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Flexible barriers have been recently proposed as a promising alternative for trapping woody debris driven by the flow in torrents and rivers before they reach elements at risks. Small-scale experiments in similitude with the real-scale have been conducted in view of addressing the interaction between the flow and the barrier. A particular attention was paid to the identification of the parameters with influence on the loading experienced by the barrier, varying the woody debris mixtures characteristics, water discharge, flume inclination and woody debris supply mode. This investigation emphasised the intricacy of the relation between the barrier loading and the characteristics of the trapped logs and of the logs accumulation. The barrier loading revealed inversely proportional to the woody debris accumulation permittivity, which quantifies its capacity to let the water seep through. Permittivity depended on the way the accumulation built up and on the evolution of its characteristics with increasing discharge and trapped logs volume. Finally, the loading exerted by the flow on the barrier was derived from the barrier elongation, revealing that it could be modelled as a hydrostatic load with a reduction factor of 0.5. [ABSTRACT FROM AUTHOR]

Seven Central Yup'ik masks from Alaska owned by the Anima Mundi Museum, the ethnological museum at the Vatican, were examined in the museum's Conservation Laboratory over five months in 2022 by Ellen Pearlstein, in consultation with Chuna McIntyre, a Yup'ik artist and culture bearer. Technical details were documented and these together with cultural meanings were explored jointly by the two authors. The authors explored the history of Catholic missionary acquisition and technologies available to Yup'ik carvers in the 1920s, and ways in which the masks departed from traditional technologies at the time of their manufacture and were altered since then within a museum setting. Such modifications were likely designed to permit Yup'ik masks to take on different functions than sacred or social performance, such that their authenticity might be questioned. In working as co-authors, the criteria for authenticity were defined to be whether the material manifestations of these Yup'ik masks evoked the intangible meanings understood by and significant to a Yup'ik culture bearer. The masks achieve this goal, as do contemporary Yup'ik masks that introduce additional new materials and techniques. It is impossible for non-Yup'ik to decide whether masks evoke sacred and social performativity, therefore conservators of other backgrounds are advised to collaborate with community members in their assessment of culturally distant materials. [ABSTRACT FROM AUTHOR]

Follett et al. (2020a, https://doi.org/10.1029/2020gl089346) developed an analytical model to predict backwater rise by log jams, using the size and packing density of logs and the jam length, as well as river slope and bed roughness. We show that the model formulas can be rewritten using the Froude number instead of river slope and roughness, thus improving their applicability in engineering practice. The equation terms and results of Follett et al. (2020a, https://doi.org/10.1029/2020gl089346) are found to be similar to those of the empirically derived formula by Schalko et al. (2018, https://doi.org/10.1061/(asce)hy.1943‐7900.0001501). However, some differences are identified, calling for further study. Most notably, these distinctions pertain to the effect of accumulation porosity, with additional minor differences in the exponent of the Froude number. Lastly, model implications for some broader applications are explored, showing a methodology to calculate the representative log size for log mixtures, and the expected effect of log orientation on backwater rise. Plain Language Summary: Accumulations of wood in rivers (log jams) can block the flow and thereby cause water level rise. Follett et al. (2020a, https://doi.org/10.1029/2020gl089346) developed a theoretical model to predict how this water level rise depends on log jam properties and local river conditions. For the local river conditions, they used the river slope and bottom roughness. In this comment, we show that the Froude number can be used instead, with exactly the same result. The Froude number is a dimensionless number that depends directly on the local river conditions, making the adapted formula easier to apply in practice. The resulting formula shows good agreement with an earlier one based on experimental work by Schalko et al. (2018, https://doi.org/10.1061/(asce)hy.1943‐7900.0001501). Still, some differences were found that raise questions. Most notably, the formulas differ for the effect of accumulation porosity. This becomes especially clear when logs are packed closely together. Next, model implications for slightly different settings than those studied by Follett et al. (2020a, https://doi.org/10.1029/2020gl089346) were explored. This showed how to determine the average log size for a mixture of logs with different sizes, and how the expected water level rise changes with log orientation. Key Points: Follett et al. (2020a, https://doi.org/10.1029/2020gl089346) predicted backwater rise by log jams using river slope and roughness. We show the Froude number can be used insteadBy using the Froude number, the link to the local river conditions becomes stronger, improving formula applicability in engineering practiceThe resulting formula is shown to be similar to earlier empirical work. But differences in jam porosity effects call for further study [ABSTRACT FROM AUTHOR]

Along the coast of northwestern Alaska, architectural wood remains are well preserved in the Birnirk and Thule coastal sites of the early 2nd millennium CE. These structural wood elements are unique archives for documenting climatic variations and cultural transformations during this key development period of Inuit culture. Along this treeless Arctic coast, driftwood accumulates from the subarctic forests of interior Alaska. Except for northwestern Alaska, regional tree-ring chronologies are too short (at best 350–400 years) to successfully date archaeological wood remains from Birnirk and Thule coastal sites using conventional dendrochronology. This paper examines the potential of tree-ring derived δ 18O signal to annually date eight architectural wood samples from the Rising Whale (KTZ-304) site at Cape Espenberg, northwestern Alaska. We developed a δ 18O master chronology, covering the period 935–1157 CE, using five wood samples from the KTZ-304 site. Blind isotope cross-dating of individual series belonging to this δ 18O master chronology (one against the other four) showed conclusive dating and a very strong coherence of the isotopic signal. We, then, used the δ 18O master chronology to cross-date three other wood samples for which we knew, from previous 14C wiggle-matching procedure, the first measured ring to be in this time interval, within a ± 18 to 30-year precision. Oxygen isotope dendrochronology provided a plausible date for one of the samples (the first measured ring at 1073 CE). This preliminary study encourages us to acquire additional data to extend in time and strengthen the δ 18O master chronology of northwestern Alaska (NWAK18O) and help refine our understanding of climate and culture change during the 2nd millennium CE. [ABSTRACT FROM AUTHOR]

