Volume Of Debris Research Articles

Snow depth and woody debris drive variation in small‐mammal winter seed removal

AbstractAimsIn temperate forests, small increases in winter temperature can lead to substantial decreases in snow accumulation, which may alter plant–consumer interactions such as seed predation. However, seed predation by small mammals may also be affected by local habitat structure (e.g., downed woody debris). We tested whether the effect of snow depth on seed predation by small mammals depends on habitat structure (woody debris) that may influence small‐mammal foraging behavior.LocationNorthern temperate forests in Wisconsin, USA.MethodsWe performed a factorial manipulation of snow depth and woody debris presence at 10 sites that differed in site‐level ambient woody debris. At these sites, we monitored seed removal of four temperate tree species (Abies balsamea, Acer rubrum, Acer saccharum, Pinus resinosa).ResultsMean rates of winter seed removal varied among species, as did the effects of snow depth and woody debris. The presence of woody debris decreased Abies balsamea seed removal in plots with snow removed. Regardless of woody debris, snow removal increased Acer saccharum seed removal. Acer rubrum seed removal was lowest at sites with high site‐level woody debris volume, especially in plots with snow removed.ConclusionsWarming winter temperatures may amplify seed removal for some tree species, but local‐scale heterogeneity in woody debris may modify these effects. Because the effects of woody debris and snow removal were much stronger for some tree species than others, changes in seed removal associated with reduced future snow cover or changes in forest management may accelerate regional changes in forest composition.

Wood-inhabiting macromycete communities in spruce stands on former agricultural land

Wood-inhabiting macromycete (WIM) communities in the ecosystem of uneven-aged spruce stands growing on former agricultural land were investigated in relation to the supply of wood substrate, degree of wood rot, and selected climatic and ecological conditions. Altogether, 58 WIM species were detected at research plots during 2016–2018. The abundance of fruiting bodies and WIM species richness increased from the youngest to the oldest forest stands. The highest numbers of fruiting body abundance were recorded for Gymnopus perforans (11 756), Hypholoma fasciculare (2 971), Coprinellus disseminatus (326), Exidia pithya (318) and Panellus mitis (147). The influence of stand age on WIM abundance was highly significant (P < 0.001), WIM abundance was not affected by precipitation (P > 0.05). The relationships between abundance and air temperature (P < 0.001), species richness and precipitation (P < 0.001), species richness and air temperature (P < 0.001) were highly significant. The most frequent damage to trees was caused by insects and forest animals (81%), which resulted in a high occurrence of resin secretion (70%). The total volume of coarse wood debris (CWD) and the decay rate were not statistically dependent. We confirmed the occurrence of Heterobasidion annosum s.s., H. abietinum s.s., H. parviporum s.s., Armillaria ostoyae s.s. and A. cepistipes s.s. by use of molecular genetic analyses.

Bees in the trees: Diverse spring fauna in temperate forest edge canopies

Temperate hardwood deciduous forest is the dominant landcover in the Northeastern US, yet its canopy is usually ignored as pollinator habitat due to the abundance of wind-pollinated trees. We describe the vertical stratification of spring bee communities in this habitat and explore associations with bee traits, canopy cover, and coarse woody debris. For three years, we sampled second-growth woodlots and apple orchard-adjacent forest sites from late March to early June every 7–10 days with paired sets of tri-colored pan traps in the canopy (20–25 m above ground) and understory (<1m). Roughly one fifth of the known New York state bee fauna were caught at each height, and 90 of 417 species overall, with many species shared across the strata. We found equal species richness, higher diversity, and a much higher proportion of female bees in the canopy compared to the understory. Female solitary, social, soil- and wood-nesting bees were all abundant in the canopy while soil-nesting and solitary bees of both sexes dominated the understory. Canopy cover increased with leaf-out, and was negatively associated with understory but not canopy bee abundance. Site-level volume of coarse woody debris (CWD) did not predict bee abundance, while approximated landscape-scale availability of woody debris was positively correlated with understory wood-nesting and solitary-bee abundance. This work expands our understanding of habitats where bees are likely foraging and reveals vertically stratified behavior. We emphasize deciduous forests as an important habitat for wild bee conservation and recommend further research into the behavior and diets of bees occupying the canopy, speculating that females forage for anemophilous tree pollen. Forest management plans that conserve above-ground deadwood may provide nest sites for wood-nesting bees.

