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For streams draining urban catchments, sediment transport capacity is the key driver of physical impacts including bed sediment removal and channel incision. The main unanswered question is the relative role of flow alteration compared to sediment supply in influencing sediment transport capacity. With this objective, we computed sand and gravel bed sediment transport capacity using the Wilcock and Kenworthy two-fraction bedload transport relation for nine streams in catchments covering a gradient of urbanisation. Computations were done for typical natural bed surface material, based on conditions in the least urban study streams. We compared transport capacity distributions and cumulative transport capacity over one-year between the streams. Transport capacity was up to three orders of magnitude higher in urban streams than in forested-catchment streams. This was driven overwhelmingly by the urbanisation-induced alterations to the flow regime, with only minor feedback from channel form changes. Transport capacity was two to three orders of magnitude greater than measured bedload transport in all but the least urban streams. This excess bedload transport capacity mobilises and removes bed sediment, produces channel incision and enlargement and reduces channel complexity. Rebalancing transport capacity with sediment supply therefore requires significant flow mitigation towards pre-urban conditions. Other responses, which may theoretically help to regain this balance – channel widening, grade control, increasing roughness, sediment augmentation – are either inappropriate or only feasible following flow mitigation measures. [ABSTRACT FROM AUTHOR]

Recent research in northern Iceland has highlighted a significant period of rock slope instability during the early Holocene due to the combined effects of postglacial rebound, relative sea-level fall, and glacially oversteepened mountain slopes. Using the Vatn landslide (Skagafjörður, central northern Iceland) as an example, this paper focuses on this period and describes the sequence of events that led to landsliding. Geomorphic mapping, stratigraphical evidence, and both radiocarbon and tephra dating were applied. Collectively, the data acquired indicate that the landslide occurred between 11,400 and 10,790 cal. yr BP. However, while rock slope failure represents a significant disintegration of mountain slopes, this study suggests that large postglacial landslides might also play a role in arresting sediment transport from other hillslope processes rather than contributing large volumes of sediment. [ABSTRACT FROM AUTHOR]

Archaeologists make inferences about past human behaviour based on patterned material residues in various depositional contexts, including existing landsurfaces. These deposits are generated by processes that may obscure patterns at some observational scales while highlighting others, and interpretive differences can arise from a lack of explicit models of deposit formation. Here, an exploratory agent-based model based on the concept of the palimpsest is used to examine the effects of episodic sediment transport on the visibility and preservation of surface archaeological deposits in a fluvial context. Outcomes from the model indicate that the compound influences of preservation and visibility are capable of transforming a static radiocarbon record into one of increasing intensity towards the present, while simultaneously displaying periodic chronological gaps – features that have been used in our Australian study area to argue for demographic change driven by social or environmental factors. To differentiate between interpretations, expectations derived from the model are assessed against a second proxy from the same study area: Optically Stimulated Luminescence dates from hearth stones in surface contexts. Results indicate that patterns in the chronometric proxies from the study area are more consistent with episodic geomorphic change than explanations invoking changes in the local organization of human activity. [ABSTRACT FROM AUTHOR]

This progress report on the discipline of fluvial geomorphology for the calendar years 2010–2011 extends the analysis carried out by Stott (2010, 2011) of papers published in Earth Surface Processes and Landforms (ESPL) during the calendar years 2006–2007 and 2008–2009 to include the period of 2010–2011. A total of 327 papers were published in the 30 issues of ESPL during the review period, up from 284 during 2006–2007 and 300 in 2008–2009. Of these papers, 175 (54%) were within the subject area of fluvial geomorphology, compared to 125 out of 284 (44%) in the 2006–2007 period, and 113 out of 297 (38%) in the 2008–2009 period. In comparing the three two-year periods covering 2006–2011, the numbers of papers in each of 10 subdisciplines within fluvial geomorphology (e.g. bank erosion, hydraulics, soil erosion) changed markedly. For example, river management, restoration and the effects of vegetation on fluvial systems changed from first in rank in 2006–2007 to tied in fourth place in 2008–2009 and eighth in 2010–2011. In contrast, the subdiscipline of soil erosion was consistently the second-ranked topic in each of the three two-year periods. Following the analysis of patterns of publications in ESPL, selected papers from each of the 10 subdisciplines are reviewed. The articles discussed were selected by searching using keywords from the 10 subdisciplines using http://scholar.google.co.uk, then selecting a relevant journal article from the first 10 hits returned. In this way, 33 papers drawn from 22 journals were sampled and their key findings are summarized. [ABSTRACT FROM AUTHOR]

This progress report on the discipline of fluvial geomorphology reviews 134 papers, 112 of which were published in Earth Surface Processes and Landforms (ESPL) during the calendar years of 2008 and 2009. It continues where the last report for 2006 and 2007 (Stott, 2010) ended. Papers are again grouped by themes to cover 10 subdisciplines within the subject area. The themes were chosen by classifying all geomorphological articles published in ESPL for the same period, of which 38% were within the subject area of fluvial geomorphology. Themes (in order of number contributing to the total) were: fluvial sediment transport; soil erosion and control; modelling the fluvial environment; river management, restoration and effects of vegetation on fluvial systems; gully and hillslope sediment transfer; river regulation, channel change and human influences; advances in methodology in fluvial geomorphology; fluvial hydraulics; fluvial chronology; and bank erosion in fluvial systems. The 2006–2007 and 2008–2009 periods are compared and it was found that broadly the same themes retained their popularity (in terms of numbers of papers published) as in the previous report for 2006–2007. [ABSTRACT FROM AUTHOR]

