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1.
Landslide susceptibility mapping for a landslide-prone area (Findikli,NE of Turkey) by likelihood-frequency ratio and weighted linear combination models 总被引:17,自引:0,他引:17
Landslides are very common natural problems in the Black Sea Region of Turkey due to the steep topography, improper use of
land cover and adverse climatic conditions for landslides. In the western part of region, many studies have been carried out
especially in the last decade for landslide susceptibility mapping using different evaluation methods such as deterministic
approach, landslide distribution, qualitative, statistical and distribution-free analyses. The purpose of this study is to
produce landslide susceptibility maps of a landslide-prone area (Findikli district, Rize) located at the eastern part of the
Black Sea Region of Turkey by likelihood frequency ratio (LRM) model and weighted linear combination (WLC) model and to compare
the results obtained. For this purpose, landslide inventory map of the area were prepared for the years of 1983 and 1995 by
detailed field surveys and aerial-photography studies. Slope angle, slope aspect, lithology, distance from drainage lines,
distance from roads and the land-cover of the study area are considered as the landslide-conditioning parameters. The differences
between the susceptibility maps derived by the LRM and the WLC models are relatively minor when broad-based classifications
are taken into account. However, the WLC map showed more details but the other map produced by LRM model produced weak results.
The reason for this result is considered to be the fact that the majority of pixels in the LRM map have high values than the
WLC-derived susceptibility map. In order to validate the two susceptibility maps, both of them were compared with the landslide
inventory map. Although the landslides do not exist in the very high susceptibility class of the both maps, 79% of the landslides
fall into the high and very high susceptibility zones of the WLC map while this is 49% for the LRM map. This shows that the
WLC model exhibited higher performance than the LRM model. 相似文献
2.
Abstract. The consequences of the following episodic phenomena for the pelagic-benthic coupling in the Nordic Seas are illustrated: (1) Advection of water masses between fjords and shelf environments, (2) freshwater run-off and vertical stability, (3) dynamics of the marginal ice zone in the central and northern Barents Sea and the Polar Ocean, (4) drift patterns of sinking particles along the North Norwegian coast, (5) advection of zooplankton into subarctic fjords and the southern Barents Sea, zooplankton overwintering and composition, and (6) transport of organic particulate matter from the Barents Sea shelf. It is shown that physical processes in the north-eastern North Atlantic and Polar Ocean can be strongly variable on time scales of days to decades. They have a significant influence on the dynamics of pelagic-benthic coupling. The physical oceanography influences the vertical and horizontal particle flux not only directly (mixing, advection, up- and down-welling), but also indirectly through its impact on the biota (for example radiation, wind, ice cover, freshwater run-off and overwintering, advection and retention of zooplankton). Understanding pelagic-benthic coupling at high latitudes depends even more on a best possible understanding of the physical oceanography and the time scales involved than elsewhere. 相似文献
3.
The cod resources in the Barents Sea constitute the most important fisheries in Norway. In order to reduce resource allocation conflicts among different gear and vessel groups and to ensure profit for all participants throughout the value chain, the sector is thoroughly organized. The institutions established to ensure long-term sustainability, have been developed within the framework of a joint Norwegian–Russian fisheries management regime. However, due to a very high fishing mortality, the cod stock is now under severe pressure. In addition, a major part of the cod fisheries is highly seasonal and unable to be a stable supplier to neither the land-based industry nor demanding international markets. In parallel, cod farming is expected to become a new emerging industry, with potential to copy the success of farmed Atlantic salmon. Many actors within the cod fisheries fear the future competition from the growing cod farming sector. With reference to important attributes that characterize the cod fisheries and cod farming, this paper discusses how a future farming industry may affect the traditional cod fisheries. Moreover, we discuss how the fisheries may be forced to organize in the future to encounter the expected competition from cod farming. 相似文献
4.
The lake Hunnebotn (A=1 km2, zmax=11 m) has become separated from the sea by isostasis, but a 1.5-m-deep channel is held open by periodic dredging. Water exchange is minor due to the small tidal range (21 cm) and the length of the channel (1.8 km), but there may be an inflow of seawater at spring tides. The terrestrial watershed runoff may be fertilized by sewage and agricultural runoff despite some measures taken to prevent this. Historical and new records of biological communities indicate variations in sensitivity to different phases of the isolation and eutrophication process. The native oyster was most sensitive and disappeared first. Later, the eelgrass disappeared possibly due to overgrowth by epiphytic algae, and finally there was a massive littoral–sublittoral invasion of green algae. The lake should not be left in this condition, for aesthetic reasons and because marine inlets and eutrophic brackish water may serve as refugia for spore populations of toxic microalgae. Improving surface water quality will require better control of anthropogenic sources, but bursts and leaks of nutrients from the anoxic monimolimnion cannot be controlled. 相似文献
5.
