A network of knowledge on applying an indicator‐based methodology for minimizing flood vulnerability     

Stefania Balica  Nigel G. Wright 《水文研究》2009,23(20):2983-2986

Flood vulnerability assessment plays a key role in the area of risk management. Therefore, techniques that make this assessment more straightforward and at the same time improve the results are important. In this briefing, we present an automated calculation of a flood vulnerability index implemented through a web management interface (PHP) that enhances the ability of decision makers to strategically guide investment. To test the applicability of this methodology using this website, many case studies are required in order to cover the full range of cases in terms of scale such as river basin, subcatchment and urban area. This requires prompt solutions with large amounts of data and this has led to the development of this automated tool to help organize, monitor, process and compare the data of different case studies. The authors aim to create a network of knowledge between different institutions and universities in which this methodology is used. It is also hoped to encourage collaboration between the members of the network on managing flood vulnerability information and also promoting further studies on flood risk assessment at all scales. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Triassic to Middle Jurassic stratigraphy of the Kerr McGee 97/12-1 exploration well,offshore southern England     

Nigel Richard Ainsworth  Leslie Arthur Riley 《Marine and Petroleum Geology》2010,27(4):853-884

The Triassic through to the Middle Jurassic (Bathonian) stratigraphy of the Kerr McGee 97/12-1 exploration well is described using petrophysical logs, in association with lithological and palaeontological analyses. Over 6210′ of sediment was penetrated, with sixteen Triassic and fourteen Lower–Middle Jurassic sedimentary units recognised, with a total measured depth (T.D) of 7310′ within the Sherwood Sandstone Group, Budleigh Salterton Pebble Beds of Early/Middle Triassic, Olenekian/Anisian age. As expected the sedimentary sequences are comparable to those described from the Wessex Basin, especially the Portland–Wight and Dorset (sub) basins. Of particular note, however, is the very thick halite sequence (1074′) within the Carnian, Dunscombe Mudstone Formation and also an expanded “Paper Shales” (27′) sequence within the earliest Toarcian. A normal fault is noted at 1260′ with the Late Bajocian, Inferior Oolite Group in fault contact with the latest Toarcian, Bridport Sand Formation, Down Cliff Clay Member. The Late Triassic (Rhaetian) to Middle Jurassic (Bathonian) yielded rich microfaunal and palynomorph assemblages, all of which have been previously described throughout northwest Europe. Four microfossils groups (foraminifera, ostracods, dinocysts and miospores) have been used to interpret stratigraphic ages and palaeoenvironments.This study provides new lithological and microfossil data for the Triassic to Middle Jurassic (Bathonian) sequences preserved in the offshore Portland–Wight Basin and provides a key tie-point/reference section for future offshore drilling.  相似文献   

Impact of a pre-existing transverse drainage system on active rift stratigraphy: An example from the Corinth Rift,Greece     

David J. P. Somerville  Nigel P. Mountney  Luca Colombera  Richard E. Ll. Collier 《Basin Research》2020,32(4):764-788

Models to explain alluvial system development in rift settings commonly depict fans that are sourced directly from catchments formed in newly uplifted footwalls, which leads to the development of steep-sided talus-cone fans in the actively subsiding basin depocentre. The impact of basin evolution on antecedent drainage networks orientated close to perpendicular to a rift axis, and flowing over the developing hangingwall dip slope, remains relatively poorly understood. The aim of this study is to better understand the responses to rift margin uplift and subsequent intrabasinal fault development in determining sedimentation patterns in alluvial deposits of a major antecedent drainage system. Field-acquired data from a coarse-grained alluvial syn-rift succession in the western Gulf of Corinth, Greece (sedimentological logging and mapping) has allowed analysis of the spatial distribution of facies associations, stratigraphic architectural elements and patterns of palaeoflow. During the earliest rifting phase, newly uplifted footwalls redirected a previously established fluvial system with predominantly southward drainage. Footwall uplift on the southern basin margin at an initially relatively slow rate led to the development of an overfilled basin, within which an alluvial fan prograded to the south-west, south and south-east over a hangingwall dip slope. Deposition of the alluvial system sourced from the north coincided with the establishment of small-scale alluvial fans sourced from the newly uplifted footwall in the south. Deposits of non-cohesive debris flows close to the proposed hangingwall fan apex pass gradationally downstream into predominantly bedload conglomerate deposits indicative of sedimentation via hyperconcentrated flows laden with sand- and silt-grade sediment. Subsequent normal faulting in the hangingwall resulted in the establishment of further barriers to stream drainage, blocking flow routes to the south. This culminated in the termination of sediment supply to the basin depocentre from the north, and the onset of underfilled basin conditions as signified by an associated lacustrine transgression. The evolution of the fluvial system described in this study records transitions between three possible end-member types of interaction between active rifting and antecedent drainage systems: (a) erosion through an uplifted footwall, (b) drainage diversion away from an uplifted footwall and (c) deposition over the hangingwall dip slope. The orientation of antecedent drainage pathways at a high angle to the trend of a developing rift axis, replete with intrabasinal faulting, exerts a primary control on the timing and location of development of overfilled and underfilled basin states in evolving depocentres.  相似文献   

