Description: ABSTRACT Landscapes exposed by glacial retreat provide an ideal natural laboratory to study the processes involved in transforming a highly disturbed, glacially influenced landscape to a stable, diverse ecosystem which supports numerous species and communities. Large-scale vegetation development and changes in sediment availability, used as a proxy for paraglacial adjustment following rapid deglaciation, were assessed using information from remote sensing. Delineation of broad successional vegetation cover types was undertaken using Landsat satellite imagery (covering a 22 year period) to document the rate and trajectory of terrestrial vegetation development. Use of a space-for-time substitution in Glacier Bay National Park, Alaska, allowed ‘back-calculation’ of the age and stage of development of six catchments over 206 years. The high accuracy (89.2%) of the remotely sensed information used in monitoring successional change allowed detection of a high rate of change in vegetation classes in early successional stages (bare sediment and alder). In contrast, later successional stages (spruce and spruce-hemlock dominated forest) had high vegetation class retention, and low turnover. Modelled rates of vegetation change generally confirmed the estimated rates of successional turnover previously reported. These data, when combined with the known influence of terrestrial succession on soil development and sediment availability, suggest how physical and biological processes interact over time to influence paraglacial adjustment following deglaciation. This study highlights the application of remote sensing of successional chronosequence landscapes to assess the temporal dynamics of paraglacial adjustment following rapid deglaciation and shows the importance of incorporating bio-physical interactions within landscape evolution models. This article is protected by copyright. All rights reserved.

Description: ABSTRACT Landscapes respond in complex ways to external drivers such as base level change due to damming events. In this study, landscape evolution modelling was used to understand and analyse long-term catchment response to lava damming events. PalaeoDEM reconstruction of a small Turkish catchment (45 km 2 ) which endured multiple lava damming events in the past 300 ka, was used to derive long-term net erosion rates. These erosion rates were used for parameter calibration and led to a best fit parameter set. This optimal parameter set was used to compare net erosion landscape time series of four scenarios: i) no uplift and no damming events, ii) no uplift and 3 damming events, iii) uplift and no damming events and iv) uplift and 3 damming events. Spatial evolution of net erosion and sediment storage of scenario iii) and iv) were compared. Simulation results demonstrate net erosion differences after 250000 yr between scenarios with and without dams. Initially, trunk gullies show less net erosion in the scenario with damming events compared to the scenario without damming events. This effect of dampened erosion migrates upstream to smaller gullies and local slopes. Finally, an intrinsic incision pulse in the dam scenario results in a higher net erosion of trunk gullies while decoupled local slopes are still responding to the pre-incision landscape conditions. Sediment storage differences also occur on a 100 ka scale. These differences behaved in a complex manner due to different timings of the migration of erosion and sediment waves along the gullies for each scenario. Although the specific spatial and temporal sequence of erosion and deposition events is sensitive to local parameters, this model study shows the manner in which past short-lived events like lava dams have long lasting effects on catchment evolution. This article is protected by copyright. All rights reserved.

Description: ABSTRACT A growing body of field, theoretical and numerical modeling studies suggests that predicting river response to even major changes in input variables is difficult. Rivers are seen to adjust rapidly and variably through time and space as well as changing independently of major driving variables. Concepts such as Self-Organised Criticality (SOC) are considered to better reflect the complex interactions and adjustments occurring in systems than traditional approaches of cause and effect. This study tests the hypothesis that riverbank mass failures which occurred both prior to, and during, an extreme flood event in south east Queensland (SEQ) in 2011 are a manifestation of SOC. Each wet-flow failure is somewhat analogous to the ‘avalanche’ described in the initial sand-pile experiments of Bak et al. (1987) and, due to the use of multitemporal LiDAR, the time period of instability can be effectively constrained to that surrounding the flood event. The data is examined with respect to the key factors thought to be significant in evaluating the existence of SOC including; nonlinear temporal dynamics in the occurrence of disturbance events within the system; an inverse power-law relation between the magnitude and frequency of the events; the existence of a critical state to which the system readjusts after a disturbance; the existence of a cascading processes mechanism by which the same process can initiate both low-magnitude and high magnitude events. While there was a significant change in the frequency of mass failures pre- and post-flood, suggesting nonlinear temporal dynamics in the occurrence of disturbance events, the data did not fit an inverse power-law within acceptable probability and other models were found to fit the data better. Likewise, determining a single ‘critical’ state is problematic when a variety of feedbacks and multiple modes of adjustment are likely to have operated throughout this high magnitude event. Overall, the extent to which the data supports a self-organised critical state is variable and highly dependent upon inferential arguments. Investigating the existence of SOC, however, provided results and insights that are useful to the management and future prediction of these features. This article is protected by copyright. All rights reserved.

