Debris flow in metropolitan area — 2011 Seoul debris flow   总被引：4，自引：2，他引：2  

Chan-Young Yune  Yun-Ki Chae  Joongcheol Paik  Gihong Kim  Seung-Woo Lee  Heung-Seok Seo 《山地科学学报》2013,10(2):199-206

A large number of debris flows occurred simultaneously at around 8:30 to 8:50 a.m. on July 27, 2011, at the center of Seoul, Korea. This area is located in the southern part of Seoul and is a densely populated district. As a result of the debris flow event, 16 people were killed, 30 houses were buried, and 116 houses were damaged around Umyeon Mountain, a relatively small mountain with a height of 312.6 m. Since the debris flow event, field investigations on the initiation and transportation zones of debris flows have been carried out. Rainfall data were collected from the automatic weather stations (AWSs) which are operated by the Korea Meteorological Administration (KMA). Video files recorded by residents were also acquired and used to analyze the flow characteristics of the debris flow. Field investigation shows that about 40 debris flows occurred around Umyeon Mountain and most of the debris flows were initiated by small slope failures. The effects of the precipitation that triggered the debris flows were analyzed as well. A landslide hazard map which considers slope gradient and aspect, strength of soil, hazard record, rainfall conditions, and vegetation, was constructed and compared with the initiation zones of debris flows.  相似文献   

Multifractal characteristics of the jet turbulent intensity depending on the outfall nozzle geometry     

Yongwon Seo  Siwan Lyu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(2):653-664

The multifractal measure enables an examination of the characteristics of a quantity distributed over a domain. This study examined the multifractal properties of turbulent intensities obtained from jet discharge experiments, where three types of nozzle geometries were examined in terms of the velocity fields and turbulent characteristics using particle image velocimetry. Depending on the nozzle geometry, the experimental results showed that the distribution of turbulent intensities and resulting dilution exhibited different behaviors. The experiment also showed that the transversal velocity profiles are similar to each other regardless of the outfall nozzle shapes and demonstrates the traditional similarity assumption at the same time. The multifractal exponents of the turbulent intensities were obtained with Box Count Method in a two-dimensional space. The results showed that the turbulent intensities obtained in two-dimensional space have a common multifractal spectrum, which was not the case for the velocity or shear stress observed in the same space. Although the transversal velocity profiles are similar, the multifractal exponent clearly shows a difference depending on the outfall geometries. In particular, the minimum value of the Lipschitz–Hölder exponent (α _min) and the entropy dimension (α ₁) tends to increase as turbulent intensity and dilution increase. These results suggest that the multifractal properties can be utilized potentially to categorize and evaluate the discharge outfall capabilities in terms of the resulting dilution.  相似文献   

LH-moment estimation of a four parameter kappa distribution with hydrologic applications     

Md. Sharwar Murshed  Yun Am Seo  Jeong-Soo Park 《Stochastic Environmental Research and Risk Assessment (SERRA)》2014,28(2):253-262

The study of distribution tails is a fundamental research in statistical frequency analysis relevant to many research fields, such as insurance, hydrological events, earthquake, etc. Here, we describe and investigate the effect and feasibility of the high-order L-moment (LH-moment) method for estimating heavy-tail conditions by fitting a four parameter kappa distribution. Details of parameter estimation using LH-moments for the four parameter kappa distribution (K4D) are described and formulated. Monte-Carlo simulation is performed to illustrate the performance of the LH-moment method in terms of heavy-tail quantiles over all quantiles using K4D and non K4D samples, respectively. The result suggests that the method is either useful (when the method of L-moment estimation fails to give a feasible solution) or as effective as the L-moment approach in handling data following K4D. Applications to the annual maximum flood and sea level data are presented.  相似文献   

Energy dependence of Ti/Fe ratio in the Galactic cosmic rays measured by the ATIC-2 experiment     

V. I. Zatsepin  A. D. Panov  N. V. Sokolskaya  J. H. Adams Jr.  H. S. Ahn  G. L. Bashindzhagyan  J. Chang  M. Christl  A. R. Fazely  T. G. Guzik  J. B. Isbert  K. C. Kim  E. N. Kouznetsov  M. Panasyuk  E. S. Seo  J. Watts  J. P. Wefel  J. Wu 《Astronomy Letters》2009,35(5):338-342