Large wood drives both the form and function of gravel‐bed rivers draining forested basins. Previously overlooked benefits of wood in rivers are now widely recognized. Together with flow and sediment regimes, the wood regime controls rivers' physical and ecological integrity. Yet large quantities of wood transported during floods can pose additional hazards, potentially damaging infrastructures like bridges or dams and exacerbating flooding. However, unlike the water and sediment regimes intensively studied over the past decades, the instream wood regime or budgeting has been only recently defined and thus is still rarely quantified. The instream wood budget describes the cascading processes from supply or recruitment, entrainment, and transport to deposition, storage and decay (i.e., fragmentation or decomposition). These processes show high spatial and temporal variability but can be characterized by magnitude, frequency, timing, duration and mode. Instream wood budgeting is challenging, primarily because of the lack of observations, monitoring stations, and standardized protocols to acquire data. This contribution reviews the most recent advances to quantify the different instream wood budget components, notably the wood supply, and transfer. Case studies showing applications of biogeochemistry, videography, artificial intelligence, numerical modelling or tracking illustrate the current progress. Because critical challenges remain, we identify and describe some of them and discuss how the wood in riverine sciences may develop in the future. [ABSTRACT FROM AUTHOR]

Accumulation of instream large wood (i.e., fallen trees, trunks, branches, and roots) at bridges during floods may exacerbate flooding, scour and cause structural failure. Yet, explaining and predicting the likelihood of a bridge trapping wood remains challenging. Quantitative data regarding wood accumulation at bridges are scarce, and most equations proposed to estimate the accumulation probability were derived from laboratory experiments, and include variables such as flow velocity, Froude number, and approaching wood volume or size which are difficult to obtain. Other evaluations based on technical reports and information regarding wood removal have been proposed but are mostly qualitative. Until now, a data-driven approach combining multiple quantitative accessible variables at the river reach and catchment scales remains lacking. As a result, the controlling parameters explaining whether a bridge is prone to trap wood are still unclear. This work aims to fill this gap by analysing a database of 49 bridges across the United Kingdom (UK) classified as prone and not prone to wood accumulation. The database contained information regarding the geometry of the bridge (i.e., number of piers and pier shape) and we added parameters describing the upstream river channel morphology, the riparian landcover, and high-flow characteristics. We applied multivariate statistics and a machine learning approach to identify the variables that explained and predicted the predisposition of bridges to wood accumulation. Results showed that the number of bridge piers, the unit stream power, the pier shape, and the riparian forested area explained 87% of the total variability for the training dataset (0.87 training accuracy), and the selected model had a testing accuracy of 0.60 (60%). Although limited by the sample size, this study sheds light on the identification of bridges prone to wood accumulation and can inform bridge design and management to mitigate wood-related hazards. [ABSTRACT FROM AUTHOR]

Abstract Follett et al. (2020a, https://doi.org/10.1029/2020gl089346) developed an analytical model to predict backwater rise by log jams, using the size and packing density of logs and the jam length, as well as river slope and bed roughness. We show that the model formulas can be rewritten using the Froude number instead of river slope and roughness, thus improving their applicability in engineering practice. The equation terms and results of Follett et al. (2020a, https://doi.org/10.1029/2020gl089346) are found to be similar to those of the empirically derived formula by Schalko et al. (2018, https://doi.org/10.1061/(asce)hy.1943‐7900.0001501). However, some differences are identified, calling for further study. Most notably, these distinctions pertain to the effect of accumulation porosity, with additional minor differences in the exponent of the Froude number. Lastly, model implications for some broader applications are explored, showing a methodology to calculate the representative log size for log mixtures, and the expected effect of log orientation on backwater rise.

Taiwan is located at the junction of plates in which the stratum is relatively unstable, resulting in frequent earthquakes. Driftwood has always been regarded as a precious asset that enables ecoscientists to track earthquakes. In the event of a typhoon or heavy rain, the surface water flows to flush the woods from the hills to the coast. More specifically, a large rainfall or earthquake may cause floods and collapses, and the trees in the forest will be washed down. Therefore, this study used high-resolution images to build an image database of the new north coast of Taiwan, and a deep learning approach is incorporated to classify the driftwoods. To improve the interpretation of driftwood in the remote images, we initially import eight pieces of textured information which are employed to the raw bands (B, G, R, and IR). The usage of spatial information image extraction technology is incorporated into a deep learning analysis using two parallel approaches. The generative adversarial network (GAN) is used to analyze the color images alongside an ancillary image with texture information. Most of the salt–pepper effects are produced by applying a high-resolution thematic map, and an error matrix is generated to compare the differences between them. The raw data (original R + G + B + IR) images, when analyzed using GAN, have about 70% overall classification outcomes. Not all of the driftwood can be detected. By applying the texture information to the parallel approach, the overall accuracy is enhanced to 78%, and about 80% of the driftwood can be recognized. [ABSTRACT FROM AUTHOR]

