Geomorphic process signatures reshaping sub‐humid Mediterranean badlands: 2. Application to 5‐year dataset

Abstract

Badland landscapes exhibit high erosion rates and represent the main source of fine sediments in some catchments. Advances in high‐resolution topographic methods allow analysis of topographic changes at high temporal and spatial scales. We apply the Mapping Geomorphic Processes in the Environment (MaGPiE) algorithm to infer the main geomorphic process signatures operating in two sub‐humid badlands with contrasting morphometric attributes located in the Southern Pyrenees. By interrogating a 5‐year dataset of seasonal and annual topographic changes, we examine the variability of geomorphic processes at multiple temporal scales. The magnitude of geomorphic processes is linked to landform attributes and meteorological variables. Morphometric differences between both adjacent badlands allow us to analyse the role of landform attributes in the main geomorphic process reshaping landscapes subjected to the same external forcing (i.e. rainfall and temperature). The dominant geomorphic process signatures observed in both badlands are different, despite their close proximity and the same rainfall and temperature regimes. Process signatures determining surface lowering in the gently sloping south‐facing badland, characterized by lower connectivity and more vegetation cover, are driven by surface runoff‐based processes, both diffuse (causing sheet washing) and concentrated (determining cutting and filling, rilling and gullying). The steeper, more connected north‐facing slopes of the other badland are reshaped by means of gravitational processes, with mass wasting dominating topographic changes. In terms of processes determining surface raising, both mass wasting and cutting and filling are most frequently observed in both badlands. There is a clear near‐balanced feedback between both surface‐raising and ‐lowering processes that becomes unbalanced at larger temporal scales due to the thresholds overcome, as the volume associated with surface lowering becomes higher than that associated with raising‐based processes. Rainfall variables control surface flow processes, while those variables associated with low temperature have a significant relation with mass movement‐based processes and other localized processes such as regolith cohesion loss. Finally, our results point out that morphometry (slope and connectivity) together with vegetation cover are key factors determining geomorphic processes and associated topographic changes. © 2020 John Wiley & Sons, Ltd.

Quantifying the spatial distribution of sediment transport in an experimental gully system using the morphological method

“…The datasets that result may provide a better means of calibrating and validating models of sediment transport in gullies (Fu et al, 2005;Gordon et al, 2007). It is possible that we can use the derived sediment transport fields to understand the spatial structure of sediment transport and to relate this to distinct geomorphic process signatures (e.g., Llena et al, 2020) and the space-time evolution in within gully sediment connection (Heckmann & Vericat, 2018) and ultimately to test and to refine sediment connectivity indices (e.g., Cavalli et al, 2013). The data can also be used to produce spatially-explicit sediment delivery ratios (Heckmann & Vericat, 2018) and to describe how these evolve through time.…”

Geomorphic process signatures reshaping sub‐humid Mediterranean badlands: 1. Methodological development based on high‐resolution topography

“…The authors thank Prof. Stuart Lane, acting as editor‐in‐chief of the journal Earth Surface Processes and Landforms , his suggestion of considering the research paper submitted by Llena et al . () where the MaGPiE algorithm is applied to a five years dataset and this one as a paper pair or two connected papers. Finally, we thank all comments and suggestions received from two anonymous referees and from the associate editor and the editor‐in‐chief of Earth Surface Processes and Landforms .…”

“…Finally, the authors also thank the British Society for Geomorphology to support the long-term geomorphological monitoring programme in the experimental badland that started in 2013; and the members of the Fluvial Dynamics Research Group for their assistance during the fieldwork campaigns. The authors thank Prof. Stuart Lane, acting as editor-in-chief of the journal Earth Surface Processes and Landforms, his suggestion of considering the research paper submitted by Llena et al (2020) where the MaGPiE algorithm is applied to a five years dataset and this one as a paper pair or two connected papers. Finally, we thank all comments and suggestions received from two anonymous referees and from the associate editor and the editor-in-chief of Earth Surface Processes and Landforms.…”

Evaluating the Ability of Multi-Sensor Techniques to Capture Topographic Complexity

“…RTK-GNSS and TLS datasets in the current research represent control data to examine the precision of the various mobile sensing platforms and their ability to capture the morphometry and topographic complexity in our field site. The findings presented herein provide insights into cost–benefit of purchasing various sUAS and sensors, precision of the sensors across a gradient of complex terrain, and their ability to capture high-definition topography, which is a fundamental boundary condition in numerical and physical modeling experiments [ 13 ] as well as change detection [ 13 , 14 ].…”