Designing a long-term flood risk management plan for the Scheldt estuary using a risk-based approach   总被引：2，自引：1，他引：1  

Steven Broekx  Steven Smets  Inge Liekens  Dirk Bulckaen  Leo De Nocker 《Natural Hazards》2011,57(2):245-266

The Scheldt is a tidal river that originates in France and flows through Belgium and the Netherlands. The tides create significant flood risks in both the Flemish region in Belgium and the Netherlands. Due to sea level rise and economic development, flood risks will increase during this century. This is the main reason for the Flemish government to update its flood risk management plan. For this purpose, the Flemish government requested a cost-benefit analysis of flood protection measures, considering long-term developments. Measures evaluated include a storm surge barrier, dyke heightening and additional floodplains with or without the development of wetlands. Some of these measures affect the flood risk in both countries. As policies concerning the limitation of flood risk differ significantly between the Netherlands and Flanders, distinctive methodologies were used to estimate the impacts of measures on flood risk. A risk-based approach was applied for Flanders by calculating the impacts of flood damage at different levels of recurrence, for the base year (2000) and in case of a sea level rise of 60 cm by 2100. Policy within the Netherlands stipulates a required minimal protection level along the Scheldt against storms with a recurrence period of 1 in 4,000 years. It was estimated how flood protection measures would delay further dyke heightening, which is foreseen as protection levels are presently decreasing due to rising sea levels. Impacts of measures (safety benefits) consist of delays in further dyke heightening. The results illustrate the importance of sea level rise. Flood risks increased fivefolds when a sea level rise of 60 cm was applied. Although more drastic measures such as a storm surge barrier near Antwerp offer more protection for very extreme storms, a combination of dykes and floodplains can offer higher benefits at lower costs.  相似文献   

The last Eurasian ice sheets – a chronological database and time‐slice reconstruction,DATED‐1          下载免费PDF全文

Anna L. C. Hughes  Richard Gyllencreutz  Øystein S. Lohne  Jan Mangerud  John Inge Svendsen 《Boreas: An International Journal of Quaternary Research》2016,45(1):1-45

We present a new time‐slice reconstruction of the Eurasian ice sheets (British–Irish, Svalbard–Barents–Kara Seas and Scandinavian) documenting the spatial evolution of these interconnected ice sheets every 1000 years from 25 to 10 ka, and at four selected time periods back to 40 ka. The time‐slice maps of ice‐sheet extent are based on a new Geographical Information System (GIS) database, where we have collected published numerical dates constraining the timing of ice‐sheet advance and retreat, and additionally geomorphological and geological evidence contained within the existing literature. We integrate all uncertainty estimates into three ice‐margin lines for each time‐slice; a most‐credible line, derived from our assessment of all available evidence, with bounding maximum and minimum limits allowed by existing data. This approach was motivated by the demands of glaciological, isostatic and climate modelling and to clearly display limitations in knowledge. The timing of advance and retreat were both remarkably spatially variable across the ice‐sheet area. According to our compilation the westernmost limit along the British–Irish and Norwegian continental shelf was reached up to 7000 years earlier (at c. 27–26 ka) than the eastern limit on the Russian Plain (at c. 20–19 ka). The Eurasian ice sheet complex as a whole attained its maximum extent (5.5 Mkm²) and volume (~24 m Sea Level Equivalent) at c. 21 ka. Our continental‐scale approach highlights instances of conflicting evidence and gaps in the ice‐sheet chronology where uncertainties remain large and should be a focus for future research. Largest uncertainties coincide with locations presently below sea level and where contradicting evidence exists. This first version of the database and time‐slices (DATED‐1) has a census date of 1 January 2013 and both are available to download via the Bjerknes Climate Data Centre and PANGAEA ( www.bcdc.no ; http://doi.pangaea.de/10.1594/PANGAEA.848117 ).  相似文献   

iGeoTrans – a novel iOS application for GPS positioning in geosciences     

Dieu Tien Bui  Chuyen Trung Tran  Biswajeet Pradhan  Inge Revhaug  Razak Seidu 《国际地球制图》2015,30(2):202-217

The iGeoTrans is an iOS application designed for navigation purposes for iPhone, iPad and iPod Touch. This application uses Global Positioning System (GPS), Assisted GPS system, GLONASS, Wi-Fi and Cellular Network for positioning. The iGeoTrans has included datum transformations and map projections that enable users to convert the collected data between different coordinate systems for almost all areas in the world. In addition, other features are also included such as distance, area measurements, and GPS results could be exported to the AutoCad dxf format for GIS softwares. The average horizontal and vertical root mean square errors (RMSEs) for the static test are around 4.11 and 3.51?m, respectively. The horizontal RMSE for the dynamic outdoor test is around 2.72?m. The iGeoTrans application can be used to support surveying, mapping and geosciences fieldworks for any area in the world.  相似文献   