Nowadays, climate change has become a serious concern, and more attention has been drawn to utilizing biomass sources instead of fossil sources and how petroleum chemical plastics should be reduced or replaced with bio-based materials. In this study, the optimized condition of liquefaction of driftwood was examined. There was a concern that driftwood might have some decay and chemical change. However, according to the Organic Micro Element Analyzer (CHN analyzer) test and Klason lignin and Wise methods, the results proved that lignin content (37.5%), holocellulose content (66.9%), and CHN compositions were very similar to regular wood. The lowest residue content of bio-polyols was produced using liquefaction conditions of 150 °C, reaction time of 180 min, catalyst content of 10%w/w, and 12.5%w/w driftwood loading. Polyurethane foam (PUF) derived from the liquefaction of driftwood and bio-based cyanate was prepared. The PUF prepared from the liquefaction of the driftwood exhibited slightly decreased thermal durability but was superior in terms of 3-time faster biodegradation and 2.8-time increased water adsorption rate compared to pure petroleum-based PUF. As a result, it was shown that driftwood can be identified as a biomass resource for biodegradable PUF. [ABSTRACT FROM AUTHOR]

Due to heavy rain such as typhoons, landslides and slope failures are caused, and driftwood occurs along with debris flows. Since the bark of driftwood peels off during flow, elucidating the bark peeling process will lead to the estimation of the source of driftwood. It is also considered to be useful for river management. There is a study of the past that examined the situation of the detachment using the branch. However, the scale of the driftwood model had a problem. It had a small real model for a scale. In this study, a driftwood model was created using the bark of grown cedar (Cryptomeria japonica) and fixed in a waterway for peeling experiments. As a result, when fresh water and earth and sand were circulated, the bark peeling rate increased in the order of upstream side, side surface, and downstream side due to the collision of earth and sand. Furthermore, the separation rate on the riverbed side was higher than that on the water's surface side. In the case that only freshwater circulated, it was revealed that the fluid power did not influence the bark exfoliation. Observation of the progress of the exfoliation confirmed two cases, exfoliation produced by the friction with sand and lump of the bark exfoliates. [ABSTRACT FROM AUTHOR]

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Hydraulic structures such as sluice gates are more sensible of driftwood that is transported by a river; all this debris, like a trunk, deadwood, and rootstocks, can be accumulated upstream hydraulic structures may cause many hydraulic troubles, so studded such as these phenomena more essential to prevent or reduce its effects on these structures. Many studies dealt with the impact of driftwood on scouring around piers and weirs and its hydraulics, but the studded dealt with sluice gate structures are few and still need deep studies. This study dealt with the sensitivity of driftwood blocking flow under a sluice gate. It found that a large gate opening and 50% of the maximum upstream head lead to a decreased probability of trapped index and an increasing likelihood of driftwood passage beneath the sluice gate, which causes scour if driftwood is blocked under a sluice gate, so this case must be avoided. The driftwood trap probability of rootstock is greater than the trunk, and accumulated driftwood causes an increasing upstream water depth by 15%. Increasing its volume increases trapping probability.

Driftwood is one of the important physical components in mountainous rivers which causes severe hazards due to the clogging of bridges, culverts, and narrow sections during floods. Therefore, the understanding of driftwood dynamics and mitigation measures are crucial for managing wood in rivers. Open check dams are the most commonly used engineering measure for preventing driftwood from reaching downstream areas. Nevertheless, these open check dams frequently lose their sediment transport function when they are blocked by sediment and driftwood, especially during major flood events. This paper proposes a new type of open check dam for preventing from clogging. Thus, flume experiments were conducted to examine the influence of different types of open check dams on the characteristics of driftwood deposition. For the model with wood length (LWD)=16.5 cm, wood diameter (D) =15 mm, and wood number (N)=172, the highest trapping efficiency was observed with 90.1% and 87.2% retention rates for the classical debris flow breaker and curved footed open check dams, respectively. Laboratory tests showed that through this proposed design, woody debris blockage in a very short time was prevented from the accumulation of woods beside the dam. In addition to this, most of the sediment passed through the check dam and most of the driftwood got trapped. It can be briefly stated that the geometrical design of the structure plays an important role and can be chosen carefully to optimize trapping efficiency. By designing this type of open check dams in mountain river basins, it may provide a better understanding of the driftwood accumulation and basis for the optimal design of these structures. Further development of the solution proposed in this work can pave the way for designing different types of open check dams for effective flood management. [ABSTRACT FROM AUTHOR]

Shipworms of the family Teredinidae were collected from driftwood along the coastal areas of Hokkaido between October 2020 and November 2021. Identification of species recorded a total of five species pervaded wooden debris: Teredo navalis Linnaeus, 1758, Lyrodus pedicellatus (Quatrefages, 1849), Bankia setacea (Tryon, 1863), Bankia bipennata (Turton, 1819), and Bankia carinata (Gray, 1827), the latter two were warm-water elements and considered a new record of species discovered from the temperate zone of Hokkaido waters. This suggests the possibility that ocean currents and suitable environmental conditions caused the settlement of these teredinids in driftwood along the vast coastal stretches of Hokkaido. Also, B. bipennata and B. carinata have been most likely distributed along the Sea of Japan and brought accidentally by typhoons from the Kuroshio region and Tsushima and Tsugaru currents to Hokkaido, respectively. Moreover, biogeographic patterns within Teredinidae from other coastal areas in the country and elsewhere were examined from the available literature. [ABSTRACT FROM AUTHOR]

The Late Medieval and Early Modern periods in the Netherlands are marked by an upsurge in the production, use and repurposing of casks in cities. This is inextricably linked with the growing marine and riverine trade markets and the increase in artisan production. Casks have been found on shipwrecks, where they were used as containers for merchandise (primary purpose) and in urban areas, where they were repurposed as shafts for wells or cesspits (secondary purpose). As a result, the initial production phase of the lifecycle of casks often remained undetected. This study aims to generate an overview of the dendrochronological studies conducted in the past decades by Dutch dendrochronologists on casks from Dutch archaeological context, in which the felling year of the wood used to construct the casks can be dated from the 12th to 18th centuries, to gain insight into their production by coopers. The first objective is to better understand the diverse provenance areas detected in the coopers' timber, after which the diachronic developments in the use of the timber from specific provenance areas can be addressed. The main objective is to assess whether it is possible to distinguish locally produced casks from casks used to import merchandise, which was successful in some cases. In addition to the dendrochronological and archaeological data, archival sources were used to contextualize and substantiate the analyses and interpretations. [ABSTRACT FROM AUTHOR]

