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(IF 3.82; Q1); International audience; The response by Van Vliet-Lanoë et al. to our paper on potential thermokarst features in Pleistocene alluvial deposits from the Paris Basin (France) presents inconsistencies that we consider here successively. These are (1) the map of the maximum extent of Pleistocene permafrost in France, (2) the genesis of liquefaction and fluidization structures in periglacial environments, (3) the origin of thermokarst lakes and recumbent folds, (4) the depositional context of sandy units, and (5) the age of the studied deposits. All structures result from the interplay between (1) the growth and degradation of ice wedges, which are responsible for the development of a mound-like topography (badland thermokarst reliefs) on the edge of the alluvial terrace and from the initiation of ponding elsewhere on the terrace, (2) the degradation of lithalsa that developed later in the lacustrine deposits. The sequence was dated confidently to the Late Weichselian.

International audience; Between October 2010 and November 2017, surveys using terrestrial laser scanning (TLS) were carried out every 4-5 months to monitor erosion on three chalk cliff faces with close structural characteristics in Normandy (the two Dieppe sites are abandoned cliffs while the Varengeville-sur-Mer site is an active one). The uniqueness of this paper is the comparison between these cliff sections and the significance of marine and/or subaerial controls in erosion. Beyond the quantification of annual retreat rates, which on the active cliff are currently 36 times greater than on the abandoned cliffs, this paper highlights the fundamental efficacy of marine controls in the current cliff erosion and the removal of falls (analyses of modalities of retreat and profile evolution according to a naturalistic approach). Subaerial processes appear to have a less erosive action than marine ones, because the studied abandoned cliffs show low erosion dynamics and have maintained a subvertical profile despite continentalization for between 30 to more than 120 years.

In Southwest China (SWC) soil loss is becoming a serious threat to the sustainable development of resources and the health of the environment. A large number of studies have been conducted to investigate the causes (e.g. environmental factors and human activities) and impacts (e.g. karst rocky desertification) of soil loss. However, the following are some important problems related to soil loss in the karst of SWC: 1) although soil loss is caused by chemical weathering, gravity and water interaction in karst, the mechanisms by which soil loss takes place in the SWC and their interaction are still not clear; 2) subsurface soil loss varies under different geological and hydrological conditions, and there is still no consensus on the common the ratio between surface soil erosion and underground soil loss; 3) traditional methods for soil loss risk assessment are difficult to apply over the whole of SWC; and 4) a large number of studies have been published only in Chinese and remain inaccessible to the international science community. Therefore, a review paper is needed to address this gap and introduce the contributions of Chinese researchers to soil loss in karst. This paper proposes a novel modelling approach for the grouped soil loss styles and presents a comprehensive discussion for the mechanism, causes, and risk assessment of the various soil loss styles in SWC karst.

Investigations of headland sand bypassing are still an under-reported subject in the literature. This paper aims to understand the contribution of currents forced by different mechanisms such as tides, winds (i.e. local wind acting over the ocean surface generating currents, without considering wave generation) and waves (as they approach/break on the coast) to headland sand bypassing. The study was carried out in an area comprising a series of seven headlands with varying wave exposure due to changes in shoreline orientation and increasing tidal influence close to a relatively large bay. This paper uses a calibrated and validated process-based model (Delft3D) to simulate a series of scenarios including spring and neap tides during flood and ebb conditions and a range of wind and wave scenarios that encompass both average and extreme conditions. The results indicate that waves are the main driving force for the headland bypassing as they transport sand at rates two orders of magnitude higher than tide- or wind-driven sediment transport. The tide-driven currents can only transport sediment during spring tides in locations where the currents are intensified. It is also demonstrated that the wave direction plays an important role in sediment transport. In exposed areas with larger headlands a combination of wave directions is required to first transport sediment offshore (out of the beach) and secondly to transport sediment alongshore and back to the next beach. Whereas in areas with little variation in wave direction exposure, the same oblique wave direction is responsible for the entire headland bypassing process. This is the first time the contribution of tide-, winds- and wave-generated sediment transport to headland bypassing have been studied.

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.

Rana and Sharma (2017) dispute our tectonic interpretation mainly on the basis of what they believe (climate?). However, we welcome their comments, as this gives us a chance to highlight the ambiguity inherent in discriminating the climate-tectonic imprints in morphotectonic records that are prevalent in current research. We should note that the paper published by Kothyari et al. (2017) was reviewed by national/international reviewers. We would like to emphasize the fact that the paper does not rule out the role of climate. However, most importantly, it presents significant features and observations that collection/assemblage points toward the dominant role of tectonics in their shaping, and not solely climate, as postulated by Rana and Sharma (2017). The objective of this paper is to identify tectonic signatures (geomorphology) in a monsoon - dominated, tectonically active terrain like the North Almora Thrust (NAT). These faults are marked by previous workers based on field evidence such as folding and faulting of lithological units; presence of slickensides parallel to the fault; offset of NAT owing to a transverse fault; and offset of drainage, drainage basin analysis, strath terraces, fluviolacustrine terraces, development of scarp, narrow river course, and deeply incised valleys. However, we disagree with the comments raised by Rana and Sharma (2017), because they are highly skewed toward the climate school of thought, and did not perceive the setting as a collection of landforms. Instead, they attempted to view them in isolation. Because these comments are important, we will try to further our research incorporating issues related to isolation of climate and tectonics imprints in the immediate future. We would like to thank Rana and Sharma (2017) for raising some basic questions on our work as this gave us an excellent opportunity to summarize and present the dominance of various processes and related landforms as earlier reported by Kothyari et al. (2017). A point-by-point detailed rebuttal/explanation of their queries is provided below.

This paper presents the results of the Schmidt Hammer Rock Tests (SHRTs) across a range of rocky coastal landforms. Northern Billefjorden (central Spitsbergen), represents typical High Arctic microtidal fjord environment. Sheltered location and prolonged sea-ice conditions limit wave action. Coastal cliffs, shore platforms and skerries are developed in various rock types including limestone, sandstone, anhydrite/gypsum, dolomite and metamorphic outcrops. SHRT demonstrated a broad variety of relationships between rock strength and distance from shoreline, presence of sediment cover, distribution of snow patches and icefoot, and accumulations of seaweed and driftwood. In general, rock cliff surfaces were the most resistant in their lower and middle zones, that are thermally insulated by thick winter snowdrifts. More exposed cliff tops were fractured and weathered. The differences in rock strength observed along the shore platforms were highly dependent on thickness of sediment cover and shoreline configuration promoting stronger rock surfaces in areas exposed to the longest wave fetch and washed from gravel deposits. Rock strength of skerry islands is influenced by tidal action controlling the duration of tide inundation and movement of sea-ice scratching boulder surfaces. The results presented in this paper emphasize the richness of rock coast geomorphology and processes operating in High Arctic settings.

Many deltas, including the Mississippi River Delta, have been losing land at fast rates compromising the safety and sustainability of their ecosystems. Knowledge of delta vulnerability has raised global concern and stimulated active interdisciplinary research as deltas are densely populated landscapes, rich in agriculture, fisheries, oil and gas, and important means for navigation. There are many ways of looking at this problem which all contribute to a deeper understanding of the functioning of coastal systems. One aspect that has been overlooked thus far, yet fundamental for advancing delta science is connectivity, both physical (how different portions of the system interact with each other) as well as conceptual (pathways of process coupling). In this paper, I propose a framework called Delta Connectome for studying connectivity in river deltas based on different representations of a delta as a network. After analyzing the classic network representation as a set of nodes (e.g., bifurcations and junctions or regions with distinct physical or statistical behavior) and links (e.g., channels), I show that from connectivity considerations the delta emerges as a leaky network that continuously exchanges fluxes of matter, energy, and information with its surroundings and evolves over time. I explore each network representation and show through several examples how quantifying connectivity can bring to light aspects of deltaic systems so far unexplored and yet fundamental to understanding system functioning and informing coastal management and restoration. This paper serves both as an introduction to the Delta Connectome framework as well as a review of recent applications of the concepts of network and connectivity to deltaic systems within the Connectome framework.

