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The outer bank slump blocks play a fundamental role in modulating the rate of bank erosion, and consequently, have a profound influence on many geomorphic and ecologic processes in meandering streams, e.g., channel evolution and habitat creation. To date, no adequate research has been developed regarding how these blocks, partially strengthened by roots of herbaceous plants, impact the near-bank flow velocity, bank erosion, and migration of streambanks. This paper analyzes 246 slump blocks in a meandering stream on the Marqu Meadow, China. Aerial surveys were conducted once a year from 2018 to 2021 and the lateral migration rates (M) of streambanks are estimated by superimposing the current-year drone imagery onto its previous-year counterpart. When compared to the outer bank segments lacking slumps, our research findings indicate that the bank segments exhibiting slumps demonstrate a reduction of 57 % and 43 % in the maximum and average bank erosion rates, respectively. Overall, the wider blocks provide stronger bank protection; nevertheless, they may also introduce or enhance local scouring in their vicinity, thereby increasing the heterogeneity of bank erosion rates. To elucidate this complex influence mechanism, we simulate the three-dimensional flow velocity field of a ~100 m meandering bend containing three slump blocks using the MIKE-3 model. Furthermore, we compare one-year bank migration distance with and without the blocks by correlating the lateral migration distance of outer banks to the longitudinal gradient of near-bank velocity. The paper provides valuable insights into the complex interplay between flow dynamics and streambank behavior in real-world settings, thereby enhancing the effectiveness of future management and restoration practices. • 246 slump blocks were analyzed in a meander on Marqu Meadow, China. • Slump blocks can persist for years but may be washed away in high flows. • The outer bank slump blocks play a vital role in modulating bank erosion rates. • Slump blocks protect outer banks by redistributing the high flow and secondary flow. • Slump blocks help protect bank overall but it may introduce scour in their vicinity. [ABSTRACT FROM AUTHOR]

Urban infrastructures built over karst settings may be at risk of collapse due to hydro-chemical erosion of underlying rock structures. In such settings, mapping cave networks and monitoring ground stability is important to assure civil safety and guide future infrastructure development decisions. However, no technique can directly and comprehensively map these hydrogeological features and monitor their stability. The most reliable method to map a cave network is through speleological exploration, which is not always possible due to restrictions, narrow corridors/passages, or high water levels. Borehole drilling is expensive and is often only performed where the presence of karsts is suggested by other techniques. Numerous indirect and cost-effective methods exist to map a karst flow system, such as geophysics, geodesy, and tracer tests. This paper presents the outcomes from a challenging application in Quebec City, Canada, where a multidisciplinary approach was designed to better understand the groundwater dynamics and cave paths. Two tracer tests in groundwater flowing through the cave system indicated that water flows along an approximately straight path from the sinking stream to the spring. It also suggests the presence of a parallel flow path close to the one already partially mapped. This observation was confirmed by combining Ground Penetrating Radar (GPR) and Electrical Resistivity Tomography (ERT) techniques, and ultimately by observing voids in several boreholes drilled close to the main cave path. Lowering the water levels at the suspected infiltration zone and inside the karst, the infiltration cracks were identified and the hydraulic link between them was confirmed. In fact, almost no infiltration occurs into the karst system when the water level at the sinking stream drops below a threshold level. Finally, SAR interferometry (InSAR) using RADARSAT-2 images detected movements on few buildings located over a backfilled sinkhole intercepted by the karst system and confirmed the stability of the rest of the karst area. The knowledge of the flow system described in this paper is used by policy makers to assure civil security of this densely populated area. [ABSTRACT FROM AUTHOR]

The quantitative estimation of changes in terrain surfaces caused by water erosion can be carried out from precise descriptions of surfaces given by means of digital elevation models (DEMs). Some stages of water erosion research efforts are conducted in the laboratory using rainfall simulators and soil boxes with areas less than 1 m 2 . Under these conditions, erosive processes can lead to very small surface variations and high precision DEMs are needed to account for differences measured in millimetres. In this paper, we used a photogrammetric Structure from Motion (SfM) technique to build DEMs of a 0.5 m 2 soil box to monitor several simulated rainfall episodes in the laboratory. The technique of DEM of difference (DoD) was then applied using GIS tools to compute estimates of volumetric changes between each pair of rainfall episodes. The aim was to classify the soil surface into three classes: erosion areas, deposition areas, and unchanged or neutral areas, and quantify the volume of soil that was eroded and deposited. We used a thresholding criterion of changes based on the estimated error of the difference of DEMs, which in turn was obtained from the root mean square error of the individual DEMs. Experimental tests showed that the choice of different threshold values in the DoD can lead to volume differences as large as 60% when compared to the direct volumetric difference. It turns out that the choice of that threshold was a key point in this method. In parallel to photogrammetric work, we collected sediments from each rain episode and obtained a series of corresponding measured sediment yields. The comparison between computed and measured sediment yields was significantly correlated, especially when considering the accumulated value of the five simulations. The computed sediment yield was 13% greater than the measured sediment yield. The procedure presented in this paper proved to be suitable for the determination of sediment yields in rainfall-driven soil erosion experiments conducted in the laboratory. [ABSTRACT FROM AUTHOR]

We explore the assumption that uplift drives erosion and hence, more dissected (eroded) terrains may indicate areas subject to more intense uplift than others, especially if other factors such as elevation and geology can be demonstrated as inconsistent with the spatial pattern of dissection. Geomorphometry and statistics are employed to recognize the enhanced erosional signal within a medium-altitude mountain terrain of the Sudetes in Central Europe, considered as a representative for moderately uplifted areas of complex bedrock diversity. This signal is understood as a meso-scale reflection of relief properties, whereas the recognition of homogeneous terrain units, different in terms of strength of erosional signal, is carried out by means of multi-criteria terrain classification, involving Principal Component Analysis and k-means grouping. Four groups covering 45% of the area have been identified. They were quantitatively compared with independent variables of altitude, lithology, structural units and rock strength, and also assessed in relation to rainfall pattern. It is concluded that their dependence on altitude and geology is only partial. Then, three types of dissected terrain are distinguished and interpreted in terms of uplift intensity, rock strength as a factor modulating erosional response to uplift and timescale. The spatial distribution of these types of terrain indicates several isolated 'hot spots' of erosional dissection on predominantly strong rocks, linked by less elevated areas, underlain by rocks of variable strength. The former are considered as having longer history of uplift and dissection, dated back to the late Palaeogene, whereas the latter record more recent history of endo -exogenic interactions, possibly since the late Miocene. The presence of canyon-like valleys incised into planar or gently sloping relief may indicate the most recent pulse of relief rejuvenation. The procedure proposed in the paper is suitable to be used in various settings, given that good quality topographic data are available. • Areas highly dissected by erosion identified through multi-variate relief classification. • Altitude, lithology and rock strength only partially explain the spatial pattern of dissection. • Different timing of uplift inferred from patterns of erosional dissection. [ABSTRACT FROM AUTHOR]

Investigations comparing surface downwearing rates derived from photogrammetry data and the micro-erosion meters (MEM) are limited due to the former's coarse spatial resolution and the temporal scale of data collection. These space and time limitations were revisited with the possibility of simultaneously using the Structure-from-Motion (SfM) photogrammetric workflow and the MEM. Using a cross-scale nested survey approach over one year to cover micro (10−2 m2) and meso (100 m2)-spatial scales, this paper presents erosion rates on uplifted intertidal shore platforms and marine terraces at Kaikōura Peninsula, New Zealand. The survey represents one of the first investigations combining the MEM and the SfM technique to estimate erosion rates on horizontal coastal bedrock. In a unique way, we applied established methods which allowed comparative accuracy between models via similar point matching to provide a detailed representation and visualisation of the changing rock surfaces at similar spatial and temporal scales. Over one year, across a microscale area (~0.01 m2) of rock, the MEM and SfM point clouds (SfM PCs) measured the lowest and highest erosion rates on a similar rock type and erosion site. The mean annual erosion rate of 2.244 mm/yr from the MEM was lower than the rates of 2.608 mm/yr and 10.299 mm/yr estimated using the SfM micro- and mesoscale PCs, respectively. A lower range of erosion rates (0.131 to 4.750 mm/yr) was measured using the MEM compared to erosion rates estimated from the SfM microscale PCs (0.194 to 10.106 mm/yr). Across the mesoscale (1 m2) areas, higher erosion rates were recorded using the SfM mesoscale PCs on all but one erosion site showing that a significant amount of erosion was undetected by the MEM. Using the SfM-orthomosaics, we link the erosion rates measured across the micro and mesoscale areas to intense granular disintegration, flaking, micro- and polygonal cracking and biological activities. These results provide statistical evidence to argue against extrapolating MEM erosion data obtained over small areas to larger areas on shore platforms affected by recent tectonic uplift. The implications of these findings are considered within the context of techniques for measuring shore platform erosion across spatial and temporal scales. • Erosion rates were acquired at similar spatial and temporal scales using MEM and SfM • A significant amount of shore platform erosion was undetected by the MEM • SfM PC models provided higher mean erosion rates for the micro (~0.01 m2) and mesoscale areas (1 m2) • Statistically similar mean erosion rates across microscale areas support substituting techniques. • MEM efficacy at capturing maximum erosion across microscale areas on the Kaikōura shore platforms has diminished [ABSTRACT FROM AUTHOR]