Late glacial and holocene 10Be production rates for western Norway     

Brent M. Goehring  Øystein Strand Lohne  Jan Mangerud  John Inge Svendsen  Richard Gyllencreutz  Joerg Schaefer  Robert Finkel 《第四纪科学杂志》2012,27(1):89-96

We present a new regional calibration of the ¹⁰Be production rate from two well‐dated surfaces in southern Norway: a rock avalanche with ¹⁴C‐dated wood and a precisely dated Younger Dryas moraine. Calculated ¹⁰Be production rates are 4.26 ± 0.13 and 4.65 ± 0.14 at g^?1 a^?1 for the Lal/Stone and Lifton scaling models, respectively. Our regional production rate for southern Norway is 5% lower than the canonical global ¹⁰Be production rate with lower uncertainties. Our ¹⁰Be production rate agrees with regional ¹⁰Be production rates from north‐eastern North America and New Zealand. The ¹⁰Be production rate estimate presented here can be used to improve the precision and accuracy of exposure‐dated ice‐marginal features, as well as other surfaces, in northern Europe. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Evaluation of remote‐sensing‐based rainfall products through predictive capability in hydrological runoff modelling     

Simon Stisen  Inge Sandholt 《水文研究》2010,24(7):879-891

The emergence of regional and global satellite‐based rainfall products with high spatial and temporal resolution has opened up new large‐scale hydrological applications in data‐sparse or ungauged catchments. Particularly, distributed hydrological models can benefit from the good spatial coverage and distributed nature of satellite‐based rainfall estimates (SRFE). In this study, five SRFEs with temporal resolution of 24 h and spatial resolution between 8 and 27 km have been evaluated through their predictive capability in a distributed hydrological model of the Senegal River basin in West Africa. The main advantage of this evaluation methodology is the integration of the rainfall model input in time and space when evaluated at the sub‐catchment scale. An initial data analysis revealed significant biases in the SRFE products and large variations in rainfall amounts between SRFEs, although the spatial patterns were similar. The results showed that the Climate Prediction Center/Famine Early Warning System (CPC‐FEWS) and cold cloud duration (CCD) products, which are partly based on rain gauge data and produced specifically for the African continent, performed better in the modelling context than the global SRFEs, Climate Prediction Center MORPHing technique (CMORPH), Tropical Rainfall Measuring Mission (TRMM) and Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks (PERSIANN). The best performing SRFE, CPC‐FEWS, produced good results with values of R²_NS between 0·84 and 0·87 after bias correction and model recalibration. This was comparable to model simulations based on traditional rain gauge data. The study highlights the need for input specific calibration of hydrological models, since major differences were observed in model performances even when all SRFEs were scaled to the same mean rainfall amounts. This is mainly attributed to differences in temporal dynamics between products. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Integrating facies-based Bayesian inversion and supervised machine learning for petro-facies characterization in the Snadd Formation of the Goliat Field,south-western Barents Sea     

Honoré Yenwongfai  Nazmul Haque Mondol  Isabelle Lecomte  Jan Inge Faleide  Johan Leutscher 《Geophysical Prospecting》2019,67(4):1020-1039

Seismic petro-facies characterization in low net-to-gross reservoirs with poor reservoir properties such as the Snadd Formation in the Goliat field requires a multidisciplinary approach. This is especially important when the elastic properties of the desired petro-facies significantly overlap. Pore fluid corrected endmember sand and shale depth trends have been used to generate stochastic forward models for different lithology and fluid combinations in order to assess the degree of separation of different petro-facies. Subsequently, a spectral decomposition and blending of selected frequency volumes reveal some seismic fluvial geomorphological features. We then jointly inverted for impedance and facies within a Bayesian framework using facies-dependent rock physics depth trends as input. The results from the inversion are then integrated into a supervised machine learning neural network for effective porosity discrimination. Probability density functions derived from stochastic forward modelling of endmember depth trends show a decreasing seismic fluid discrimination with depth. Spectral decomposition and blending of selected frequencies reveal a dominant NNE trend compared to the regional SE–NW pro-gradational trend, and a local E–W trend potentially related to fault activity at branches of the Troms-Finnmark Fault Complex. The facies-based inversion captures the main reservoir facies within the limits of the seismic bandwidth. Meanwhile the effective porosity predictions from the multilayer feed forward neural network are consistent with the inverted facies model, and can be used to qualitatively highlight the cleanest regions within the inverted facies model. A combination of facies-based inversion and neural network improves the seismic reservoir delineation of the Snadd Formation in the Goliat Field.  相似文献   