Floods are a crucial agent of geomorphic change in the channels and valley floors of mountains watercourses. At the same time, they can be highly damaging to property, infrastructure, and life. Because of their high energy, mountain watercourses are highly vulnerable to environmental changes affecting their catchments and channels. Many factors have modified and frequently still tend to modify the environmental conditions in mountain areas, with impacts on geomorphic processes and the frequency, magnitude, and timing of floods in mountain watercourses. The ongoing climate changes vary between regions but may affect floods in mountain areas in many ways. In many mountain regions of Europe, widespread afforestation took place over the twentieth century, considerably increasing the amounts of large wood delivered to the channels and the likelihood of jamming bridges. At the same time, deforestation continues in other mountain areas, accelerating runoff and amplifying the magnitude and frequency of floods in foreland areas. In many countries, in-channel gravel mining has been a common practice during recent decades; the resultant deficit of bed material in the affected channels may suddenly manifest during flood events, resulting in the failure of scoured bridges or catastrophic channel widening. During the past century many rivers in mountain and foreland areas incised deeply; the resultant loss of floodplain water storage has decreased attenuation of flood waves, hence increasing flood hazard to downstream river reaches. On the other hand, a large amount of recent river restoration activities worldwide may provide examples of beneficial changes to flood risk, attained as a result of increased channel storage or reestablished floodplain water storage. Relations between geomorphic processes and floods operate in both directions, which means that changes in flood probability or the character of floods (e.g., increased wood load) may significantly modify the morphology of mountain rivers, but morphological changes of rivers can also affect hydrological properties of floods and the associated risk for societies. This paper provides a review of research in the field of floods in mountain environments and puts the papers of this special issue dedicated to the same topic into context. It also provides insight into innovative studies, methods, or emerging aspects of the relations between environmental changes, geomorphic processes, and the occurrence of floods in mountain rivers.

Schumann et al. (2016) presented a field assessment of late Pleistocene to Holocene fluvial sediments preserved in the valleys of Santa Rosa Island, California. This is a rigorous study, based on stratigraphic descriptions of 54 sections and numerous radiocarbon ages. The paper makes important contributions that we would like to highlight, but other parts of the paper rely upon overly simplistic interpretations that lead to misleading conclusions. In one case, a conclusion of the Schumann et al. paper has important management implications for Santa Rosa Island and similar locations, compelling us to discuss and qualify this conclusion.

This paper provides a review of recent publications dealing with different issues of sandstone geomorphology, which was long an under-researched theme. Nevertheless, considerable advances have been made recently regarding the origin of various characteristic landforms and landscapes developed in sandstones. The structure of this review reflects the diversity of spatial scales, so that it begins with minor landforms and moves towards regional landscapes, considering both the form and the process. It first focuses on the origin and evolution of microforms on rock surfaces, especially honeycombs and arcades, which have been demonstrated to reflect the distribution of stress within the rock mass and the hydraulic field. A distinction is made between ‘organizing’ and ‘decay’ factors, with the latter varying depending on local circumstances, whereas the overarching role of the former explains equifinality. Then the concept of negative feedback between stress and erosion is reviewed, with reference to medium-scale landforms, mainly pedestal rocks and rock arches. In the next part new evidence and ideas about the role of subsurface processes in shaping medium-size and major landforms is presented, with emphasis on chemical decay (arenization), mechanical erosion and sapping. Larger landforms discussed are rock cities and ruiniform relief, canyons and mesas. It is argued that subsurface processes play an important part in the evolution of rock cities and boulder-filled canyons, whereas recent work on residual hills shows that plateau ➔ mesa ➔ butte ➔ pinnacle trajectory is but one possible pathway of geomorphic evolution of tablelands. In the following part a new concept of in situ disintegration of sandstone-capped escarpments is presented as complementary to the widely accepted model emphasizing large scale, often catastrophic mass movements. Finally, recent attempts to use geomorphometry tools to characterize rugged sandstone relief are presented. The paper is closed with an outline of challenges for the future.

Coastal dunes have received growing attention in recent years because of the ecosystem services they provide and the high anthropic pressure that they have historically been subjected to and continue to endure. Such pressure especially affects arid dune fields where any changes are more noticeable due to their natural dynamics. The aim of this paper is to analyze the relationship between the degradation of an arid aeolian sedimentary system (El Medano, Tenerife, Spain) due to historical long-term land uses and its subsequent biogeomorphological evolution. The methodology combines historical sources (historical documents, aerial and common photographs and oral sources) and current ones (orthophotos, LiDAR data and field work). In order to analyze the response of the system to these uses, 8 plots were chosen in which 3 different historical land uses had resulted in the total or partial elimination of the vegetation and landforms. Biogeomorphological variables were measured on 461 nebkhas in these plots. The main results show that the historical land uses studied in this paper (aerodrome, aggregate extraction and crop cultivation) modified the entire system, with changes observed in the topography, vegetation cover and sediment availability for transport. Changes in topography and distance from shore were important factors in its recovery capacity. This research contributes to our understanding of the different aeolian sedimentary dynamics that can be detected in the same dune field (especially with nebkha landforms) and is of particular importance for making appropriate environmental management decisions to facilitate the recovery of the ecosystem.

The Colorado River's course through Grand Canyon and across the topographic high imposed by the Kaibab Plateau represents one of the most well-known transverse drainages. Only four processes allow a river to flow across a topographic obstruction: antecedence, superimposition, piracy, and overflow. Since Powell first described the canyon in 1875, various authors have repeatedly proposed variations of all four mechanisms to explain the formation of the Grand Canyon, and this paper does not review or try to refute this prior scholarship. This paper's purpose rests in providing a detailed evaluation of evidence associated with overflow upstream, across, and downstream of the East Kaibab monocline paleodivide. Upstream of the paleodivide, we re-interpreted the Bidahochi Formation. The older units of this formation represent a fluctuating system between playa and lacustrine deposition fed by multiple localized tributaries entering a topographically barred basin. The younger Bidahochi units signify the abrupt arrival of an additional drainage with a distinctive geochemical signature into the basin roughly 6.8 Ma, supported by three lines of evidence: (1) an order of magnitude increase in depositional rates from 3 m/Ma in the older units to 50 m/Ma in the younger units that buried the paleo-landscape, at least locally, up to an elevation of at least 2250 m (7380 ft); (2) new evidence of an elevated 87Sr/86Sr ratio in the younger units when compared to the older units and the modern Colorado River; and (3) fossil evidence of the existence of large, freshwater lakes and rivers in the Bidahochi Basin during deposition of the younger units. Newly re-evaluated evidence at the East Kaibab paleodivide focuses on a southern bend of the Colorado River's path across the Kaibab Plateau, as well as the confluence of the Colorado and the Little Colorado rivers at the junction of the Kaibab Plateau and Cedar Ridge. Both lines of evidence at the paleodivide focus on the impact of topography on Grand Canyon incision, and both lines of evidence are consistent only with an overflow process. Evidence downstream of the paleodivide includes the abrupt arrival of river water with an elevated 87Sr/86Sr ratio followed by Colorado River sediment into a series of successively lower downstream basins that integrated via overflow. New 10Be/9Be geochemistry data support the relative timing of deposition of the Bidahochi Formation followed soon after by deposition of the Bouse Formation downstream of the Grand Canyon. We conclude that newly presented and re-evaluated available evidence supports an overflow process for the Colorado River's transverse section across the Kaibab Plateau, ultimately resulting in incision of the Grand Canyon.