The North Atlantic islands of the Faroe Islands, Iceland and Greenland have always been relatively poor in terms of native timber resources, due to their cold climate and exposed topography. Nevertheless, timber was vital to the material culture of the Norse settlers of these islands, and driftwood often met this need. As in subarctic Norway, where trees are also scarce, driftwood use and ownership were prescribed in medieval law codes. Historical documentary evidence shows that wealthy landowners bought driftwood rights as valuable assets, and ethnohistorical sources reveal a wide range of local and regional customs related to driftwood exploitation. However, driftwood was an unstable resource, and its delivery depended on a range of unpredictable factors related to climate and ocean currents. There is also ongoing debate regarding the relative importance of imported timber, which is for example often referenced in the Icelandic sagas. The use of driftwood is difficult to demonstrate through macroscopic, microscopic, or (geo-)chemical analysis. Similarities in the microscopic anatomy of boreal wood taxa preclude definitive provenancing through taxonomic analysis, and material traces of immersion in seawater are often either impermanent or ambiguous, especially in archaeological wood remains. This paper presents a comprehensive review of current historical and archaeological research on the exploitation of driftwood timber in the Medieval North Atlantic and explores potential future directions in this field. Furthermore, it asserts that this line of research should be pursued with some urgency, as anthropogenic climate change threatens both driftwood delivery and the preservation of archaeological wood remains. [ABSTRACT FROM AUTHOR]

Debris flow is one of the dominant processes distributing large wood (LW) within mountainous catchments. However, little has been reviewed on wood‐laden debris flow (WLDF), presumably owing to limited reviewable works. This article, therefore, navigates the international readers through 40 years of WLDF studies, most of which have been published only in Japanese. Firstly, we reviewed the historical development of Japanese WLDF particularly focusing on the 1980s and the 1990s. A series of post‐disaster fieldworks from the July 1982 Nagasaki flood to the July 1990 Kumamoto flood provided 32 catchment‐scale wood budgeting data; empirical relationships among drainage area, dominant tree species, sediment yield, and wood loads associated with single debris flow disasters were illustrated. Secondly, the characteristics of WLDF were summarized based on relevant previous studies on the recruitment, transport, and deposition processes of LW during debris flows. Thirdly, we discussed the connectivity between those Japanese WLDF studies and international LW studies by relating/contrasting their research approaches and spatiotemporal scales. In contrast to global LW research trends, Japanese WLDF studies have almost exclusively regarded LW as hazardous materials (i.e., "driftwood" or "woody debris") that need to be retained upstream of the inhabited areas. Those practice‐oriented WLDF studies were concentrated on drainage areas of 10−2 to 100 km2, representing 1–6 orders of magnitude smaller spatial scales than those generally covered by existing international LW studies. Strongly motivated by engineering requirements, "dynamic" interactions between debris flows and LW during floods have also been physically presented, mainly based on unique laboratory experiments involving steep flume (> 0.05) and mobile bed conditions. Finally, some future works for WLDF were briefly stated from practical and scientific perspectives. By "rediscovering" those WLDF studies domestically developed in Japanese debris flow channels since the 1980s, a more comprehensive understanding of LW dynamics in the river system may be achieved. [ABSTRACT FROM AUTHOR]

In largely treeless Arctic and subarctic environments driftwood is a key raw material, and this was no less so in Norse Greenlandic society (AD 985–1450). Driftwood was used for various purposes such as construction, transport, tools, utensils and for decoration. It has been argued that driftwood was a non-renewable resource which by the fourteenth century led to timber shortage in Norse Greenland. This paper presents data from taxonomic identifications on wood remains from five farmsteads in Norse Greenland where excavations have produced large collections of wood artefacts and wood debris. The study shows that 67% of the combined assemblage (total of 8552 pieces) are non-native coniferous taxa, the majority of which came to Greenland as drift. The Norse farms had more or less equal proportions of driftwood. In addition, this study finds no significant change in driftwood availability throughout the Norse period in Greenland nor does the composition of driftwood taxa change. [ABSTRACT FROM AUTHOR]

Taiwan is located at the junction of plates in which the stratum is relatively unstable, resulting in frequent earthquakes. Driftwood has always been regarded as a precious asset that enables ecoscientists to track earthquakes. In the event of a typhoon or heavy rain, the surface water flows to flush the woods from the hills to the coast. More specifically, a large rainfall or earthquake may cause floods and collapses, and the trees in the forest will be washed down. Therefore, this study used high-resolution images to build an image database of the new north coast of Taiwan, and a deep learning approach is incorporated to classify the driftwoods. To improve the interpretation of driftwood in the remote images, we initially import eight pieces of textured information which are employed to the raw bands (B, G, R, and IR). The usage of spatial information image extraction technology is incorporated into a deep learning analysis using two parallel approaches. The generative adversarial network (GAN) is used to analyze the color images alongside an ancillary image with texture information. Most of the salt–pepper effects are produced by applying a high-resolution thematic map, and an error matrix is generated to compare the differences between them. The raw data (original R + G + B + IR) images, when analyzed using GAN, have about 70% overall classification outcomes. Not all of the driftwood can be detected. By applying the texture information to the parallel approach, the overall accuracy is enhanced to 78%, and about 80% of the driftwood can be recognized.

