Description: U-Th and 10 Be constraints on sediment recycling in proglacial settings, Lago Buenos Aires, Patagonia Antoine Cogez, Frédéric Herman, Éric Pelt, Thierry Reuschlé, Gilles Morvan, Christopher M. Darvill, Kevin P. Norton, Marcus Christl, Lena Märki, and François Chabaux Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-45,2017 Manuscript under review for ESurf (discussion: open, 0 comments) Sediment produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and all together we know that this has an impact on climate. One key factor is time, but the duration of this journey is largely unknown. We were able here to measure the average time that sediment spend only in the glacial area. This time is 100–200 kyr, which is long and allow lot of processes to act on those sediments during their journey.

Description: Identification of stable areas in unreferenced laser scans for automated geomorphometric monitoring Daniel Wujanz, Michael Avian, Daniel Krueger, and Frank Neitzel Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-41,2017 Manuscript under review for ESurf (discussion: open, 0 comments) The importance of increasing the degree of automation in the context of monitoring natural hazards or geological phenomena is apparent. A vital step in the processing chain of monitoring deformations is the transformation of captured epochs into a common reference systems. This lead to the motivation to develop an algorithm that realibly carries out this task. The algorithm was tested on three different geomorphic events while the results were quite satisfactory.

Description: Extracting information on the spatial variability in erosion rate stored in detrital cooling age distributions in river sands Jean Braun, Lorenzo Gemignani, and Peter van der Beek Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-42,2017 Manuscript under review for ESurf (discussion: open, 0 comments) We present a new method to interpret a type of data that geologists obtained by dating minerals in river sand samples. We show that such data contains information about the spatial distribution of erosion rate (wear of surface rocks by natural processes such as river incision, land sliding or weathering) in the regions neighboring the river. This is important to understand the nature and efficiency of the processes responsible for surface erosion in mountain belts.

Description: Efficient retention of mud drives land building on the Mississippi Delta plain Christopher R. Esposito, Zhixiong Shen, Torbjörn E. Törnqvist, Jonathan Marshak, and Christopher White Earth Surf. Dynam., 5, 387-397, https://doi.org/10.5194/esurf-5-387-2017, 2017 Our work presents a novel method of measuring the capacity of deltaic landforms to trap and retain river-borne sediments, and we demonstrate that sediment retention is closely connected to sedimentary composition. Our results, supported by a unique high-resolution coring dataset in a major crevasse splay, show that finer sediments are a much larger component of the Mississippi Delta than is often acknowledged and that their abundance indicates exceptionally high rates of sediment retention.

Description: Geomorphometric delineation of floodplains and terraces from objectively defined topographic thresholds Fiona J. Clubb, Simon M. Mudd, David T. Milodowski, Declan A. Valters, Louise J. Slater, Martin D. Hurst, and Ajay B. Limaye Earth Surf. Dynam., 5, 369-385, https://doi.org/10.5194/esurf-5-369-2017, 2017 Floodplains and fluvial terraces can provide information about current and past river systems, helping to reveal how channels respond to changes in both climate and tectonics. We present a new method of identifying these features objectively from digital elevation models by analysing their slope and elevation compared to the modern river. We test our method in eight field sites, and find that it provides rapid and reliable extraction of floodplains and terraces across a range of landscapes.

Description: Quantifying uncertainty in high-resolution remotely sensed topographic surveys for ephemeral gully channel monitoring Robert R. Wells, Henrique G. Momm, and Carlos Castillo Earth Surf. Dynam., 5, 347-367, https://doi.org/10.5194/esurf-5-347-2017, 2017 As technology presents a gateway to finer-resolution survey information, caution must be exercised in the evaluation of alignment error and subsequent morphological determinations. Three survey technologies were evaluated: ground-based photogrammetry, unmanned aerial vehicle photogrammetry, and ground-based lidar. Initial project planning necessitates the effective use of ground control to facilitate alignment and proper morphological conclusions.