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.

We provide comments on the paper: “Geomorpho-tectonic evolution of the Jamaican restraining bend” by Dominguez-Gonzalez et al. (2015). The literature review given is lacking in significant elements, particularly recent papers detailing the geology and uplift history of Jamaica. The paper undertakes a GIS analysis of a DEM and produces a drainage network for Jamaica, yet the networks created do not match the actual drainage network of the island. River profiles were extracted using 150 m contours and many of the knickpoints identified are not related to tectonics. The recognition of different erosional (and thus evolutionary) stages does not take into account the differing geology and the different geomorphological processes that were in operation, and the proposed model for the progressive uplift of different parts of Jamaica must therefore be treated with caution. This is particularly the case where their uplift model agrees neither with recent models based on provenance analysis or on the origin of Jamaican bauxite deposits. This paper demonstrates the problems of relying on remote sensing using inadequate datasets, no ground truthing and incomplete consideration of previous research.

Debris flow is a major geohazard in mountainous regions and poses a significant threat to life and property. The damage caused by debris flows have increased with the expansion of human settlements and activity into the mountainous regions of China. In regards to risks from debris flows, previously unrecognized low-frequency debris flow catchments constitute an especially significant threat. According to our investigation, only about 500 catchments have debris flow records in >2000 catchments of Bailong River basin. The main purpose of this paper is to introduce a new methodology using Artificial Intelligence (AI) that can simultaneously input parameters related to geomorphological conditions and material conditions to better distinguish low-frequency debris flow catchments (LFDs) from medium-high frequency debris flow catchments (MHFDs). A total of 449 prototypical debris flow catchments, 15 parameters, and 9 commonly used learning machines were used to build identification models. Debris flow catchments are divided into 4 cases (LO1-LO4) based on different sample ratios of LFDs and MHFDs, which are input into each classifier one by one. Based on model evaluation, the CHAID model in the case LO2 performs best, which only uses five parameters (formation lithology index, land use index, vegetation coverage index, drainage density and landslide density index) to predict LFDs. The results indicate that LFDs are mainly distributed in areas with less landslide distribution and better vegetation coverage compared with MHFDs. However, the distribution of LFDs is concentrated on FLI (formation lithology index) =4, which is the weak lithology area. The tree classifier seems to be better at classifying fluvial processes. The model developed in this paper can help us quickly find LFDs in similar areas, and help to assess the risk of debris flows.

Balls Pyramid is the southernmost island in a linear island chain in the southwest Pacific Ocean, 24 km south of the limit of known coral reef formation at Lord Howe Island. This paper describes the geomorphometric structure of the shelf surrounding Balls Pyramid through the application of remote sensing data to create a high-resolution digital elevation model of the shelf (5 m cell size) and seafloor feature classification. Seafloor features were delineated using the bathymetry model together with slope, backscatter and sub-bottom profile data. The average depth of the 260.6 km2 shelf was 55 m (± 21 m), with the majority of shelf area (77%) within 30–60 m water depth. Dominating the shelf is an extensive, mid-shelf reef at 30–50 m depth, dissected by basin and channel features. Outer-shelf reef and platform features surround the mid shelf, with terrace sequences marking the seaward outer-shelf rim in 65–100 m depth. Sub-bottom profiles and backscatter data demonstrate substantial accumulation (up to 16.5 m) of unconsolidated sediments within basin and channel features. The submerged mid-shelf reefs of Balls Pyramid are similar to the fossil coral reef system discovered on the Lord Howe Island shelf, implying origins as a drowned coral reef system. This paper reveals complex shelf topography with extensive submerged reefs on what was previously considered to be a planated volcanic shelf outside of reef-forming seas.

Sinkholes represent a natural risk that may hit catastrophically without clearly detectible precursors. However, they are often overlooked by people and administrators. Therefore sinkhole monitoring and associated early warnings constitute important research topics but, currently, only a few papers about sinkhole prediction can be found. In this paper an experience of sinkhole monitoring and early warning with GB-InSAR is described. The latter is a highly precise instrument that is able to produce displacement maps with metric spatial resolution. The described activities were carried out on Elba Island (central Italy), where karstified limestone set off the occurrence of nine sinkholes since 2008, all within less than 3000 m2, causing major damage to an important road and many indirect losses. In 1 year of monitoring two deforming areas were detected, and the point where a sinkhole was about to propagate to the street level was predicted, thus permitting the preventive closure of the road. The deformation area was larger than the hole generated by the sinkhole, thus showing a subsidence that continued for a prolonged time even after the cavity was filled up. The occurrence of a 1.5-m-wide sinkhole, undetected by the GB-InSAR, also showed the lower detection limit of the instrument.

In tectonically active areas, such as in the northwest Peloponnese of western Greece, geomorphic processes are strongly influenced by active faulting; in many cases such faults cannot be easily identified. In this paper we apply multidisciplinary analysis (morphotectonic indices, neotectonic mapping, geophysical surveys and remote sensing techniques) to map the recently-recognized east–west trending Pineios River normal fault zone with a high degree of accuracy, and to better understand its contribution to the evolution of the ancient region of Elis during Holocene time. Fault activity seems to be related to frequent changes in river flow patterns and to displacements of the nearby shoreline. We argue that fault activity is the main reason for migration of Pineios river mouth as documented for several time periods during historical time. Quantitative constraints on deformation caused by the faulting were applied through the application of the morphotectonic indices proposed in this paper, including drainage network asymmetry and sinuosity, and mountain front sinuosity, all of which indicate that this is a highly active structure. Slip rates calculated to be as high as 0.48 mm/yr for the last 209 ka (based on previously published dating) were verified by applied geophysical methods. The fault surface discontinuity was identified at depth using vertical electrical resistivity measurements and depositional layers of different resistivity were found to be clearly offset. Displacement increases toward the west, reaching an observed maximum of 110 m. The most spectacular landform alteration due to surface deformation is the north–south migration of the river estuary into completely different open sea areas during the late Quaternary, mainly during the Holocene. The sediment transport path has been altered several times due to these changes in river geometry with and the most recent seeming to have occurred almost 2000 years ago. The river estuary migrated to its contemporary position along the southern coast, settled on the hanging wall, inducing retrograding of the northern coast, and settled on the foot wall, with rates reaching the order of 0.52 m/yr, as concluded from historical and recently-acquired remote sensing data.

This paper investigates the controls on the formation of subglacially eroded bedrock bedforms beneath the topographically confined region upstream of the Uummannaq Ice Stream (UIS). During the last glacial cycle, palaeoglaciological conditions are believed to have been similar for all sites in the study, characterised by thick, fast-flowing ice moving over a rigid bedrock bed. Classic bedrock bedforms indicative of glacially eroded terrain were mapped, including p-forms, roches moutonnees, and whalebacks. Bedform long axes and plucked face orientations display close correlation (parallel and perpendicular) to palaeo-ice flow directions inferred from striae measurements. Across all sites, elongation ratios (length to width) varied by an order of magnitude between 0.8:1 and 8.4:1. Bedform properties (length, height, width, and long axis orientation) from four subsample areas, form morphometrically distinct populations, despite their close proximity and hypothesised similarity in palaeoglaciological conditions. Variations in lithology and geological structures (e.g., joint frequency; joint dip; joint orientation; bedding plane thickness; and bedding plane dip) provide lines of geological weakness, which focus the glacial erosion, in turn controlling bedform geometries. Determining the relationship (s) between bedding plane dip relative to palaeo-ice flow and bedform shape, relative length, amplitude, and wavelength has important ramifications for understanding subglacial bed roughness, cavity formation, and likely erosion style (quarrying and/or abrasion) at the ice-bed interface. This paper demonstrates a direct link between bedrock bedform geometries and geological structure and emphasises the need to understand bedrock bedform characteristics when reconstructing palaeoglaciological conditions.