Rocky shores occur along much of the world's coastline and include a wide range of coastal morphologies, such as intertidal shore platforms. Considerable research effort has been placed on trying to understand developmental processes on rocky shores, but progress has been forestalled because these landscapes develop slowly and preserve little evidence of evolution through time. This paper presents a new exploratory numerical model developed to study long-term shore profile evolution on rock coasts. The model purposely considers only a limited number of processes, each represented in a highly abstracted way. Despite these simplifications, the model exhibits a large range of emergent shore profile shapes. This behavior is enabled both by broader spatial representation of the driving erosion forces and the flexibility provided by a grid discretization scheme. Initial model testing shows the development of varied rocky profile geometries, ranging from steep plunging cliffs, cliffs with narrow benches, and cliffs with a variety of shore platform shapes. Most of the model geometries are similar to those observed in the field, and model behavior is robust and internally consistent across a relatively large parameter space. This paper provides a detailed description of the new model and its subsequent testing. Emphasis is placed on comparison of model results with published field observations in which morphometric relationships are described between shore platform gradient and tidal range, and platform elevation and platform width. The model adequately simulates these morphometric relationships, while retaining its ability to simulate a wide range of profile shapes. The simplicity of process representations, and the limited number of processes implemented, means that model outputs can be interpreted reasonably easily. Hence, an opportunity is now provided, following the testing described in this paper, to use the model to systematically investigate the broader controlling conditions on rock shore profile development. [ABSTRACT FROM AUTHOR]

Abstract Geo-spatial studies are increasingly using photogrammetry technology because the cost of the equipment is becoming cheaper, the techniques are accessible to non-experts and can generate better quality topographic data than traditional approaches. NSPAS (Near-Surface Photogrammetry Assessment of Surface Roughness) was developed to quantify the micro-topographic changes in ground surface roughness caused by simulated rainfall, to better understand the comparative erodibility of two non-soil and one soil slope forming materials from a mine in West Africa. This innovative approach creates DEMs (digital elevation models) using image pairs acquired by near-surface stereo photogrammetry (<300 m), to measure surface roughness within Leica Photogrammetry Suite 2011 (LPS) in ERDAS Imagine software and ESRI Arc-GIS. NSPAS can readily quantify aggregate breakdown processes across a 0.02 m2 surface by accurately detecting 0.84 mm to 2.49 mm changes in surface topography. The methodology is advantageous to micro-scale (<1 cm2) studies that require a high number of accurate DEMs, because it will produce image pairs even when the target does not have contrasting surface features in shot, which can be a constraint for the automated technique Structure from Motion. This paper demonstrates how NSPAS is more suitable to assess erosion from slope forming materials that do not have a high content of large rocks (>2 mm) at the surface. With further development NSPASS has the capability to be used in many other types of geospatial investigations. [ABSTRACT FROM AUTHOR]

Hillslope erosion and accelerated lake sedimentation are often reported as the source and main stores of sediment in the upland sediment cascade during extreme flood events. While upland valley floodplain systems in the transfer zone have the potential to influence sediment continuity during extreme events, their geomorphic response is rarely quantified. This paper quantifies the sediment continuity through a regulated upland valley fluvial system (St John's Beck, Cumbria, UK) in response to the extreme Storm Desmond (4–6 December 2015) flood event. A sediment budget framework is used to quantify geomorphic response and evaluate sediment transport during the event. Field measurements show 6500 ± 710 t of sediment was eroded or scoured from the river floodplains, banks and bed during the event, with 6300 ± 570 t of sediment deposited in the channel or on the surrounding floodplains. <6% of sediment eroded during the flood event was transported out of the 8 km channel. Floodplain sediment storage was seen to be restricted to areas of overbank flow where the channel was unconfined. Results indicate that, rather than upland floodplain valleys functioning as effective transfer reaches, they instead comprise significant storage zones that capture coarse flood sediments and disrupt sediment continuity downstream. [ABSTRACT FROM AUTHOR]

Numerical modeling of landform evolution is the key to understanding the formation of land surfaces. However, landform evolution occurs under certain initial topographic conditions, while existing landform evolution models often use a plane or a randomly produced surface to establish the initial topographic conditions. This misunderstanding of the initial topographic conditions causes the landform evolution results to deviate greatly from the real terrain. Therefore, the initial topographic conditions must be reconstructed and integrated into the current numerical landform evolution model. In this paper, the Loess Plateau of China was selected as a typical sample area. The paleotopography was reconstructed and integrated into the numerical landform evolution model. Based on the evolutionary mechanism of loess landforms, modules of surface erosion, matter diffusion and precipitation were selected to construct a numerical model of loess landform evolution. Moreover, randomly produced terrain was used as the initial conditions during the landform evolution process and compared with the paleotopography-constrained evolution results. In addition, the results of the landform evolution process were evaluated with different terrain factors, and the uncertainty of the model was assessed by comparing different model conditions. The results show that, due to the control of paleotopography, the evolution results can maintain the main morphological structure of valleys in the loess landscape. Without considering the paleotopography, a large difference exists between the evolution results and the true ground terrain. These results show that paleotopography is an important feature of loess landform evolution modeling and is indispensable for reasonably expressing the process of landform evolution. Finally, the numerical modeling of loess landform evolution with the consideration of paleotopography can not only help to achieve a better understanding of the loess landform evolution process but also provide a reference for feature dependent landform evolution modeling in different landform applications. • Paleotopography affects the evolution of loess landform in the Loess Plateau. • We integrate the paleotopography into the numerical loess landform evolution model. • Our results can maintain the main morphological structure of loess landform. • Our research provides a reference for feature-concerned landform evolution modeling. [ABSTRACT FROM AUTHOR]

Meandering river channels are often associated with cohesive banks. Yet only a few river modelling packages include geotechnical and plant effects. Existing packages are solely compatible with single-threaded channels, require a specific mesh structure, derive lateral migration rates from hydraulic properties, determine stability based on friction angle, rely on nonphysical assumptions to describe cutoffs, or exclude floodplain processes and vegetation. In this paper, we evaluate the accuracy of a new geotechnical module that was developed and coupled with Telemac-Mascaret to address these limitations. Innovatively, the newly developed module relies on a fully configurable, universal genetic algorithm with tournament selection that permits it (1) to assess geotechnical stability along potentially unstable slope profiles intersecting liquid-solid boundaries, and (2) to predict the shape and extent of slump blocks while considering mechanical plant effects, bank hydrology, and the hydrostatic pressure caused by flow. The profiles of unstable banks are altered while ensuring mass conservation. Importantly, the new stability module is independent of mesh structure and can operate efficiently along multithreaded channels, cutoffs, and islands. Data collected along a 1.5-km-long reach of the semialluvial Medway Creek, Canada, over a period of 3.5 years are used to evaluate the capacity of the coupled model to accurately predict bank retreat in meandering river channels and to evaluate the extent to which the new model can be applied to a natural river reach located in a complex environment. Our results indicate that key geotechnical parameters can indeed be adjusted to fit observations, even with a minimal calibration effort, and that the model correctly identifies the location of the most severely eroded bank regions. The combined use of genetic and spatial analysis algorithms, in particular for the evaluation of geotechnical stability independently of the hydrodynamic mesh, permits the consideration of biophysical conditions for an extended river reach with complex bank geometries, with only a minor increase in run time. Further improvements with respect to plant representation could assist scientists in better understanding channel-floodplain interactions and in evaluating channel designs in river management projects. [ABSTRACT FROM AUTHOR]

In this paper, we retrace the geomorphological evolution of a 6.5 km-long segment of the Blanco Este River, which drains the Calbuco volcano in southern Chile, highlighting the geomorphic signatures of the disturbances caused by the 1961 and 2015 eruptions. In particular, we track the geomorphological changes and the evolution of the geomorphological units and discuss the underlying processes. In addition, we use the NDVI (Normalize Difference Vegetation Index) to characterise the vegetation recovery at the basin and the active channel scales. The reconstruction of the geomorphological changes is performed by means of photointerpretation and supervised classification image analysis. Moreover, we quantify braiding indices and active channel widths to characterise the fluvial corridor and to describe its evolution after the two eruptive events. It is found that the evolutionary trajectories of the Blanco River immediately after the eruptive events of 1961 and 2015 exhibited strong similarities. In fact, the major geomorphological adjustment of the Blanco Este River occurred during the first period of observation (19 years) after the 1961 eruption. Subsequently the river progressed gradually towards an advanced relaxation stage in 2014. For 53 years (between 1961 and 2014), the reduction of the active channel width was the dominant process, followed by erosion, which favoured the regeneration and consequent expansion of vegetation cover within the river corridor. The 2015 eruption reset the fluvial landform and a new cycle of sedimentation, braiding and formation of central bars began; the highly dynamic pattern is still observed today. [ABSTRACT FROM AUTHOR]

Unsteadiness of the vertical velocity profile and secondary flow in open channel bends poses serious problems in hydraulic engineering design. Insertion of vertical submerged vanes in the channel bend at an optimum angle with the tangential component of flow can minimize the unsteadiness and generation of secondary flow resulting in the reduction of scour depth at the outer bank. A series of experiments were conducted in a 180° bend laboratory channel to study flow erosion and effective ness of the submerged vane in reducing scour depth. The average approach to flow velocity at 0.20 m flow depth above the lowest initial bed level was 25 cm/s. An Acoustic Doppler Velocimeter (ADV) was used to measure the three-dimensional time-averaged velocity components at different azimuthal sections on stabilized nonscoured beds without vane. Scour bed profile without vanes shows that bank erosion in a 180° parabolic-shaped bed channel occurs mostly at the zone from bend angles 120° to 140°. Vanes were installed at angles of 10°, 15°, 20°, 30°, and 40° to the tangential flow component maintaining a spacingof 75 cm distance from one vane to another. Experimental results show that a 15° vane angle produces best result in reducing outer bank scour in a parabolic-shaped channel. The data presented in this paper can also be used for validating three-dimensional turbulence models for simulating flows in a curved channel. [ABSTRACT FROM AUTHOR]

