Description: ABSTRACT Historically, management of coastal dune systems has most commonly involved artificial stabilisation in order for coastal areas to be more easily controlled and modified for human benefit. In North America, the introduction of invasive grasses, namely European and American (marram) grasses ( Ammophila spp .) has been one of the most successful strategies used for stabilising drifting sands in coastal areas. Recent research has demonstrated, however, that stabilisation of coastal dunes often leads to reduced landform complexity and resilience, as well as declines in species diversity. More ‘dynamic’ restoration efforts have emerged over the past 20 years that encourage dune mobility and aeolian activity in order to provide an overall more resilient biogeomorphic system. In North America, in general, there is very little research relating restoration methods and outcomes to geomorphic responses despite the fundamental importance of sedimentary processes and dune morphodynamics in broader ecosystem function. This paper aims to better situate dynamic dune restoration within current geomorphic understanding. A brief review of key terms and concepts used in the emerging field of dynamic dune restoration is provided and these are expanded to include geomorphologic considerations. This discussion provides context for a recently initiated restoration effort in Pacific Rim National Park Reserve, British Colombia, Canada. At this site European Marram Grass, coupled with a warming climate and increased precipitation in recent decades, is thought to be largely associated with a rapid decline in aeolian activity, system stabilisation and accelerated ecological succession. The response of the dune system to mechanical removal of Ammophila is discussed at a preliminary level and based on these results a research framework for the broader monitoring effort is presented. Recommendations for improving treatment methodologies are provided to aid future restoration projects of this nature. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT The Coregistration of Optically Sensed Images and Correlation (COSI-Corr) algorithm was used to estimate dune migration and sand flux rates from a series of remotely-sensed optical image pairs. Several areas of barchan and transverse dunes transport sand along definite pathways, feeding the southern part of the Namib Sand Sea from beaches and deflationary basins in the Sperrgebiet. We give a detailed description of the pre- and post-processing routines used for our COSI-Corr analysis, and we evaluate the sub-pixel dune migration results at the dune and dune field scales. The best set of parameters for the application of the algorithm was systematically derived, resulting in methodological refinements of the cross-correlation windows. The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) sensor aboard the Terra satellite provided the remote sensing imagery. Few comparisons have been made between dune migration measurements using COSI-Corr and other types of change detection analysis, and few dune fields have served as test cases for COSI-Corr. We suggest that analysis and interpretation of COSI-Corr output from ASTER data is more valuable if combined with other image analysis techniques, such as manual digitization of dunes in a Geographic Information system (GIS), processing of write memory function insertion (WMFI) imagery and multispectral image (MSI) analysis of composition. The dune migrations estimated from COSI-Corr results were validated using GIS and WMFI, and later MSI analysis added an important regional, contextual framework of sand transport pathways. The synthesis of these works lends more confidence to understanding the Namib dune system's dynamics and provides a basis for future comparisons to other dune fields. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT With enhanced rates of sea-level rise predicted for the next century, the upstream extent of sea level influence across coastal plains is a topic of public importance. Australian coastal rivers provide a testing ground for exploring this issue because the area is tectonically stable, was not glaciated, and experienced a Holocene highstand between 7.4 and 2 ka of up to 1.5 m above Australian Height Datum (AHD). In the Shoalhaven River of New South Wales, investigation of a confined bedrock reach at Wogamia, 32 km inland, has identified a unit of dark, cohesive silt and sand with marine diatoms, shell fragments, and enhanced pyrite content, interpreted as estuarine. The unit is up to 13 m thick, thickens downstream, and is overlain by fluvial channel and floodplain deposits. The estuarine unit on-laps a remnant Pleistocene terrace and extends to approximately +2.2 m AHD. OSL and radiocarbon ages suggest that estuarine deposition commenced prior to 7.8 ka cal B.P., predating the highstand by ~ 500 years, and that marine influence in the area continued to 5.3 ± 0.7 ka. During this period, a delta probably persisted at Wogamia, where a narrow upstream reach opens out, and subsequently advanced to fill the broad Shoalhaven coastal embayment. Although the effect of sea-level rise depends on many factors, the results suggest that, during a highstand at or above present sea level, a strong marine influence may extend for tens of kilometres inland and penetrate confined bedrock reaches landward of coastal embayments. