Using a landform evolution model to study ephemeral gullying in agricultural fields: the effects of rainfall patterns on ephemeral gully dynamics

Abstract

Water driven soil erosion is a major cause of land degradation worldwide. Ephemeral gullies (EGs) are considered key contributors to agricultural catchment soil loss. Despite their importance, the parameters and drivers controlling EG dynamics have not been adequately quantified. Here we investigate the effects of rainfall characteristics on EGs, using the physically based landform evolution model (LEM) CAESAR‐Lisflood. An initial goal of this study was to test the feasibility of using a LEM to estimate EG dynamics based on an easily obtainable and moderate spatial resolution (2 × 2 m) Digital Elevation Model (DEM). EG evolution was simulated for two rainfall seasons in a 0.37 km2 agricultural plot situated in a semiarid catchment in central Israel. The 2014 rainfall season was used to calibrate the model and the 2015 season was used for validation. The model overall well predicted the EG network structure and average depth but tended to underestimate the EG length. The effects of rainfall characteristics on EG dynamics were investigated by comparing simulations employing seven rainfall scenarios. Four of these scenarios differ in their overall rainfall volume relative to observed precipitation (+20%, +10%, −10%, −20%). The remaining three scenarios vary in the temporal distribution of rainfall during each storm, allowing us to isolate the effect of rainfall intensity on EG evolution. The results show that: (1) EG dynamics strongly correlated with changes in rainfall volume; (2) small‐scale morphological behavior varies between rainfall scenarios, resulting in different meandering and connectivity variability; (3) EG evolution is divided into two main stages, an initial rapid development occurring after the first two weeks of the rainy season, followed by a stable development period; (4) a 12 mm h−1 intensity threshold was observed to initiate and, later, modify EGs; and (5) inner storm rainfall variability can have a considerable effect on EG evolution. Copyright © 2016 John Wiley & Sons, Ltd.

Temperature effects on the spatial structure of heavy rainfall modify catchment hydro-morphological response

“…5), located in central Switzerland (47 • N, 8 • E). There are several reasons for the selection of this catchment: (i) intense convective rainfall events are common over the region during summer, and rainfall is associated with high spacetime variability (Isotta et al, 2014;Molnar et al, 2015;Panziera et al, 2018); (ii) the catchment is well monitored in terms of rainfall and streamflow, including the extreme rainfall and flood event that occurred in August 2005 with an estimated return period exceeding 100 years (Beniston, 2006;Jaeggi, 2008;Rickenmann et al, 2016;Rickenmann and Koschni, 2010); (iii) the hydrology and geomorphology Figure 5. Topographic map of the Kleine Emme catchment.…”

Modeling Sediment Yield in Land Surface and Earth System Models: Model Comparison, Development, and Evaluation

“…For the second direction, a simple physically based landslide model could be incorporated into the Morgan model. For the third direction, the calculation of gully erosion requires GIS data of gully density, which is still not available (de Vente & Poesen, ), so we will explore this direction in future studies (Hoober et al, ).…”

Assessment of soil factors controlling ephemeral gully erosion on agricultural fields

“…Several studies have remarked on the importance of different rainfall erosivity parameters on the final value of the TSL recorded (e.g. Archibold et al, 2003;Poesen et al, 2003;Valentin et al, 2005;Capra et al, 2009;Han et al, 2017;Hoober et al, 2017), among others. In order to make the erosion rates for each EG comparable, soil loss was quantified by normalizing the variable TSL through Equation (2) (Yoshimura et al, 2015).…”