High resolution digital models, combined with GIS or other terrain modelling software, allow many new possibilities in geoscience. In this paper we develop, describe and test a novel method, the GLA method, to detect active tectonic uplift or subsidence along river courses. It is a modification of Hack's SL-index method in order to overcome the disadvantages of the latter. The core assumption of the GLA method is that over geological time river profiles quickly adjust to follow an exponential decrease in elevation along the river course. Any large deviation can be attributed to active tectonic movement, or to disturbances in erosion/sedimentation processes caused by an anthropogenic structure (e.g. artificial dam). During the testing phase, the locations of identified deviations were compared to the locations of faults, identified on a 1:100,000 geological map. Results show that higher magnitude deviations are found within a maximum radius of 200 m from the fault, and the majority of detected deviations within a maximum radius of 600 m from faults or thrusts. However, these results are not the best that could be obtained because the geological map that was used (and the only one available for the area) is not of the appropriate scale, and was therefore not precise enough. Comparison of deviation magnitudes against PSInSAR measurements of vertical displacements in the vicinity revealed that in spite of the very few suitable points available, a good correlation between both independent methods was obtained (R 2 = 0.68 for the E research area and R 2 = 0.69 for the W research area). The GLA method was applied to the three test sites where previous studies have shown active tectonic movements. It shows that deviations occur at the intersections between active faults and river courses, as well as also correctly detected active uplift, attributed to the increased sedimentation rate above an artificial hydropower dam, and an increased erosion rate below. The method gives promising results, and it is acknowledged that the GLA method needs to be tested in other locations around the world. [ABSTRACT FROM AUTHOR]

Gully erosion represents one of the most significant types of land degradation in the Mediterranean areas, giving place to important on- and off-site effects. In this paper, a second-order gully located in SW Spain is analyzed. Along the gully, 28 cross-sections were established and measured with a Leica TCRM1102 laser total station, approximately every 6 months from 2001 to 2007. The sections were located at variable distance, placing them in areas where active erosion was evident. In total, 13 field measurements were carried out, and the geometric characteristics of 28 cross-sections were obtained. Morphometric analyses were carried out in both the main gully and a tributary reach by applying an empirical relationship between channel length and eroded volume. Morphometric variables of the gully sections were combined into two dimensionless groups, and a morphological similarity between different linear erosion landforms (rills, ephemeral and permanent gullies) was obtained. Then, the coefficient of variation of the calculated volumes was used to compare the instability between the main gully and the tributary reach. Finally, the hydraulic geometry of the gully was assessed by calibrating three empirical power equations, which relate bankfull discharge with mean flow velocity, cross-sectional depth and width. The hydraulic characterization of the main gully and the tributary reach was investigated for each field survey and a different behavior was detected. The hydraulic analysis also demonstrated that higher values of discharge provide better predictions of flow velocity; the size of the main and tributary gullies affects the discharge–width relationship; and that gully depth is the variable which can be predicted with the highest accuracy. [ABSTRACT FROM AUTHOR]

Abstract: The ability to develop spatially distributed models of topographic change is presenting new capabilities in geomorphic research. High resolution maps of elevation change indicate locations, processes, and rates of geomorphic change, and provide a means of calibrating temporal simulation models. Methods of geomorphic change detection (GCD), based on gridded models, may be applied to a wide range of time periods by utilizing cartometric, remote sensing, or ground-based topographic survey data to measure volumetric change. Advantages and limitations of historical DEM reconstruction methods are reviewed with a focus on coupling them with subsequent DEMs to construct DEMs of difference (DoD), which can be created by subtracting one elevation model from another, to map erosion, deposition, and volumetric change. The period of DoD analysis can be extended to several decades if accurate historical DEMs can be generated by extracting topographic data from historical data and selecting areas where geomorphic change has been substantial. The challenge is to recognize and minimize uncertainties in data that are particularly elusive with early topographic data. This paper reviews potential sources of error in digitized topographic maps and DEMs. Although the paper is primarily a review of methods, three brief examples are presented at the end to demonstrate GCD using DoDs constructed from data extending over periods ranging from 70 to 90years. [Copyright &y& Elsevier]

Abstract: Numerous reports of “flash floods”, “mud torrents” and “landslides” in burnt landscapes of south-east Australia were only recently linked to debris flows and recognised as a significant process that warrant more detailed investigation. This paper provides a systematic documentation of high-magnitude erosion events after wildfire in south-east Australia, focusing on small (<5km2), upland catchments in eastern Victoria that were burnt by wildfire between 2003 and 2009. The aims of the study were to i) collect and show evidence of debris flow occurrence after wildfire; ii) quantify erosion rates from debris flows and; iii) identify rainfall thresholds and key hydrological properties. The result showed that 13 out of the 16 recorded high-magnitude erosion events were runoff generated debris flows. These occurred in dry eucalypt forests burnt at high or very high severity in steep headwater catchments throughout the eastern uplands of Victoria. The debris flows were triggered by intense, short duration rainfall events (I 30 35–59mmh−1) with annual exceedance probability in the order of 20%. This is the first paper to document the occurrence of post-fire runoff generated debris flows in Australia, so the discussion draws on literature from the western USA, where a large body of research has been dedicated to evaluating the risk posed by post-fire debris flows and their role in landscape processes. Typical features common to both systems include low infiltration capacity of burnt catchments; widespread sheet erosion and levee lined rills on steep upper hillslopes; and severe channel erosion initiated in response to convergent flow in previously un-scoured drainage lines. The depth of sheet erosion on surveyed slopes in the upper catchments (4.6±0.96 mm to 18.4±2.7mm) indicates that hillslope material provides an important source of sediment. The average channel entrainment rate of three debris flows ranged from 0.6 to 1.4m3 m−1. Runoff generated debris flows were not recorded in wet or damp forest types suggesting that this process is unlikely to operate in these forest environments. One isolated case of mass failure generated debris flow was recorded in wet forest. The outcome of the study indicates that runoff generated debris flows in dry eucalypt forest are an important process to be considered during post-fire risk assessment of hydrological hazards. [Copyright &y& Elsevier]

Abstract: A jökulhlaup burst from the head of Grasshopper Glacier in Wyoming''s Wind River Mountains during early September 2003. Five reaches with distinct sedimentation patterns were delineated along the Dinwoody Creek drainage. This paper focuses on a portion of the jökulhlaup route where erosion of the forested banks created 16 large logjams spaced at longitudinal intervals of tens to hundreds of meters. Aggradation within the main channel upstream from each logjam created local sediment wedges, and the jams facilitated overbank deposition during the jökulhlaup. Field surveys during 2004 and 2006 documented logjam characteristics and associated erosional and depositional features, as well as initial modification of the logjams and flood deposits within the normal seasonal high-flow channel. Overbank deposits have not been altered by flows occurring since 2003. Field measurements supported three hypotheses that (i) logjams present along the forested portions of the jökulhlaup route are larger and more closely spaced than those along adjacent, otherwise comparable stream channels that have not recently experienced a jökulhlaup; (ii) logjams are not randomly located along the jökulhlaup route, but instead reflect specific conditions of channel and valley geometry and flood hydraulics; and (iii) the presence of logjams facilitated significant erosional and depositional effects. This paper documents a sequence of events in which outburst floodwaters enhance bank erosion and recruitment of wood into the channel, and thus the formation of large logjams. These logjams sufficiently deflect flow to create substantial overbank deposition in areas of the valley bottom not commonly accessed by normal snowmelt peak discharges, and through this process promote valley-bottom aggradation and sediment storage. Changes in the occurrence of glacier outburst floods thus have the potential to alter the rate and magnitude of valley-bottom dynamics in these environments, which is particularly relevant given predictions of worldwide global warming and glacial retreat. Processes observed at this field site likely occur in other forested catchments with headwater glaciers. [Copyright &y& Elsevier]

Abstract: This paper presents a rational method for estimating the maximum discharge of a landslide-induced debris flow. The method has five basic principles or steps: (a) to identify and measure representative bends and straight zones along a channel through which a debris flow went down; (b) to evaluate peak debris flow velocity in the bends; (c) to assess peak debris flow velocity in the straight channel zones; (d) to use the peak velocities to estimate the distribution of peak discharge along the entire channel; and (e) to find the maximum velocity and discharge of the debris flow. The method is illustrated with a case study of a landslide-induced debris flow at a mountainous region near Chengdu, southwestern China. The results show that the peak debris velocity was between 2.4 and 4.7 m s−1 and the peak debris discharge was between 6.7 and 35.7 m3 s−1. The peak discharge initially increased at the upper portion of the channel, then decreased at the lower portion, indicating that the upper channel experienced erosion but the lower channel experienced deposition. The location with the maximum debris flow discharge corresponds to the point where the volume of the debris flow started to decrease. The method presented in this paper can help to prevent or mitigate debris flow hazards. [Copyright &y& Elsevier]