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT Broadleaf coppice forests have the capacity to mitigate the threat posed by rockfall in many mountainous regions. Other forest types alike the rockfall protective effect is determined by the mechanical resistance of the coppice tree stems. In addition, the rockfall protective function of coppice forests is enhanced by specific stem aggregations (clumps) that have a rock interception and retention effect difficult to evaluate. The main objectives of this study are to quantify the mechanical resistance of small diameter coppice stems and to gain qualitative insight on breakage behavior. The aim is to supply data for more reliable assessments of the rockfall protective function of coppice forests with rockfall simulation models and to provide a basis for better estimating the rockfall protective effect of coppice clumps. To achieve these objectives we assessed the mechanical resistance of 73 beech ( Fagus sylvatica L.) coppice stems using an impact pendulum device. We found an exponential relationship between the stem diameter at breast height (DBH) and mechanical resistance (loss of momentum or kinetic energy of the impactor during impact). Moreover, the results show that the high flexibility of the stems leads to relatively long lasting impacts and only negligible damage at the point of impact on the stem. As a result, the mechanical resistance of the stems is partly determined by impactor velocity and mass. These findings question the practicality of defining mechanical resistance by means of the change of momentum or energy of the impactor. Moreover, the results highlight the limits of up- or downscaling the data of this study to conclude for the mechanical resistance of beech trees of other than the tested dimensions. For the target DBH range the obtained dataset is nevertheless more reliable than data of previous studies, because the DBH specific impact process could be considered. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT An understanding of the temporal variation in reservoir sedimentation and identification of the main sources of sediment are necessary for the maintenance of sustainable reservoirs. For this purpose, field measurements, sampling, and fingerprinting of reservoir sediment were undertaken from July 2005 to November 2007. Source fingerprinting of reservoir sediment was conducted using 137 Cs. The relative contributions of gully bank and forest road, and forest floor material to reservoir sediment were calculated using a mixing model. Bank and forest road material, estimated to make up about 96% of the reservoir sediment, was the dominant source. Enormous reservoir sedimentation, which amounted to about 60% of the total reservoir sedimentation during the observation period, occurred during a heavy rainstorm with an 80-year recurrence time. To maintain the sustainability of the reservoir in this study, therefore, temporal and spatial preparation strategies for heavy rainstorms and bank and forest road erosion should be considered. However, spatial information on sediment sources from 137 Cs fingerprinting is limited. To better identify the sediment sources spatially and temporally, further studies applying soil erosion models and more detailed field studies are needed. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT Threlkeld Knotts (ca 500 m asl) in the English Lake District has hitherto been considered to be a glacially-modified intrusion of microgranite. However, its surface features are incompatible with glacial modification; neither can these nor the subsurface structures revealed by ground-penetrating radar (GPR) be explained by postglacial subaerial processes acting on a glacially-modified microgranite intrusion. Here we reinterpret Threlkeld Knotts as a very large postglacial landslide involving the microgranite, with an estimated volume of about 4 x 10 7  m 3 . This interpretation is tested against published and recent information on the geology of the site, the glacial geomorphic history of the area and newly-acquired ground-penetrating radar data. More than 60 large post-LGM (Last Glacial Maximum) rock-slope failures have significantly modified the glaciated landscape of the Lake District; this is one of the largest. Recognition of this major landslide deposit in such a well-studied environment highlights the need to continuously re-examine landscapes in the light of increasing knowledge of geomorphic processes and with available technology in currently active or de-glaciating environments. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT In the past few years the systematic study of caves intercepted by mine workings in Southwest Sardinia has permitted us to observe morphologies due to rare speleogenetic and minerogenetic processes related to ancient hydrothermal activity. These relic morphologies are slowly being overprinted by recent speleogenetic processes that tend to obscure the hypogene origin of these caves. A combined geomorphological and mineralogical investigation has permitted a fairly detailed recontruction of the various phases of evolution of these caves. Cave formation started already in Cambrian times, but culminated in the Carboniferous, when most of the large voids still accessible today were formed. A key role in carbonate dissolution was played by sulphuric acid formed by the oxidation of the polymetallic ores present in the rocks since the Cambrian. During the Quaternary a variety of minerals formed inside the caves: calcite and aragonite, that yield sequences of palaeo-environmental interest, and also barite, phosgenite, hydrozincite, hemimorphite and many others. These minerals are in part due to a phreatic thermal hypogenic cave forming phase, and in part to later epigene overprinting in an oxidising environment rich in polymetallic ores. Massive gypsum deposits, elsewhere typical of this kind of caves, are entirely absent due to dissolution during both the phreatic cave formation and the later epigenic stage. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT In analytical and numerical models of river meandering, initiation of meandering typically occurs uniformly along the streamwise coordinate in the channel. Based on a historical analysis of the Nierskanaal, here we show how and under which circumstances meandering has initiated in isolated sections of a channel. The Nierskanaal was constructed by the end of the 18th century, as a straight channel between the river Niers and the river Meuse. The purpose of this measure was to reduce flood risk in the downstream reaches of the river Niers. The banks on the Dutch part of the channel were left unprotected and developed into a morpho-dynamically active channel, featuring a meandering planform and valley incision. The planform development and incision process is analyzed using topographic maps and airborne LiDAR data. Meandering initiated in three sections of the channel, where the channel sinuosity developed asynchronously. Sedimentary successions in the study area show layers of iron oxide, indicating groundwater seepage from aeolian river dunes and river deposits located nearby. Only at the spots where meandering has initiated, iron oxide is found close to the surface level. This provides a clue that, seepage triggered bank erosion by increasing moisture content of the banks. The isolated meandering sections expanded in the longitudinal direction. Valley incision has developed in the first decades after the construction of the channel, and diminished after a gravel layer was reached. Gravel was deposited in the downstream half of the channel bed, acting as an armouring layer. The spatial variation in meandering behavior, as observed in the Nierskanaal, justifies efforts to implement the influence of floodplain heterogeneity and the effect of seepage on bank erosion in meander models. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT Mineral weathering rates and a forest macronutrient uptake stoichiometry were determined for the forested, metabasaltic Hauver Branch watershed in north-central Maryland, USA. Previous studies of Hauver Branch have had an insufficient number of analytes to permit determination of rates of all the minerals involved in chemical weathering, including biomass. More equations in the mass-balance matrix were added using existing mineralogic information. The stoichiometry of a deciduous biomass term was determined using multi-year weekly to biweekly stream-water chemistry for a nearby watershed, which drains relatively unreactive quartzite bedrock. At Hauver Branch, calcite hosts ˜38 mole percent of the Ca 2+ contained in weathering minerals, but its weathering provides ˜90 percent of the stream water Ca 2+ . This occurs in a landscape with a regolith residence time of more than several Ka. Previous studies indicate that such old regolith does not typically contain dissolving calcite that affects stream Ca 2+ /Na + ratios. The relatively high calcite dissolution rate likely reflects dissolution of calcite in fractures of the deep critical zone. Of the CO 2 consumed by mineral weathering, calcite is responsible for approximately 27 percent, with the silicate weathering consumption rate far exceeding that of the global average. The chemical weathering of mafic terrains in decaying orogens thus may be capable of influencing global geochemical cycles, and therefore, climate, on geological time scales. Based on carbon-balance calculations, atmospheric-derived sulfuric acid is responsible for approximately 22 percent of the mineral weathering occurring in the watershed. Our results suggest that rising air temperatures, driven by global warming and resulting in higher precipitation, will cause the rate of chemical weathering in the Hauver Branch watershed to increase until a threshold temperature is reached. Beyond the threshold temperature, increased recharge would produce a shallower groundwater table and reduced chemical weathering rates. Copyright © 2012 John Wiley & Sons, Ltd.

Description: ABSTRACT The term rockfall is often used ambiguously to describe various mass movement processes. Here we propose more precise terminology based on the physical nature of the moving mass, differentiating between two distinct types of rockfall: fragmental rockfall and rock mass fall. For both rockfall types, the current knowledge of the mechanisms controlling propagation of the mass movement are described, showing how these mechanisms can be simulated with different modelling approaches. However, we point out that almost no development has been realized concerning dynamic behaviour of the transitional processes between these two end-member rockfall types. Some simplified means of dealing with these complications are suggested, but we emphasize that a considerable amount of fundamental methodological development remains necessary. Copyright © 2012 John Wiley & Sons, Ltd.