Description: ABSTRACT Channelization of the severely polluted Odra and Vistula rivers in Poland induced intensive accumulation of fine-grained deposits rich in organic matter and heavy metals. These sediments have been identified in vertical profiles in a narrow zone along river banks both in groyne-created basins and on the floodplain. Grain size, organic matter, Zn, Pb, Cu content and 137 Cs was used for sediment dating and, stratigraphy and chemistry have been diagnostic features for these deposits, named industrial alluvium. In the most polluted river reaches stabilized by bank reinforcements and groynes, 2 -m -thick slack water groyne deposits are composed of uniform strata of polluted silts with organic matter content over 10%, Zn content over 1000 mg/kg and average Cu and Pb over 100 mg/kg. The average rate of sediment accretion in groynes is higher than on the floodplain and reaches 5 cm/year. Stratification which appears at higher levels in the groyne fields and on the levees reflects a change from in-channel to overbank deposition and is typified by dark layers separated by bright, sandy, and less polluted strata. Stratified, 4 -m -thick, sediment sequences have been found in groyne fields of incised river reaches. The average rate of sediment accretion in these reaches is of the order of 5 cm/year. In stable and relatively less polluted river reaches, vertical-accretion organic deposits are finely laminated and the average rate of deposition amounts to a few millimeters per year. Investigations indicate that groyne construction favours conditions for long term storage of sediments at channel banks. For this reason, groynes should be considered as structures that efficiently limiting sudden release of sediment-associated heavy metals stored in channels and in floodplains of the historically polluted rivers. This article is protected by copyright. All rights reserved.

Description: ABSTRACT Gully cut-and-fill dynamics are often thought to be driven by climate and/or deforestation related to population pressure. However, in this case-study of nine representative catchments in the North Ethiopian Highlands, we find that neither climate changes nor deforestation can explain gully morphology changes over the 20 th century. Firstly, by using a Monte Carlo simulation to estimate historical catchment-wide curve numbers, we show that the landscape was already heavily degraded in the 19 th and early 20 th century – a period with low population density. The mean catchment-wide curve number (〉80) one century ago was, under the regional climatic conditions, already resulting in considerable simulated historical runoff responses. Secondly, 20 th century land cover and runoff coefficient changes were confronted with 20 th century changing gully morphologies. As the results show, large-scale land cover changes and deforestation cannot explain the observed processes. The study therefore invokes interactions between authigenic factors, small-scale plot boundary changes, cropland management and sociopolitical forces to explain the gully cut processes. Finally, semi-structured interviews and sedistratigraphic analysis of three filled gullies confirm the dominant impact of (crop)land management (tillage, check dams in gullies and channel diversions) on gully cut-and-fill processes. Since agricultural land management – including land tenure and land distribution – has been commonly neglected in earlier related research, we argue therefore that it can be a very strong driver of 20 th century gully morphodynamics. This article is protected by copyright. All rights reserved.

Description: ABSTRACT Knowledge and understanding of shore platform erosion and tidal notch development in the tropics and subtropics relies mainly on short-term studies conducted on recently deposited carbonate rocks, predominantly Holocene and Quaternary reef limestones and aeolianites. This paper presents erosion rates, measured over a ten year period on notches and platforms developed on the Permian, Ratburi limestone at Phang Nga Bay, Thailand. In so doing it contributes to informing a particular knowledge gap in our understanding of the erosion dynamics of shore platform and tidal notch development in the tropics and subtropics - notch erosion rates on relatively hard, ancient limestones measured directly on the rock surface using a microerosion meter (MEM) over time periods of a decade or more. The average intertidal erosion rate of 0.231 mm/yr is lower than erosion rates measured over 2 – 3 years on recent, weaker carbonate rocks. Average erosion rates at Phang Nga vary according to location and site and are, in rank order from highest to lowest: Mid-platform (0.324 mm/yr) 〉 Notch Floor (0.289 mm/yr) 〉 Rear notch wall (0.228 mm/yr) 〉 Lower platform (0.140 mm/yr) 〉 Notch roof (0.107 mm/yr) and Supratidal (0.095 mm/yr). The micro-relief of the eroding rock surfaces in each of these positions exhibit marked differences that are seemingly associated with differences in dominant physical and bio-erosion processes. The results begin to help inform knowledge of longer term shore platform erosion dynamics, models of marine notch development and have implications for the use of marine notches as indicators of changes in sea level and the duration of past sea levels. This article is protected by copyright. All rights reserved.

