SPOT multispectral analysis for producing supraglacial debris‐load estimates for Batura glacier,Pakistan     

Michael P. Bishop  John F. Shroder Jr.  James L. Ward 《国际地球制图》2013,28(4):81-90

Abstract

SPOT multispectral and panchromatic data were evaluated to determine their utility to detect debris‐load characteristics of the Batura Glacier located in the Karakoram Himalaya. Debris‐depth measurements, surface samples, and ground photography were obtained and used with satellite‐derived information to produce supraglacial debris‐load and discharge estimates. Visual analysis of panchromatic data indicated that structural characteristics of the glacier exhibited unique textures associated with surface structure characteristics. Multispectral analysis revealed that stratified unsupervised classification of principal components can be used to produce classifications depicting supraglacial lithology and shallow debris‐load variability. Debris‐load discharge estimates ranged from 48–97 x 103 m3 yr1. These results indicate that SPOT multispectral data may be used to produce reasonable quantitative estimates of debris‐load characteristics for glacier mass balance and regional denudation studies.  相似文献   

Stability analysis of the 2007 Chehalis lake landslide based on long-range terrestrial photogrammetry and airborne LiDAR data   总被引：1，自引：1，他引：0  

Marc-André Brideau  Matthieu Sturzenegger  Doug Stead  Michel Jaboyedoff  Martin Lawrence  Nicholas J. Roberts  Brent C. Ward  Thomas H. Millard  John J. Clague 《Landslides》2012,9(1):75-91

On December 4th 2007, a 3-Mm³ landslide occurred along the northwestern shore of Chehalis Lake. The initiation zone is located at the intersection of the main valley slope and the northern sidewall of a prominent gully. The slope failure caused a displacement wave that ran up to 38 m on the opposite shore of the lake. The landslide is temporally associated with a rain-on-snow meteorological event which is thought to have triggered it. This paper describes the Chehalis Lake landslide and presents a comparison of discontinuity orientation datasets obtained using three techniques: field measurements, terrestrial photogrammetric 3D models and an airborne LiDAR digital elevation model to describe the orientation and characteristics of the five discontinuity sets present. The discontinuity orientation data are used to perform kinematic, surface wedge limit equilibrium and three-dimensional distinct element analyses. The kinematic and surface wedge analyses suggest that the location of the slope failure (intersection of the valley slope and a gully wall) has facilitated the development of the unstable rock mass which initiated as a planar sliding failure. Results from the three-dimensional distinct element analyses suggest that the presence, orientation and high persistence of a discontinuity set dipping obliquely to the slope were critical to the development of the landslide and led to a failure mechanism dominated by planar sliding. The three-dimensional distinct element modelling also suggests that the presence of a steeply dipping discontinuity set striking perpendicular to the slope and associated with a fault exerted a significant control on the volume and extent of the failed rock mass but not on the overall stability of the slope.  相似文献   

Organic micropollutants in marine plastics debris from the open ocean and remote and urban beaches   总被引：2，自引：0，他引：2  

Hirai H  Takada H  Ogata Y  Yamashita R  Mizukawa K  Saha M  Kwan C  Moore C  Gray H  Laursen D  Zettler ER  Farrington JW  Reddy CM  Peacock EE  Ward MW 《Marine pollution bulletin》2011,62(8):1683-1692

To understand the spatial variation in concentrations and compositions of organic micropollutants in marine plastic debris and their sources, we analyzed plastic fragments (∼10 mm) from the open ocean and from remote and urban beaches. Polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), dichloro-diphenyl-trichloroethane and its metabolites (DDTs), polybrominated diphenyl ethers (PBDEs), alkylphenols and bisphenol A were detected in the fragments at concentrations from 1 to 10,000 ng/g. Concentrations showed large piece-to-piece variability. Hydrophobic organic compounds such as PCBs and PAHs were sorbed from seawater to the plastic fragments. PCBs are most probably derived from legacy pollution. PAHs showed a petrogenic signature, suggesting the sorption of PAHs from oil slicks. Nonylphenol, bisphenol A, and PBDEs came mainly from additives and were detected at high concentrations in some fragments both from remote and urban beaches and the open ocean.  相似文献   

Autochthonous inheritance of zircon through Cretaceous partial melting of Carboniferous plutons: the Arthur River Complex,Fiordland, New Zealand   总被引：1，自引：0，他引：1  

Andrew J. Tulloch  Trevor R. Ireland  David L. Kimbrough  William L. Griffin  Jahandar Ramezani 《Contributions to Mineralogy and Petrology》2011,161(3):401-421