Abstract: This paper explores how, and to what extent, a phase of relief-rejuvenation modifies the mode of surface erosion in an approximately 63 km2 drainage basin located at the northern border of the Swiss Alps (Luzern area). In the study area, the retreat of the Alpine glaciers at the end of the Last Glacial Maximum (LGM) caused base level to lower by approximately 80 m. The fluvial system adapted to the lowered base level by headward erosion. This is indicated by knickzones in the longitudinal stream profiles and by the continuous upstream narrowing of the width of the valley floor towards these knickzones. In the headwaters above these knickzones, processes are still to a significant extent controlled by the higher base level of the LGM. There, frequent exposure of bedrock in channels and especially on hillslopes implies that sediment flux is to a large extent limited by weathering rates. In the knickzones, however, exposure of bedrock in channels implies that sediment flux is supply-limited, and that erosion rates are controlled by stream power. The morphometric analysis reveals the existence of length scales in the topography that result from distinct geomorphic processes. Along the tributaries where the upstream sizes of the drainage basins exceed 100,000–200,000 m2, the mode of sediment transport and erosion changes from predominantly hillslope processes (i.e., landsliding, creep of regolith, rock avalanches and to some extent debris flows) to processes in channels (fluvial processes and debris flows). This length scale reflects the minimum size of the contributing area for channelized processes to take over in the geomorphic development (i.e., threshold size of drainage basin). This threshold size depends on the ratio between production rates of sediment on hillslopes, and export rates of sediment by processes in channels. Consequently, in the headwaters, erosion rates and sediment flux, and hence landscape evolution rates, are to a large extent limited by weathering processes. In contrast, in the lower portion of the drainage basin that adjusts to the lowered base-level, rates of channelized erosion and relief formation are controlled mainly by stream power. Hence, this paper shows that base-level lowering, headward erosion and establishment of knickzones separate drainage basins in two segments with different controls on rates of surface erosion, sediment flux and relief formation. [Copyright &y& Elsevier]

Abstract: In recognition of the fundamental control exerted by weathering on landscape evolution and topographic development, the 35th Binghamton Geomorphology Symposium was convened under the theme of Weathering and Landscape Evolution. The papers and posters presented at the conference imparted the state-of-the-art in weathering geomorphology, tackled the issue of scale linkage in geomorphic studies and offered a vehicle for interdisciplinary communication on research into weathering and landscape evolution. The papers included in this special issue are encapsulated here under the general themes of weathering mantles, weathering and relative dating, weathering and denudation, weathering processes and controls and the ‘big picture’. [Copyright &y& Elsevier]

Erosion and deposition processes lie at the centre of geomorphological explanation, but progress in understanding has been limited by a lack of appropriate high-resolution monitoring methodologies which permit detection of erosion and deposition dynamics. This paper presents a case for monitoring erosion and deposition at high temporal resolutions, and uses hypothetical approaches supported by example erosion and deposition events and analyses drawn from estuarine and fluvial systems. The paper first presents testable hypotheses to demonstrate the complexity of possible event combinations, sequences and juxtapositions for the erosion driving forces which underpin the need for high-resolution monitoring. Second, it summarises recent improvements to the Photo-Electronic Erosion Pin (PEEP) automatic erosion and deposition monitoring system, including the novel concept of Thermal Consonance Timing (TCT), which is particularly promising because it helps to define the timing of nocturnal events and through the entire hydrograph. Third, example results are discussed from high-resolution monitoring of bank erosion at a tidal site at Burringham on the River Trent in northern England. Tidal banks are revealed to be much more dynamic than previous conventional monitoring has indicated. A key result is that, because the high-resolution approach allows erosional and depositional activity to be assigned to specific periods of tidal inundation, it becomes possible for the first time routinely to produce ‘event-based’ erosion (36 mm h-1) and deposition rates (4.5 and 8.4 mm h-1). Such rate determinations are potentially very useful in the field validation of sedimentological and geomorphological models, including grain settling and resuspension theory. Fourth, through a longer term of aggregated daily data, a striking 2-week cycle of deposition and erosion emerges which correlates most strongly with spring-neap tidal cycling, but is moderated by wind stress effects. Sediment was deposited on the bank relatively quickly, over 4–5 days, but then removed by erosion rather slowly, over 9–10 days. Fifth, the dangers of low-resolution monitoring are illustrated by comparing the daily PEEP data set with a series resampled at a lower (14-day) frequency, to simulate the information generated by conventional resurvey methodologies. The low-frequency series failed adequately to represent the cyclicity, mean, range, variability and trend of bank elevation changes, and without this dynamics information, rate and process definition is very difficult, largely because of self-concealing activity. Sixth, a useful advance is illustrated by the fluvial erosion sequence for the River Wharfe (N. England). This shows how TCT can generate rare and important results with the definition of the precise time of an erosion event within the hydrograph: bank retreat here occurred very quickly, after initial inundation, and within 4 h of the flow peak-information which can be used to define thresholds for entrainment (e.g. critical shear stresses). Such high-resolution monitoring helps to unravel some of the erosional effects of complex sequences, combinations and juxtapositions of similar or different forcing events. Finally, high-resolution approaches have been adopted worldwide for fluvial, estuarine, mudflat and canal systems, but considerable potential exists for their development and use in these and other contexts (e.g. gully, hillslope, beach and dune environments), to improve understanding and modelling of geomorphological processes more widely. [Copyright &y& Elsevier]

Understanding and predicting shoreline change along sandy coasts requires continuous (in both time and space) long-term (decades) shoreline data at good spatial (e.g. 100 s of metres) and temporal (e.g. months) resolution. Publicly available satellite imagery can now provide such time series. However, satellite-derived shorelines (SDS) are associated with uncertainties, particularly at high-energy meso-macrotidal coasts, which challenge the assessment of long-term trends and interannual variability. In this paper we address the 1984–2020 time- and space-evolution of 269 km of high-energy meso-macrotidal sandy coast in southwest France using uncertain (no tide and runup correction) SDS data. The shoreline trends are validated with field data collected over the period 2008–2019. Over 1984–2020, the shoreline eroded by 0.55 m/yr with maximum erosion (accretion) reaching 15.61 m/yr (6.94 m/yr), with the largest changes observed along coasts adjacent to the inlet and estuary mouths. We show that, away from the presence of ebb-tide deltas and swash bars affecting offshore wave transformation and nearshore circulation, the long-term shoreline trend is well explained by the gradients in longshore drift computed from a regional wave hindcast and an empirical longshore transport formula. By averaging the yearly SDS along the entire coastline, we find that interannual shoreline variability is well correlated with the winter West Europe Pressure Anomaly (WEPA), which outscores the other conventional teleconnection pattern indices. WEPA even explains >80 % of the space-averaged shoreline variability over the recent period 2014–2020 when more and higher quality satellite images are available. A more local assessment of the links between climate indices and shoreline response shows that correlation with all climate indices dramatically drops downdrift of the large-scale estuary mouths and inlets. This suggests that along this 10–20 km stretch of downdrift coast, shoreline response is controlled factors internal to the estuary mouth/inlet system. The rest of the coast is mostly controlled by factors external to the system, which are primarily the variability in winter-mean wave height correlated to winter WEPA index. Overall, we demonstrate that an adapted space-averaging of uncorrected (noisy) SDS dataset can allow addressing the time- and space variability of shoreline change and their primary drivers including large-scale climate patterns of atmospheric variability. We also advocate that such SDS analysis can be performed along any coastline in the world in order to guide future model development and application. [Display omitted] • 1984–2020 satellite-derived shorelines (SDS) collected along 269 km of sandy coast. • Gradients in longshore drift control shoreline trends away from estuary mouths. • Space-averaged SDS interannual variability is correlated with some climate indices. • Sectors downdrift of inlets and estuary mouths are affected by internal dynamics. • SDS can guide the development and application of shoreline change models. [ABSTRACT FROM AUTHOR]

Gullies that terminate at a vertical-wall are ubiquitous throughout arid and semiarid regions. Multi-year assessments of gully evolution and headcut advance are typically accomplished using traditional ground surveys and aerial photographs, with much recent research focused on integrating data collected at very high spatial resolutions using new techniques such as aerial surveys with blimps or kites and ground surveys with LiDar scanners. However, knowledge of specific processes that drive headcut advance is limited due to inadequate observation and documentation of flash floods and subsequent erosion that can occur at temporal resolutions not captured through repeat surveys. This paper presents a method for using very-high temporal resolution ground-based time-lapse photography to capture short-duration flash floods and gully head evolution in response. In 2004, a base level controlling concrete weir was removed from the outlet of a 1.29 ha semiarid headwater drainage on the Walnut Gulch Experimental Watershed in southeastern Arizona, USA. During the ten year period from 2004 to 2014 the headcut migrated upchannel a total of 14.5 m reducing the contributing area at the headwall by 9.5%. Beginning in July 2012, time-lapse photography was employed to observe event scale channel evolution dynamics. The most frequent erosion processes observed during three seasons of time-lapse photography were plunge pool erosion and mass wasting through sidewall or channel headwall slumping that occurred during summer months. Geomorphic change during the ten year period was dominated by a single piping event in August 2014 that advanced the channel head 7.4 m (51% of the overall advance) and removed 11.3 m 3 of sediment. High temporal resolution time-lapse photography was critical for identifying subsurface erosion processes, in the absence of time-lapse images piping would not have been identified as an erosion mechanism responsible for advancing the gully headwall at this site. [ABSTRACT FROM AUTHOR]