Partially carbonized driftwood recovered from a lag deposit at the Arkadelphia Formation–Midway Group Contact (K–Pg) near Malvern, Arkansas contains an abundance of macrobioerosion. Macroborings are oriented perpendicular and oblique to the wood grain, straight to sinuous in shape, ≤8 cm long, may have calcitic linings, and belong to Teredolites clavatus (Kelly & Bromley, 1984). The abundance and tightly spaced position of borings on all driftwood surfaces suggests the wood was afloat and/or exposed on or near the seafloor in a shallow marine setting for an extended period of time before becoming buried. Transverse, radial, and tangential thin section analysis of the driftwood identifies distinct growth rings, tracheid and ray cells, ray pits, and resin canals of the bald cypress genus, Taxodium. The presence of Taxodium wood in addition to a diverse and abundant assemblage of transitional to shallow marine vertebrates in the Gulf Coastal Plain of southwestern Arkansas indicate that brackish water swamps were in proximity to the ancestral shoreline around the K–Pg boundary and that these remains were concentrated into a lag deposit as the result of storm events, sea-level cyclicity, and possibly impact generated tsunamis. [ABSTRACT FROM AUTHOR]

In this article, I attend to two stories from the floodland of Eeyou Istchee/James Bay, where in the mid-2000s the massive infrastructure of Hydro-Québec's Eastmain-Rupert project flooded a portion of Eeyouch ancestral lands, submerging Eeyouch grave sites and places of meaning and memory. Reading across literature and public art, and engaging with ghosts and other-than-human presences, I analyse two works rooted in Eeyouch territory and this shared event of colonial resource extraction. The novel Ourse bleue (2007) by Cree-Métis writer Virginia Pésémapéo Bordeleau and the large-scale sculpture Iiyiyiu-Iinuu (2008) by Cree artist Tim Whiskeychan conjure place-based connections to the departed that contend with the recent history of Hydro in Eeyou Istchee. Both pieces model a form of storying in the wake that refuses the smooth passage of Hydro over the dead and suggests that these are relationships to nourish in the present. [ABSTRACT FROM AUTHOR]

Natural debris deposited by the sea is essential for the functioning of the beach ecosystem. As tourist demands on the coast grow, aesthetic values become more important, and the indiscriminate cleaning of debris spreads from urban to natural beaches. A change in beach debris management is needed to ensure that organic debris plays its role where the sea has deposited it., Competing Interests: Declaration of interests The author declares no competing interests., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Driftwood belongs to natural rivers just like water and sediment do. A sound ecosystem requires driftwood, although it might jam at civil structures, altering the flow section and rise the backwater. Safety considerations suggest removing wood from rivers, whereas ecological experience asks for its presence. The situation might become critical if spillways clog during floods, so that their discharge capacity reduces. For narrow bays, full racks mounted upstream of the weir or overhanging piers trap the driftwood distant from the flow control section. The hydraulic capacity is then maintained, but the driftwood has to be removed after the event. We thus investigated herein with a physical model a novel partial rack, motivating the driftwood for uncongested appearance to partially pivot and pass, but ensuring a high discharge capacity under hypercongested appearance. The partial rack configuration was specified, together with the related trapping rate and discharge efficiency. [ABSTRACT FROM AUTHOR]

Jørgen Koch introduced mycologists to a unique habitat for marine fungi, namely the sand dunes of Grønhøj, Jutland, Denmark. The high diversity of marine fungi obtained from the site provided abundant sporulating structures for a number of research areas in marine mycology including ecological surveys, ultrastructure examination of ascospore appendage development, spore attachment studies and phylogeny. This review highlights the key observations in these areas. Also, a list of 102 species of marine fungi documented for Denmark is provided. [ABSTRACT FROM AUTHOR]

Along the coasts of northern Alaska, in a treeless tundra environment, the primary wood resource for coastal populations is driftwood, a seasonal and exogenous resource carried by the major rivers of western North America. The potential of Alaskan coastal archaeological wood for tree-ring research was first assessed in the 1940s by archaeologist and tree-ring research pioneer J. L. Giddings. Despite his success, the difficulties of dendrochronological studies on driftwood and the development of radiocarbon dating during the 1950s resulted in the near-abandonment of dendrochronology to precisely date archaeological sites and build long sequences using archaeological wood in Alaska. In this study, we explored the possibilities and limitations of standard ring-width dendrochronological methods for dating Alaskan coastal archaeological wood. We focus on the site of Pingusugruk, a late Thule site (15th–17th CE) located at Point Franklin, northern Alaska. The preliminary results have been obtained from the standard dendrochronological analyses of 40 timber cross-sections from two semi-subterranean houses at Pingusugruk. We cross-correlated individual ring-width series and built floating chronologies between houses before cross-dating them with existing regional 1000-year-long master chronologies from the Kobuk and Mackenzie rivers (available on the International Tree-Ring Databank, ITRDB). Additional work on various dendro-archaeological collections using an interdisciplinary approach (geochemical analyses of oxygen isotopes and radiocarbon dating) will help develop and expand regional tree-ring chronologies and climatic tree-ring sequences in Alaska. [ABSTRACT FROM AUTHOR]

Forests are a potential solution to numerous global environmental issues, and their restoration is widely pursued. Forty percent of Japan's forests are planted forests. This has caused the common occurrence of forest ecosystem disservices in the country, like—wildlife damage, pollinosis, and driftwood damage. Forest policy processes in Japan are characterized by incrementalism, central mobilization, and hegemony of career civil servants. Responses to forest ecosystem disservices have changed the central mobilization policy pattern. Punctuated equilibrium theory can be applied to several policy processes in Japan, but it provides only limited explanation for policy responses to forest ecosystem disservices. The responses are influenced by national governance and public administration traditions and cultures. It is relevant to expand research on policy responses to forest ecosystem disservices, recognizing that ideal responses may require unusual approaches not within traditional policy making or outside of established policy cultures. [ABSTRACT FROM AUTHOR]