Micro-cleanliness of Hard Tissue Debris After Advanced Irrigation and Comparison Between EndoVac and XP-endo Finisher: A Microcomputed Tomographic Study.

ABSTRACTIntroduction:Conventional irrigation techniques do not remove debris adequately. The remaining tissue debris cause infection inside the root canal and may also affect the seal of the root canal. The study aimed to compare the ability of EndoVac (EV) with XP-endo finisher (XPF) in debris removal using micro-CT analysis.Materials and Methods:We used 12 lower first permanent molar human teeth for this study. The root canals were instrumented using a small TF adaptive system. Then, the volume of debris was calculated. Teeth were divided into two groups, according to advanced irrigation methods, with six teeth per group: EV group and XPF group. The volume of debris was calculated again. The paired-sample t-test was used to compare the volume of the debris before and after the use of advanced irrigation methods with the statistical significance of P < 0.05. The percentage of debris reduction was also calculated.Results:Both EV and XPF showed a significant decrease of debris in the mesial canals (P < 0.05), whereas EV only showed a significant reduction of debris in the distal canals.Conclusion:Both EV and XPF were able to significantly reduce debris after instrumentation in the mesial canals of lower first mandibular molars.Clinical Significance:The study provides insight into the recent advanced methods used in debris removal and canal disinfection.

New approaches to the development of construction technologies

The paper presents data on the volume of materials consumed by builders and the carbon dioxide emissions that occur during this process. The reasons for the formation and volume of construction debris are considered. Recycling technologies currently used in the demolition of buildings are associated with crushing. The resulting concrete mix is used only for filling low-level earthworks due to the rapid carbonation of concrete surfaces. The scrap metal formed during crushing is used for remelting, polluting the atmosphere and requiring a large amount of energy. It is proved that due to the low economic and environmental efficiency, this method of recycling is a dead end. Studies have found that the constant increase in the strength of concrete and the absence of a decrease in the strength characteristics of reinforcing steels, stone materials, bricks, which are operated for a long time in favorable temperature and humidity conditions, allows them to be reused. General approaches have been developed that require changes in the existing technologies for the renovation of urban areas, the demolition of individual buildings and structures that currently exist. To reduce CO2 emissions and construction debris, it is enough to increase the volume of gentrification, reconstruction, major repairs, and re-profiling of the existing residential and industrial stock. When demolishing buildings, it is necessary to abandon the method of collapse of building structures with their further fragmentation. The method of piecemeal dismantling with repeated use of materials, products and structures (after determining their strength indicators by specialists), allows you to dramatically reduce the problems of construction debris and carbon dioxide emissions.

The Eureka Valley Landslide: Evidence of a Dual Failure Mechanism for a Long-Runout Landslide

Abstract Long-runout landslides are well-known and notorious geologic hazards in many mountainous parts of the world. Commonly encompassing enormous volumes of debris, these rapid mass movements place populations at risk through both direct impacts and indirect hazards, such as downstream flooding. Despite their evident risks, the mechanics of these large-scale landslides remain both enigmatic and controversial. In this work, we illuminate the inner workings of one exceptionally well-exposed and well-preserved long-runout landslide of late Pleistocene age located in Eureka Valley, east-central California, Death Valley National Park. The landslide originated in the detachment of more than 5 million m3 of Cambrian bedrock from a rugged northwest-facing outcrop in the northern Last Chance Range. Its relatively compact scale, well-preserved morphology, varied lithologic composition, and strategic dissection by erosional processes render it an exceptional laboratory for the study of the long-runout phenomenon in a dry environment. The landslide in Eureka Valley resembles, in miniature, morphologically similar “Blackhawk-like” landslides on Earth, Mars, and minor planet Ceres, including the well-known but much larger Blackhawk landslide of southern California. Like these other landslides, the landslide in Eureka Valley consists of a lobate, distally raised main lobe bounded by raised lateral levees. Like other terrestrial examples, it is principally composed of pervasively fractured, clast-supported breccia. Based on the geologic characteristics of the landslide and its inferred kinematics, a two-part emplacement mechanism is advanced: (1) a clast-breakage mechanism (cataclasis) active in the bedrock canyon areas and (2) sliding on a substrate of saturated sediments encountered and liquefied by the main lobe of the landslide as it exited the main source canyon. Mechanisms previously hypothesized to explain the high-speed runout and morphology of the landslide and its Blackhawk-like analogs are demonstrably inconsistent with the geology, geomorphology, and mineralogy of the subject deposit and its depositional environment.