Surtsey is a small volcanic island in the Vestmannaeyjar archipelago, off the south coast of Iceland. The eruption leading to the island's emersion lasted for 3.5 yr (1963–1967) while destructive forces have been active for over 50 yr (1963–present-day) during which Surtsey has suffered rapid subaerial and submarine erosion and undergone major morphological changes. Surtsey is a well-documented modern example of the post-eruptive degradational stage of island volcanoes, and has provided the unique opportunity to continuously observe and quantify the effects of intense geomorphic processes. In this paper we focus on coastal and marine processes re-shaping the shoreline and shallow-water portions of the Surtsey complex since its formation and on the related geomorphological record. Analogies with the post-eruptive morphological evolution of recently active island volcanoes at the emerging stage, encompassing different climatic conditions, wave regimes and geological contexts, are discussed. [ABSTRACT FROM AUTHOR]

Tectonically controlled landforms develop morphologic features that provide useful markers to investigate crustal deformation and relief growth dynamics. In this paper, we present results of morphotectonic experiments obtained with an innovative approach combining tectonic and surface processes (erosion, transport, and sedimentation), coupled with accurate model monitoring techniques. This approach allows for a qualitative and quantitative analysis of landscape evolution in response to active deformation in the three end-member geological settings: compression, extension, and strike–slip. Experimental results outline first that experimental morphologies evolve significantly at a short time scale. Numerous morphologic markers form continuously, but their lifetime is generally short because erosion and sedimentation processes tend to destroy or bury them. For the compressional setting, the formation of terraces above an active thrust appears mainly controlled by narrowing and incision of the main channel through the uplifting hanging-wall and by avulsion of deposits on fan-like bodies. Terrace formation is irregular even under steady tectonic rates and erosional conditions. Terrace deformation analysis allows retrieving the growth history of the structure and the fault slip rate evolution. For the extensional setting, the dynamics of hanging-wall sedimentary filling appears to control the position of the base level, which in turn controls footwall erosion. Two phases of relief evolution can be evidenced: the first is a phase of relief growth, and the second is a phase of upstream propagation of topographic equilibrium that is reached first in the sedimentary basin. During the phase of relief growth, the formation of triangular facets occurs by degradation of the fault scarp, and their geometry (height) becomes stationary during the phase of upstream propagation of the topographic equilibrium. For the strike–slip setting, the complex morphology of the wrench zone, composed of several interacting fault segments, enhances the interactions with the drainage network. Because of the widening of the main fault zone toward the surface, a significant amount of distributed deformation is observed along the wrench zone. Locally, where two terminations of fault segments interact, less than a quarter of the far field displacement can remain measurable using fault offsets, leading to a systematic underestimation of the real fault slip rate. These different experimental examples illustrate the great potential of the approach coupling deformation mechanisms and erosion–transport–sedimentation processes to investigate qualitatively and quantitatively the morphotectonic evolution of tectonically controlled landscapes. [ABSTRACT FROM AUTHOR]

Long-term monitoring of river restoration and streambank stabilization projects has often been neglected, resulting in a poor understanding of the effectiveness of different types of restoration methods. This study utilized unmanned aircraft systems (UAS) to monitor and assess the effectiveness of streambank stabilization projects in the Cottonwood River valley, an incised river system in east-central Kansas, USA. Streambanks have been acknowledged as a dominant sediment source to downstream waterbodies in incised fluvial systems and are therefore high priority targets of restoration and stabilization strategies. Volumes of sediment eroded at 14 streambank stabilization sites along the Cottonwood River were analyzed to compare: (1) pre-construction and post-construction periods; and (2) stabilized sites and unmodified sites. As monitoring and assessment were not part of the original design plans for stabilization efforts, this paper outlines methods to generate appropriate datasets and models to assess stabilization effectiveness. Results from three years of UAS monitoring, together with historical pre-construction assessment, indicate that stabilization projects significantly reduced local-scale erosion at stabilized sites. However, evidence of continued bank erosion after construction, including erosion of the lower bank above installed toe protection, bank steepening, and mass wasting, suggests that the benefits of reduced erosion from stabilization might change over time. Overall, our investigation demonstrates the viability of UAS surveys for long-term monitoring of streambank stabilization projects along incised river channels. [Display omitted] • Unmanned aircraft systems provide an effective tool to monitor bank stabilization effectiveness. • Stabilization projects significantly reduced local-scale erosion at the stabilized site. • Substantial erosion of the lower bank above toe protection was observed. [ABSTRACT FROM AUTHOR]

This paper examines relationships between the morphology of cold desert hydrological features and the water sources, and it relates the formation of diagnostic deposits and erosion patterns to environmentally controlled patterns of discharge. In particular, three sets of landforms found in the McMurdo Dry Valleys of Antarctica are compared to similar features on Mars: Antarctic streams/rivers to Amazonian valleys, terrestrial gullies to Martian gullies, and water tracks to recurring slope lineae. Similarities in landform morphology are highlighted for each set. Hydrological characteristics are aggregated or calculated, and they are shown to scale comparably across the landforms for the terrestrial and Martian groups. Accordingly, a hydrological continuum is proposed, linking the magnitude and the persistence of water sources in cold desert environments to flow response and the formation of diagnostic landforms. This concept provides a framework for examining the relationships between climate, hydrology, and geomorphology in the cold desert environments of these two worlds. [ABSTRACT FROM AUTHOR]

Calanchi (plural of calanco ) are typical badland landforms of the Italian landscape. They consist of dense networks of V-shaped valleys, with a sparse or absent vegetation cover, which frequently develop on unconsolidated or poorly consolidated clayey deposits. In this paper, the dimensional analysis and the incomplete self-similarity theory were used to deduce a model relating the volume of sediments eroded from the calanchi area to a set of geometric attributes of their tributary areas. The morphometric characteristics of 209 calanchi basins were used to calibrate and validate the model. The predictive skill of the model was assessed by calculating the mean square error and the Nash–Sutcliffe model efficiency coefficient. The model was found to provide a reliable prediction of eroded volume from basins entirely covered by calanchi landforms as well as from basins only partially affected by badland erosion processes. Furthermore, as the residuals between the calculated and the measured volume of the eroded material are normally distributed, the deterministic model may be considered complete, meaning that no other variables are necessary to explain the studied physical process. In other words, the model is able to predict erosion volume in calanchi landforms from a deterministic point of view. [ABSTRACT FROM AUTHOR]

Based on a range of evidence, Cook (2019) concluded that increased erosion and sedimentation followed the movement of Europeans into new regions of Australia soon after A.D. 1788. Woodward (this issue) takes issue with this position, based largely on the interpretation of lake sediment records from a single study site on the New England Tablelands of eastern Australia. Many of Woodward's comments (and their singular focus) are beyond the aims and scope of Cook (2019), which examined the evidence for human impacts on soils and erosion in early colonial Australia. This paper addresses the following issues raised by Woodward: (1) that there is no evidence of environmental impacts from the first half century of 'illegal' settlers and land use in Australia, and (2)that other historical and scientific records of increased erosion and sedimentation before 1840 cannot be relied on. Further, this paper corrects other errors and inaccuracies found in Woodward's reply. This paper draws on many datasets to expand the argument that European land use, resource extraction, and agriculture resulted in landscape disturbance before 1840 in Australia. Finally, this reply demonstrates why Woodward's claim of no major impacts from illegal Europeans before 1840 in Australia is, for many locations, improbable based on the evidence available, and for large swathes of eastern Australia, difficult to support. [ABSTRACT FROM AUTHOR]

Although tidal flats appear homogeneous from a distance, morphological variations are found on various spatial scales. These are driven by physical and/or biological processes. In this paper, we consider the creeks that are present on fringing tidal flats and which are orientated approximately perpendicular to the main channel. To explain why these creeks occur, we analysed high-resolution aerial pictures and yearly measured LiDAR data of the Ems-Dollard and Western Scheldt estuaries, located in the Netherlands. We selected nine bare fringing tidal flats, with and without creeks in both estuaries. Subsequently, we related the flat shape to the creek occurrence by evaluating cross-sections of tidal flats from the two estuaries. Finally, we studied how the flat shape affects the cross-shore flow velocity with a 1D numerical model to link creek occurrence to tidal flow. The results show highest ebb velocities, the largest velocity gradients and the largest erosion potential at the transition area between the lower and the upper flat. The milder the slope of the upper flat and the shorter the transition zone, the larger the flow velocities. Based on the data analysis and numerical model outcomes, we conclude that the conditions are favourable for creeks on convex-up intertidal flats with a sharp transition between the upper part and lower part of the flat and that they are predominantly found in this transition zone. We finally argue that these tidal creeks are not only a consequence of the tidal flat profile, but also affect the (equilibrium) profile of the tidal flat. • Creeks are found at the transition from steep to mild slope on convex-up tidal flats. • Flow velocities are influenced by the tidal flat geometry and bottom friction. • The convex-up shape results in maximum flow velocities in the transition zone. • The maximum erosion leads to creek establishment in the transition zone. • Creeks can be used as an indicator for the cross-shore shape of tidal flats. [ABSTRACT FROM AUTHOR]