This paper proposes a method to establish a morphological classification of Tenerife's cinder cones on the basis of a dual analysis of qualitative (existence, geometry and disposition of craters) and quantitative morphometric parameters (major and minor diameters and cone elongation, major and minor diameters and crater elongation). The result obtained is a morphological classification of the cinder cones of Tenerife, which can be sub-divided into four types: ring-shaped-cones, horseshoe-shaped-volcanoes, multiple volcanoes and volcanoes without crater. In Tenerife there is a clear dominance of horseshoe-shaped volcanoes (69.0%) over ring-shaped cones (13.1%), volcanoes without craters (11.4%) and multiple volcanoes (6.4%). The classification presented in this paper is characterized by its simplicity which makes it possible to include all morphological types of volcanoes found in Tenerife. This fact also renders our classification a useful tool to apply in other, both insular and continental volcanic areas to eventually analyze and systematize the study of eruptive edifices with similar traits.

This paper analyses with the help of tree-ring studies the recurrence of extreme snow avalanches in a path situated in the upper Bodalen valley and originating from an outlet glacier of the Jostedalsbreen ice cap. By analysing tree-ring patterns of 91 trees, four extreme snow-avalanche events, extending over the entire valley floor and up to a distance of 800 m from the foot of the slope, are clearly highlighted during the 20th century and at the beginning of the 21st century. Return periods of 15 to 20 years for the most extreme events are extracted from the analyses, and recurrence intervals of 10 to 15 years for avalanches presenting distinct deposition lobes uphill of the distal torrent. Results obtained by tree-ring analyses are successfully compared with available documents at different spatial and temporal scales. Rock-face snow-avalanche occurrences in the area, of small to medium size, are associated with heavy wintry precipitation combined with strong winds. However this normal situation is not valid for extreme snow avalanches crossing the path investigated in the paper, which result from the outlet glacier located in the starting zone; this glacier commands spatial and inter-annual variations of snow accumulation in the departure zone.

The scientific literature describes two types of cheniers. These two types differ in the origin of the coarse sediments that constitute the ridge and the relative significance of the transversal and longitudinal wave transport. In both cases storm waves are described as the main factor responsible of the origin and development, and both final facies are characterized by ridges of coarse sediments above the finer sediments of a tidal flat. The Odiel–Tinto estuary is one of the most significant estuarine systems of the mesotidal Huelva Coast, on the northwestern portion of the Gulf of Cadiz, and Saltes Island is a part of the closure history of the estuarine system. Previous works on Saltes Island described the surficial disposition of sandy landforms as a classic ridge chain or a barrier-island succession; nevertheless an architectural scheme based on a vibracore study shows a disposition that accord to the typical chenier plain facies model. This disagreement was the basis for a controversy about the origin of the ridges. In this study historical nautical charts and aerial photographs document the evolution of the last of these cheniers during the past 200 years. In contrast to the accepted models of chenier evolution, the cheniers of Saltes Island migrated on the tidal flat but did not evolve only during storms, indeed their development occurred mainly during high spring tides. The data presented in this paper are used as the basis for a new conceptual model of chenier generation and evolution. The model consists of a migration of sand bars in a similar way to the classic beach ridges, with the difference that in our case, the bars migrate over a tidal flat. From a local point of view this paper removes the controversy about the origin of the island's geomorphology, but from a global point of view this mechanism can explain certain chenier plains in estuarine mouths located in other coasts of the world.

Fluvial systems include natural and human-created barriers that modify local base level; as such, these discontinuities alter the longitudinal flux of water and sediment by storing, releasing, or changing the flow path of those materials. Even in the absence of distinct barriers, fluvial systems are typically discontinuous and patchy. The size of fluvial discontinuities ranges across scales from 10 0 m, such as riffles, to 10 4 m, such as lava dams or major landslides. The frequency of occurrence appears to be inversely related to size, with creation and failure of the small features, such as beaver dams, occurring on a time scale of 10 0 to 10 1 years and a frequency of occurrence at scales as low as 10 1 m. In contrast, larger scale discontinuities, such as lava dams, can last for time scales up to 10 5 years and have a frequency of occurrence of approximately 10 4 m. The heterogeneity generated by features is an essential part of river networks and should be considered as part of river management. Therefore, we suggest that “natural” dams are a useful analog for human dams when evaluating options for river restoration. This collection of papers on the studies of natural dams includes bedrock barriers, log jams and beaver dams. The collection also addresses the discontinuity generated by a floodplain — in the absence of an obvious barrier in the channel — and tools for evaluation of riverbed heterogeneity. It is completed with a study of impact of human dams on floodplain sedimentation. These papers will help geomorphologists and river managers understand the factors that control river heterogeneity across scales and around the world.

Increases in human development of the coastal zone, sea level rise and intensity of coastal storms will test the resilience of coastal systems. An integrated approach is needed to describe geomorphic–biologic dependencies, feedbacks between processes and responses, and determine how coastal systems can be maintained or restored. The 2013 Binghamton geomorphology symposium focused on three themes in these research areas (1) the geomorphic response of coastal landforms to changes in sea level and episodic storms; (2) the way these stressors alter geomorphic–biotic interactions and reduce the resilience of coastal environments; and (3) the way natural and human processes are being integrated to restore or maintain dynamic geomorphic and biologic linkages. This issue contains eighteen papers presented at the symposium; six papers are devoted to each of these themes. The papers point to the importance of ecological systems in modulating the responses to natural physical processes and, in turn, responding to geomorphic change and the role of humans in assisting natural processes.

This paper provides a cumulative review of important specific features in the formation and development of Proval Bay (Lake Baikal) as a large seismic dislocation element. This bay appeared during one of the largest historical earthquakes in Siberia (M LH 7.5) on January 12, 1862. As a result, more than 230 km 2 of the shore was submerged. The paper considers the formation of Proval Bay in the context of analysis conducted on general morphological characteristics of the Baikal rift and in terms of the occurrence of the main elements in the mechanism of its neotectonic development. It is precisely these seismotectonic phenomena, associated with the subsidence of large tectonic blocks, which primarily cause the growth of Lake Baikal basin. In spite of the fact that the northwestern side of the rift has a more pronounced morphological structure, whose general elements are high and steep monolithic tectonic escarpments, major lithospheric extension and its associated extension of the rift, thinning and rearrangement of blocks in the upper lithosphere slab occur on the more gently sloping eastern side.

A fundamental geological tenet is that as landscapes evolve over graded to geologic time, geologic structures control patterns of topographic distribution in mountainous areas such that terrain underlain by competent rock will be higher than terrain underlain by incompetent rock. This paper shows that in active orogens where markedly weak and markedly strong rocks are juxtaposed along contacts that parallel regional structures, relatively high topography can form where strain is localized in the weak rock. Such a relationship is illustrated by the topography of the central Coast Ranges between the Pacific coastline and the San Andreas fault zone (SAFZ), and along the length of the Gabilan Mesa (the “Gabilan Mesa segment” of the central Coast Ranges). Within the Gabilan Mesa segment, the granitic upper crust of the Salinian terrane is in contact with the accretionary-prism melange upper crust of the Nacimiento terrane along the inactive Nacimiento fault zone. A prominent topographic lineament is present along most of this lithologic boundary, approximately 50 to 65 km southwest of the SAFZ, with the higher topography formed in the melange on the southwest side of the Nacimiento fault. This paper investigates factors influencing the pattern of topographic development in the Gabilan Mesa segment of the central Coast Ranges by correlating shortening magnitude with the upper-crust compositions of the Salinian and Nacimiento terranes. The fluvial geomorphology of two valleys in the Gabilan Mesa, which is within the Salinian terrane, and alluvial geochronology based on optically-stimulated luminescence (OSL) age estimates, reveal that the magnitude of shortening accommodated by down-to-the-southwest tilting of the mesa since 400 ka is less than 1 to 2 m. Our results, combined with those of previous studies, indicate that at least 63% to 78% of late-Cenozoic, northeast–southwest directed, upper-crustal shortening across the Gabilan Mesa segment has been accommodated within the Nacimiento terrane. This is significant because perpendicular to orogenic strike the Nacimiento terrane constitutes less than ¼ of the distance between the coast and the SAFZ, and the other ¾ (or greater) of the distance between the coast and the SAFZ is underlain by the granitic upper crust of the Salinian terrane. We propose that strain and mountain building are localized within the Nacimiento terrane because it consists predominantly of the relatively weak Franciscan Complex melange, and because the upper crust of the Salinian terrane is composed of relatively strong granitic rocks. Our hypothesis is supported by the distribution of post-seismic surface uplift associated with the 2003, 6.5 M W San Simeon earthquake, which mimics the topography of the southwestern part of the Gabilan Mesa segment of the central Coast Ranges.