Study On Fly Ash as a Partial Replacement Material in Highway Embankment

Fly debris (FA)-is a side-effect failure extracted from coal terminated force plants by electrical / electrostatic clarifier. India does have the planet’s very largest coal reserves. In the current scenario, about 160 million tonnes of fly-debris have been produced, almost double in the last decade. A significant proportion of warm-force plants in India use bitumen and subbituminous coal and generate huge volumes of fly debris. High debris material (30 percent-half) of fossil fuels adds to these enormous fly debris volumes. Fly-debris is used in various sections such as block making, construction of streets and banks, concrete processing, agricultural uses, low-lying areas recovery, mines filling. Dust Dyke Raising the wasted enormous volume of fly debris has attracted analysts’ attention to explore new wide use techniques. Fly debris bank is one of the drive regions to mass disperse fly dust. As in India, the actual condition of street and dike fly debris use is just 6 percent. The present study refers to the potential uses as a dike material for fly debris. Fly debris does have the larger part of the important and good geophysical patent for its use as bank fill.

Ground-Dwelling Invertebrate Abundance Positively Related to Volume of Logging Residues in the Southern Appalachians, USA

Invertebrates, especially those dependent on woody debris for a portion of their life cycle, may be greatly impacted by the amount of downed wood retained following timber harvests. To document relationships between invertebrates and logging residues, we sampled invertebrates with pitfall traps placed near or far from woody debris in 10 recently (2013–2015) harvested sites in western North Carolina with varying levels of woody debris retention. We measured the groundcover and microclimate at each trap and estimated site-level woody debris volume. We modeled predictors (e.g., site-level woody debris volume, percent woody debris cover at the trap site, site type) of captures of spiders (Araneae), harvestmen (Opiliones), centipedes/millipedes (Chilopoda/Diplopoda), ground beetles (Carabidae), rove beetles (Staphylinidae), other beetles, ants (Formicidae), grasshoppers (Acrididae/Tetrigidae), crickets (Gryllidae), and cave crickets (Rhaphidophoridae). In addition, we modeled ant occurrence at a finer taxonomic resolution, including red imported fire ants (Solenopsis invicta Buren) and 13 other genera/species. Forest type, whether hardwood or white pine (Pinus strobus L.) overstory preharvest, was a predictor of invertebrate response for 21 of 24 taxonomic analyses. Invertebrate captures or the occurrence probability of ants increased with increasing site-level woody debris volume for 13 of the 24 taxa examined and increased with increasing coarse woody debris (CWD; diameter ≥ 10 cm) cover at the trap level for seven of 24 taxa examined. Our results indicate that woody debris in harvested sites is important for the conservation of a majority of the taxa we studied, which is likely because of the unique microclimate offered near/under woody debris. Stand-scale factors typically were more important predictors of invertebrate response than trap-level cover of woody debris. We recommend implementing sustainability strategies (e.g., Biomass Harvesting Guidelines) to retain woody debris scattered across harvested sites to aid in the conservation of invertebrates.

Characterizing the evolution life cycle of the Sunkoshi landslide in Nepal with multi-source SAR data

A catastrophic landslide disaster happened on 2 August 2014 on the right bank of Sunkoshi River in Nepal, resulting in enormous casualties and severe damages of the Araniko highway. We collected multi-source synthetic aperture radar (SAR) data to investigate the evolution life cycle of the Sunkoshi landslide. Firstly, Distributed Scatterers SAR Interferometry (DS-InSAR) technology is applied to analyze 20 ALOS PALSAR images to retrieve pre-disaster time-series deformation. The results show that the upper part, especially the top of the landslide, has long been active before collapse, with the largest annual LOS deformation rate more than − 30 mm/year. Time series deformations measured illustrate that rainfall might be a key driving factor. Next, two pairs of TerraSAR-X/TanDEM-X bistatic data are processed to identify the landslide affected area by intensity change detection, and to generate pre- and post-disaster DSMs. Surface height change map showed maximum values of − 150.47 m at the source region and 55.65 m in the deposit region, leading to a debris volume of 5.4785 ± 0.6687 million m3. Finally, 11 ALOS-2 PALSAR-2 and 82 Sentinel-1 SAR images are analyzed to derive post-disaster annual deformation rate and long time series displacements of the Sunkoshi landslide. The results illustrated that the upper part of the landslide were still in active deformation with the largest LOS displacement velocity exceeding − 100 mm/year.

