Description: Establishing a sediment budget in the newly created “Kleine Noordwaard” wetland area in the Rhine–Meuse delta Eveline Christien van der Deijl, Marcel van der Perk, and Hans Middelkoop Earth Surf. Dynam., 6, 187-201, https://doi.org/10.5194/esurf-6-187-2018, 2018 To study the effectiveness of river delta restoration, we used field observations and elevation data to quantify the magnitude and spatial patterns of aggradation and erosion in a restored wetland in the Rhine-Meuse delta. Erosion and aggradation rates decrease over time, but aggradation compensates for sea-level rise and soil subsidence. Channels in the centre had aggraded, whereas the inlet and outlet eroded. Furthermore, sediment is in general uniformly distributed over the intertidal area.

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., 6, 121-140, https://doi.org/10.5194/esurf-6-121-2018, 2018 Sediments produced by glaciers are transported by rivers and wind toward the ocean. During their journey, these sediments are weathered, and 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 to measure the average time that sediment spends only in the glacial area. This time is 100–200 kyr, which is long and allows a lot of processes to act on sediments during their journey.

Description: Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard) Ruth S. Hindshaw, Nicholas J. Tosca, Alexander M. Piotrowski, and Edward T. Tipper Earth Surf. Dynam., 6, 141-161, https://doi.org/10.5194/esurf-6-141-2018, 2018 For many applications in Earth sciences it is important to know where river and ocean sediments have originated. In this study we used geochemical and mineralogical tracers to characterise sediments from Svalbard. We find that the sediments are formed from two sources: old rocks in Greenland and younger rocks in Siberia. Glaciation influences how much of each end-member is present in the river sediments today, implying that the sediment composition can change through time as the climate changes.

Description: How to explain variations in sea cliff erosion rates? Insights from a literature synthesis Mélody Prémaillon, Vincent Regard, Thomas J. B. Dewez, and Yves Auda Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-12,2018 Manuscript under review for ESurf (discussion: open, 0 comments) Coastal erosion is of major concern for society, our study focus on rocky coast whose evolution remains poorly understood. We use the increasing number of erosion-related data and compiled it for better understanding how and how much rocky coasts erode. We found that rock resistance explain in first order erosion rates whereas influence of climate and sea is secondary. Weak rock coasts loose in median 23 meters per century, about ten times more than hard rock coasts.

Description: Effect of changing vegetation on denudation (part 2): Landscape response to transient climate and vegetation cover Manuel Schmid, Todd A. Ehlers, Christian Werner, Thomas Hickler, and Juan-Pablo Fuentes-Espoz Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-13,2018 Manuscript under review for ESurf (discussion: open, 1 comment) We present a numerial modelling investigation into the interactions between transient climate and vegetation cover with hillslope and fluvial processes. We use a state-of-art landscape evolution model library (Landlab) and designed model experiments to investigate the effect of climate change and associated changes in surface vegetation cover on main basin metrics. This paper is a companion paper to Part 1 (this journal) which investigates the effect of climate change to surface vegetation cover.

Description: Morphology of bar-built estuaries: relation between planform shape and depth distribution Jasper R. F. W. Leuven, Sanja Selaković, and Maarten G. Kleinhans Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-18,2018 Manuscript under review for ESurf (discussion: open, 0 comments) Fluvial-tidal transitions in estuaries are used as major shipping fairways and are characterised by complex bar and channel patterns with a large biodiversity. Habitat suitability assessment and study of interactions between morphology and ecology therefore require bathymetric data. While imagery offers data of planform estuary dimensions, only for a few natural estuaries bathymetries are available. Here we study the relation between along-channel planform geometry, obtained as the outline from imagery, and hypsometry, which characterises the distribution of along-channel and cross-channel bed-levels. We fitted the original function of Strahler (1952) to bathymetric data along four natural estuaries. Comparison to planform estuary shape shows that hypsometry is concave at narrow sections with large channels, while complex bar morphology results in more convex hypsometry. We found a relation between hypsometric function shape and the degree to which the estuary width deviates from an ideal convergent estuary, which is calculated from river width and mouth width. This implies that the occurring bed level distributions depend on inherited Holocene topography and lithology. Our new empirical function predicts hypsometry and along-channel variation in intertidal and subtidal width. Combination with the tidal amplitude allows an estimate of inundation duration. A validation of the results on available bathymetry shows that predictions of intertidal and subtidal area are accurate within a factor 2 for estuaries of different size and character. Locations with major human influence deviate from the general trends, because dredging, dumping, land reclamation and other engineering measures cause local deviations from the expected bed-level distributions. The bathymetry predictor can be used to characterise and predict estuarine subtidal and intertidal morphology in data-poor environments.