Annual bank erosion was measured at multiple cross sections along the free-flowing meandering Powder River in the western United States from 1979 through 2019. Bank erosion was separated into two components—above water and underwater erosion. Above water erosion was measured as the annual bank retreat rate (0–15.4 m y−1). Underwater erosion rate (0–47 m3 m−1 y−1) was calculated as the volume eroded below the water level corresponding to the dominant annual peak discharge, Q p. This paper focuses primarily on the underwater erosion. A total of 491 annual erosion rates were calculated for 23 bank sites along a 90-km study reach in southeastern Montana. Sites were not just hotspots for bank erosion but represent the spectra of variables such as the radius of curvature divided by channel width, R / w (2–86), the peak discharge, Q p (22.7–314 m3 s−1), and the bank orientation (0–360°). Local annual bank erosion was extremely variable in time and space. It was episodic and unsynchronized along the study reach with the maximum annual bank erosion occurring in different years at different bank sites. The composite probability distribution of all 491 annual bank erosion rates was best modeled by a zero-adjusted Weibull distribution. Individual probability distributions for each of the 23 sites were all different from each other and from the composite distribution highlighting the extreme variability. The correlation of the annual underwater erosion with channel geometry and bank variables was low (R2 < 0.31) but the correlation was higher for peak discharge with 25% of the sites having R2 > 0.50. Time-averaging reduced the variability at each site and when grouped into five peak-discharge classes each class was correlated with R / w as a power law with an exponent of about −1. Reach-averaging also reduced the variability for each year, and when grouped by bank orientation (north-, east-, south-, and west-facing), bank erosion was linearly related to Q p with south- and west-facing orientations having about twice as much erosion per unit discharge (0.030 m3 m−1 y−1/m3 s−1) than north- and east-facing orientations. Bank erosion was found to be not just a multi-variate complex process with little correlation and high variability that suggests randomness, but also a process that was a function of a different combinations of variables at different sites at the same time. However, this high variability was reduced by time- and reach-averaging, which produced predictable results analogous to the central limit theorem. Annual underwater volumetric bank erosion for Powder River. Dotted lines are the time-averaged relations, { uwBV e }, versus ratio of radius of curvature and top width { R / w (Q)} for five discharge classes. Solid lines are the reach-averaged relation, | uwBV e |, versus dominant annual peak discharge Q p for four bank orientations. [Display omitted] • Annual bank erosion is extremely variable and characterized by frequent years with no erosion. • Variability at a site is a complex sum of mechanisms and variables, which differs from year to year and from site to site. • Time- and reach-averaging reduce the variability and produce predictable relations. • Time and reach-averaged relations depend on water discharge and bank orientation. [ABSTRACT FROM AUTHOR]

A recent paper published in Geomorphology by Gabet et al. (2014) presents the results of a numerical model supporting the hypothesis that burrowing mammals build Mima mounds - small, densely packed hillocks found primarily in the western United States. The model is based on field observations and produces realistic-looking mounds with spatial distributions similar to real moundfields. Alternative explanations have been proposed for these Mima mounds, including formation by seismic shaking and vegetation-controlled erosion and deposition. In this short communication, we present observations from moundfields in the coastal states of the western U.S. that are incompatible with these alternative theories. [ABSTRACT FROM AUTHOR]

Abstract: Physically-based, catchment scale sediment delivery models have become increasingly complex, sophisticated and are suitable for a diverse range of environmental contexts. However, in their attempts to best represent the physical processes of erosion and deposition, these models require large and detailed input datasets. When such data are unavailable, annual sediment yield models are relied upon. However, in this class of models, widely available data such as daily precipitation and discharge are disregarded resulting in a reduction in temporal accuracy. To fill this scientific and management gap, the landscape evolution model LAPSUS was adapted (LAPSUS-D) for a meso-scale catchment to model sediment yield on a daily resolution. The water balance component within the model enables the calibration of the model in terms of water discharge with measured daily discharge at the outlet. This methodology is especially important when modeling sediment yield from catchments which are ungaged catchments in terms of sediment, but where hydrological data are available. As the simulation of sediment yield was the main objective of the study, the calibration focused on peak discharge. The focus on peak discharge provides insight into the capability of the model to generate, route and deliver sediment at the outlet of a meso-scale catchment. LAPSUS-D has daily temporal resolution and requires a 10 to 30m pixel size DEM, soil map, land-use map and daily hydrological records (precipitation and discharge). In this paper we present the first assessment of the hydrological model performance and an analysis of the sensitivity of the model to input parameters. Our study site is a 23-km2 catchment in Upper Nysa Szalona, southwest Poland with temperate climate. Results show that the model can reliably predict peak discharge, which is expected in future studies to allow reliable estimates of sediment transport capacity, redistribution and yield. [Copyright &y& Elsevier]

Abstract: This paper addresses the problem of the erosion of salt marsh edges. Flume laboratory experiments were carried out aimed at reproducing the instability and retreat of the scarps that typically delimit the salt marshes under the attack of wind waves during the tidal cycle. The bank model and hydrodynamic forcing in the flume were such as to simulate the conditions observed in the field in Venice Lagoon. Experiments were conducted for the same hydrodynamic forcing in the case of two identical banks but with and without the inclusion of the vegetation. Experimental results show that bank retreat involves a variety of processes (including particle erosion, cantilever and slide failures). The effect of the vegetation was to produce a delay in the mass failures, related to a certain growth of plant roots, thus providing an overall stabilizing effect. Bank instability was related to the formation of tension cracks at the bank top and to the impulsive effects associated with wave energy dissipation. [Copyright &y& Elsevier]

Abstract: This paper uses a multifaceted remote sensing and morphometric approach to investigate if the surface of subcatchments in the Parana Valles area of Mars (20–30°S, 0–20°W) is reflective of hydrology and sediment transport by water. Using digital elevation model (DEM) data obtained from the Mars Orbiter Laser Altimeter (MOLA), three nested subcatchments were examined using a suite of terrestrial geomorphic and hydrologic statistics to determine if their shape and form lies within the known range of fluvial catchment properties on Earth. Further, an examination of statistical accuracy via an innovative pixel-by-pixel solution of two statistics established that despite mineralogical homogeneity confirmed by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) spectral survey, erosion processes were likely to be variable across the study site. The DEM-based methods outlined here can be employed at other sites to investigate geomorphic properties and attributes of the Martian surface. [Copyright &y& Elsevier]

Abstract: A regional assessment of the spatial variability in sediment yields allows filling the gap between detailed, process-based understanding of erosion at field scale and empirical sediment flux models at global scale. In this paper, we focus on the intrabasin variability in sediment yield within the Blue Nile and Atbara basins as biophysical and anthropogenic factors are presumably acting together to accelerate soil erosion. The Blue Nile and Atbara River systems are characterized by an important spatial variability in sediment fluxes, with area-specific sediment yield (SSY) values ranging between 4 and 4935t/km2/y. Statistical analyses show that 41% of the observed variation in SSY can be explained by remote sensing proxy data of surface vegetation cover, rainfall intensity, mean annual temperature, and human impact. The comparison of a locally adapted regression model with global predictive sediment flux models indicates that global flux models such as the ART and BQART models are less suited to capture the spatial variability in area-specific sediment yields (SSY), but they are very efficient to predict absolute sediment yields (SY). We developed a modified version of the BQART model that estimates the human influence on sediment yield based on a high resolution composite measure of local human impact (human footprint index) instead of countrywide estimates of GNP/capita. Our modified version of the BQART is able to explain 80% of the observed variation in SY for the Blue Nile and Atbara basins and thereby performs only slightly less than locally adapted regression models. [Copyright &y& Elsevier]

Abstract: This paper investigates wood recruitment and deposition dynamics in a large gravel-bed, braided river (Tagliamento River, Italy). We used a combination of field measurements, automatically repeated ground images, and remotely sensed surveys to quantify wood input through bank erosion and associated downstream deposition. Two sites were investigated where floods caused the erosion of vegetated island edges. A lidar survey preceding the erosion events provided data on the morphology and vegetation structure of the eroded areas, allowing estimation of the number of trees that were uprooted. Sequences of ground-based images acquired automatically (and supported by field measurements) showed the time, number, and location of deposited trees. Results show that the complex morphology of braided rivers induces specific deposition patterns. We observed wide dispersal of wood on gravel bars, with jams characterised by a small number of logs (on average 2–3) and, in many cases, only a single log. A large proportion of the eroded trees (up to 40%) were deposited on the nearest downstream bar. This illustrates significant wood retention close to the recruitment site, with the remaining wood dispersed widely downstream. Differences in the observed level of local wood retention were associated with the proximity of the erosion site to the main channel and differences were also observed in retention between the peak and the falling limb of flood events, confirming that water depth and probably flow velocity are the crucial parameters controlling wood deposition. [Copyright &y& Elsevier]

Abstract: Due to overgrazing and agricultural intensification, gully erosion severely affects sub-Saharan countries; however, insufficient quantitative studies exist for this part of the world. This paper presents data on gully head retreat rates in Northern Ethiopia and relates these rates to gully and environmental characteristics. The monitoring of headcuts over one rainy season (2010) revealed that present-day retreat rates are low, with average annual linear (R l), areal (R a) and volumetric (V e) retreat rates of 0.34my−1, 1.70m2 y−1 and 5.2m3 y−1, respectively. These results express the positive effects of recent soil and water conservation practices on gully stabilization. Significantly higher values of R l (up to 1.93my−1) occurred in the Vertisol areas affected by soil piping. When considering the medium- to long time scale (1–47years) using archival terrestrial (and aerial) photographs, headcut retreat rates proved to be significantly higher than those in the short term. The averages for R l, R a and V e are 3.8my−1, 31.5m2 y−1 and 47.7m3 y−1, respectively. Retreat rates are up to 10 times higher after road construction. For the medium to long term, headcut retreat rates were positively related to the catchment area (A). A power relationship that best describes the relation between V e and A is V e =0.53 A 0.31 (r 2 =0.27, n =18). Compared to other areas worldwide, regressive erosion has been rapid in Ethiopia as a result of the degraded and steep landscape combined with erosive rains and the occurrence of Vertisols. In Vertisols, headcut retreat is controlled by soil piping. Because no adequate techniques exist to control gully initiation and development in Vertisols, alternative techniques should be developed that deactivate soil pipes. [Copyright &y& Elsevier]