• Globally more than 3 million tons of river driftwood are extracted annually. • Driftwood transportations eliminate bark without degrading the macromolecules. • Wood fraction of river driftwood has similar properties to fresh wood. • River driftwood can be thermally processed without any prior separation. Driftwood in river catchments might pose a hazard for the safety of infrastructures, such as dams and river dwellers, and thus is often removed. Génissiat dam in France presents a case study where annually approximately 1300 tons of driftwood are removed to prevent driftwood sinking and to protect the dam infrastructure. Collected river driftwood is rarely studied for utilization purposes and is commonly combusted or landfilled. However, driftwood can be valorized for biochar production through pyrolysis or hydrothermal carbonization (HTC). This study follows a novel approach in characterizing river driftwood by identifying the different common genera present at Génissiat dam on the upper Rhône, France. Moreover, the research provides for the first time a comprehensive analysis of river driftwood different physico-chemical properties, such as moisture content, major elemental composition (CHNSO), HHV, and macromolecular composition (cellulose, hemicellulose, lignin, and extractives). The study shows that the transportation of driftwood through rivers can enhance its properties by reducing the bark content resulting in lower ash content. Results indicate that driftwood can be mixed and further processed as a feedstock regardless of their genera and type for biochar production by pyrolysis or hydrothermal carbonization. [ABSTRACT FROM AUTHOR]

We present a 500‐year history of naturally felled driftwood incursion to northern Svalbard, directly reflecting regional sea ice conditions and Arctic Ocean circulation. Provenance and age determinations by dendrochronology and wood anatomy provide insights into Arctic Ocean currents and climatic conditions at a fine spatial resolution, as crossdating with reference chronologies from the circum‐Arctic boreal forests enables determination of the watershed the driftwood originated from. Sample crossdating may result in a wide range of matches across the pan‐boreal region, which may be biased toward regions covered by the reference chronologies. Our study considers alternate approaches to selecting probable origin sites, by weighting scores via reference chronology span and visualizing results through spatiotemporal density plots, as opposed to more basic ranking systems. As our samples come from naturally felled trees (not logged or both), the relative proportions of different provenances are used to infer past ocean current dominance. Our record indicates centennial‐to decadal‐scale shifts in source regions for driftwood incursion to Svalbard, aligning with Late Holocene high variability and high frequency shifts in the Transpolar Drift and Beaufort Gyre strengths and associated fluctuating climate conditions. Driftwood occurrence and provenance also track the northward ice formation shift in peripheral Arctic seas in the past century. A distinct decrease in driftwood incursion during the last 30 years matches the observed decline in pan‐Arctic sea ice extent in recent decades. Our new approach successfully employs driftwood as a proxy for Arctic Ocean surface circulation and sea ice dynamics. Plain Language Summary: We present a 500‐year history of driftwood arriving to the shorelines of northern Svalbard. Driftwood in the Arctic results from dying trees entering the large rivers that drain the circum‐Arctic land masses, which upon flowing into the Arctic Ocean can become locked up in forming sea ice. This enables the wood to travel across the Arctic Ocean without sinking, making it an invaluable proxy for sea ice extent by recording variations in Arctic Ocean surface currents (and therefore sea ice drift) and ice cover. With comparison of tree ring width (TRW) measurements of these driftwood samples to TRW series from trees throughout the boreal forests, we can determine the region each sample came from. We can thus approximate its likely trajectory across the Arctic Ocean. Arctic sea ice is rapidly declining in extent and thickness, with impacts on local and global climatic and ecological conditions. Knowledge of past changes is needed to place this modern trend within a broader context to aid future predictions for Arctic sea ice. Our record matches the observational record of Arctic Ocean surface circulation patterns and climate conditions, supporting the use of driftwood as a proxy for Arctic Ocean surface current and sea ice dynamics. Key Points: We present a novel approach to utilizing naturally felled driftwood as a proxy for Arctic Ocean surface circulation and sea ice dynamicsA 500‐year record of driftwood incursion to Svalbard reflects centennial to decadal variability in surface circulation and sea ice extentA distinct decrease in driftwood from all provenances in the last 30 years matches the observed decline in pan‐Arctic sea ice extent [ABSTRACT FROM AUTHOR]

Copyright of Engineer Military Bulletin / Muszaki Katonai Közlöny is the property of National University of Public Service and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Driftwood is abundant in coastal zones, and is increasingly being incorporated in nature-based shore protection and restoration projects. However, accumulations of driftwood, and their mobilization by storms or other disturbances, can pose hazards to coastal communities, infrastructure, and ecosystems. An improved understanding of driftwood dynamics in nearshore, wave-dominated environments is needed to inform sustainable use and management of wood in coastal zones. An optical tracking technique was applied to quantify mean transport and dispersion of driftwood in a 1/30 Froude-scaled coastal model exposed to oblique waves. The results provided new insight to factors controlling driftwood mobility and dispersion on beaches exposed to oblique waves, including the effects of sea state, wave-induced currents and circulation, water levels, driftwood length, driftwood roughness, driftwood buoyancy, and coastal structures. • Surf-zone driftwood transport correlates with H s 2 T p − 1 when unconstrained by shore interactions. • Offshore transport by rip currents is countered by breaking waves, Stokes drift, and beach friction. • Vertical profiles of wave-induced velocities affect driftwood interactions with the shore. • Structure length at the water line relative to driftwood length influences trapping potential. • Driftwood length, roughness and buoyancy all influence beaching and mobility. [ABSTRACT FROM AUTHOR]

