Flash flood susceptibility mapping using a novel deep learning model based on deep belief network,back propagation and genetic algorithm

Flash floods are responsible for loss of life and considerable property damage in many countries.Flood susceptibility maps contribute to flood risk reduction in areas that are prone to this hazard if appropriately used by landuse planners and emergency managers.The main objective of this study is to prepare an accurate flood susceptibility map for the Haraz watershed in Iran using a novel modeling approach(DBPGA) based on Deep Belief Network(DBN) with Back Propagation(BP) algorithm optimized by the Genetic Algorithm(GA).For this task, a database comprising ten conditioning factors and 194 flood locations was created using the One-R Attribute Evaluation(ORAE) technique.Various well-known machine learning and optimization algorithms were used as benchmarks to compare the prediction accuracy of the proposed model.Statistical metrics include sensitivity,specificity accuracy, root mean square error(RMSE), and area under the receiver operatic characteristic curve(AUC) were used to assess the validity of the proposed model.The result shows that the proposed model has the highest goodness-of-fit(AUC = 0.989) and prediction accuracy(AUC = 0.985), and based on the validation dataset it outperforms benchmark models including LR(0.885), LMT(0.934), BLR(0.936), ADT(0.976), NBT(0.974), REPTree(0.811), ANFIS-BAT(0.944), ANFIS-CA(0.921), ANFIS-IWO(0.939), ANFIS-ICA(0.947), and ANFIS-FA(0.917).We conclude that the DBPGA model is an excellent alternative tool for predicting flash flood susceptibility for other regions prone to flash floods.     

The Development of Laser Ablation ICP-MS and Calibration Strategies: Examples from the Analysis of Trace Elements in Volcanic Glass Shards and Sulfide Minerals

This contribution presents a review of the recent developments in laser ablation inductively coupled plasma-mass spectrometry. We describe the important developments which have occurred in the laser systems used, leading to a spatial resolution of around 20 (im, and give an overview of the major instrument developments which have affected the geological applications of laser ablation ICP-MS. We describe the calibration of laser ablation for the analysis of trace elements in two different matrices: volcanic glass shards and sulfide minerals. We show how single glass shards can be analysed using the National Institute of Standards and Technology (NIST) glass certified reference materials for calibration and demonstrate the effect of using single spot analyses compared to rastering of the calibration sample. We show the importance of inter-shard variation and demonstrate that averaged single shard analyses produce data which compare well with bulk analyses. The calibration of the laser system for sulfide mineral analysis is discussed and two different strategies are proposed, one using spiked pressed powder pellets of sulfides and the other metal reference materials. We present conclusions and recommendations for the calibration of laser ablation ICP-MS instruments.     

Modelling the impact of climate change on Pacific skipjack tuna population and fisheries

IPCC-type climate models have produced simulations of the oceanic environment that can be used to drive models of upper trophic levels to explore the impact of climate change on marine resources. We use the Spatial Ecosystem And Population Dynamics Model (SEAPODYM) to investigate the potential impact of Climate change under IPCC A2 scenario on Pacific skipjack tuna (Katsuwonus pelamis). IPCC-type models are still coarse in resolution and can produce significant anomalies, e.g., in water temperature. These limitations have direct and strong effects when modeling the dynamics of marine species. Therefore, parameter estimation experiments based on assimilation of historical fishing data are necessary to calibrate the model to these conditions before exploring the future scenarios. A new simulation based on corrected temperature fields of the A2 simulation from one climate model (IPSL-CM4) is presented. The corrected fields led to a new parameterization close to the one achieved with more realistic environment from an ocean reanalysis and satellite-derived primary production. Projected changes in skipjack population under simple fishing effort scenarios are presented. The skipjack catch and biomass is predicted to slightly increase in the Western Central Pacific Ocean until 2050 then the biomass stabilizes and starts to decrease after 2060 while the catch reaches a plateau. Both feeding and spawning habitat become progressively more favourable in the eastern Pacific Ocean and also extend to higher latitudes, while the western equatorial warm pool is predicted to become less favorable for skipjack spawning.     

Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment: Extreme events in the Himalaya

Recession of high‐mountain glaciers in response to climatic change frequently results in the development of moraine‐dammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km²) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an ice‐contact moraine‐dammed lake to develop. The lake had a maximum volume of 5.5 × 10⁵ m³ and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 10⁵ m³ of material was removed from the terminal moraine during breach development. Numerical dam‐breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine‐dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146–2200 m³ s^‐1. Results from two‐dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s^‐1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine‐dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine‐dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact. © 2014 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

Abrupt changes (Heinrich events) in late Quaternary North Atlantic marine environments: a history and review of data and concepts

In the last several years evidence has mounted that a series of abrupt changes in sediment delivery and palaeoceanography effected the North Atlantic; they are recorded in a variety of proxy records but most dramatically in changes of grain-size and mineralogy associated with postulated iceberg rafting events, specifically Heinrich (H) events. This review paper examines the evidence for such evidence prior to the development of the ‘Heinrich event’ concept (1988–1992), and then examines the explosion of data and correlations that stemmed from the acceptance and use of this paradigm. Specific attention is focused on ideas pertaining to the cause(s) of glaciological mechanisms, sediment delivery, and sediment source, and major gaps in our understanding of the underlying glaciological, glacial geological, and glacial marine processes are stressed. Abrupt changes across boundaries associated with H-2 in the Labrador Sea are illustrated from core HU87033-009LCF. The case is made that correlations between records need to be more rigorous, especially within the range of radiocarbon dating, but it appears that abrupt changes in the delivery of iceberg rafted debris, which characterize these intervals, are multisourced. It is unclear how global ‘climate’ can simultaneously influence the abrupt behaviour of ice margins in different parts of the world—for marine-based margins, changes in relative sea-level are one possibility. A qualitative model is presented for triggering H events, which includes global changes in mass balance, changes in relative sea-level at ice margins due to glacial isostasy, and changes in the basal thermal regime of tidewater ice-streams. © 1998 John Wiley & Sons, Ltd.     

Coastal flooding in Scotland: towards national-level hazard assessment

This study investigated contributory factors to flood hazard around Scotland. There is a need to develop preliminary assessments of areas potentially vulnerable to flooding for compliance with the European Union Directive on the Assessment and Management of Flood Risks (2007/60/EC). Historical accounts of coastal flood events in Scotland, notably in a storm in January 2005, had shown that estimates of risk based on still water levels required further information to identify sites at which waves and surges could combine. Additionally, it was important to add the effect of future sea-level rise and other drivers from published sources. Analysis of multiple years’ tidal data at seven sites, including estuaries, compared recorded water levels at high-return periods to those derived from a spatially interpolated numerical model contained within a publicly available flood risk map. For gauges with the longest records, increases were seen over time that reflected rises in mean sea level. Exposure to wave energy was computed from prevailing wind strength and direction at 36 stations, related to wave fetch and incident wind direction. Although the highest wave exposure was at open coast locations exposed to the long Atlantic fetch, GIS analysis of coastal rasters identified other areas in or close to estuaries that also had high exposure. Projected sea-level change, when added to the surge and wave analyses, gives a spatially extensive structured variable flood risk assessment for future coastal flood hazard to complement the public flood risk map. Such tools can help fulfil the requirements of the EC Directive and may be a useful approach in other regions with high spatial variability in coastal flood risk related to exposure to waves and wind.     

Growth of large sulfide structures on the endeavour segment of the Juan de Fuca ridge