This paper investigates the glacial evolution on the east face of Pico de Penalara (40°51′N, 3°57′W; 2428 m), the highest elevation of Sierra de Guadarrama in the center of the Iberian Peninsula. The geomorphologic stability of glacial landforms and permanence of snow cover were examined, and 18 samples were selected for dating with cosmogenic isotope 36Cl from moraine formations in four well-differentiated phases, as well as from a pre-glacial periglacial blockfield and a glacial threshold near the headwall. The results show the synchrony between the Last Glacial Maximum (LGM) advance and most results obtained recently by cosmogenic dating in southern Europe, within the MIS (Marine Isotope Stage) 2 stadial but earlier than the global LGM, i.e. between 25 and 19 ka BP. There was slow glacial retreat with minor re-advances between 19 and 16 ka and rapid deglaciation from 16 ka. This paper presents initial results, still pending confirmation, for the minimum age of the periglacial summit block formation around 80 ka for the existence of moraine formations older than the last advance and for the existence of glaciers during the Younger Dryas stadial. To explain the synchrony between two moraine formations at different altitudes, this paper formulates the hypothesis of the ‘secondary moraine’ evidenced in currently existing glaciers similar to those which existed on Penalara.

The submarine glacial geomorphology and sedimentology of the cross-shelf troughs and the adjacent continental slope around the Antarctic Peninsula and West Antarctica have been the focus of a series of marine geophysical and geological investigations over the last decade (e.g., [Shipp et al., 1999], [Canals et al., 2000], [Wellner et al., 2001], [Lowe and Anderson, 2002], [O Cofaigh et al., 2002], [Dowdeswell et al., 2004], [Heroy and Anderson, 2005], [Evans et al., 2005], [Domack et al., 2006], [Mosola and Anderson, 2006], [Wellner et al., 2006], [Dowdeswell et al., 2006], [O Cofaigh et al., 2007], O Cofaigh et al., 2008 C. O Cofaigh, J.A. Dowdeswell, J. Evans and R.D. Larter, Geological constraints on Antarctic palaeo-ice stream retreat, Earth Surface Processes and Landforms 33 (2008), pp. 513–525.[O Cofaigh et al., 2008] and [Dowdeswell et al., 2008]). These studies have interpreted sets of characteristic streamlined glacial bedforms and sediments on the shelf, which in numerous cases occur in front of modern ice streams, as largely the product of fast-flowing palaeo-ice streams that drained across the shelf during or following the last glacial maximum. A key feature of these studies is the observation of highly attenuated bedforms known as mega-scale glacial lineations (MSGL), formed in soft sediment on the outer continental shelf. These lineations are regarded as key evidence for streaming flow. In their recent paper, Shaw et al. present a radically different interpretation of the glacial geomorphology of Antarctic cross-shelf troughs in terms of catastrophic discharge of subglacial meltwater floods across the shelf. In their interpretation, MSGL are regarded as the product of erosion by turbulent meltwater flow. The following comment discusses a number of the key assertions made in their paper.

The magnitude of bankfull discharge is an important indicator of the discharging capacity of the Lower Yellow River (LYR), and bankfull discharges at key sections need to be accurately estimated before each experiment of regulating water and sediment in the Yellow River. In this paper, a definition of bankfull stage is first proposed for complicated cross sections in the LYR, including the identification of the main-channel zone and corresponding bankfull elevation, and the geometrical characteristics of typical cross-sectional profiles are investigated during different periods. Four different approaches are listed herein to determine the magnitude of bankfull discharge in the LYR, including a method using the mean daily stage–discharge relation, a method using the instantaneous stage–discharge relation, a method using the stage–velocity relation, and a method using the simulated stage–discharge relation from a one-dimensional hydrodynamic model. The advantages, disadvantages, and applicability of these approaches are pointed out. Finally, the Huayuankou section in the braided reach of the LYR is selected as a study section, and the bankfull discharges at this section during different periods are estimated using these four methods. In addition, the predicted water levels from these approaches are compared with the observed values for the corresponding maximum discharges occurring in the next year. Calculated results show that existing approaches determining the magnitude of bankfull discharge are usually only applicable to specified hydrometric sections with negligible morphological changes during flood seasons, and the fourth method proposed in this paper has higher prediction accuracy than the other methods.

This paper reports the mapping of monthly soil erosion risk on Mauritius which was carried out using GIS, decision rules and readily available data namely, monthly rainfall depth, soil types, slope and land cover. Slope and soil were first combined to produce soil erosion susceptibility followed by land cover to produce erosion sensitivity, and then rainfall to produce erosion risk. The high erosion areas of the Island have been extracted from the soil erosion risk maps, whereby these areas can face land degradation problems and can be responsible for sediment discharge into wetlands located at the outlet of drainage basins. As such, drainage basins have been delineated using automatic catchment delineation tools and their percentage of high erosion areas computed. Basins with the greatest percentage of high erosion areas and particularly those that directly have a wetland at the outlet can be given priority for soil and water conservation efforts. The mapping reported in this paper can be adapted to other countries which need an erosion assessment for the identification of high erosion areas and priority action areas.

Remote sensing data have become more and more popular for geomorphological investigations because their steadily increasing level of detail and accessibility opens up new potentials. In this context, this paper examines the application and quality of digital elevation models (SRTM and ASTER DEMs), high resolution satellite imagery (Quickbird) and GIS techniques for the detection and mapping of karst landforms (mainly enclosed depressions) at different scales in the Ida Mountains of Central Crete. Besides discussing methodological issues and evaluating suitability potentials, we conducted an exemplary case study based on spatial analysis of the regional karst morphology. Different input datasets and processing methods are applied (GIS-based analysis, land cover classification, raster calculations, etc.) in order to carry out an area-wide surveying and mapping of karst depressions. The findings are supported and validated by auxiliary field studies. Due to the level of detail and occasional data errors, an exclusive use of satellite imagery or digital elevation models for automatic karst landform detection performs insufficiently. Our results demonstrate that mapping karst features through remote sensing is significantly dependent on scale of interest, existing environmental conditions and data quality. A semi-automatic data integration approach on the basis of digital datasets generated by combined satellite image processing and DEM analysis yields the best results, especially when indirect karst-indicating variables like iron oxide-rich sediments are included as detection criteria. The multi-component application presented in this paper provides a time-saving and effective tool for meso- to macro-scale object detection and extensive study areas. However, the potential of fully automated karst feature mapping still needs to be explored in future work. Concerning the spatial dimension of karstification in Central Crete, the GIS-based results allow differentiating further geomorphological characteristics, e.g. by indicating a significant altitudinal change of karst forms within the study area. Size and shape of depressions (dolines, uvalas, and poljes) vary considerably due to the geological setting, climatic impacts, neotectonics and elevation.