The stochastic properties of the drag force maxima on a circular cylinder subjected to nonlinear random waves are investigated. Unseparated laminar high Reynolds number flow is considered. A simplified approach based on second order Stokes waves is presented, including the sum-frequency effect only. It is demonstrated how a drag force formula valid for regular linear waves can be used to find the cumulative distribution function of individual drag force maxima for nonlinear irregular waves. Here the [Wang, 1968] drag force coefficient is used. 相似文献
6.
Traditional wave steepness s = H/L does not define steep asymmetric waves uniquely. Three additional parameters characterising single zero-downcross waves in a time series are crest front steepness, vertical asymmetry factor and horizontal asymmetry factor. Parametric models for joint probability density distributions for deep water waves are presented. The joint distributions are for crest front steepness-wave height, vertical asymmetry factor-wave height, total wave steepness-wave height and wave height-wave period. The parametric models are estimated from zero-downcross analysis of wave data obtained from measurements at sea on the Norwegian continental shelf. The results of the analysis presented here can be used in the estimation of the probabilities of occurrence of steep asymmetric waves and breaking waves in deep water. Thus the results are useful for the practical naval architect and ocean engineer who are considering unusual events in the sea, the associated accidents or responses and the probability of occurrence of such events. 相似文献
7.
Stochastic Structural Modeling 总被引:3,自引:0,他引:3
Lars Holden Petter Mostad Bjørn Fredrik Nielsen Jon Gjerde Chris Townsend Signe Ottesen 《Mathematical Geology》2003,35(8):899-914
A consistent stochastic model for faults and horizons is described. The faults are represented as a parametric invertible deformation operator. The faults may truncate each other. The horizons are modeled as correlated Gaussian fields and are represented in a grid. Petrophysical variables may be modeled in a reservoir before faulting in order to describe the juxtaposition effect of the faulting. It is possible to condition the realization on petrophysics, horizons, and fault plane observations in wells in addition to seismic data. The transmissibility in the fault plane may also be included in the model. Four different methods to integrate the fault and horizon models in a common model is described. The method is illustrated on an example from a real petroleum field with 18 interpreted faults that are handled stochastically. 相似文献
8.
Sergey Zubtsov Franois Renard Jean-Pierre Gratier Robert Guiguet Dag K Dysthe Vladimir Traskine 《Tectonophysics》2004,385(1-4):45-57
Experimental observations are reported of weakening of sediment-like aggregates by addition of hard particles. Sieved mixtures of calcite and halite grains are experimentally compacted in drained pressure cells in the presence of a saturated aqueous solution. The individual halite grains deform easily by pressure solution creep whereas calcite grains act as hard objects and resist compaction. The fastest rate of compaction of the mixed aggregate is not obtained for a 100% halite aggregate but for a content of halite grains between 45% and 75%. We propose that this unusual compaction behavior reflects the competition between two mechanisms at the grain scale: intergranular pressure solution at grain contacts and grain boundary healing between halite grains that prevent further compaction. 相似文献
9.
The paper provides a joint distribution of significant wave height and characteristic surf parameter. The characteristic surf parameter is given by the ratio between the slope of a beach or a structure and the square root of the characteristic wave steepness in deep water defined in terms of the significant wave height and the spectral peak period. The characteristic surf parameter is used to characterize surf zone processes and is relevant for e.g. wave run-up on beaches and coastal structures. The paper presents statistical properties of the wave parameters as well as an example of results corresponding to typical field conditions. 相似文献
10.
Dag Myrhaug Muk Chen Ong Henrik Føien Cecilie Gjengedal Bernt J. Leira 《Ocean Engineering》2009,36(8):605-616
This paper provides a method by which the scour depth below pipelines and around single vertical piles for combined random waves plus current including effects of second-order wave asymmetry can be derived. Here the empirical formulas proposed by Sumer and Fredsøe [1996. Scour below pipelines in combined waves and current. In: Proceedings of the 15th OMAE Conference, Florence, Italy. Vol. 5, ASME, New York, pp. 595–602] for pipelines, and by Sumer and Fredsøe [2002. The mechanics of scour in the marine environment. World Scientific, Singapore] for vertical piles are used together with Stokes second-order wave theory by assuming the basic harmonic wave motion to be a stationary Gaussian narrow-band random process. Comparisons are made with the Sumer and Fredsøe [1996. Scour below pipelines in combined waves and current. In: Proceedings of the 15th OMAE Conference, Florence, Italy. Vol. 5, ASME, New York, pp. 595–602; 2001. Scour around pile in combined waves and current. Journal of Hydraulic Engineering, 127(5), 403–411] data for linear random waves plus current. An example of calculation is also presented. 相似文献