TIMS and SHRIMP U–Pb analyses of zircons from Milford Orthogneiss metadiorite (P = 1–1.4 GPa; T ≥ 750°C) of the Arthur River Complex of northern Fiordland reveal a bimodal age pattern. Zircons are predominantly either Paleozoic (357.0 ± 4.2 Ma) and prismatic with oscillatory zoning, or Cretaceous (133.9 ± 1.8 Ma) and ovoid with sector or patchy zoning. The younger age component is not observed overgrowing older grains. Most grains of both ages are overgrown by younger Cretaceous (~120 Ma) metamorphic zircon with very low U and Th/U (0.01). We interpret the bimodal ages as indicating initial igneous emplacement and crystallisation of a dioritic protolith pluton at ~357 Ma, followed by Early Cretaceous granulite-facies metamorphism at ~134 Ma, during which a significant fraction (~60%) of the zircon grains dissolved, and subsequently reprecipitated, effectively in situ, in partial melt pockets. The remaining ~40% of original Paleozoic grains were apparently not in contact with the partial melt, remained intact, and show only slight degrees of Pb loss. Sector zoning of the Cretaceous grains discounts their origin by solid state recrystallisation of Paleozoic grains. The alternative explanation—that the Paleozoic component represents a 40% inherited component in an Early Cretaceous transgressive dioritic magma—is considered less likely given the relatively high solubility of zircon in magma of this composition, the absence of 134 Ma overgrowths, the single discrete age of the older component, equivalent time-integrated ¹⁷⁷Hf/¹⁷⁶Hf compositions of both age groups, and the absence of the Cambrian-Proterozoic detrital zircon that dominates regional Cambro-Ordovician metasedimentary populations. Similar bimodal Carboniferous-Early Cretaceous age distributions are characteristic of the wider Arthur River Complex; 8 of 12 previously dated dioritic samples have a Paleozoic component averaging 51%. Furthermore, the age and chemical suite affinity of these and several more felsic rocks can be matched with those of the relatively unmetamorphosed Carboniferous plutonic terrane along the strike of the Mesozoic margin in southern Fiordland, also supporting the in situ derivation of the Carboniferous “inherited” component.  相似文献   

Coastal inundation and damage exposure estimation: a case study for Jakarta   总被引：2，自引：2，他引：0  

P. J. Ward  M. A. Marfai  F. Yulianto  D. R. Hizbaron  J. C. J. H. Aerts 《Natural Hazards》2011,56(3):899-916

Coastal flooding poses serious threats to coastal areas, and the vulnerability of coastal communities and economic sectors to flooding will increase in the coming decades due to environmental and socioeconomic changes. It is increasingly recognised that estimates of the vulnerability of cities are essential for planning adaptation measures. Jakarta is a case in point, since parts of the city are subjected to regular flooding on a near-monthly basis. In order to assess the current and future coastal flood hazard, we set up a GIS-based flood model of northern Jakarta to simulate inundated area and value of exposed assets. Under current conditions, estimated damage exposure to extreme coastal flood events with return periods of 100 and 1,000 years is high (€4.0 and €5.2 billion, respectively). Under the scenario for 2100, damage exposure associated with these events increases by a factor 4–5, with little difference between low/high sea-level rise scenarios. This increase is mainly due to rapid land subsidence and excludes socioeconomic developments. We also develop a detemporalised inundation scenario for assessing impacts associated with any coastal flood scenario. This allows for the identification of critical points above which large increases in damage exposure can be expected and also for the assessment of adaptation options against hypothetical user-defined levels of change, rather than being bound to a discrete set of a priori scenarios. The study highlights the need for urgent attention to the land subsidence problem; a continuation of the current rate would result in catastrophic increases in damage exposure.  相似文献   

Impacts of Drought, Flow Regime, and Fishing on the Fish Assemblage in Southern Australia’s Largest Temperate Estuary   总被引：1，自引：0，他引：1  

Greg J. Ferguson  Tim M. Ward  Qifeng Ye  Michael C. Geddes  Bronwyn M. Gillanders 《Estuaries and Coasts》2013,36(4):737-753

