• Title/Summary/Keyword: basin-to-basin comparison

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Experimental Comparison of the Wave Force on Crown Wall of Sloping Breakwater Armored with Tetrapods under Obliquely Incident Waves (경사입사 시 테트라포드로 피복된 경사제 상부구조물에 작용하는 파력 비교 실험)

  • Oh, Sang-Ho;Lee, Jooyeon
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.32 no.3
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    • pp.161-169
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    • 2020
  • Physical experiments have been performed in a wave basin to investigate change of the wave loading on the crown wall under obliquely incident wave conditions. The measurement was carried out with wave incidence angle of 0, 15, 30 and 45°. The pressure transducers were placed on the front and bottom face of the crown wall to obtain horizontal and uplift force as well. It was found that both the horizontal and vertical force decreases with the incidence angle. Based on the analysis of the experimental data, a formula was suggested to estimate the reduction rate of horizontal and vertical forces under obliquely incident waves.

Characteristic Nature of the Unconformity between Holocene and Late Pleistocene in the Tidal Deposits along the Western Coast of Korea

  • Park, Yong-Ahn
    • The Korean Journal of Quaternary Research
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    • v.17 no.2
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    • pp.13-14
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    • 2003
  • It is generally well known that Quaternary is characteristic geologically in terms of glacial and interglacial repeats and their associated unconformity formation. This paper deals with the first finding of the characteristic and significant meaningful unconformity between Holocene and late Pleistocene, which implies submergence and emergence of the tidal sedimentary basin along the western coastal zone of Korea during interglacial stage(IOS-5e) and glacial time(IOS-2). The stratigraphy of intertidal deposits in the Haenam Bay, western coast of Korea shows two depositional sequence units (Unit I of Holocene and Unit II of late Pleistocene) bounded by an erosional surface of disconformity. The disconformity is related to the latest Pleistocene sea-level lowstands (probably during the LGM). The Unit II is interpreted as intertidal deposit showing tidal sedimentary structures and crab burrow ichnology and has two parts (the upper part and the lower part) showing different lithology and character. The upper part of Unit II shows characteristic subaerial exposure features (emergence) and its related lithology. Such subaerially exposed upper part (more or less 4m to 5m in thickness) is characterized by yellow-brownish sediment color, cryoturbat-ed structure, crab burrow ichnofacies and high value of shear strength. Geochemical and clay mineral analyses of the upper part sediments also indicate subaerial exposure and weathering. In particular, very high value of magnetic susceptibility of the upper part in comparison to that of the lower part is interpreted as pedogenetic weathering during the subaerial exposure period.

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Evaluation the Climatic Influence during El Nino and La Nina Periods of Aridity Index, Precipitation Effectiveness and Runoff in Basins (이상기후 (엘니뇨, 라니냐) 기간의 유역별 건조지수, 강수효율, 유출량의 영향성 평가)

  • Lee, Jun-Won;Kim, Gwang-Seob
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.4
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    • pp.115-125
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    • 2012
  • The comparison between the spatial and temporal variability of aridity index, precipitation effectiveness and runoff during El-Nino and La-Nina periods and that of the normal period was conducted to evaluate the regional impacts of El-Nino, La-Nina in hydrologic variables. Aridity index and precipitation effectiveness were estimated using 59 nationwide weather stations data and runoff data of WAMIS were used. The ratio of the difference between El-Nino, La-Nina year value and that of normal year was analyzed. Temporal variation demonstrated that aridity index, precipitation effectiveness and run-off discharge increase in March, April, August, November, December and decrease in February, June, September, October according to El-Nino effect. Aridity index, precipitation effectiveness and run-off discharge increase in March, May, September and decrease in June, August, November, December according to La-Nina effect. The spatial variation of those variables analyzed for different basins showed that impacts in the Han river basin relatively higher than that of other basins.

P-wave velocity analysis around BSR depth using surface and ocean bottom seismic data (탄성파 자료를 이용한 BSR 부근의 속도 분석)