Ichnology and sedimentology of aeolian and shallow-marine interactions in the Permian Unayzah Group of central Saudi Arabia: Towards a mechanism for infaunal colonization of coastal dune fields and erg margins     

Camilo A. Polo  John Melvin  Nigel P. Hooker  Andrew J. Rees  Murray K. Gingras  S. George Pemberton 《Sedimentology》2020,67(4):1797-1843

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Intra-clinothem variability in sedimentary texture and process regime recorded down slope profiles     

Grace I. E. Cosgrove  Miquel Poyatos-Moré  David R. Lee  David M. Hodgson  William D. McCaffrey  Nigel P. Mountney 《Sedimentology》2020,67(1):431-456

Shelf-margin clinothem successions can archive process interactions at the shelf to slope transition, and their architecture provides constraints on the interplay of factors that control basin-margin evolution. However, detailed textural analysis and facies distributions from shelf to slope transitions remain poorly documented. This study uses quantitative grain-size and sorting data from coeval shelf and slope deposits of a single clinothem that crops out along a 5 km long, dip-parallel transect of the Eocene Sobrarbe Deltaic Complex (Ainsa Basin, south-central Pyrenees, Spain). Systematic sampling of sandstone beds tied to measured sections has captured vertical and basinward changes in sedimentary texture and facies distributions at an intra-clinothem scale. Two types of hyperpycnal flow-related slope deposits, both rich in mica and terrestrial organic matter, are differentiated according to grain size, sorting and bed geometry: (i) sustained hyperpycnal flow deposits, which are physically linked to coarse channelized sediments in the shelf setting and which deposit sand down the complete slope profile; (ii) episodic hyperpycnal flow deposits, which are disconnected from, and incise into, shelf sands and which are associated with sediment bypass of the proximal slope and coarse-grained sand deposition on the medial and distal slope. Both types of hyperpycnites are interbedded with relatively homogenous, organic-free and mica-free, well-sorted, very fine-grained sandstones, which are interpreted to be remobilized from wave-dominated shelf environments; these wave-dominated deposits are found only on the proximal and medial slope. Coarse-grained sediment bypass into the deeper-water slope settings is therefore dominated by episodic hyperpycnal flows, whilst sustained hyperpycnal flows and turbidity currents remobilizing wave-dominated shelf deposits are responsible for the full range of grain sizes in the proximal and medial slope, thus facilitating clinoform progradation. This novel dataset highlights previously undocumented intra-clinothem variability related to updip changes in the shelf process-regime, which is therefore a key factor controlling downdip architecture and resulting sedimentary texture.  相似文献   

Effects of sea states on seafloor compliance studies     

Jui-Hsien Wang  Wu-Cheng Chi  R. Nigel Edwards  Eleanor C. Willoughby 《Marine Geophysical Researches》2010,31(1-2):99-107

Gas hydrates affect the bulk physical properties of marine sediments, in particular, elastic parameters. Shear modulus is an important parameter for estimating the distribution of hydrates in the marine sediments. However, S-wave information is difficult to recover without proper datasets. Seafloor compliance, the transfer function between pressure induced by surface gravity waves and the associated seafloor deformation, is one of few techniques to study shear modulus in the marine sediments. The coherence between recorded time series of displacement and pressure provides a measure of the quality of the calculated transfer function, the seafloor compliance. Thus, it is important to understand how to collect high coherence datasets. Here we conducted a 10-month pilot experiment using broadband seismic sensors and differential pressure gauges. We found that data collected in shallow water depth and during rough seas gave high coherence. This study is the first time long-term data sets have been employed to investigate seafloor compliance data quality and its dependence on sea state. These results will help designing future large-scale compliance experiments to study anomalously high shear moduli associated with the presence of gas hydrate or cold vents, or alternatively anomalously low shear moduli, associated with partial melt and magma chamber.  相似文献   