We analysed a 25-year time series of fishery catch and effort data, and age/size information for four large-bodied, native fish species to investigate the hypotheses that under conditions of reduced freshwater inflows and high fishing pressure: (1) the structure of fish assemblages in the lower Murray River system have changed, (2) species diversity of fishes has declined and (3) population age structures of large-bodied, late-maturing, native fish (Macquaria ambigua, Argyrosomus japonicus, Rhombosolea tapirina and Acanthopagrus butcheri) have been reduced. Annual catches and effort in the lower Murray River system were stable for 25 years, but proportional contribution to the total catch from each of freshwater, estuarine and adjacent marine habitats, and the species within them varied. Fish assemblages generally differed between subsequent 5-year periods, with the exception of 1989–1993 when floods occurred in 4 out of 5 years, and the following 5-year period (1994–1998). Species richness declined steeply over 25 years in freshwater and estuarine habitat and species diversity (Hill’s H ₂) also declined after 2001 in estuarine habitat. Species with rapid growth and early maturation (opportunistic strategists), increasingly dominated catches, whilst species with slow growth and late maturation (periodic strategists) declined. Truncated population age structures suggested longevity overfishing of three periodic strategist species: golden perch (M. ambigua), black bream (A. butcheri), mulloway (A. japonicus) and a fourth species with an intermediate strategy, greenback flounder (R. tapirina). This has implications for management because loss of older/larger individuals suggests reduced capacity to withstand or recover from deteriorated environmental conditions associated with a historically extreme drought in the lower Murray River system. Management of these species should seek to preserve the remnant population age structures and then to rebuild age structures by allowing recruits to become established in the adult population. We recommend that assessment of multi-species fisheries in changeable environments, such as occur in estuaries and other end-river environments, requires a suite of indicators that address changes in fish assemblages and populations.  相似文献   

Effectiveness of a market-based instrument for the allocation of water in a tropical river environment     

A. T. Straton  Sc. Heckbert  J. R. Ward  Alex Smajgl 《Water Resources》2009,36(6):743-751

The seasonal nature of Australia’s tropical rivers means that connected groundwater aquifers are an important source of both consumptive and non-consumptive water, particularly during the dry season. The management of these common pool groundwater resources is one of the predominant water issues facing northern Australia. A national program of water reform stipulates the expansion of water trading as a key instrument for water allocation. The effectiveness of new institutional arrangements such as water markets will be determined mostly by how well they coordinate with local environmental requirements, local institutions and local norms. This paper describes a novel application of combined field work, institutional analysis, experimental economics and agent-based modeling to the analysis of a potential water market in the Katherine region of the Northern Territory, Australia. The effectiveness of different versions of the policy instrument is assessed in light of local conditions. Instruments that enable personal relationships and local institutions and norms to play a role in water management are found to be more effective in terms of both farming income and environmental impact.  相似文献   

An Atlas of ShakeMaps and population exposure catalog for earthquake loss modeling     

Trevor I. Allen  David J. Wald  Paul S. Earle  Kristin D. Marano  Alicia J. Hotovec  Kuowan Lin  Michael G. Hearne 《Bulletin of Earthquake Engineering》2009,7(3):701-718

We present an Atlas of ShakeMaps and a catalog of human population exposures to moderate-to-strong ground shaking (EXPO-CAT) for recent historical earthquakes (1973–2007). The common purpose of the Atlas and exposure catalog is to calibrate earthquake loss models to be used in the US Geological Survey’s Prompt Assessment of Global Earthquakes for Response (PAGER). The full ShakeMap Atlas currently comprises over 5,600 earthquakes from January 1973 through December 2007, with almost 500 of these maps constrained—to varying degrees—by instrumental ground motions, macroseismic intensity data, community internet intensity observations, and published earthquake rupture models. The catalog of human exposures is derived using current PAGER methodologies. Exposure to discrete levels of shaking intensity is obtained by correlating Atlas ShakeMaps with a global population database. Combining this population exposure dataset with historical earthquake loss data, such as PAGER-CAT, provides a useful resource for calibrating loss methodologies against a systematically-derived set of ShakeMap hazard outputs. We illustrate two example uses for EXPO-CAT; (1) simple objective ranking of country vulnerability to earthquakes, and; (2) the influence of time-of-day on earthquake mortality. In general, we observe that countries in similar geographic regions with similar construction practices tend to cluster spatially in terms of relative vulnerability. We also find little quantitative evidence to suggest that time-of-day is a significant factor in earthquake mortality. Moreover, earthquake mortality appears to be more systematically linked to the population exposed to severe ground shaking (Modified Mercalli Intensity VIII+). Finally, equipped with the full Atlas of ShakeMaps, we merge each of these maps and find the maximum estimated peak ground acceleration at any grid point in the world for the past 35 years. We subsequently compare this “composite ShakeMap” with existing global hazard models, calculating the spatial area of the existing hazard maps exceeded by the combined ShakeMap ground motions. In general, these analyses suggest that existing global, and regional, hazard maps tend to overestimate hazard. Both the Atlas of ShakeMaps and EXPO-CAT have many potential uses for examining earthquake risk and epidemiology. All of the datasets discussed herein are available for download on the PAGER Web page (). T. I. Allen and M. G. Hearne—contracted through Synergetics Incorporated.  相似文献   