Enhancing preparedness for managing debris from earthquakes: lessons from Italy

Earthquakes can generate large volumes of debris which may threaten public health, hinder reconstruction and impact the environment. The present paper aims at investigating how the current Italian regulatory framework may be further developed to improve communities’ ability to manage debris from earthquakes. Since the lack of preparedness for managing disaster debris is not confined to Italy, the paper may be valuable to stimulate a broader debate on this issue. The research work is based on selected case studies (L’Aquila 2009, Regione Emilia-Romagna—Circolare n. 2 of 12.06.2012 (2012) “Provisions for the resumption of production activities according to art. 3 paragraphs 7 to 10 of Legislative Decree June 6, 2012 n. 74” and Central Italy 2016–2017 earthquakes) and the review of the relevant literature and legislation. It shows that preparedness could have contributed to reducing or avoiding significant delays and problems in managing debris after the above-mentioned Italian earthquakes. It further suggests that disaster debris management in Italy could benefit from the existence of a comprehensive ex ante regulatory framework including a range of different tools (laws, guidelines, contingency plans and the like) and from the proper implementation of laws that are already part of our legal order. The above findings may directly feed into decision-making addressing disaster debris management. Overall, the paper focuses on a research topic which is becoming increasingly relevant, given the rise in the number and severity of natural disasters, but which is still not widely explored.

Effects of titanium and carbon nanotubes on nano/micromechanical properties of HA/TNT/CNT nanocomposites

In this study, hydroxyapatite/titanium nanotube/carbon nanotube (HA/TNT/CNT) nanocomposites with different CNT contents were fabricated using a combination of hydrothermal and sol–gel methods. The nanocomposite powders were pressed at 350 MPa using the cold isostatic pressing technique and sintered at 1050 °C in a tube furnace in the presence of Ar gas. The nano/micromechanical properties, biocompatibility, and tribological characteristics of HA-based composites (with versatile mass ratios of CNT: 1.0, 1.5, and 2.0 wt%) were investigated. According to hardness-test results, the HA/TNT/CNT (2.0 wt% CNTs) composite exhibited the highest surface hardness (235.9 HV) among the samples. Wear-resistance tests were performed under different normal loadings. HA/TNT/CNT with higher CNT content exhibited a lower wear rate than the other samples. Nanoindentation tests were performed, and the nanohardness and elastic modulus of the HA were 62.41 and 1.821 GPa, respectively. These values were increased to approximately 98.7 and 5.3 GPa, respectively, for HA/TNT/CNT-2.0 (after the addition of TNTs and CNTs). The inclusion of 2.0 wt% CNTs in the HA/TNT composite reduced the wear debris volume by ∼ 66% owing to the enhanced modulus of elasticity and hardness. Moreover, in-vitro biocompatibility tests revealed that HA/TNT/CNT-2.0 had no cytotoxicity.

Effect of Fibers on the Bond Behavior of Deformed Steel Bar Embedded in Recycled Aggregate Concrete

A large volume of concrete debris is being produced in many countries on the globe due to the demolition of old concrete structures and testing of concrete specimens in laboratories. One of the ways to reuse concrete debris is to produce Recycled Aggregates (RA) and use them in new concrete. In recent years, Recycled Aggregates Concrete (RAC) has experienced increasing demand in various non-structural and structural applications. In reinforced concrete structures, one of the sources of brittle failure is sudden loss of bond between reinforcing bars and concrete in anchorage zones. Therefore, for the structural application of any new kind of concrete such as fiber reinforced RAC, knowledge of bond characteristics of reinforcing bars embedded in concrete becomes essential for determining the overall structural response under different modes of loading. In this regard, this study experimentally investigated the effect of fibers on the bond stress-slip behavior of deformed steel re-bar embedded in RAC. Concrete mixes having 0, 50 and 100% RAs were prepared with and without the addition of fibers. Two types of fibers were investigated in mono form: hooked-ends steel and polypropylene fibers. The dosage of steel and polypropylene fibers was kept 40 and 4.4 kg/m3, respectively. Axial compression and standard pull-out tests were performed. Test specimens for pull-out test were prepared using deformed steel re-bars of 19mm (#6) diameter. The results of strength tests confirmed that the compressive strength of concrete is decreased by replacing Natural Aggregates (NA) with RAs. For bond behavior of steel re-bar, the results of this study showed that replacement of 50% NA with RAs did not affect the bond response of steel bar, however, 100% replacement of NA with RAs showed detrimental effect on bond stress slip behavior. The results further showed that the addition of both types of fibers made it possible to recover the loss in compressive strength, bond strengths and bond toughness occurred because of replacing NA with RAs. In case of RA concrete mixes containing hooked-ends steel fibers, strength values were found even greater than the strength values of Natural Aggregates Concrete (NAC). From the results of this study, it was found that it is possible to design a structural concrete mix using 100% RAs and steel fibers at relatively low dosage of 40kg/m3.