Description: Glacial Isostatic Adjustment modelling: historical perspectives, recent advances, and future directions Pippa L. Whitehouse Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-6,2018 Manuscript under review for ESurf (discussion: open, 2 comments) This article is a contribution to a special issue on “Two centuries of modelling across scales”. It describes the historical observations, evolving hypotheses, and early calculations that led to the development of the field known as Glacial Isostatic Adjustment (GIA) modelling, which seeks to understand feedbacks between ice-sheet change, sea-level change, and solid Earth deformation. Recent advances are discussed. Future research in the field is likely to involve an interdisciplinary approach.

Description: Scales of collective entrainment and intermittent transport in collision-driven bed load Dylan B. Lee and Doug Jerolmack Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-8,2018 Manuscript under review for ESurf (discussion: open, 3 comments) The transport of pebbles in a river is smooth and continuous under high flow conditions, but under typical flows becomes erratic and unpredictable. We perform experiments to learn more about the origins of this unpredictable, intermittent behavior. Our results show that this unpredictability is similar to how infrequent avalanches occur in a sandpile. Transport events are similar in size but become more infrequent and erratic as the river transports less and less sediment.

Description: Tracking the 26 Al/ 10 Be source-area signal in sediment-routing systems of arid central Australia Martin Struck, John D. Jansen, Toshiyuki Fujioka, Alexandru T. Codilean, David Fink, Réka-Hajnalka Fülöp, Klaus M. Wilcken, David M. Price, Steven Kotevski, L. Keith Fifield, and John Chappell Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-76,2018 Manuscript under review for ESurf (discussion: final response, 3 comments) Measurements of cosmogenic nuclides 10 Be and 26 Al in sediment along central Australian streams show that lithologically-controlled magnitudes of source-area erosion rates (0.2–11 m/m.y.) are preserved downstream despite sediment mixing. Conversely, downstream-increasing sediment burial signals (〉 400 k.y.) indicate sediment incorporation from adjacent, long-exposed storages, which, combined with low sediment supply and discontinuous flux, likely favours source-area 10 Be- 26 Al signal masking.

Description: Temporal variability in detrital 10 Be concentrations in large Himalayan catchments Elizabeth H. Dingle, Hugh D. Sinclair, Mikael Attal, Ángel Rodés, and Vimal Singh Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2017-73,2018 Manuscript under review for ESurf (discussion: open, 3 comments) Accurately quantifying sediment fluxes in large rivers draining tectonically active landscapes is complicated by the stochastic nature of sediment inputs. Cosmogenic 10 Be concentrations measured in modern river sands have been used to estimate 10 2 –10 4 year sediment fluxes in these types of catchments, where upstream drainage areas are often in excess of 10,000 km 2 . It is commonly assumed that within large catchments, the effects of stochastic sediment inputs are buffered such that 10 Be concentrations at the catchment outlet are relatively stable in time. We present eighteen new 10 Be concentrations of modern river and dated Holocene terrace and floodplain deposits from the Ganga River near to the Himalayan mountain front. We demonstrate that 10 Be concentrations measured in modern Ganga River sediments display a notable degree of variability, with concentrations ranging between ~ 9,000–19,000 atoms g −1 . We propose that this observed variability is driven by two factors. Firstly, by the nature of stochastic inputs of sediment (e.g. the dominant erosional process, surface production rates, depth of landsliding, degree of mixing) and, secondly, by the evacuation timescale of individual sediment deposits which buffer their impact on catchment-averaged concentrations. Despite intensification of the Indian Summer Monsoon and subsequent doubling of sediment delivery to the Bay of Bengal at ~ 11–7 ka, we also find that Holocene sediment 10 Be concentrations documented at the Ganga outlet have remained within the error of modern river concentrations. We demonstrate that in these systems, sediment flux cannot be simply approximated by converting detrital concentration into mean erosion rates and multiplying by catchment area as it is possible to generate considerably larger volumetric sediment fluxes whilst maintaining comparable average 10 Be concentrations.