The methodological assessment of the quality and the usefulness of borehole logs for karst analysis versus the use of data obtained via direct observation is the first objective of this paper. The second objective of the paper is to present — in the form of a case study — regional analysis of karst in Devonian carbonates of the Świetokrzyskie (Holy Cross) Mountains, south-central Poland. The subjects of the discussion are karst evolution stages, karst horizons, and their relationship to relief development. The analyzed examples (sites) presented herein, where the reliability of borehole data has often been verified by field observations, prove that descriptions of borehole logs can be used for karst analysis. However, borehole log data analysis is subject to many limitations and requires extensive validation. The basic condition that has to be met is the explicitness of the descriptions of karst forms in borehole logs. The number and the length of logs (“macro-records”) as well as the number and the size of karst forms (“micro-records”) are other important factors that affect log interpretation quality. Nevertheless, the principal general advantage of borehole log analysis is the representative nature of the obtained information. The formation of karst horizons independent of the lithology and the stratigraphy of the Kowala Fm in the Świetokrzyskie Mountains but controlled by external morphological factors suggests an isotropic character of this formation. Two general vertical types of karst systems are distinguished in this formation: (1) karst horizons, and (2) extensive karst development without distinct differentiation. The former could have been connected with fluvial base levels whereas the latter represents systems formed within the vadose zone.

A jokulhlaup 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 jokulhlaup 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 jokulhlaup. 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 jokulhlaup route are larger and more closely spaced than those along adjacent, otherwise comparable stream channels that have not recently experienced a jokulhlaup; (ii) logjams are not randomly located along the jokulhlaup 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.

This paper assesses river channel management activities in the context of the interaction between coarse sediment delivery, climate change, river channel response and flood risk. It uses two main sources of evidence: (1) an intensive instrumentation of an upland river catchment using both traditional hydrometric and novel sediment sensing methods; and (2) a sediment delivery model that combines a treatment of sediment generation from mass failure with a treatment of the connectivity of this failed material to the drainage network. The field instrumentation suggests that the precipitation events that deliver sediment from hillslopes to the drainage network are different to those that transfer sediment within the network itself. Extreme events, that could occur at any time in the year (i.e. they are not dependent on wet antecedent conditions), were crucial for sediment delivery. However, sustained high river flows were responsible for the majority of transfer within the river itself. Application of three downscaling methods to climate model predictions for the 2050s and 2080s suggested a significant increase in the number and potential volume of delivery events by the 2050s, regardless of the climate downscaling scenario used. First approximations suggested that this would translate into annual bed level aggradation rates of between 0.10 and 0.20 m per year in the downstream main channel reaches. Second, the importance of this delivery for flood risk studies was confirmed by simulating the effects of 16 months of measured in-channel simulation with river flows scaled for climate change to the 2050s and 2080s. Short-term sedimentation could result in similar magnitude increases in inundated area for 1 in 0.5 and 1 in 2 year floods to those predicted for the 2050s in relation to increases in flow magnitude. Finally, we were able to develop an alternative approach to river management in relation to coarse sediment delivery, based upon reducing the rates of coarse sediment delivery through highly localised woodland planting, under the assumption that reducing delivery rates should reduce the rate of channel migration and hence the magnitude of the bank erosion problem. Thus, the paper demonstrates the need to conceptualise local river management problems in upland river environments as point scale manifestations of a diffuse sediment delivery process, with a much more explicit focus on the catchment scale, if our river systems are to become more insulated from the impacts of future climate changes.

Global climate change may have a noticeable impact on the northern environment, leading to changes in permafrost, vegetation and fluvial morphology. In this paper we compare the results from three geomorphological models and study the potential effects of changing climatic factors on the river channel types in North-European Russia. Two of the selected models by Romashin [Romashin, V.V., 1968. Variations of the river channel types under governing factors, Annals of the Hydrological Institute, vol. 155. Hydrometeoizdat, Leningrad, pp. 56-63.] and Leopold and Wolman [Leopold, L.B., Wolman, M.G., 1957. River channel pattern: braided, meandering and straight, Physiographic and hydraulic studies of rivers. USA Geological Survey Professional Paper 252, pp. 85-98.] are conventional QS-type models, which predict the existence of either multi-thread or single-tread channel types using data on discharge and channel slope. The more advanced model by Van den Berg [Van den Berg, J.H., 1995. Prediction of alluvial channel pattern of perennial rivers. Geomorphology 12, 259-270.] takes into account the size of the sediment material. We used data from 16 runoff gauges to validate the models and predict the channel types at selected locations under modern and predicted for the future climatic conditions. Two of the three models successfully replicated the currently existing channel types in all but one of the studied sites. Predictive calculations under the hypothetical scenarios of 10%, 15%, 20% and 35% runoff increase gave different results. Van den Berg's model predicted potential transformation of the channel types, from single- to multi-thread, at 4 of 16 selected locations in the next few decades, and at 5 locations by the middle of the 21st century. Each of the QS-type models predicted such transformation at one site only. Results of the study indicate that climatic warming in combination with other environmental changes may lead to transformation of the river channel types at selected locations in north-western Russia. Further efforts are needed to improve the performance of the fluvial geomorphological models and their ability to predict such changes. © 2007 Elsevier B.V. All rights reserved.

This special issue presents a collection of papers that address a wide range of important challenges and exciting advances in the field of glacial landscape evolution. Primarily, these papers reflect persistent uncertainty that surrounds the mechanisms and timescales of glacial landscape evolution. For example, estimates of the duration of glacial occupancy required for the evolution of characteristic glacial valley forms from previously fluvial landscapes range from 100 kyrs for landscapes beneath large ice sheets (Jamieson et al.) to ~ 400–600 kyrs for glaciated alpine terrains (Brook et al.). Further, the mechanisms of glacial erosion are debated through analyses of the importance of ice thickness (Brocklehurst et al.; van der Beek and Bourbon), ice surface steepness (Vieira) and, in the case of large ice sheets, the co-evolution of ice sheet thermal regime, dynamics, and subglacial topography (Kleman et al.; Swift et al.). Debate concerning the potential climatic impacts of landscape evolution in alpine terrains is represented by van der Beek and Bourbon, who infer a significant increase in relief as a direct result of glacial erosion, and by Brocklehurst et al. and Heimsath and McGlynn, who demonstrate respectively that glacial relief production can be surprisingly modest and that rates of glacial erosion may be lower than those for fluvial incision. Further confirmation that valleys beneath large ice sheets evolve through selective linear erosion comes from studies that have combined geomorphological evidence with cosmogenic nuclide (Briner et al.) and apatite (U–Th)/He thermochronometry (Swift et al.), and the resulting style of landscape evolution is demonstrated by the antiquity of fjords in East Greenland (Swift et al.) and of deep erosion zones and thick drift covered zones in Fennoscandia (Kleman et al.), although the location of areal scouring zones may be subject to major alteration during single glacial events (Kleman et al.). Another set of papers shows that analyses of glacial lineation systems continue to provide important data on the dynamics of glacial landscape evolution, whether the lineations are formed underneath ice streams (Bradwell et al.; Andreassen et al.) or not (Jansson and Glasser), and whether they indicate intricate patterns of landscape modification (Andreassen et al.) or preservation (Jansson and Glasser). The final three papers address rarely-reported issues relating to landscapes of glacial deposition, including moraine degradation (Putkonen et al.), proglacial hydrogeology (Robinson et al.), and the evolution of hummocky-till topography (Clayton et al.).