Mapping and sampling with DSRV “Alvin” has established that sulfide blocks 0.5 m across, dredged from the axial valley of the Endeavour Segment at 47°57′N, are samples of unusually large sulfide structures. The steep-sided structures, up to 30 m in length, 20 m in height, and 10–15 m across, are localized by venting along normal faults at the base of the western axial valley wall, and are distributed for about 200 m along strike paralleling the 020 trend of the ridge crest. High-temperature fluids (350 to more than 400°C) pass through the massive sulfide structures and enter seawater through small, concentric “nozzle-like” features projecting from the top or the sides of the larger vent structures. Diffuse, low-temperature flow is pervasive in the vicinity of the active sulfide structures, exiting from basalt and sulfide surfaces alike. Evidence of recent volcanic activity is sparse.The two largest samples taken with the dredge would not have been recoverable using the submersible. These samples represent massive, complex portions of the sulfide structures which were not closely associated with rapid high-temperature fluid flow at the time of sampling; they contain textural evidence of sealed hydrothermal fluid exit channels. Mineralogy is dominated by Fe sulfides nnd amorphous silica. Pyrite, marcasite, wurtzite, chalcopyrite, and iss are the most common sulfide phases. Pyrrhotite, galena, and sphalerite are present in trace amounts. Barite, amorphous silica, and chalcedony are the only non-sulfide phases; anhydrite is not observed in any of the dredge samples, although it is common in the chimney-like samples recovered by “Alvin”.Specific mineralogical-textural zones within the dredge samples are anaoogous to individual layers in East Pacific Rise at 21°N and southern Juan de Fuca Ridge samples, with two exceptions: a coarse-grained, highly porous Fe sulfide-rich interior containing sulfidized tubeworm casts, and a 2–5 cm thick zone near the outer margin of the samples dominated by late stage amorphous silica. The porous interior may have formed by dendritic crystal growth from a slowly circulating fluid within a large enclosed chamber. The amorphous silica deposited from a seawater/hydrothermal fluid mixture percolating slowly through the walls of the enclosed chamber; conductive cooling of the fluid as it traversed the walls allowed amorphous silica to precipitate. These silica-rich zones are the densest, most durable portions of the structures and may be responsible for the lasting stability of the large sulfide features.Observations in these samples are consistent with two distinct phases of development. Phase 1 is analogous to chimney growth and construction at 21°N and ends when flow channels become sealed to rapid flow of through-going fluid. The flow is evidently redirected within the structure. Phase 2 includes dissolution of anhydrite and precipitation of amorphous silica during conductive cooling of sluggishly circulating hydrothermal fluid or seawater/hydrothermal fluid mixtures. Evolution of vent structures through phase 2 allows lateral and vertical growth of unusually large structures.     

Characterization of hard‐to‐differentiate dune stratification types in the Permian Coconino Sandstone (Arizona,USA)

Dune stratification types, which include grainfall, grainflow and ripple lamination, provide a record of the fine‐scale processes that deposited sediment on palaeo‐dune foresets. While these facies are relatively easy to distinguish in some cross‐bedded sandstones, for others – like the Permian Coconino Sandstone of northern and central Arizona – discrete stratification styles are hard to recognize at the bedding scale. Furthermore, few attempts have been made to classify fine‐scale processes in this sandstone, despite its renown as a classic aeolian dune deposit and Grand Canyon formation. To interpret depositional processes in the Coconino Sandstone, cross‐bed facies were characterized using a suite of sedimentary textures and structures. Bedding parameters were described at multiple scales via a combination of field and laboratory methods, including annotated outcrop photomosaics, strike and dip measurements, sandstone disaggregation and laser‐diffraction particle analysis, high‐resolution scans of thin sections, and scanning electron microscopy. Cross‐beds were observed to be laterally extensive along‐strike, with most dip angles ranging from the mid‐teens to mid‐twenties. While some cross‐bed sets are statistically coarser near their bases, others exhibit no significant vertical sorting trends. Both massive and laminated textures are visible in high‐resolution scans of thin sections, but laminae contacts are commonly indistinct, making normal and reverse grading difficult to define. Diagenetic features, such as stylolite seams and large pores, are also present in some samples and might indicate alteration of original textures like detrital clay laminae and carbonate minerals. Observed textures and sedimentary structures suggest that the cross‐beds may consist of grainflow and grainfall deposits, but these remain difficult to differentiate at outcrop and thin‐section scales. This characterization of fine‐scale processes will play a critical part in the development of depositional models for the Coconino Sandstone and elucidate interpretations for similar cross‐bedded formations.     

Laboratory and case studies of thermal cycling and stored strain on the stability of selected marbles

Studies of marble panels from the exterior of two buildings document the processes leading to bowing of the material. Bowing of panels is most extensive in those areas that are exposed to direct or reflected thermal energy. The thermal anisotropic behavior of calcite results in grain-boundary separation, grain sliding and microfracturing. The resulting loss of strength is one factor leading to bowing. The development of bows further reduces the panel strength as the outer portions elongate by inelastic deformation mechanisms. Laboratory experiments cycling marble samples for over 200 cycles at three temperatures up to 107°C above room conditions show similar strength losses as the natural situation. The second factor contributing to the bowing process is the release of residual elastic strain. The strain is in part stored in the marble from its geologic history, but may also be accumulated during thermal cycling due to the properties of calcite. Marble panels have been found to bow when stored outside, but not attached to any framework, indicating that the release of residual strain is a critical factor in producing the bows.