Intercomparison of multiple statistical downscaling methods: multi-criteria model selection for South Korea     

Hyung-Il?EumEmail author  Alex?J.?Cannon  Trevor?Q.?Murdock 《Stochastic Environmental Research and Risk Assessment (SERRA)》2017,31(3):683-703

A number of statistical downscaling methodologies have been introduced to bridge the gap in scale between outputs of climate models and climate information needed to assess potential impacts at local and regional scales. Four statistical downscaling methods [bias-correction/spatial disaggregation (BCSD), bias-correction/constructed analogue (BCCA), multivariate adaptive constructed analogs (MACA), and bias-correction/climate imprint (BCCI)] are applied to downscale the latest climate forecast system reanalysis (CFSR) data to stations for precipitation, maximum temperature, and minimum temperature over South Korea. All methods are calibrated with observational station data for 19 years from 1973 to 1991 and validated for the more recent 19-year period from 1992 to 2010. We construct a comprehensive suite of performance metrics to inter-compare methods, which is comprised of five criteria related to time-series, distribution, multi-day persistence, extremes, and spatial structure. Based on the performance metrics, we employ technique for order of preference by similarity to ideal solution (TOPSIS) and apply 10,000 different weighting combinations to the criteria of performance metrics to identify a robust statistical downscaling method and important criteria. The results show that MACA and BCSD have comparable skill in the time-series related criterion and BCSD outperforms other methods in distribution and extremes related criteria. In addition, MACA and BCCA, which incorporate spatial patterns, show higher skill in the multi-day persistence criterion for temperature, while BCSD shows the highest skill for precipitation. For the spatial structure related criterion, BCCA and MACA outperformed BCSD and BCCI. From the TOPSIS analysis, we found that MACA is the most robust method for all variables in South Korea, and BCCA and BCSD are the second for temperature and precipitation, respectively. We also found that the contribution of the multi-day persistence and spatial structure related criteria are crucial to ranking the skill of statistical downscaling methods.  相似文献   

Late Pleistocene talus flatiron formation below the Coal Cliffs cuesta,Utah, USA          下载免费PDF全文

Christopher E. Sheehan  Dylan J. Ward 《地球表面变化过程与地形》2018,43(9):1973-1992

Cuesta escarpment retreat is a principal mode of exhumation in regions of layered sedimentary rock. On the Colorado Plateau, this process acts as a mechanism for maintaining high‐relief topography and facilitating drainage divide migration. Quantitative estimates of cuesta evolution are difficult to evaluate over glacial‐interglacial timescales, and thus rates of geomorphic change along individual escarpments have mostly been constrained over millions of years. Several studies have addressed this problem by dating colluvium‐mantled talus flatirons. However, this technique has not been applied systematically on the Colorado Plateau. This study quantifies geomorphic change along a single Colorado Plateau cuesta using ³⁶Cl surface exposure dating. We present 33 ages from a single generation of talus flatirons below the Coal Cliffs of central Utah. Landscape evolution is further constrained using 14 ages from in‐situ bedrock, 3 ages from boulders on gully interfluves, and two ages from terrace alluvium. Results suggest a colluvial apron was deposited below the cuesta beginning as early as Marine Isotope Stage 3, and the latest depositional phase occurred near the Last Glacial Maximum. A switch from apron deposition to incision initiated flatiron formation sometime between 19.7 ± 2.5 and 11.8 ± 1.6 ka, broadly coincident with the transition from glacial to interglacial conditions. Our results have several important implications. Climatic changes during the end of the last glacial period appear to have shifted the balance between deposition and erosion below the Coal Cliffs, emptying the sediment reservoir at their base and increasing their height via bedrock incision. The climatic forcing could be imparted by several mechanisms, including local controls on debris generation / mobilization and base level changes exerted by transverse streams. Similar processes may have occurred during previous glacial‐interglacial transitions, implying that the escarpment retreat processes may be partially modulated by orbitally‐controlled variations in Earth's climate over larger timescales. Copyright © 2018 John Wiley & Sons, Ltd.  相似文献