Soil moisture is a critical component of the earth system and plays an integrative role among the various subfields of physical geography. This paper highlights not just how soil moisture affects atmospheric, geomorphic, hydrologic, and biologic processes but that it lies at the intersection of these areas of scientific inquiry. Soil moisture impacts earth surface processes in such a way that it creates an obvious synergistic relationship among the various subfields of physical geography. The dispersive and cohesive properties of soil moisture also make it an important variable in regional and microclimatic analyses, landscape denudation and change through weathering, runoff generation and partitioning, mass wasting, and sediment transport. Thus, this paper serves as a call to use research in soil moisture as an integrative and unifying theme in physical geography. [ABSTRACT FROM AUTHOR]

Lacustrine sediments are often used for paleoclimate reconstructions as continuous archives of several physical and biological proxies. The relation between autochthonous and allochthonous sedimentation in alpine lakes is a complex system that may cause difficulties when interpreting biological and physical parameters. Results from previous studies of alpine lakes in northern Sweden have demonstrated that non-glacial processes produce minerogenic lake deposits with similar physical characteristics (density, LOI, magnetic susceptibility, grain-size) as those that have been associated with glacier fluctuations in proglacial lakes. In this study of two consecutive proglacial alpine lakes we show that fluvial redeposition of alluvial fan deposits significantly affects the Holocene lake sedimentation. Depending on the geomorphological setting, such fluvial redeposition signals may actually overprint a glaciofluvial signal. We also show that minerogenic laminations of fluvial origin are impossible to separate from the type of laminations usually used to infer glacier activity using the most common lithological sediment parameters. This emphasizes the complexity of sediment transport system in proglacial (paraglacial) settings where redeposition of older glacial sediment is of major importance. Our results highlight the need for thorough understanding of the geomorphological setting before inferences are made about climate variations from sedimentation in alpine lakes. Both lakes in this study contain sediment sequences with both episodic (turbidites) and continuously deposited sediments. Unfortunately we have too few radiocarbon dates to exactly date the turbidites but it is clear that turbidite layers in any case should be excluded from age model constructions since episodic sedimentation significantly influences the sediment age—depth relationship. In our age-model turbidites cause a potential dating error of several hundred, up to a thousand, years. [ABSTRACT FROM AUTHOR]

This review highlights recent work in coastal geomorphology that challenges existing wisdom, breaks new ground or contributes in some way to wider principles. Sediment transport by currents and by waves remains a major focus of coastal process geomorphology, and the contribution of this work to our appreciation of landform dynamics is particularly evident at the beach scale. Reconstructive studies over Holocene to historical timescales are yielding new insights into the adjustment of coastal sedimentary systems to progressive environmental forcing, high-magnitude events and human activities. Coastal geomorphology is currently buoyed by opportunities afforded by the implied threats of climate change and sea-level rise, and by the conceptual and technical challenges of predicting morphodynamic behaviour at the all-important 'engineering' scales. Of some concern is the lack of dialogue with other major strands of geomorphology. One of the main challenges, to create models capable of revealing emergent aspects of spatially distributed interactions between form and process, is common to all geomorphologists engaged with the meso-scale. Yet coastal specialists seem reluctant both to draw inspiration from and also to contribute ideas to what might be seen as a single, extremely broad, research front. More generally, there is little exchange of ideas or contribution to a shared intellectual endeavour. Coastal geomorphology is at the forefront of the discipline when it comes to the exploitation of new environmental instrumentation and remote sensing technologies. It can only be hoped that the plethora of high-resolution multitemporal data sets will contribute to the advance of geomorphological thinking rather than merely being used to constrain sediment budgets as a basis for the management of localized erosion problems. [ABSTRACT FROM AUTHOR]

The rivers of India reveal certain special characteristics because they undergo large seasonal fluctuations in flow and sediment load. The rivers are adjusted to an array of discharges, and most rivers exhibit morphologies that are related to high-magnitude floods. In the last 100 years primarily hydraulic engineers have contributed to the understanding of the fluvial forms and processes. Though this trend has continued even today, in recent decades some interesting fluvial research has also been carried out by earth scientists. Four large rivers, namely Brahmaputra, Kosi, Indus and Narmada, have received greater attention from fluvial geomorphologists. The major themes in Indian fluvial geomorphology include the hydrology of monsoonal rivers; forms and processes in alluvial channels; causes of avulsion, channel migration; and anomalous variations in channel patterns; dynamics of suspended sediment; and the geomorphic impacts of floods. Studies of bedrock channels are far less than similar studies in alluvial channels. Only a few rivers have been investigated in this respect. Studies indicate that the Himalayan rivers are different in many respects from those of the Indian Peninsula. The former occupy a highly dynamic environment with extreme variability in discharge and sediment load. Earthquakes and landslides also have a great impact on these rivers from time to time. Consequently, the rivers are characterized by frequent changes in shape, size, position and planform. In comparison, the adjustments in Peninsular rivers are less frequent and of a much smaller magnitude. An inescapable conclusion is that in the tropical monsoonal environment, large floods are important geomorphic agents that temporarily affect the forms and behavioural characteristics of some rivers, but leave a lasting effect on others. In magnitude-frequency terms, large floods are major formative events in many rivers of the Indian region in general and the Indian Peninsula in particular. [ABSTRACT FROM AUTHOR]

Evaluates published work on fluvial geomorphology for the year 2000 and first six months of 2001. Effects of tectonics on drainage initiation and evolution; Impact of Quaternary climate change; Palaeflood hydrology; Sediment yield; Bed load transport; Floodplains; Channel pattern and type; Vegetation, sediment and geomorphology interactions; Human-induced channel change.