Description: Bayesian inversion of a CRN depth profile to infer Quaternary erosion of the northwestern Campine Plateau (NE Belgium) Eric Laloy, Koen Beerten, Veerle Vanacker, Marcus Christl, Bart Rogiers, and Laurent Wouters Earth Surf. Dynam., 5, 331-345, https://doi.org/10.5194/esurf-5-331-2017, 2017 Over very long timescales, 100 000 years or more, landscapes may drastically change. Sediments preserved in these landscapes have a cosmogenic radionuclide inventory that tell us when and how fast such changes took place. In this paper, we provide first evidence of an elevated long-term erosion rate of the northwestern Campine Plateau (lowland Europe), which can be explained by the loose nature of the subsoil.

Description: 3D topographic monitoring of earth surface deformation using multitemporal UAV photography François Clapuyt, Veerle Vanacker, Fritz Schlunegger, and Kristof Van Oost Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-38,2017 Manuscript under review for ESurf (discussion: open, 0 comments) Accurately assessing geohazards and quantifying landslide risks in mountainous environments gain importance in the context of the on-going global warming. For an in-depth understanding of slope failure mechanisms, accurate monitoring of the mass movement topography at high spatial and temporal resolutions remains essential. The choice of the acquisition framework for high-resolution topographic reconstructions will result from the trade-off between the spatial resolution needed and the extent of the study area. Recent advances in the development of UAV-based (Unmanned Aerial Vehicle) image acquisition combined with Structure-from-Motion (SfM) algorithm for 3D reconstruction makes the UAV-SfM framework a competitive alternative to other high-resolution topographic techniques. In this study, we test the performance of the UAV-SfM framework to monitor ground surface displacements at very high spatial and temporal resolution, and apply it to the Schimbrig earthflow located in the foothills of the Central Swiss Alps. We produced distinct topographic datasets for three acquisition dates between 2013 and 2015 in order to conduct a comprehensive 3D analysis of the landslide. Therefore, we computed (1) the horizontal and (2) the 3-dimensional surface displacements, and (3) the sediment budget of the hillslope. The multitemporal UAV-SfM based topographic reconstructions allowed us to quantify rates of sediment redistribution and surface movements. Our data show that the Schimbrig earthflow is very active with mean annual horizontal displacement ranging between 6 and 9 meters. The reconstruction of the dynamic topography at very high spatial resolution reveals the internal mechanisms of the earthflow and its complex rotational structure. Although there are major changes in the internal structure of the earthflow in the 2013–2015 period, the sediment budget of the drainage basin is nearly in equilibrium. As a consequence, our data show that the time lag between sediment mobilization by landslides and enhanced sediment fluxes in the river network can be considerable.

Description: A hydro-climatological approach to predicting regional landslide probability using Landlab Ronda Strauch, Erkan Istanbulluoglu, Sai Siddhartha Nudurupati, Christina Bandaragoda, Nicole M. Gasparini, and Gregory E. Tucker Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-39,2017 Manuscript under review for ESurf (discussion: open, 0 comments) We develop a model of annual probability of shallow landslide initiation triggered by soil water from a hydrologic model. Our physically-based model accommodates data uncertainty using a Monte Carlo approach. We found elevation-dependent patterns in probability related to the stabilizing effect of forests and soil and slope limitation at high elevations. We demonstrate our model in Washington, U.S.A., but it is designed to run elsewhere with available data for risk planning using the Landlab.

Description: A probabilistic framework for the cover effect in bedrock erosion Jens M. Turowski and Rebecca Hodge Earth Surf. Dynam., 5, 311-330, https://doi.org/10.5194/esurf-5-311-2017, 2017 Bedrock incision by rivers is driven by the impacts of sediment particles moved by the water flow. Sediment residing on the bed can protect the rock from impacts, thereby reducing erosion rates, a phenomenon known as the cover effect. The cover effect has been shown to be important in many field and laboratory experiments. Here, we develop a mathematical framework to describe the cover effect which can be used to compare data and to predict the extent of cover in streams.