Simulation of Debris-Flow Runout Near a Construction Site in Korea

This study analyzed landslide susceptibility and numerically simulated the runout distance of debris flows near a construction site in Korea. Landslide susceptibility was based on a landslide prediction map of the study area. In the prediction map, 3.5% of the area had a 70–90% landslide probability, while 0.79% had over 90% probability. Based on the landslide susceptibility analysis, debris flows in four watersheds were simulated to assess possible damage to the construction site. According to the simulations, debris flow in Watershed C approaches to within 9.6 m of the site. Therefore, the construction site could be impacted by debris flow in Watershed C. Although the simulated flows in Watersheds A and D do not directly influence the construction site, they could damage the nearby road and other facilities. The simulations also show that debris runout distance is strongly influenced by the volume of debris in the on-slope source area and by the slope angles along the debris-flow path.

Assessment of barrier location effect on debris flow based on smoothed particle hydrodynamics (SPH) simulation on 3D terrains

Debris flows are one of the perilous landslide-related hazards due to their fast flow velocity, large impact force, and long runout, in association with poor predictability. Debris-flow barriers that can minimize the energy of debris flows have been widely constructed to mitigate potential damages. However, the interactions between debris flows and barriers remain poorly understood, which hampers the optimal barrier installation against debris flows. Therefore, this study examined the effect of barrier locations, in particular source-to-barrier distance, on velocity and volume of debris flows via the numerical approach based on smoothed particle hydrodynamics (SPH). A debris-flow event was simulated on a 3D terrain, in which a closed-type barrier was numerically created at predetermined locations along a debris-flow channel, varying the source-to-barrier distance from the initiation point. In all cases, the closed-type barrier significantly reduced the velocity and volume of the debris flows, compared to the cases without a barrier. When the initial volume of source debris was small, or when the flow path was short, the barriers effectively blocked the debris flow regardless of the source-to-barrier distance. However, with a long flow path, installation of the barrier closer to the initiation location appeared more effective by preventing the debris volume from growing by entrainment. Our results contribute to a better understanding of how source-to-barrier distance influences debris-flow behavior, and show that the methodology presented herein can be further used to determine optimum and efficient designs for debris-flow barriers.