Abstract: The rate of migration, calculated by numerical models of river meandering, is commonly based on a method that relates the rate of migration to near-bank excess velocity multiplied by a dimensionless coefficient. Notwithstanding its simplicity, since the early 1980s this method has provided important insight into the long-term evolution of meander planforms through theoretical exercises. Its use in practice has not been as successful, because the complexity of the physical processes responsible for bank retreat, the heterogeneity in floodplain soils, and the presence of vegetation, make the calibration of the dimensionless coefficient rather challenging. This paper presents a new approach that calculates rates of meander migration using physically-based streambank erosion formulations. The University of Illinois RVR Meander model, which simulates meandering-river flow and bed morphodynamics, is integrated with algorithms for streambank erosion of the US Department of Agriculture channel evolution computer model CONCEPTS. The performance of the proposed approach is compared to that of the more simple classic method through the application to several test cases for idealized and natural planform geometry. The advantages and limitations of the approach are discussed, focusing on simulated planform pattern, the impact of soil spatial heterogeneity, the relative importance of the different processes controlling bank erosion (hydraulic erosion, cantilever, and planar failure), the requirements for obtaining stable migration patterns (centerline filtering and interpolation of bank physical properties), and the capability of predicting the planform evolution of natural rivers over engineering time scales (i.e., 50 to 100years). The applications show that the improved physically-based method of bank retreat is required to capture the complex long-term migration patterns of natural channels, which cannot be merely predicted from hydrodynamics only. [Copyright &y& Elsevier]

Abstract: The tropics of northern Australia have received relatively little attention with regard to the impact of soil erosion on the many large river systems that are an important part of Australia''s water resource, especially given the high potential for erosion when long dry seasons are followed by intense wet season rain. Here we use 137Cs concentrations to determine the erosion processes supplying sediment to two major northern Australian Rivers; the Daly River (Northern Territory), and the Mitchell River (Queensland). We also present data from five sediment samples collected from a 100km reach of the Cloncurry River, a major tributary of the Flinders River (Queensland). Concentrations of 137Cs in the surface soil and subsurface (channel banks and gully) samples were used to derive ‘best fit’ probability density functions describing their distributions. These modelled distributions are then used to estimate the relative contribution of these two components to the river sediments. Our results are consistent with channel and gully erosion being the dominant source of sediment, with more than 90% of sediment transported along the main stem of these rivers originating from subsoil. We summarize the findings of similar studies on tropical Australian rivers and conclude that the primary source of sediment delivered to these systems is gully and channel bank erosion. Previously, as a result of catchment scale modelling, sheet-wash and rill erosion was considered to be the major sediment source in these rivers. Identifying the relative importance of sediment sources, as shown in this paper, will provide valuable information for land management planning in the region. This study also reinforces the importance of testing model predictions before they are used to target investment in remedial action. [Copyright &y& Elsevier]

Abstract: Niue is an uplifted limestone island, which preserves an atoll morphology with a sequence of terraces around its outer margin. A modern terrace fringes much of the island and this paper examines the extent to which this terrace can be considered accretionary and constructed by coral and coralline algae, or erosional and truncated by those processes that form shore platforms. The occurrence of Pleistocene limestone outcropping across this terrace and the continuation of caves and other karst features, dissecting the sub-aerial limestones, onto the forereef indicate the overall significance of erosion. At present live coral cover is restricted to isolated colonies growing in grooves, potholes and karstic channels eroded into the modern terrace surface. Coralline algae coat the outer margin of this terrace, and also veneer prominent surf benches that occur on the windward shore, 1–2m above the terrace surface. Terrace evolution on Niue therefore appears to be primarily erosional in origin. There is little accommodation space for reef growth and, as a result, accretional fringing reefs are absent around most of the island. Erosional processes have also dominated landscape evolution for at least the past few eustatic cycles. Fringing reef growth is absent or severely restricted during the last interglacial and occurs as sporadic small reefs on the seaward margin of an erosional terrace during the penultimate interglacial. The development of terrace features in uplifting reef settings does not necessarily originate through accretional reef processes and may in fact be entirely erosional. Although reef terraces are frequently depositional in other settings, those present on Niue indicate a predominance of erosion, indicating the need to discriminate emergent terraces in terms of the extent to which they are erosional or accretionary when using such features to reconstruct island palaeoenvironments. [Copyright &y& Elsevier]

Abstract: On 10th March 2008, the high energy storm Johanna hit the French Atlantic coast, generating severe dune erosion on Vougot Beach (Brittany, France). In this paper, the recovery of the dune of Vougot Beach is analysed through a survey of morphological changes and hydrodynamic conditions. Data collection focused on the period immediately following storm Johanna until July 2010, i.e. over two and a half years. Results showed that the dune retreated by a maximum of almost 6m where storm surge and wave attack were the most energetic. Dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre- and post-storm dune toe, and reducing impacts of the storm surge. Dune recovery started in the month following the storm event and is still ongoing. It is characterised by the construction of “secondary” embryo dunes, which recovered at an average rate of 4–4.5cm per month, although average monthly volume changes varied from −1 to 2m3.m−1. These embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune. These dune-construction processes were facilitated by growth of vegetation on low-profile embryo dunes promoting backshore accretion. After more than two years of survey, the sediment budget of the beach/dune system showed that more than 10,000m3 has been lost by the upper tidal beach. We suggest that seaward return currents generated during the storm of 10th March 2008 are responsible for offshore sediment transport. Reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross-shore sediment redistribution inducing net erosion in the tidal zone. [Copyright &y& Elsevier]

Abstract: The aim of this paper is to investigate the morphological implications of the interplay between tectonic movements at different rates, timescales, and spatial extent in a catchment of intermediate size, the Huang Shui River (a main tributary of the Yellow River in the NE Tibet Plateau). River incision started from a peneplain-like surface that developed in post-Miocene–Pliocene times. At the end of the Tertiary, a general tectonic uplift of the Tibetan Plateau initiated river incision. This general uplift also caused local fragmentation of the Huang Shui catchment into blocks (kilometers or maximally, a few tens of kilometers) of local extent that have subsided and/or uplifted relative to one another. Fluvial deposition of >30m in the subsiding blocks contrasts with erosion and formation of gorges in the uplifted blocks. Incision into the former peneplain was not continuous but a staircase of terraces developed under climatic influences. Terrace deposits are sometimes capped by interglacial soils or soil-derived material. Apparently, terrace incision occurred at the transition to the next cold period. The different rates of uplift and subsidence of the individual blocks resulted in the simultaneous development of erosion and accumulation terraces of different sizes within the same catchment, even within the same tectonic block. This makes it impossible to connect the terraces of the different blocks, except for the three youngest terraces (representing the last 300,000years), thus illustrating the uniform tectonic history of the catchment since that time. [Copyright &y& Elsevier]

Abstract: Our understanding about the regional variation of Sediment Yield (SY) in Europe and its scale dependency currently relies on a limited number of data for mainly larger river systems. SY is the integrated result of all erosion and sediment transporting processes operating in a catchment and is therefore of high value for environmental studies and monitoring purposes. Most global assessments of SY consider catchment area (A), climate and topography as the main explanatory variables. However, it is still unclear if these factors also control regional variations of SY within Europe. This paper aims at bridging this gap. Therefore, we i) present a large database of SY-values which was constructed through an extensive literature review; ii) describe the spatial patterns of SY across Europe; and iii) explore its relation with A, climate, and topography. In total, sediment yield data from 1794 different locations throughout Europe were collected (507 reservoirs and 1287 gauging stations), representing a minimum of 29,203 catchment-year data. Only SY-data measured at gauging stations or derived from reservoir siltation rates over a period of a minimum of one year were included in the database. This database comprises a large range of catchment areas (A): i.e from small upland catchments (≥0.01km²) to major European river basins (≤1,360,000km²). An overview of the collected SY-data is provided and sources of uncertainty on the available data are discussed. Despite potentially large uncertainties on several of the individual SY-values, analysis of this database indicates clear spatial patterns of SY in Europe. The temperate and relatively flat regions of Western, Northern and Central Europe generally have relatively low SY-values (with ca. 50% of the SY< 40tkm−2 yr−1 and ca. 80% of the data <200tkm−2 yr−1), while Mediterranean and Mountainous regions generally have higher SY-values (with around 85% of the SY-data >40tkm−2 yr−1 and more than 50% of the data >200tkm−2 yr−1). These differences are attributed to a combination of factors, such as differences in climate, topography, lithology and land use. Although larger differences in SY were found between the climatic regions than between topographic zones, it is currently difficult to identify the individual importance of the various controlling factors of SY. SY–A relationships were calculated for the entire dataset and for subgroups stratified according to the measurement method (gauging stations or reservoir surveys), range of the catchment area, climatic region, topographic zone of the river outlet, and major European river system. Although typically a negative relationship between SY and A is expected due to a decrease in topsoil erosion rates on more gentle slopes and an increase in sediment deposition with an increase in catchment size, this relationship was found to be generally very weak and subject to a lot of scatter. Furthermore, results illustrate important differences in scale dependency: whereas a weak but significant negative trend is generally observed for the temperate and relatively flat regions, no significant or even positive trends were observed in mountain regions and Mediterranean Europe. When only larger river catchments (i.e. >100km² and especially >10,000km²) are considered, catchment area exerted a larger control on SY. These findings confirm previous studies and indicate that the relationship between SY, spatial scale and other controlling factors is often complex and non-linear. [Copyright &y& Elsevier]