James Stanley Hey, 1909–2000     

Nigel Henbest  Heather Couper 《Astronomy& Geophysics》2000,41(3):3.38-3.38

Fellow and Eddington Medallist of the RAS, Fellow of the Royal Society, MBE,pioneer in radar and radio astromy.
Click HERE to view the article.  相似文献   

Pleistocene decalcification of Late Pliocene Red Crag shelly sands from Walton-on-the-Naze, England     

Alan C. Kendall  & Nigel M. Clegg 《Sedimentology》2000,47(6):1199-1209

Uppermost sands of the Red Crag at Walton-on-the-Naze (Essex) and elsewhere in East Anglia have been decalcified to iron-stained quartz sands. In contrast, lower sands are only minimally altered and contain aragonitic and calcitic shells. Aragonitic shells are slightly dissolved (chalkified), but calcitic shells are unaffected. Cementation is limited to an addition of iron oxides, now mainly haematite, which also coat carbonate grains. Abundant iron-oxide fines in the upper decalcified sands were liberated from the coatings of shells; shells that have since dissolved. The diagenetic nature of the contact between decalcified upper and unaffected lower sands is evident where it transects cross-bedding. The contact is knife-sharp, even smoothly truncating large shells, and is usually planar and subhorizontal. Shelly sands immediately beneath the boundary contain similar amounts of aragonitic material, as do sands further below. Locally the decalcification boundary has been contorted by cryoturbation, implying that carbonate dissolution was a Pleistocene event. Decalcification probably occurred when the area was affected by permafrost. Lower sands were cemented by ice and protected from dissolution. Upper sands were above the ice table and subject to chemically aggressive waters during summer thaws. Decalcification is believed to have taken place during an episode of climate amelioration when downward retreat of the ice table accompanied replacement of tundra by boreal forest. Highly acidic and podzolic soils developed, beneath which shell-carbonate dissolved. Sharp based decalcified zones in Lowestoft Till and Devensian deposits in other parts of England can also be attributed to dissolution associated with permafrost.  相似文献   

体视学对于睾丸生物学研究的贡献     

Nigel Wreford 《CT理论与应用研究》2000,9(Z1):145-147

男性和女性的生育控制问题是本世纪一个重要的生物学研究领域。女性生育的有效控制方法已存在好多年了，然而，用于男性的有效的方法还没有找到。近年来，人们试图确定荷尔蒙对精子产生的调节作用，期望找到与女性避孕同样有效并可接受的方法。睾丸包括生精管和裂隙腔，生精管中容纳的是滋养幼芽上皮细胞的Sertoli细胞，裂隙腔中容纳的是产生睾丸激素的Leydig细胞。在精子产生过程中，精原细胞通过有丝分裂繁殖，其下一代经过减数分裂产生单倍体圆形精子细胞，接着发生一系列复杂的形态变化成为成熟的长形精子细胞，成熟后的精子就具有受精能力。 维持幼芽上皮细胞的Sertoli细胞在人的一生中不发生大的变化。Sertoli细胞维持幼雅细胞的能力是有限的，但在不同人之间其能力有一个较大的变化范围。因而，Sertoli细胞的数目决定了睾丸产生精子的最大能力。对于精子产生的调节涉及到内分泌、副分泌和自分泌机制。体视学和各种形态测定工具已成为实验条件和自然条件下睾丸生物学研究的一把钥匙，这些研究包括了解Sertoli细胞的繁殖以及调节精原细胞转变为成熟细胞的效率的因素。从而提出精子发育的规律性，由荷尔蒙对精子产生调节作用的模型。  相似文献   

Falling-stage features of a precambrian braided stream: Criteria for sub-aerial exposure     

Nigel L. Banks 《Sedimentary Geology》1973,10(2):147-154

In a Precambrian braided stream deposit in north Norway a series of small terraces are exposed in a plan view over an area of 1500 sq. metres. These features compare closely with features formed during falling stages on exposed bars in modern rivers. Using the evidence of terracing a detailed history of deposition and erosion during fluctuating discharge has been unravelled. Since these structures provide direct evidence of both sub-aerial exposure and fluctuating water level they are of considerable palaeoenvironmental importance.  相似文献