Orbital debris ontology, terminology, and knowledge modeling

ABSTRACT The looming threat orbital debris poses to assets in orbit demands solutions. As the orbital population grows, so does the risk of collision, as well as the volume of associated data. It is, however, an opportunity for interdisciplinary innovation and cooperation. This paper focuses on the data management and knowledge modeling aspect of developing solutions for a sustainable and safe orbital space environment. An in-progress work to develop an orbital debris reference ontology [Rovetto, 2015] is summarized in order to discuss knowledge modeling for orbital debris. The formal analysis of this effort can contribute to standards development, as well as terminological and policy challenges. Leveraging the growing volumes of orbital debris and space situational awareness (SSA) data will create a more complete picture of the orbital space environment. Part of the solution will be: consistent and correct data interpretation, sharing orbital debris and SSA data in one form or another, terminology development & harmonization, and knowledge or domain modeling. To facilitate this, [Rovetto, 2015] proposed ontology development for the orbital debris and broader space domain. This paper summarizes concepts from that paper, and subsequently developed concepts [2-9]. See also https://purl.org/space-ontology and https://purl.org/space-ontology/odo . Ontology engineering is an interdisciplinary area of research related to knowledge representation and reasoning in artificial intelligence, model-based systems engineering, semantic technologies and the so-called semantic web. An ontology is effectively a computable and semantically rich terminology that presents a knowledge or domain model for a topic area. Expressions of knowledge, beliefs, or assertions are stored using formally defined terms. This knowledge base is reasoned over to yield answers to database queries, among other things. Ontologies have been developed in knowledge-based projects across various disciplines, and used for such things as search engines, chatbots, and enterprise knowledge graphs. Ontologies aim to support: interoperability, automated reasoning, data sharing and integration, data search and retrieval, and communicating the meaning of data. The Orbital Debris Ontology (ODO) [1], and related ontologies [Rovetto & Kelso 2016] [Rovetto 2016, 2017], were proposed to help achieve this. ODO, for instance, is intended as a domain ontology that can be used across federated databases, offering an explicitly specified set of concepts describing the orbital debris domain. Its meaning-rich taxonomy will provide a sharable semantics for orbital debris data to, in part, consistently communicate the meaning of data to both humans and machines, and tag data elements in space object catalogs to help afford automated reasoning tasks, decision support, knowledge discovery, and information integration. ODO and the SSA ontology (SSAO) [2] is part of the overall Orbital Space Ontology concept, which is conceived as a unifying domain reference ontology. It aims to provide a knowledge representation structure of orbital space, a common semantic model, and develop a sharable terminology. Collectively this will provide common meaning for datasets, a high-level taxonomy or classification for orbital space objects, and a means to characterize space objects. Ongoing efforts have included using visualizations, R, JSON-LD, and contemporary semantic technologies. Potential applications include web-based platforms, web apps, visualizations, modeling and simulations. Community input and participation may yield a more widely understood domain model as well as facilitate terminological standards. For example, conceptual, terminological, and ontological analysis can make helpful contributions to such efforts as the Space Debris Mitigation Requirements by developing more precise, consistent and coherent terms and definitions. Other projects can also use ODO (and its related ontologies) as a common knowledge model, metadata set, taxonomy or vocabulary. Readers interested in supporting development are encouraged to make contact.

Salinity, Water Level, and Forest Structure Contribute to Baldcypress (Taxodium distichum) Rhizosphere and Endosphere Community Structure

As rising sea levels alter coastal ecosystems, there is a pressing need to examine the effects of saltwater intrusion on coastal communities. Using 16S Illumina profiling, we characterized the communities of baldcypress tree (Taxodium distichum) root endosphere and rhizosphere soil bacteria. Our study utilized established sites along salinity and flooding gradients in the United States of Georgia, Louisiana, and South Carolina. We hypothesized that environmental variables, namely salinity and water level, as well as distance between sites would be correlated with baldcypress-associated rhizosphere and root endosphere bacterial communities. We found that geographic distance correlated with rhizosphere but not root endosphere bacterial communities, suggesting that the trees may have stabilized their endosphere communities via recruitment of a more specific suite of taxa from the surrounding soil. Mean water level, mean salinity, and the volume of woody debris were associated with both endosphere and rhizosphere bacterial communities in baldcypress trees. The density of host trees was also associated with endosphere community composition. Our study is the first to use 16S Illumina sequencing to characterize bacterial communities in baldcypress trees— a key restoration species in coastal swamp ecosystems under threat from rising sea levels.

A hybrid machine-learning model to estimate potential debris-flow volumes

Empirical-statistical models of debris-flow are challenging to implement in environments where sedimentary and hydrologic triggering processes change through time, such as after a large earthquake. The flexible and adaptive statistical methods provided by machine learning algorithms may improve the quality of debris flow predictions where triggering conditions and the nature of sediment that can bulk flows varies with time. We developed a hybrid machine-learning model of future debris-flow volumes using a dataset of measured debris-flow volumes from 60 catchments that generated post-Wenchuan Earthquake (Mw 7.9) debris flows. We input topographic variables (catchment area, topographic relief, channel length, distance from seismic fault, and average channel gradient) and the total volume of co-seismic landslide debris into the PSO-ELM_AdaBoost machine-learning model, created by combining Extreme learning machine (ELM), particle swarm optimization (PSO) and adaptive boosting machine learning algorithm (AdaBoost). The model was trained and tested using post-2008 Mw 7.9 Wenchuan Earthquake debris flows, then applied to understand potential volumes of post-earthquake debris flows associated with other regional earthquakes (2013 Mw 6.6 Lushan Earthquake, 2010 Mw 6.9 Yushu Earthquake). We compared the PSO-ELM_Adaboost method with different machine learning methods, including back-propagation neural network (BPNN), support vector machine (SVM), ELM, PSO-ELM. The Comparative analysis demonstrated that the PSO-ELM_Adaboost method has a higher statistical validity and prediction accuracy with a mean absolute percentage error (MAPE) less than 0.10. The prediction accuracy of debris-flow volumes trigged by other earthquakes decreases to 0.11–0.16 (absolute percentage error), suggesting that once calibrated for a region this method can be applied to other regional earthquakes. This model may be useful for engineering design to mitigate the risk of large post-earthquake debris flows.