Titanium is a rare, secondary nucleus among Galactic cosmic rays. Using the Silicon matrix in the ATIC experiment, Titanium has been separated. The energy dependence of the Ti to Fe flux ratio in the energy region from 5 GeV per nucleon to about 500 GeV per nucleon is presented. The article was translated by the authors.  相似文献   

Neoproterozoic tectonic evolution of the Hongseong area, southwestern Gyeonggi Massif, South Korea; implication for the tectonic evolution of Northeast Asia     

C.W. Oh  S.-G. Choi  J. Seo  V.J. Rajesh  J.H. Lee  M. Zhai  P. Peng 《Gondwana Research》2009,16(2):272

Two types of Neoproterozoic metabasites occur together with regionally intruded arc-related Neoproterozoic granitoids (ca. 850–830 Ma) in the Hongseong area, southwestern Gyeonggi Massif, South Korea, which is the extension of the Dabie–Sulu collision belt in China. The first type of metabasite (the Bibong and Baekdong metabasites) is a MORB-like back-arc basin basalt or gabbro formed at ca. 890–860 Ma. The Bibong and Baekdong metabasites may have formed during back-arc opening by diapiric upwelling of deep asthenospheric mantle which was metasomatized by large ion lithophile element (LILE) enriched melt or fluid derived from the subducted slab and/or subducted sediment beneath the arc axis. The second type of metabasite (the Gwangcheon metabasite) formed in a plume-related intra-continental rift setting at 763.5 ± 18.3 Ma and is geochemically similar to oceanic island basalt (OIB). These data indicate a transition in tectonic setting in the Hongseong area from arc to intra-continental rift between ca. 830 and 760 Ma. This transition is well correlated to the Neoproterozoic transition from arc to intra-continental rift tectonic setting at the margin of the Yangtze Craton and corresponds to the amalgamation and breakup of Rodinia Supercontinent.  相似文献   

Laboratory Simulation Of Vertical Plume Dispersion Within A Convective Boundary Layer     

O. H. Park  S. J. Seo  S. H. Lee 《Boundary-Layer Meteorology》2001,99(1):159-169

Mesoscale measurements of the vertical dispersion coefficient ₂ by using a composite turbulence water tank were validated through a comparison with CONDORS (Convective Diffusion Observed with Remote Sensors) field data, and were analysed with respect to the intensity of the thermal flux, mechanical turbulence, and plume release height.It seems possible to correct the plume _z values for different release heights below 0.5z_i (z_i is the mixing height) by applying an equation expressing the height dependency of turbulence intensity. The downwind distance where the plume's mass centre height approaches its final level was also analysed with respect to the above three parameters, and an empirical equation to estimate the downwinddistance derived.  相似文献   

Rainfall estimation using raingages and radar — A Bayesian approach: 2. An application     

D. -J. Seo  J. A. Smith 《Stochastic Environmental Research and Risk Assessment (SERRA)》1991,5(1):31-44

In Seo and Smith (this issue), a set of estimators was built in a Bayesian framework to estimate rainfall depth at an ungaged location using raingage measurements and radar rainfall data. The estimators are equivalent to lognormal co-kriging (simple co-kriging in the Gaussian domain) with uncertain mean and variance of gage rainfall. In this paper, the estimators are evaluated via cross-validation using hourly radar rainfall data and simulated hourly raingage data. Generation of raingage data is based on sample statistics of actual raingage measurements and radar rainfall data. The estimators are compared with lognormal co-kriging and nonparametric estimators. The Bayesian estimators are shown to provide some improvement over lognormal co-kriging under the criteria of mean error, root mean square error, and standardized mean square error. It is shown that, if the prior could be assessed more accurately, the margin of improvement in predicting estimation variance could be larger. In updating the uncertain mean and variance of gage rainfall, inclusion of radar rainfall data is seen to provide little improvement over using raingage data only.  相似文献   

Estimates of velocity-pressure and velocity-pressure gradient interactions in the surface layer over plant canopies     

T. Maitani  T. Seo 《Boundary-Layer Meteorology》1985,33(1):51-60

The budget equations of turbulent kinetic energy and shear stress contain interaction terms of velocity-pressure and velocity-pressure gradient. These terms were estimated in the surface layer using the air pressure observed at the surface and wind velocity components over plant canopies. The magnitude of the pressure interaction terms was significantly large; it was not negligible compared with the production terms in each budget equation. The present results obtained over a rough surface also confirmed previous results that pressure terms play an important role in the turbulent kinetic energy budgets and the shear stress budget. The height dependency of nondimensional pressure terms versus (z - d)/z ₀ was not clear.  相似文献   