Quartz cementation in Late Cretaceous mudstones,northern North Sea: Changes in rock properties due to dissolution of smectite and precipitation of micro-quartz crystals     

Brit Thyberg  Jens JahrenTurid Winje  Knut BjørlykkeJan Inge Faleide  Øyvind Marcussen 《Marine and Petroleum Geology》2010

Late Cretaceous mudstones from two wells located in the northern North Sea and the Norwegian Sea have been examined with respect to quartz cement. Two different types of quartz cement (Type 1 and Type 2) have been identified using SEM/EDS/CL-analysis of drill-bit cuttings at depths 2370–2670 m (80–85 °C). Type 1 appears as relatively large aggregates (30–100 μm) of depth/temperature related crypto- or microcrystalline to macrocrystalline irregular quartz cement formed by local re-crystallization of biogenic silica. The CL-responses of Type 1 quartz cement give a clear indication of an authigenic origin. Type 2 quartz cement represents relatively high amounts of extremely fine-grained micro-sized (1–3 μm) crystals embedded as discrete, short chains or small clusters/nests within the illitized clay matrix. The CL-responses of micro-quartz crystals indicate an authigenic origin. The micro-quartz is most probably sourced from silica released during the smectite to illite dissolution–precipitation reaction. The petrographic evidence indicates that most of the silica released by the smectite to illite reaction has not been exported out of the mudstones. The silica released produce a subtle inter-connected micro-quartz network interlocked with aggregates of micro-quartz and authigenic clay crystals. This micro-quartz cementation process causes a significant and sharp change in the mudstone stiffness at the onset of the chemical compaction regime. This is indicated by an abrupt increase in well log velocity (Vp) and change in seismic facies close to 2500 m (80/85 °C).  相似文献   

Pre-23 magnetic anomalies between Jan Mayen and Greenland-Senja fracture zones in the Norwegian sea     

Terje Hagevang  Olav Eldholm  Inge Aalstad 《Marine Geophysical Researches》1983,5(4):345-363

Analysis of magnetic data between the Jan Mayen and Senja fracture zones indicates that the anomaly 24A-B sequence extends from the Lofoten Basin onto the outer Vøring Plateau. Anomaly patterns, including those on the conjugate margin, suggest that the pre-23 sea floor spreading was characterized by an unstable plate boundary between fracture zones. The pre-23 spreading rate was at least 2.5 cm yr^-1 which is remarkably high compared with the post-23 rates. An evolutionary model which assumes Cenozoic oceanic crust as far landward as the Vöring Plateau and Greenland escarpments is suggested.  相似文献   

A comparison of Martian albedo features with topography     

Jay L. Inge  William A. Baum 《Icarus》1973,19(3):323-328

Martian albedo features photographed from the Earth are compared with the topography observed by Mariner 9. We present three Lambert azimuthal equal-area charts prepared to facilitate the comparison. No correlation between large-scale albedos and topography can be generalized, but several different kinds of relationships seem to be indicated in particular regions. Examples of these are discussed.  相似文献   

Nighttime subvisual high-latitude auroras     

V. G. Vorobjev  I. A. Kornilov  T. A. Kornilova  O. I. Yagodkina  P. E. Sandholt  B. Lybekk 《Geomagnetism and Aeronomy》2008,48(5):606-614

Special methods for processing TV images have been used to study the characteristics of nighttime auroras based on the observations at high-latitude observatories on Spitsbergen. Weak subvisual auroras (SVAs), originating 3°–4° north of brighter auroras in the auroral oval, have been detected in the interval 1900-0400 MLT. The average lifetime of SVAs is approximately 7 min, and the average velocity of the equatorward shift is ～0.6 km/s. SVAs were observed during relatively quiet periods, when the IMF B _z component is mainly positive. However, SVAs are not polar-cap auroras since they are oriented from east to west rather than toward the Sun. The optical observations indicate that the SVA intensity is 0.2–0.5 and 0.1–0.3 kR in the 630 and 557.7 nm emissions, respectively. The average ratio of the emission intensities (I ₅₅₇₇/I ₆₃₀₀) is about 0.5. According to the direct satellite observations, the SVA electron spectrum has a maximum at 0.4–1.0 keV. In this case the energy flux of precipitating electrons is approximately an order of magnitude as low as such a flux in brighter auroral arcs in the auroral oval.  相似文献