Abstract: In the Highlands of Northern Ethiopia gully occurrence is linked to poverty-driven unsustainable use of the land in a vulnerable semi-arid and mountainous environment, where intensive rainfall challenges the physical integrity of the landscape. Trends in gully and river channel erosion, and their relation to triggering environmental changes can proffer valuable insights into sustainable development in Northern Ethiopia. In order to assess the region-wide change in gully and river channel morphology over 140years, a set of 57 historical photographs taken in Tigray, and, clearly displaying gully cross-sections, were precisely repeated from 2006 till 2009. Ninety-two percent of the gully and river sections (n=38) increased in cross-sectional area during the studied period, especially after 1975. Two repeatedly photographed catchments of Lake Ashenge and Atsela allowed a detailed study of gully development from 1936 until 2009. A conceptual hydrogeomorphic model was devised for these catchments and validated for the Northern Ethiopian Highlands. Three major phases can be distinguished in the hydrological regime of the catchments. In the first phase, between 1868 (or earlier) and ca. 1965, the relatively stable channels showed an oversized morphology inherited from a previous period when external forcing in environmental conditions had caused the channels to shape. In the second phase (ca. 1965 – ca. 2000), increased aridity and continued vegetation clearance accelerated the channel dynamics of the gully and river system. The third phase (ca. 2000 – present) started after the large-scale implementation of soil and water conservation measures. In 2009, 23% of the gully and river sections were stabilizing. This paper validates previous research indicating severe land degradation in the second half of the 20th century. Additionally, it demonstrates that the recent erosive cycle started around 1965 and, that at the present time, improved land management stabilizes headwater streams. [Copyright &y& Elsevier]

Abstract: Development of experimental landform with rainfall erosion and uplift is expected to provide some ideas for better understanding how landform evolves through the interaction between uplift and erosion. This paper reports three runs of the rainfall-erosion experiment (runs I, II, and III), in which miniature erosion landform developed with artificial rainfall on a square mound of a mixture of fine sand and kaolinite. The mound is the upper half of a square column (ca. 90×90×24cm) of the material exposed on the ground, and another half is under the ground on the uplift-generating device. All runs lasted for 1759h, and the uplift started from 255h in runs II and III after the mound was eroded to a low-relief surface. While average height decreased exponentially in run I (no uplift), it decreased linearly with 0.041mm/h uplift (run II) and stayed approximately constant with 0.067mm/h uplift (run III). Local relief decreased exponentially after reaching its maximum in the early stage, but the uplift made it stay around a certain height corresponding to its rate. Two prominent types of fluvial erosion, “erosion with knickpoints,” which makes slopes steeper, and “erosion of declining slopes,” which makes slopes gentler, were observed through the experiment. Although the erosion with knickpoints faded with the decrease in relief in run I, it was active even in later stages in runs II and III. The uplift promoted erosion with knickpoints to make local relief and erosion rate higher depending on its rate. The uplift of a higher rate in run III, which was seemingly above a certain threshold, promoted more erosion with knickpoints and helped hills grow until slope failures occurred. In run II, the uplift rate was below the threshold and erosion was exclusively fluvial under the detachment-limited condition, in which local relief (and erosion rate) has a certain limit determined by mound erodibility and rainfall intensity regardless of the uplift rate. The linear decrease in average height indicates that the critical erosion rate exceeded the uplift rate. In run III, on the other hand, increased sediment supply from hill slopes made fluvial erosion transport-limited. Upstream deposition of sediments made channel slopes increase until fluvial erosion matched the sediment supply. Erosion and uplift balanced to keep average height constant (dynamic equilibrium) and similar landforms continued to exist, while hills gradually narrowed through the process of repeated growth and failure (quasi-steady state). [Copyright &y& Elsevier]

Abstract: Extensive areas of the French Alps are underlain by Jurassic black marls. Wherever these “terres noires” crop out they become subject to intense erosion, causing major sedimentation in regional reservoirs and river systems. In the badlands near Draix (Alpes de Haute-Provence, France), measured sediment rates were obtained at the plot scale by surface elevation change-based methods and at the catchment scale by monitoring sedimentation in dams. In this study, we use a dendrogeomorphic approach based on anatomical changes in exposed roots of Pinus sylvestris L. to accurately quantify continuous denudation rates. A total of 123 cross sections (75 from buried and 48 from exposed roots of 23 trees) were sampled in the Moulin basin. The size and position of roots at the time of exposure was determined via anatomical variations in the annual growth rings of roots. In cross sections of buried roots, a sharp reduction of earlywood tracheid lumen area — a growth signature which has traditionally been used to determine the moment of root denudation — was observed as soon as erosion reduced soil cover to ≤3cm. As a consequence, estimates of eroded soil thickness had to be adjusted to take account of this bias. Bias-adjusted, averaged, medium-term erosion rates derived from exposed roots vary between 6 and 7mm y–1 at Moulin basin depending on the importance accorded to the uplift of roots after exposure. Values are significantly correlated to slope angle and match with erosion rates derived from monitored iron stakes (5.7mm y–1) or measurements of sediment yield in retention dams (4.7mm y–1) at the outlet of the Moulin basin. Besides demonstrating that the interpretation of anatomical signatures in tree roots to erosion have to be revised, this paper also shows that dendrogeomorphic analyses of roots are indeed a powerful tool for the quantification of minimal rates of soil erosion in environments where measurements of past activity are not available. [Copyright &y& Elsevier]

Abstract: Biogeomorphology, defined as the two-way interaction between geomorphology and ecology, is a relatively recent subfield in disciplines such as geography, hydrology, and geomorphology, among others. However, the ecologic processes that influence geomorphic processes and vice versa have been addressed to varying extents for decades in geomorphology textbooks. This paper aims to analyze the presence and role of biogeomorphology in geomorphology textbooks from 1939 to 2007. The history of ecologic–geomorphic interactions is important for the understanding of how biogeomorphology has developed and its current position within geography. Geomorphology textbooks were assessed for material on ecologic components. A temporal analysis was completed by reviewing textbooks that span 68years. International textbooks were included in the research in order to assess how they may compare to American textbooks. Results indicated that geomorphology textbooks have addressed biogeomorphology over time, but the amount varied and was minimal overall. Some of the most common topics included coral reefs and the role of vegetation and burrowing animals in erosion processes. The amount of material devoted to ecologic components in geomorphology ranged from brief mention of organisms to an entire chapter covering the various ecologic actions and their influences on geomorphology. The findings of this assessment will provide a contextualized view of the role of biogeomorphology within geomorphology and lend a better understanding to the history and current position of biogeomorphology. [ABSTRACT FROM AUTHOR]

Abstract: Progressive glacier thinning, retreat and mass loss in the High-Arctic is increasingly exposing forefield sediments to processes of mobilisation and redistribution. In this paper, we quantify forefield sediment redistribution at Midtre Lovénbreen, Svalbard, using repeat light detection and ranging (lidar) surveys conducted in 2003 and 2005 in combination with field-based observations. Average surface lowering of the forefield over the observation period identified from lidar surveys is −0.05ma−1; and two primary areas of sediment reworking are identified: active fluvial incision of proglacial streams by ~2m and lateral moraine downwasting of similar magnitude. Multivariate analysis of fluvial and climatological field data indicates that observed forefield sediment mobilisation is driven primarily by discharge forcing, but with contributions from thermoerosive processes and stochastic, autogenic sediment supply. During the period of observation, disparity between sediment loss in forefield fluvial systems as calculated from lidar data (3000–4000×103 kg) and monitoring of fluvial sediment load (1600–3500×103 kg) suggests the likely presence of significant quantities of buried ice beneath a thick debris mantle, as evidenced by field observations. Relatively uniform lowering of the moraine crest identified from our repeat lidar surveys indicates thermoerosion of an ice core. However, simple debris layer thickness modelling indicates an increase in variation of debris layer thickness at lower elevations, providing support for the assertion that moraine disintegration is driven by complex combinations of both thermal and mechanical processes. This study demonstrates the viability of using lidar in conjunction with field monitoring to better understand sedimentary deglaciation dynamics and processes, and also highlights the significance of forefield areas in controlling the sediment yield from deglaciating catchments. [Copyright &y& Elsevier]

Abstract: This paper summarizes process-oriented field and numerical studies undertaken on the river plume in the partially-mixed Changjiang River estuary. Both estuarine circulation and tidal asymmetry are of great importance to the fine sediment processes. Mean suspended sediment concentration (C̄) and bottom shear stress are the dominant physical parameters controlling the flocculation and settling velocities (w s ) of mud flocs in suspension. Two important physical processes are revealed by acoustic imaging, i.e. (i) the near-bed impulsive resuspension and (ii) the transport processes driven by fine sediment-induced plumes during a spring tide. A turbidity maximum, associated with a suspended sediment front, is observed. Its formation is caused mainly by tidal asymmetry, near-bed periodic tidal resuspension and turbulence suppression by suspension/salinity stratifications. A conceptual sketch of the turbidity maximum is cautiously proposed for the Changjiang River estuary. Four different settling velocity equations, taking flocculation into account, have different effects on the modeled concentration profiles of fine sediment: apparently, Cao and Wang (1994, pp. 252–253) would be the best for spring tide and Thorn (1982, Fig. 3/page 66) for neap tide. Both tidal acceleration and tidal deceleration have strong effects on the concentration profiles of fine sediment within the Changjiang River estuary. [Copyright &y& Elsevier]