Turbulent transport of scalar quantities within and above a paddy field     

T. Maitani  T. Seo 《Boundary-Layer Meteorology》1985,33(2):197-208

An experiment was conducted to study turbulent transport processes of scalar quantities within and above a rice plant canopy. A sonic anemometer-thermometer and a Lyman- humidiometer were used to measure the turbulent fluxes of sensible and latent heat and related turbulence statistics within a paddy field. The sensible and latent heat fluxes measured at two heights within and above the plant canopy showed that the upper layer of this plant canopy was an active source region and that the source strength of sensible and latent heat depended on the solar radiation and physiology of rice plants. Analysis of joint probability distributions of w and T and of w and q within this plant canopy showed that downdrafts were remarkably efficient for upward transport of sensible and latent heat in the daytime. The vertical fluxes of temperature and humidity variance were also divergent from the upper layer of plant canopies. The power spectra of temperature and humidity within the plant canopy decreased rapidly in the high frequency range, compared with the - 2/3 law relationship of nS(n) vs log n observed above plant canopies.  相似文献   

Atmospheric carbon dioxide variations at coastal site, Shibukawa, in Seto Inland Sea, Japan     

E. Ohtaki  T. Maitani  T. Seo 《Meteorology and Atmospheric Physics》1984,35(1-2):31-44

Summary Four years of measurements (1980–83) of carbon dioxide at the northern coast site, Shibukawa, are presented. The data reveal well defined diurnal and seasonal variations. The amplitude of the daily carbon dioxide variation is about 30 ppm during the colder season (January–March; November–December), and about 60 ppm during the warmer season (April–October). The seasonal variation of daily minimum concentration of carbon dioxide has a maximum in the middle of summer (July–September) and a minimum in the winter months. This variation does not correspond to that expected from vegetation activity. The summer peak in carbon dioxide concentration seems to be inherent features at the coast site, Shibukawa; it is probably due to less activity of the vertical mixing under stable stratification of the air layer prevailing throughout the day. The year-to-year comparison of minimums in the winter months reveals an average annual increase of the carbon dioxide content of 6 ppm/year, which is much greater than 1.5 ppm/year observed in the troposphere over Japan [1]. This indicates that the carbon dioxide concentration and its variations at Shibukawa station represent the local scale values rather than the large scale one. The horizontal distribution of carbon dioxide concentration, measured over sea surface near Shibukawa station, also suggests the existence of many patches of high concentration of carbon dioxide due to the local point sources related to the human activity such as ships and industries distributed at the coast site.

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Variationen des atmosphärischen CO₂ bei Shibukawa im Küstengebiet des Inlandsees Seto in Japan

Zusammenfassung Es werden Ergebnisse über Tages- und Jahresgänge von vierjährigen Messungen (1980–83) des CO₂ bei Shibukawa an der nördlichen Küste des Sees vorgelegt. Die Amplitude des Tagesganges beträgt in der kalten Jahreszeit ungefähr 30 ppm und in der warmen Jahreszeit ungefähr 60 ppm. Im Jahresgang des täglichen Minimums des CO₂ fällt das Maximum auf den Sommer und das Minimum auf Wintermonate. Dies entspricht nicht der aus der Aktvität der Vegetation zu erwartenden Variation. Das Sommermaximum scheint eine Besonderheit der Lage von Shibukawa an der Küste zu sein und ist wahrscheinlich auf die zu geringe vertikale Durchmischung bei der tagsüber dort vorherrschenden stabilen Schichtung zurückzuführen. Der Vergleich der Minima der Wintermonate von Jahr zu Jahr läßt eine Zunahme um 6 ppm pro Jahr erkennen, die bedeutend größer ist als die Zunahme um 1,5 ppm pro Jahr in der Troposphäre über Japan [ 1 ]. Dies weist darauf hin, daß die CO₂-Konzentration und ihre Variationen in Shibukawa eher lokale als großräumige Werte darstellen.Die über der Seeoberfläche in der Nähe von Shibukawa gemessene Verteilung der CO₂-Konzentrationen zeigt viele Stellen mit hoher CO₂-Konzentration, die auf lokale Punktquellen menschlicher Aktivität wie auf Schiffe und auf an der Küste verteilte Industrien hinweisen.

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