Description: ABSTRACT The distribution of trace metals in alluvial sediments depends on their natural background concentrations, and on the dynamics of contemporary depositional and erosional (mainly flood-induced) processes. Geological and geochemical investigations were carried out in the valley of Vistula River near Magnuszew (central Poland). Sediment samples were collected from a depth of 35 cm and comprise sediments of all defined geomorphological features. Identification and geological interpretation of the morphodynamic sediment features was supported by aerial photographs and high-resolution satellite images. These studies revealed that the distribution of trace metals is closely linked to the morphogenesis of the alluvial floodplain. The highest concentrations of Cu, Co, Zn, V, Cr and Ni were observed in crevasse-splays deposits. By contrast, Sr, Pb and As were concentrated in deposits which fill oxbow lakes (partly infilled with organic deposits). The lowest concentrations of trace metals were detected in flood sediments deposited within erosional troughs. The geomorphological and sedimentological history of the fluvial features explains the pattern of heavy metal distribution on the current floodplain surface. This article is protected by copyright. All rights reserved.

Description: ABSTRACT The archetypal badass is individualistic, non-conformist, and able to produce disproportionate results. The badass concept is applied here to geomorphology. The individualistic concept of landscape evolution (ICLE) is introduced, based on three propositions: excess evolution space, capacity of all landforms to change, and variable selection pressure from environmental factors within and encompassing landscapes. ICLE indicates that geomorphic systems are idiosyncratic to some extent, and that even where two systems are similar, this is a happenstance of similar environmental selection, not an attractor state. As geomorphic systems are all individualistic, those that are also non-conformist with respect to conventional wisdoms and have amplifier effects are considered badass. Development of meander bends on a section of the Kentucky River illustrates these ideas. The divergence of karst and fluvial forms on the inner and outer bends represents unstable amplifying effects. The divergence is also individualistic, as it can be explained only by combining general laws governing surface and subsurface flow partitioning with a specific geographical and environmental setting and the history of Quaternary downcutting of the Kentucky River. Landscape evolution there does not conform to any conventional theories or conceptual frameworks of geomorphology. The badass traits of many geomorphic systems have implications for the systems themselves, attitudes toward geomorphic practice, and appreciation of landforms. Badass geomorphology and the ICLE reflect a view, and approach to the study of, landforms as the outcome of the interplay of general laws, place-specific controls, and history. Badass geomorphology also implies a research style receptive to contraventional wisdoms. Aesthetically, amplifier effects and individualism guarantee an essentially infinite variety of landforms and landscapes that geoscientists can appreciate both artistically and scientifically. Non-conformity makes the interpretation and understanding of this variety more challenging—and while that increases the degree of difficulty, it also makes for more interesting and compelling professional challenges. This article is protected by copyright. All rights reserved.

Description: ABSTRACT This short communication describes the development and application of analytical reasoning to quantify instability of an aeolian environment using scale-dependent information coupled with conceptual knowledge of process and feedback mechanisms. Specifically, a simple Fuzzy Cognitive Map (FCM) for aeolian landscape instability was developed that represents conceptual knowledge of key biophysical processes and feedbacks. Model inputs include satellite-derived surface biophysical and geomorphometric parameters. FCMs are a knowledge-based Artificial Intelligence (AI) technique that merges fuzzy logic and neural computing in which knowledge or concepts are structured as a web of relationships that is similar to both human reasoning and the human decision-making process. Given simple process-form relationships, the analytical reasoning model is able to map the influence of land management practices and the geomorphology of the inherited surface on aeolian instability within the South Texas Sandsheet. Results suggest that FCMs can be used to formalize process-form relationships and information integration analogous to human cognition with future iterations accounting for the spatial interactions and temporal lags across the sand sheets. This article is protected by copyright. All rights reserved.