  • Kim, Byoung-Yeop;Koo, Nam-Hyung;Yoo, Dong-Geun
    • 한국지구물리탐사학회:학술대회논문집
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    • 2007.06a
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    • pp.151-156
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    • 2007
  • In December 2006, 2D surface streamer and Ocean Bottom Seismometer (OBS) data were acquired in the Ulleung basin in Korea where strong Bottom Simulating Reflectors (BSR) were shown as a result of 2D and 3D multichannel (MCS) reflection survey. The aim of this study is to provide another reliable source for estimating P wave velocity around BSR depth using OBS data in addition to velocity information from 2D surface seismic data. Four OBSs were deployed and four 20-km shot lines which pass two OBSs respectively were designed. To derive P wave velocity profile, interactive interval velocity analysis using ${\tau}$-p trajectory matching method (Kumar, 2005) was used for OBS data and semblance analysis was used for surface data. The seismic profiles cross the OBS instruments in two different directions yield recordings for four different azimuths. This raised the confidence for the results. All velocity profiles in the vicinity of BSR depth of four OBS sites show almost definite velocity changes which we could consider as upper BSR and free gas layer. Making comparison between velocity from OBS and that from 2D seismic semblance velocity analysis gives consistency in result.

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A Comparison of Univariate and Multivariate AR Models for Monthly River Flow Series (월유량에 대한 일변량 및 다변량 AR모형의 비교)

  • 이원환;심재현
    • Water for future
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    • v.23 no.1
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    • pp.99-107
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    • 1990
  • The statistical analysis based on the past hydrologic data required to set up the water resources development plan and design the hydraulic structres rationally. Because hydrologic events have random factors implied, the sotchastic analysis is necessary. In this paper, same order of stochastic models of monthly runoff data(multivariate AR(1) and AR(2) models, univariate AR(1) and AR(2) models) are applied to compare the statistical characteristics. The other purpose of this paper is to compare the monthly series, which is generated by univariate and multivariate models. By comparing and estimating of each simulated series, it is known that the multivariate models, including the time and spatial colinearity, are better in prediction than univariate models in the analysis of monthly flow at south Han river basin.

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Forecasting Monthly Runoff Using Ensemble Streamflow Prediction (앙상블 예측기법을 통한 유역 월유출 전망)

  • Lee, Sang-Jin;Kim, Joo-Cheol;Hwang, Man-Ha;Maeng, Seung-Jin
    • Journal of The Korean Society of Agricultural Engineers
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    • v.52 no.1
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    • pp.13-18
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    • 2010
  • In this study the validities of runoff prediction methods are reviewed around ESP (Ensemble Streamflow Prediction) techniques. The improvements of runoff predictions on Yongdam river basin are evaluated by the comparison of different prediction methods including ESP incorporated with qualitative meteorological outlooks provided by meteorological agency as well as the runoff forecasting based on the analysis of the historical rainfall scenarios. As a result it is assessed that runoff predictions with ESP may give rise to more accurate results than the ordinary historical average runoffs. In deed the latter gave the mean of yearly absolute error as to be 60.86 MCM while the errors of the former ones amounted to 44.12 MCM (ESP) and 42.83 MCM (ESP incorporated with qualitative meteorological outlooks) respectively. In addition it is confirmed that ESP incorporated with qualitative meteorological outlooks could improve the accuracy of the results more and more. Especially the degree of improvement of ESP with meteorological outlooks shows rising by 10.8% in flood season and 8% in drought season. Therefore the methods of runoff predictions with ESP can be further used as the basic forecasting information tool for the purpose of the effective watershed management.

Comparative Validation of WindCube LIDAR and Remtech SODAR for Wind Resource Assessment - Remote Sensing Campaign at Pohang Accelerator Laboratory (풍력자원평가용 윈드큐브 라이다와 렘텍 소다의 비교.검증 - 포항가속기 원격탐사 캠페인)

  • Kim, Hyun-Goo;Chyng, Chin-Wha;An, Hae-Joon;Ji, Yeong-Mi
    • Journal of the Korean Solar Energy Society
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    • v.31 no.2
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    • pp.63-71
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    • 2011
  • The remote-sensng campaign was performed at the Pohang Accelerator Laboratory where is located in a basin 6km inland from Yeongil Bay. The campaign aimed uncertainty assessment of Remtech PA0 SODAR through a mutual comparison with WindCube LIDAR, the remote-sensing equipment for wind resource assessment. The joint observation was carried out by changing the setup for measurement heights three times over two months. The LIDAR measurement was assumed as the reference and the uncertainty of SODAR measurement was quantitatively assessed. Compared with LIDAR, the data availability of SODAR was about half. The wind speed measurement was fitted to a slope of 0.94 and $R^2$ of 0.79 to the LIDAR measurement. However, the relative standard deviation was about 17% under 150m above ground level. Therefore, the Remtech PA0 SODAR is judged to be unsuitable for the evaluation of wind resource assessment and wind turbine performance test, which require accuracy of measurement.

