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: Optimising 4-D surface change detection: an approach for capturing rockfall magnitude–frequency Jack G. Williams, Nick J. Rosser, Richard J. Hardy, Matthew J. Brain, and Ashraf A. Afana Earth Surf. Dynam., 6, 101-119, https://doi.org/10.5194/esurf-6-101-2018, 2018 We present a method to analyse surface change using 3-D data collected at hourly intervals. This is applied to 9000 surveys of a failing rock slope, acquired over 10 months. A higher proportion and frequency of small rockfall is observed than in less-frequent (e.g. monthly) monitoring. However, quantifying longer-term erosion rates may be more suited to less-frequent data collection, which contains lower accumulative errors due to the number of surveys and the lower proportion of small events.

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: Topographical change caused by moderate and small floods in a gravel bed ephemeral river – a depth-averaged morphodynamic simulation approach Eliisa S. Lotsari, Mikel Calle, Gerardo Benito, Antero Kukko, Harri Kaartinen, Juha Hyyppä, Hannu Hyyppä, and Petteri Alho Earth Surf. Dynam., 6, 163-185, https://doi.org/10.5194/esurf-6-163-2018, 2018 This paper analyses the timing of topographical changes of a gravel bed ephemeral river channel during consecutive and moderate- and low-magnitude floods by applying a morphodynamic model calibrated with pre- and post-event surveys using RTK-GPS and mobile laser scanning. The channel acted as a braided river during lower flows but as a meandering river during higher flows. The channel changes can be greater during the long-lasting receding phase than during the rising phase of the floods.

Description: Mechanical State of Gravel Soil in Mobilization of Rainfall-Induced Landslide in Wenchuan seismic area, Sichuan province, China Liping Liao, Yunchuan Yang, Zhiquan Yang, Yingyan Zhu, Jin Hu, and D. H. Steve Zou Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-15,2018 Manuscript under review for ESurf (discussion: open, 0 comments) Although gravel soils generated by seismic shaking in Wenchuan earthquake area have subjected to natural consolidation process for nearly ten years, geological hazards, such as slope failures with ensuing landslides, frequently are haunting the area. In this paper, artificial flume model tests and triaxial tests were used to make close observation on the mechanical state of gravel soil in Wenchuan seismic area. The results showed that: (1) The timing and patterns of landslide initiations were closely related to their initial dry densities, and the initiation processes were accompanied with a variation of dry density and void ratio; (2) Fine particle migration in soil and coarse-fine particle content rearrangement contributed to the internal micro structure reorganization, which was supposed to be the main reason for variation of dry density and void ratio; (3) Gravel soils with unchanged grain compositions, if under the same hydrostatic compression, they approached to an identical critical void ratio to fail; (4) The mechanical state of certain sort of gravel soil can be identified by its relative position between state parameter ( e, p' ) and e c -p' planar critical state line; (5) Gravel soil slope failed and then evolved into landslide under lasting rainfall leaching, while in gravel slope there co-existed soil dilatation and contraction, but the dilatation was dominant. Above research findings not only could be used to interpret landslide initiation but also would provide an insight for landslide warning forecast of gravel slope in seismic area.

Description: How concave are river channels? Simon M. Mudd, Fiona J. Clubb, Boris Gailleton, and Martin D. Hurst Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-7,2018 Manuscript under review for ESurf (discussion: open, 1 comment) Rivers can reveal information about erosion rates, tectonics, and climate. In order to make meaningful inferences about these influences one must be able to compare headwaters to downstream parts of the river network. We describe new methods for normalizing river steepness for drainage area to better understand how rivers record erosion rates in eroding landscapes.

Description: A lattice grain model of hillslope evolution Gregory E. Tucker, Scott W. McCoy, and Daniel E. J. Hobley Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-4,2018 Manuscript under review for ESurf (discussion: open, 0 comments) This article presents a new technique for computer simulation of slope forms. The method provides a way to study how events that disturb soil or turn rock into soil add up over time to produce landforms. The model represents a cross section of a hypothetical landform is represented as a lattice of cells, each of which may represent air, soil, or rock. Despite its simplicity, the model does a good job of simulating a range of common of natural slope forms.

Description: Statistical modeling of the long-range dependent structure of barrier island framework geology and surface geomorphology Bradley A. Weymer, Phillipe Wernette, Mark E. Everett, and Chris Houser Earth Surf. Dynam. Discuss., https//doi.org/10.5194/esurf-2018-5,2018 Manuscript under review for ESurf (discussion: open, 0 comments) This research presents a new method for quantifying the geologic controls on modern barrier island evolution. We used statistical time series analysis to evaluate the scale-dependent vs. scale-independent behavior of a barrier island in south Texas, USA. By integrating subsurface geophysical with surface geomorphological measurements we show that the island exhibits both free, and forced evolutionary behavior that has important implications for how the island may respond to rising sea levels.

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: 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.