Santa Rosa Island is an 85 km-long, wave-dominated low-lying barrier island situated along the northwestern Florida coast, facing the Gulf of Mexico. The entire island was severely impacted by Ivan, a strong category 3 hurricane that made landfall about 45 km to the west in September of 2004. Ten months later in July of 2005, Dennis, another category 3 hurricane, made landfall about 30 km east of the western tip of the island. Santa Rosa Island is characterized by well-developed but relatively low dunefields, described in this paper as incipient and established dunes, based on the presence of grassy and woody types of vegetation, respectively. The dunes were severely eroded by the two hurricanes. This paper investigates the factors controlling the regional-scale destruction and survival of the dunefields. Dune survival is controlled by: 1) hurricane characteristics, including intensity, duration, and frequency, and 2) morphological parameters including width of the barrier island, height and width of the dunefields, vegetation type, distance of the dunes to the ocean, and continuity of the dunefields. Three processes of dune destruction are described including, from most to least severe, inundation, overwash, and scarping. The interaction of all the above factors determines the different dune responses to the storm impacts. In general, the extensive and densely woody vegetated dunefields near the bay-side shoreline survived the storms, while the discontinuous dunes with grassy vegetation near the Gulf shoreline were almost completely destroyed.

Published accounts of peat mass movements throughout the last 500 years reveal common characteristics among the failures; however, there has been no consistency in the terminology used to describe them. Given the apparently increasing frequency of peat failures in the British Isles and the possibility of more peat failures elsewhere in the world as a consequence of climate change, there is a need for a specific classification scheme. This paper proposes a scheme that uses clearly defined terms that can be readily applied and reliably used to understand and assess future hazards from peat mass movements. The paper begins with a general definition of what should constitute a ‘peat failure’, then presents a precisely defined classification scheme for peat landslides (i.e. excluding creep), using type of peat deposit and failure morphology as the key criteria. The new scheme for peat failures is discussed in the context of existing landslide classification systems. Definitions are provided for bog bursts (flow failure of raised bogs), bogflows (flow failure of blanket bogs), bog slides (shear failure and sliding of blanket bogs), peat slides (shear failure at peat–mineral interface in blanket bogs), peaty-debris slides (shear failure within mineral substrate beneath blanket bogs) and peat flows (natural failures of other types of peat deposits including flow failure caused by head-loading). Some practical problems of classifying peat failures are discussed.

This paper presents an automated classification system of landform elements based on object-oriented image analysis. First, several data layers are produced from Digital Terrain Models (DTM): elevation, profile curvature, plan curvature and slope gradient. Second, relatively homogenous objects are delineated at several levels through image segmentation. These object primatives are classified as landform elements using a relative classification model, built both on the surface shape and on the altitudinal position of objects. So far, slope aspect was not used in classification. The classification has nine classes: peaks and toe slopes (defined by the altitudinal position or the degree of dominance), steep slopes and flat/gentle slopes (defined by slope gradients), shoulders and negative contacts (defined by profile curvatures), head slopes, side slopes and nose slopes (defined by plan curvatures). Classes are defined using flexible fuzzy membership functions. Results are visually analyzed by draping them over DTMs. Specific fuzzy classification options were used to obtain an assessment of output accuracy. Two implementations of the methodology are compared using (1) Romanian datasets and (2) Berchtesgaden National Park, Germany. The methodology has proven to be reproducible; readily adaptable for diverse landscapes and datasets; and useful in respect to providing additional information for geomorphological and landscape studies. A major advantage of this new methodology is its transferability, given that it uses only relative values and relative positions to neighboring objects. The methodology introduced in this paper can be used for almost any application where relationships between topographic features and other components of landscapes are to be assessed.

This paper presents the results of an experiment to compare glacial geomorphology mapped from remotely sensed imagery with 1 : 10,000-scale field mapping. The field mapping was validated against high resolution LiDAR imagery of an area glacierized during the Younger Dryas and found to provide an essentially reliable, if not complete, representation of the glacial geomorphology. The experiment consists of comparing the field mapping with digital elevation models (Shuttle Radar Topography Mission C-Band, Landmap, OS Panorama®, OS Profile®, NEXTMap) and satellite imagery (Landsat Thematic Mapper) of a 100-km2 region of central Scotland, north of Glasgow, that was last glaciated during the Last Glacial Maximum and during the Younger Dryas, respectively c. 14.5 and 11.5 cal. ka BP. For the purposes of this exercise, we concentrated on glacial lineaments (flutes, drumlins, and crag and tail), but attention was also given to moraine ridges and eskers. Qualitative and quantitative comparisons are performed and the results show that of the remotely sensed data sets, only NEXTMap Great Britain™ provided results that showed any approximation to the field mapping. OS Panorama® and OS Profile® provided very poor approximations, and the other methods fail to provide any information of value. Attention is given to the issues of scale and the differences between a small-scale detailed study, such as this experiment, in which a high resolution glacial geomorphological reconstruction is required, and the small-scale studies where the remote sensing techniques used here provide important evidence of regional significance when glaciers formed the largest elements of the landscape. The paper concludes with a consideration of protocols for future geomorphological mapping exercises, and outlines some of the requirements that must be adopted as these protocols are developed.

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.

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.

The term “incision wave” was coined in the 1990s to describe wave-like patterns of stream incision propagating through numerically modeled bedrock-channel river systems. An incision wave consists of a crest where available stream power is greatest, and where vertical incision is most rapid. The crest is flanked by limbs where there is less available stream power and where vertical incision rates are slower. Farther away from the crest, available stream power is less and incision rates are slower than in the limbs. Modeling results suggest tectonically induced base-level fall triggers incision waves that propagate upstream through bedrock-stream networks. However, it has recently been postulated that the equation underpinning incision-wave models cannot realistically simulate river systems. This paper provides field-geological evidence supporting the hypothesis that tectonically induced base-level fall triggers incision waves that propagate through bedrock-stream networks for tens of kilometers. Mid and late Pleistocene alluvial morphostratigraphy in the Rio Andarax drainage basin, southeast Spain is interpreted to indicate that patterns of paleo stream power were controlled by an incision wave. In the conceptual model proposed in this paper, the signature of an incision wave in the Rio Andarax drainage network is recorded by the contrasting morphostratigraphy of oxygen isotope stage 8 (“OIS8”) time landforms. At the crest of the incision wave during OIS8, there is no record of a paleoalluvial level because available stream power exceeded critical stream power and streams were incising vertically. The crestal area is flanked by OIS8-time strath terraces, which record the position of the two limbs of the incision wave. Farther upstream, OIS8-time alluvial fills mark an area unaffected by the incision wave. During oxygen isotope Stage 2 (“OIS2”) and/or oxygen isotope Stage 1 (“OIS1”), sediment availability in the Rio Andarax catchment was low, and the pattern of relative stream power was threshold-like rather than wave-like. Differences in the manifestation of the incision wave during OIS8 vs. during OIS2 and/or OIS1 indicate that climate and sediment availability can control how incision waves propagate through fluvial systems.

Floodplains are ecotones that form a transition between aquatic and terrestrial environments. These important ecosystems can be described as dynamic spatial mosaics in which water plays an important role in connecting various patches on the floodplain surface. Hydrological connections facilitate the exchange of carbon and nutrients between the river channel and the floodplain and therefore influence the productivity of the entire river system. This paper examines the influence of hydrological connections on the potential exchange of dissolved organic carbon between a large Australian floodplain to a river channel, and the effects of land and water developments on these exchanges. The paper proposes that an understanding of floodplain ecosystems requires an interdisciplinary approach—a recognition of the importance of the three disciplines hydrology, geomorphology and ecology. Large-scale water-resources and floodplain development has significantly altered the spatial and temporal patterns of hydrological characteristics in the Lower Balonne floodplain, Australia. The magnitude, frequency and duration of flooding events have all been reduced. The construction of levees and water storages has also reduced the reactive floodplain surface area. The presented data show the impacts of these changes on the potential supply of dissolved organic carbon from the floodplain surface during periods of inundation. Annual reductions of up to 1293 tonnes of dissolved organic carbon supply were noted and reductions were especially significant for floods with an average recurrence interval of 2 years or less. Some small flood events no longer facilitate the potential supply of dissolved organic carbon from the floodplain to the river channel because of water-resources and floodplain developments.

