was inferred from the crossing of the PE = 0.5 line. The proposed methodology was applied to experimental data collected to study the impact of soil subsurface hydrology on soil erosion and sediment transport processes. Sustained net deposition occurred under drainage condition while PE for seepage conditions mostly stayed in the net erosion regime. Results from this study suggest pulsating erosion patterns along concentrated flow networks with intermittent increases in PE to local maxima followed by declines to local minima. These short-range erosion patterns could not be explained by current Tc-based erosion models. Nevertheless, Tc-based erosion models adequately capture observed decline in local PE maxima as ω increased. Applying the proposed approach suggests a dependence of Tc on subsurface hydrology with net deposition more likely under drainage conditions compared to seepage conditions.

A trapping capacity constraint model for sediment transport in vegetative filter strips (VFS) on sloping surfaces

“…Firstly, it can change the runoff and sediment routing path in VFS, which may further complicate the results (Appels et al, 2011, 2017; Chen et al, 2013; Chen, Sela, et al, 2016; Nouwakpo et al, 2017; Jan et al, 2018; Wu et al, 2020). Secondly, the microtopography is closely related to sediment trapping capacity of VFS due to the depression storage (Nouwakpo et al, 2021). Therefore, the ultrafine resolution 2‐D model is worthy investigating to further analyse the impacts of microtopography on sediment transport in VFS.…”

Introduction to the Special Issue “Ecohydrologic Feedbacks between Vegetation, Soil, and Climate”

“…In a laboratory study, Nouwakpo et al [4] evaluated the effect of shallow subsurface hydrology on soil transport capacity. They developed a new methodology to quantify transport capacity based on changes in soil surface microtopography.…”

“…Elevation change maps and flow hydraulics data were derived from laboratory concentrated flow erosion experiments and used to calculate the probability of erosion at regular flow hydraulics intervals and an exceedance threshold for transport capacity, where probability of erosion = probability of deposition. Nouwakpo et al [4] found that erosion patterns during experiments were not readily explainable by commonly applied transport capacity-based concepts. Based on their experiments, the authors presented a new framework for transport capacity that addresses dynamic conditions associated with concentrated flow and subsurface processes.…”

Application of Artificial Intelligence in the Evaluation of Positional Accuracy and Statistical Validation of Digital Elevation Models for Hydrological Studies

“…Digital elevation models (DEMs) are crucial for hydrology and water resources management. They provide a three-dimensional representation of the Earth's surface, which is essential for understanding and managing the flow and distribution of water, presenting several critical applications of DEMs in hydrology such as in watershed delineation [7][8] [9][8] [10] [11], hydrological modeling [12], flood risk analysis [13] [14], soil erosion and sediment transport [15] [16], river and stream network analysis [17] [18], rainfall-runoff analysis [19] [20], wetland mapping and analysis [21] [22], groundwater flow and recharge analysis [23] [24], irrigation planning and management [25], climate change impact assessment [10] [26].…”