Contents of Heavy Metals in Soils of the Kum-Ho River Basin (금호강류성 하상토양중 중금속함량)

  • 문효노;장봉기;김두희
    • Journal of environmental and Sanitary engineering
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    • v.5 no.1
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    • pp.1.1-14
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    • 1990
  • This study was conducted to investigate the contents of heavy metals in soils of the Kumho river basin, by analyzing soils according to the distance from edge of the river and to the soil layers. The contents of heavy metals in soils showed highly in its downstream. Namely there was shown a remarkably high contents of these heavy metals in the Kum-ho bridge areas where Kongdan stream joins Dalseo stream, such as 39.52ppm for zinc, 35.92ppm for copper, 97.90ppm for iron, 102.45ppm for manganese, 13.92ppm for lead, respectively, and 0.48ppm for cadmium. However, the heavy metals contents in soils around Kangchang bridge tended to gradually decrease in its contents, probably because its main soils consisting of sand. Based on their soil layers, the average contents of these heavy metals in the surface soils were higher than one of the subsurface soil. Its contents according to the distance from the river edge indicated some difference every individual area. Nevertheless, its contents showed lower contents in the area far away from the edge. And its contents tended to again increase in the outside bank. In addition, a remarkable positive correlation is shorten between individual heavy metals, except correlation between iron and lead. Also cadmium just shows reverses correlation in the statistics. With respect to comparison between soil layers, there was a remarkable positive correlation between surface layers and subsurface layers. Considering the above results, it seems that the pollution of river bed's soil is in proportion to it of stream.

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Assessment of Probability Flood according to the Flow Regulation by Multi-purpose Dams in Han-River Basin (한강유역의 다목적댐 운영에 따른 빈도홍수량의 평가)

  • Kim, Nam-Won;Lee, Jeong-Eun
    • Journal of Korea Water Resources Association
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    • v.42 no.2
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    • pp.161-168
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    • 2009
  • The purpose of this study is to evaluate the variation of probability flood according to the flow regulation by multi-purpose dams (Soyang and Chungju) in the Han-river basin, Korea. SWAT-K (Soil and Water Assessment Tool-Korea) was used in order to generate regulated and unregulated daily streamflows upstream of Paldang dam. Simulated flow regulated by the Soyang and Chungju dams was calibrated by comparison with the observed inflow data at Paldang reservoir. Generally the ratio of flood flows to daily streamflows is known to decrease with drainage area in a watershed. Regulated and unregulated flood flows were obtained from the relationship between flood flows and daily streamflows. Extreme Type-I distribution was applied for flood frequency analysis and L-moment method was used for parameter estimation. This is a novel approach capable of understanding the variation in flood frequency with dam operation for the relatively large watershed scale, and this will helps improve the applicability of daily stream flow data for use in flood control as well as in water utilization.

A Pilot Study on Environmental Understanding and Estimation of the Nak-Dong River Basin Using Fuyo-1 OPS Data (Fuyo-1 OPS 자료를 이용한 낙동강 하류지역의 환경계측 시고)

  • Kim, Cheon
    • Korean Journal of Remote Sensing
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    • v.12 no.2
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    • pp.169-198
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    • 1996
  • The objectives of this investigation are : 1. To analyze spectral signature and the associated vegetation index for geometric illumination conditions inf1uenced by low solar elevation and high slope orientations in mountainous forest. 2. To assess the accuracy of the spectral angle mapper classification for the a winter land cover in comparison with the maximum likelihood classification. 3. To produce the image of water quality and water properties that could be used to estimate the water pollution sources and the tide-included by turbid water in estuarine and coastal areas. These objectives are to characterize environmental and ecological monitoring applications of the Nak-Dong River Basin by using Fuyo-1 OPS VNIR data acquired on December 26, 1992. The results of this paper are as follows : 1. The spectral digital numbers and vegetation indexes (NDVI and TVI) of mountainous forest are higher on the slope facing the sun than on the slope hidden the sun under low sun elevation condition. 2. The spectral angle mapper algorithm produces a more accurate land cover classification of areas with steep slope, various aspects and low solar elevation than the maximum likelihood classifier. 3. The maximum likelihood classification images can be used for identifying the location and movement of both freshwater and salt water, regardless of geometric illumination conditions. 4. The color-coded density sliced image of selected water bodies by using the near-infrared band 3 can provide distribution of the water quality of the Lower Nak-Dong River. 5. The color-coded normalized difference vegetation index image of the selected mountain forest is suitable to classify winter vegetation cover types, i.e., forest canopy densities for slope orientations.