Landslides triggered by rainfall are the cause of thousands of deaths worldwide every year. One possible approach to limit the socioeconomic consequences of such events is the development of climatic thresholds for landslide initiation. In this paper, we propose a method that incorporates antecedent rainfall and streamflow data to develop a landslide initiation threshold for the North Shore Mountains of Vancouver, British Columbia. Hydroclimatic data were gathered for 18 storms that triggered landslides and 18 storms that did not. Discriminant function analysis separated the landslide-triggering storms from those storms that did not trigger landslides and selected the most meaningful variables that allow this separation. Discriminant functions were also developed for the landslide-triggering and nonlandslide-triggering storms. The difference of the discriminant scores, ΔCS, for both groups is a measure of landslide susceptibility during a storm. The variables identified that optimize the separation of the two storm groups are 4-week rainfall prior to a significant storm, 6-h rainfall during a storm, and the number of hours 1 m3/s discharge was exceeded at Mackay Creek during a storm. Three thresholds were identified. The Landslide Warning Threshold (LWT) is reached when ΔCS is −1. The Conditional Landslide Initiation Threshold (CTLI) is reached when ΔCS is zero, and it implies that landslides are likely if 4 mm/h rainfall intensity is exceeded at which point the Imminent Landslide Initiation Threshold (ITLI) is reached. The LWT allows time for the issuance of a landslide advisory and to move personnel out of hazardous areas. The methodology proposed in this paper can be transferred to other regions worldwide where type and quality of data are appropriate for this type of analysis.

This review paper aims at discussing aspects and concepts of the significance of the spatial and temporal distribution of permafrost on glacial and gravitational processes in southern Norway. The study first reviews the distribution of mountain permafrost in southern Norway in comparison with high-relief alpine areas like the Alps, and then discusses the influence of permafrost on gravitational and glacial–geomorphological processes. The basis for the paper is a regional-scale distribution model of mountain permafrost in southern Norway, which is analysed in relation to topographic variations within the same area. The model allows a crude extrapolation to past and future permafrost distribution, which is discussed in relation to geomorphic processes.

The fluvial environment of the central Po Plain, the largest plain in Italy, is discussed in this paper. Bounded by the mountain chains of the Alps and the Apennines, this plain is a link between the Mediterranean environment and the cultural and continental influences of both western and eastern Europe. In the past decades, economic development has been responsible for many changes in the fluvial environment of the area. This paper discusses the changes in fluvial dynamics that started from Late Pleistocene and Early Holocene due to distinct climatic changes. The discussion is based on geomorphological, pedological, and archaeological evidences and radiocarbon dating. In the northern foothills, Late Pleistocene palaeochannels indicate several cases of underfit streams among the northern tributaries of the River Po. On the other hand, on the southern side of the Po Plain, no geomorphological evidence of similar discharge reduction has been found. Here, stratigraphic sections, together with archaeological remains buried under the fluvial deposits, show a reduction in the size of fluvial sediments after the 10th millennium BC. During the Holocene, fluvial sedimentation became finer, and was characterised by minor fluctuations in the rate of deposition, probably related to short and less intense climatic fluctuations. Given the high rate of population growth and the development of human activities since the Neolithic Age, human influence on fluvial dynamics, especially since the Roman Age, prevailed over other factors (i.e., climate, tectonics, vegetation, etc.). During the Holocene, the most important changes in the Po Plain were not modifications in water discharge but in sediment. From the 1st to 3rd Century AD, land grants to war veterans caused almost complete deforestation, generalised soil erosion, and maximum progradation of the River Po delta. At present, land abandonment in the mountainous region has led to reafforestation. Artificial channel control in the mountain sector of the basins and in-channel gravel extraction (now illegal but very intense in the 1960s and 1970s) are causing erosion along the rivers and along large sectors of the Adriatic coast. These changes are comparable with those occurring in basins of other Mediterranean rivers.

This paper describes the application of a commercially available, three-dimensional computational fluid dynamic (CFD) model to simulate the flow structure in an upland river that is prone to flooding. Simulations use a rectangular channel geometry, smooth sidewalls and a bed topography obtained from the field site that contains a subdued pool–riffle sequence. The CFD model uses the RNG κ–var epsilon turbulence closure scheme of Yakhot and Orszag (J. Sci. Comput. 1 (1986) 1), as implemented in FLUENT 4.4.4, with a free surface. Results are shown for numerical runs simulating a 1:100 year return interval flood. Output from the numerical model is compared to a physical model experiment that uses a 1:35 scale fibreglass mould of the field study reach and measures velocity using ultrasonic Doppler velocity profiling (UDVP). Results are presented from the numerical and flume models for the water surface and streamwise velocity pattern and for the secondary flows simulated in the numerical model. A good agreement is achieved between the CFD model output and the physical model results for the downstream velocities. Results suggest that the streamwise velocity is the main influence on the flow structure at the discharge and channel configuration studied. Secondary flows are, in general, very weak being below the resolution of measurement in the physical model and less than 10% of the streamwise velocity in the numerical model. Consequently, there is no evidence for a ‘velocity dip’. It is suggested that the subdued topography or inlet morphology may inhibit the development of secondary flows that have been recorded in previous flat-bed, rectangular open channel flows. A significant corollary of these results is that the morphological evolution of the pool–riffle sequence at high discharges may be controlled primarily by the downstream distribution of velocity and sediment transport with little role for lateral sorting and sediment routing by secondary flows. This paper also raises a number of issues that may be of use in future CFD modelling of three-dimensional flow in open channels within the geomorphological community.

This paper presents semi-quantitative data concerning the pattern of erosion under present-day humid climatic conditions for a ca. 10-km2 large soil-mantled drainage basin located in the northern foothills of the Central Swiss Alps. The present-day pattern of erosion was presumably initiated at ca. 15 ka at the time when the last glacial period was terminated. Present-day erosional processes are characterized by fluvial dissection and hillslope mass failure, resulting in linear geomorphic features. As fluvial dissection proceeds, the rivers tend to adapt steady state longitudinal stream profiles. In this case, the stream profiles display power–law relationships between channel gradient and upstream size of the drainage basin. Our study shows that establishment of steady state longitudinal stream profiles requires a balanced mass flux between processes on hillslopes and in channels. This situation is interpreted for locations where the downslope flux of mass on hillslopes does not exceed the erosional potential and the transport capacity in channels. Consequently, the development of steady state drainage systems appears to be controlled by erosional processes in channels as they dictate the elevation of the base level. In contrast, systems that are at transient states of longitudinal stream profile development very often display non-balanced mass flux between processes in channels and on hillslopes. Specifically, low mechanical strength of the bedrock (e.g. glacial till, marls) results in a downslope flux of mass that exceeds the transport capacity and the erosional potential in the channel, causing the elevation of the channel floor to increase. In this case, processes on hillslopes are not necessarily coupled with erosion in channels and appear to control the evolution of the drainage basin for a limited time interval. Besides interpretations of controls on surface erosion, this paper also estimates post-glacial sediment-yield for the analyzed drainage basin. These estimates are achieved by determination of the difference between the elevation of the glacial and the present-day surface. The data show that ca. 30% of the analyzed drainage basin experiences present-day surface erosion. Furthermore, average post-glacial sediment yield measures ca. 4.6 m/ka if the post-glacial volume of sediment is related to the area that has experienced surface erosion, or ca. 1.4 m/ka if it is related to the whole drainage basin. Interestingly, the erosional efficiency appears to be significantly higher for systems that display steady state stream profiles than for transient rivers.