Trees and timber are of great importance in many cultures across the globe, whether used as a construction material, as a fuel source, or for making tools and items of everyday life. This was also true in medieval Norse communities, resulting in the presence of considerable amounts of wooden artifacts and raw materials in sites across the North Atlantic. Because of a limited or even sometimes nonexistent timber supply, the Norse needed to rely on external wood sources, drifted or imported wood, for their everyday needs. Following the recent work of researchers in Iceland and the Faroe Islands, this paper presents results obtained from 710 artifacts distributed across seven sites in the Eastern and Western Settlements of medieval Greenland. Taxa identification is used first not only to discuss the strategies of wood exploitation by the Norse but also to give insights into the provenance of wooden materials. These, then, contribute to our understanding of timber management, human-environmental relations and mobility across the North Atlantic. [ABSTRACT FROM AUTHOR]

Dams are civil structures essential to modern civilization. However, they can be a threat if not properly designed and operated. A particular risk that potentially can lead to dam failure is the blocking of the spillway inlet with driftwood or debris. This study investigated, on the basis of physical modeling, this blocking as well as the related backwater rise and discharge-capacity reduction. Considerable quantities of driftwood were supplied upstream of an ogee weir with piers, and the subsequent reservoir level rise was measured. Particular focus was placed on extreme events in terms of driftwood occurrence (volume) and discharges (design value). It was found that a gated ogee blocked with driftwood performs with a reduced discharge coefficient as long as no countermeasures are taken, such as pier overhang, the removal of piers, or the installation of a rack. The performance of these countermeasures was studied, and criteria were developed to control the perturbing effect of driftwood. [ABSTRACT FROM AUTHOR]

The central problem we investigate is how coastal communities in the Arctic can plan for future storms in the absence of continuous, long-term data and/or instrumentation to monitor climatic events. The native village of Shaktoolik, Alaska recognizes these limitations and seeks increased monitoring of life-threatening storms affecting their village in their adaptation planning documents. To address this situation, and with the consent of the Tribal Council, we establish a baseline to monitor storm intensity in this data-poor region by dating and mapping storm surges in the Shaktoolik area. A storm surge is a proxy of storm intensity. We use driftwood in two ways to reconstruct past storm surges. First, we plot GPS points of driftwood lines on remote sensing imagery and digital elevation model data to map the maximum extent of storm surge for the November 2011 and 2013, and August 2019 storms. Second, in order to demonstrate that a particular log could have been deposited by those storms, dendrochronological analysis of individual logs within those deposits provides an estimate of when those trees died and could have entered the water as driftwood. These techniques, however, cannot determine the date of when those logs were deposited on a given beach. To narrow the date of the driftwood deposits from past storms, that is, to determine when the driftwood landed on the beach, local knowledge and observations are coupled with newspaper accounts. From these three lines of evidence, we show that the maximum storm surge the village can withstand without inundation is equivalent to the 2011 and 2019 storms. Those storms can be used as baseline indicators for future storms. This method of monitoring storm surges can be scaled up to other locations that also have minimal storm monitoring infrastructure. [ABSTRACT FROM AUTHOR]

Originating from the boreal forest and often transported over large distances, driftwood characterizes many Arctic coastlines. Here we present a combined assessment of radiocarbon (14C) and dendrochronological (ring width) age estimates of driftwood samples to constrain the progradation of two Holocene beach-ridge systems near the Lena Delta in the Siberian Arctic (Laptev Sea). Our data show that the 14C ages obtained on syndepositional driftwood from beach deposits yield surprisingly coherent chronologies for the coastal evolution of the field sites. The dendrochronological analysis of wood from modern drift lines revealed the origin and recent delivery of the wood from the Lena River catchment. This finding suggests that the duration of transport lies within the uncertainty of state-of-the-art 14C dating and thus substantiates the validity of age indication obtained from driftwood. This observation will help us better understand the response of similar coastal systems to past climate and sea-level changes. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Engineering Geology / Gongcheng Dizhi Xuebao is the property of Journal of Engineering Geology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In recent years, the damage caused to human settlements in Japan by large woody debris (LWD) has been increasing. For example, the 2013 Izu Oshima typhoon resulted in a large number of fatalities and missing persons, and the Kagoshima Typhoon Disaster and Northern Kyusyu torrential downpour caused vast infrastructure damage due to the associated LWD. Current countermeasures for preventing LWD are insufficient to maintain the safety of residential areas. One type of protective barrier, the open sabo dam, has been constructed in Japan during the past 30 years. The primary function of open sabo dams is to block the flow of boulders, thereby also reducing sediment flow by reducing the gap size. However, because Japanese open sabo dams are designed specifically for boulder-trapping, the ability of these dams to trap LWD remains uncertain. In particular, many problems have been reported with respect to sediment trapping by driftwood with roots in an open sabo dam setting. The objective of this study was to examine the trapping efficiency of open sabo dams for LWD and sediment. The experimental approach clarified the influence of driftwood, without and with roots, on sediment trapping for a straight-channel flume. The flexible roots of the driftwood were shown to have a significant effect on the sediment trapping efficiency of the dam. • This study is to report the trapping efficiency of sediment in an open Sabo dam. • The 4 kinds of driftwood models were evaluated. • Driftwood with flexible roots largely influenced the trapping efficiency of sediment. • The roots entrap a larger volume of sediment. [ABSTRACT FROM AUTHOR]