Sensitivity analysis of influencing parameters on slit-type barrier performance against debris flow using 3D-based numerical approach

Extreme rainfall-induced debris flow can be catastrophic to an urban area, and installation of slit-type barriers can prevent such damage while minimizing negative impact on environments. However, the performance of slit-type barriers against debris flows remains poorly identified partly due to the innate complexity in interactions between debris flow and solid structure. This paper investigated the flow behaviors of debris affected by slit-type barriers using the computational fluid dynamics (CFD) method, in which the numerical model based on the volume of fluid method was verified using the physical modeling results. The sensitivity analysis was performed by building metamodels to determine the primary parameters influencing the barrier performance against debris flows among various variables, in which the effect of input properties and design parameters, particularly the soil concentration in fluidized debris, initial velocity and volume of debris, the barrier height, and the opening ratio, was evaluated from the perspectives of the flow energy reduction and debris trapping. The initial velocity and volume of debris were found to play a significant role in determining the debris flow characteristics. A decrease in the opening ratio in the channel primarily facilitated the energy reduction and trapping due to the reduced opening size. However, the barrier height exhibited a limited effect when the height was sufficiently high to block the debris flow volume. In addition, it was observed that the double barrier system effectively increased the energy reduction while keeping the benefit of open-type barrier. The developed simulation method and obtained results provide an effective tool and an insight that can contribute to an optimum design of the debris-flow barrier.

Does post-fire salvage logging affect foraging activity by rodents?

Following wildfires, salvage logging is applied for silvicultural, safety or even aesthetic reasons. Such operations impact on biological legacies, impair natural vegetation recovery and may affect several animal species that depend on vegetation structure and specific plant resources. Rodents, such as wood and Algerian mice, use vegetation cover as protection against predators and are important prey, moderately effective seed dispersers and efficient seed predators. Different post-fire management strategies may either promote rodent abundance, enhancing their key biological roles, or result in low rodent abundance, creating a low seed predation window of opportunity when assisted regeneration of burnt forests is required. In order to evaluate the effects of post-fire salvage logging on plant-animal interactions, we compared plant regeneration, the availability of trophic resources (seeds and fleshy fruits), rodent foraging activity and rodent relative abundance between unlogged and logged burnt pine forests in the north-eastern Iberian Peninsula at different distances (up to 700 m) from the burnt area perimeter. The results show that vegetation recovered more slowly in salvage logged than in unlogged areas. Foraging activity of rodents increased both with the volume of woody debris, mainly derived from salvage logging, and with increasing foliage cover. Management strategies aimed at promoting the presence of rodents and associated biodiversity can, however, hamper assisted regeneration by seed sowing.

Estimation of plastic marine debris volumes on beaches using unmanned aerial vehicles and image processing based on deep learning

Plastic marine debris (PMD) is of global concern. To help address this problem, a novel approach for estimating PMD volumes using a combination of unmanned aerial vehicle (UAV) surveys and image processing based on deep learning is proposed. A three-dimensional model and orthoscopic image of a beach, constructed via Structure from Motion software using UAV-derived data, enabled PMD volumes to be computed by edge detection through image processing. The accuracy of the method was verified by estimating the volumes of test debris placed on a beach in known sizes and shapes. The proposed approach shows potential for estimating PMD volumes with an error of <5%. Compared with subjective methods based on beach surveys, this approach can accurately, rapidly, and objectively calculate the PMD volume on a beach and can be used to improve the efficiency of beach surveys and identify beaches that need preferential cleaning.