Evolution of overland flow connectivity in bare agricultural plots

Abstract

Soil surface roughness not only delays overland flow generation but also strongly affects the spatial distribution and concentration of overland flow. Previous studies generally aimed at predicting the delay in overland flow generation by means of a single parameter characterizing soil roughness. However, little work has been done to find a link between soil roughness and overland flow dynamics. This is made difficult because soil roughness and hence overland flow characteristics evolve differently depending on whether diffuse or concentrated erosion dominates. The present study examined whether the concept of connectivity can be used to link roughness characteristics to overland flow dynamics. For this purpose, soil roughness of three 30-m 2 tilled plots exposed to natural rainfall was monitored for two years. Soil micro-topography was characterized by means of photogrammetry on a monthly basis. Soil roughness was characterized by the variogram, the surface stream network was characterized by network-based indices and overland flow connectivity was characterized by Relative Surface Connection function (RSCf) functional connectivity indicator. Overland flow hydrographs were generated by means of a physically-based overland flow model based on 1-cm resolution digital elevation models. The development of eroded flow paths at the soil surface not only reduced the delay in overland flow generation but also resulted in a higher continuity of high flow velocity paths, an increase in erosive energy and a higher rate of increase of the overland flow hydrograph. Overland flow dynamics were found to be highly correlated to the RSCf characteristic points. By providing information regarding overland flow dynamics, the RSCf may thus serve as a quantitative link between soil roughness and overland flow generation in order to improve the overland flow hydrograph prediction. Elevation at the grid location (i, j) (mm) z(x)Elevation of the point x (mm)

Modeling of spatiotemporal variations in runoff contribution areas and analysis of hydrologic connectivity

“…Of all the small depressions on Surface 3, most were gradually filled and thus, exhibited a smooth, rather than sudden, stepwise increases in CA (Figure a). This finding is similar to those from the RSCf analyses by Antoine et al () and Peñuela et al ().…”

“…From the D‐cubed delineation and P2P simulation, the new NACf analysis was developed. Other studies have identified and quantified contributing area by dividing it into two parts, contributing to the outlet and noncontributing area (Antoine et al, ; Peñuela et al, , ). In this study, a noncontributing area was further divided by identifying and quantifying connectivity of areas that were not connected to the outlet to investigate how these ACs changed spatially and temporally.…”

Influence of DEM resolution on modelling hydrological connectivity in a complex agricultural catchment with woody crops

“…These differences were dependent on the different land uses and tillage practices. This proposal agreed with observations by Peñuela et al (2016) who proposed a link between differences in soil roughness values and overland flow dynamics (diffuse or concentrated) in tilled plots monitored for two years using 0.01 m resolution DEMs. The evolution of these metrics agreed with the results of Brasington et al (2012), who found that all geospatial metrics in a long braided river reach experienced a significant loss of topographic complexity with decreasing DEM resolution (from 0.1 to 1 m).…”

“…Soil roughness characterisation in tilled soils depends on the spatial resolution of the topographic data; whereas, at the same time, soil roughness, overland flow dynamics and functional connectivity evolve differently depending on whether diffuse or concentrated runoff dominates (Peñuela et al, 2016). However, we did not find any studies that investigated the effect of DEM resolution on the magnitude and patterns of modelling HC in woody crops.…”

A model for catchment soil erosion management in humid agricultural environments

“…As a consequence, this approach does not reflect the effect of conservative tillage and no‐tillage practices in minimizing soil erosion by reducing the soil disturbance and allowing more surface residue (Busari et al ., ). The MMMF approach does not take into account the direction of tillage or that roughness elements created by tillage, especially when parallel to the slope, can concentrate flow in non‐permanent channels, thereby increasing the erosion and sediment transport capacity of the flow (Govers et al ., ; Kirkby et al ., ; Gómez and Nearing, ; Peñuela et al ., ).…”