The flow of driftwood and soil into drainage from agricultural areas accelerates sedimentation and inflicts overflow damage after rainfall events due to insufficient discharge capacity, causing flooding on agricultural land. However, there have been few efforts to develop a driftwood capture trellis for agricultural drainage ditches, except for some suggested design criteria. In this study, we developed a driftwood capture trellis to capture driftwood in agricultural drainage ditches and evaluated its performance based on hydraulic characteristics. The facility was designed considering criteria for drainage and driftwood control barriers, as well as the properties of driftwood found near agricultural drainage ditches. Performance evaluation was conducted through hydraulic experiments. Driftwood capture trellises were installed in 400 mm drainage pipes and a total of 216 experimental runs were conducted: six runs each in six different velocity variations and six water depth variations. The results showed that the driftwood capture efficiency of the facility exceeded 60% at a velocity of 0.144 m³/s. Limited conditions for hydraulic experiments should be considered. The driftwood capture trellis for agricultural drainage ditches developed in this study could contribute to a reduction in overflow damage caused by driftwood sedimentation. [ABSTRACT FROM AUTHOR]

The paper addresses the influence of intense sediment transport (bed load and debris flow) on the efficiency of the structures aimed at the interception of wood logs. In the literature different devices designed to intercept woods are proposed: steel barriers, net barriers, check dam with steel bars positioned in the opening. In this paper we firstly define some fundamental dimensionless parameter governing the phenomenon, in order to determine a rational criterion to evaluate the efficiency of the different kind of devices. In particular, we deepen the interaction between slit check dams and driftwood, in both bed load and debris flow conditions. Starting from the results of this first analysis, we propose some arrangements of steel bars be installed in the check dam. Through a laboratory experimental investigation, by now conduced in simplified conditions (i.e. spherical mono-dispersed sediments), we define some criteria to obtain the best design parameters for the bars, that is their optimal disposition and spacing, in function of the logs characteristics (mainly the lengths). We investigate also the influence of different lengths of the transported woods, finding a general criterion to evaluate an overall length representing the logs ensemble. [ABSTRACT FROM AUTHOR]

Predicting the motion of driftwood around hydraulic structures such as bridge piers and spur dikes is important. We propose a numerical model for simulating driftwood motion that is based on coupling an Eulerian-type three-dimensional flow model and a Lagrangian-type two-dimensional driftwood model. Laboratory tests were carried out on the driftwood motion in a curved channel and around obstacles to obtain reference data. The computational results showed that three-dimensional flow features considerably affect the motion of driftwood in a curved channel. We defined the driftwood Richardson number (DRI) to classify the three-dimensional behavior of driftwood around obstacles. The experimental results showed that an increasing DRI indicates more three-dimensional behavior by driftwood and a decreased capture ratio by obstacles. We also developed a two-way model in which the drag force from driftwood on the flow is modeled to simulate the backwater elevation and the flow deceleration behind the stacked driftwood. The computational results showed that the two-way model could reproduce the increase of water level and the decrease of velocity at the upstream region of the obstacles. However, such effects caused by the driftwood jamming were underestimated if the jamming happened in a three-dimensional manner. [ABSTRACT FROM AUTHOR]

Coastal foredune evolution involves complex processes and controls that result from the interaction of aeolian and nearshore dynamics. No studies to date have quantified and examined the role of large woody debris (LWD) as a modulator of sediment delivery across the backshore and as a control on foredune development and maintenance. Results from a 4‐year research initiative on a high‐energy, macrotidal beach, and foredune system show that storm events lead to wave‐induced erosion of the backshore and consequent reworking of the LWD matrix. The exposed LWD matrix subsequently traps wind‐blown sand on the upper beach, reducing sediment delivery to the foredune by 99% in some cases. In turn, deposition within the LWD matrix leads to rapid burial of the LWD, at least until the next reworking or dune erosion event occurs. Interannual observations at this site indicate that infilling of the accommodation space within the LWD matrix can be rapid, so sediment starvation of the foredune is typically a relatively short‐lived phase. This suggests that that the LWD matrix is a highly effective, yet ephemeral, sand‐trapping reservoir. Critical to these interactions is the frequency and magnitude of nearshore events that erode the beach periodically and reorganize the LWD matrix, which directly impacts the ability of LWD to modulate onshore sand transport to the foredune, store sediment in the backshore, and act as a buffer against erosive events. An empirically derived conceptual model explaining these relationships is presented. Plain Language Summary: Beaches on the Canadian west coast are often covered with dead trees and large logs (what researchers call large woody debris but is commonly referred to as driftwood). The motivation for this research was to understand whether driftwood influences how sediment moves between a beach and a sand dune, something that is well studied on "clean" beaches free of debris. Driftwood was monitored on a beach for 4 years, and the results show that high tides and waves move and reorganize the driftwood. Sand that moves onshore, first by waves and then by wind, buries the driftwood because the exposed logs slow down the wind and trap the moving sand. During this period when the driftwood is being buried, sand is prevented from moving into the sand dunes, as it might if the driftwood were not there. The time it takes for the driftwood to be buried is rather short, so in order to understand how important this trapping effect is, there is a need to also understand how frequently storms occur that erode the beach and reorganize the driftwood, making it effective for trapping sand again. A series of drawings is presented that show how these complicated interactions occur. Key Points: Changes in LWD accumulation and sand volumes at this site were pronounced during storm events with high‐water levels and strong windsThe impact on foredune morphology of a LWD matrix on the beach was most apparent when LWD was exhumed and reworked frequentlyForedune growth may be limited in the presence of exposed LWD, which traps aeolian sand and interrupts sediment supply to the foredune [ABSTRACT FROM AUTHOR]