• Title/Summary/Keyword: Flood area

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Interannual Changes of Bar Morphology in the Han River Estuary Using Satellite Imagery (인공위성에 의한 한강 하구역 퇴적상 경년 변동 특성 조사)

  • Yang, Chan-Su
    • Proceedings of KOSOMES biannual meeting
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    • 2007.11a
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    • pp.57-60
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    • 2007
  • The Han River is divided into North and South Korea by NLL(Northern Limit Line) and its area has been blocked by CCL(Civil Control Line) since the Korean War in 1950. Satellite remote sensing, therefore, is uniquely suited to monitoring bar transformation in the region. In river with bar, the characteristics of its physical conditions have a close relationship with bar morphology. In this paper, a monitoring approach of bar transformation in the Han River Estuary is presented using RADARSAT/SAR images from 2000 to 2005 and spatial patterns of bar morphology are presented. It could be said that in the estuary vegetated area and natural levees are developed well, but bars are shifted after an event like a flood. It is also showed that suspended solids such as silt transported through the estuary could contribute highly to a sedimentation environment around Incheon.

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Applications of the Sediment-Transport Path Model to the Tidal Flats of Garolim Bay, West Coast of Korea

  • Shin, Dong-Hyeok;Yi, Hi-Il;Han, Sang-Joon;Oh, Jae-Kyung;Won, Joong-Sun
    • International Union of Geodesy and Geophysics Korean Journal of Geophysical Research
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    • v.23 no.1
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    • pp.39-51
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    • 1995
  • Bidirectional transport trend using the sediment-transport path model was identified in the two areas, sand ridge area and tidal mudflat in Garolim Bay, which is located in the mid-western coast of Korean Peninsular. This model exhibits the two-dimensional view of clear sediment transport trend based on data of changes in sediment statistics such as mean, sorting, and skewness, Garolim Bay was selected to test for the sediment-transport path model developed by McLaren and Bowles [1985]. Line-S, a typical tidal mudflat and representative of the Garolim Bay tidal flats, is well tested by this model, showing a clear seasonal change and coarsening-trend seaward (case C). This indicates that strong ebb currents carried relatively coarser sediments seaward with respect to high energy regime. Seasonally, this energy regime slowly decreases toward the summer in contrast with an increase of energy regime of flood tides, carrying coarser sediments landward (case C) in the summer. However, the Line-D area does not show consistent transport trend with respect to time-series. Separated and scattered events show fining trend landward (case B) in the sand ridge itself. The finining-trend (case B) either seaward and landward is not chiefly important in both the entire Line-D area and sand ridge itself. Also, the coarsening-Trend (case C) landward is not significant in the sand ridge itself. Consequently, in reality, the selection of suitable and representative locations are very important to fit with this model.

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Development of Regional Regression Model for Estimating Mean Low Flow in Ungauged Basins (미계측 유역 평균갈수량 산정을 위한 지역회귀모형의 개발)

  • Lee, Tae Hee;Lee, Min Ho;Yi, Jaeeung
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.36 no.3
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    • pp.407-416
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    • 2016
  • The purpose of this study is to develop regional regression models to estimate mean low flow for ungauged basins. The unregulated streamflow data observed at 12 multipurpose dams and 4 irrigation dams were analyzed for determining mean low flows. Various types of regression models were developed using the relationship between mean low flows and various sets of watershed characteristics such as drainage area, average slope, drainage density, mean annual precipitation, runoff curve number. The performance of each regression model for estimating mean low flows was assessed by comparison with the results obtained from the observed data. It was found that a regional regression model explained by drainage area, the mean annual precipitation, and runoff curve number showed the best performance. The regression model presented in this study also gives better estimates of mean low flow than the estimates by the drainage-area ratio method and the previous regression model.

Fundamental Theory of flow of water in bends of open channel (하천의 만곡류에 관한 이론적 고찰)

  • 선우중호;윤영남
    • Water for future
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    • v.10 no.1
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    • pp.53-70
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    • 1977
  • The analysis performed here is aimed to increase the familiarity of hydrologic process especially for the small basins which are densely gaged. Kyung An and Mu Shim river basins are selected as a representative basin according to the criteria which UNESCO has established back in 1964 and being operated under the auspice of Ministry of Construction. The data exerted from these basins is utilized for the determination of characteristics of procipitation and runoff phenomena for the small basin, which is considered as a typical Korean samall watershed. The study found that the areal distribution of preciptation did not show any significant deviation from the point rainfall. Since the area studied is less than 20 km#, the pointrainfall may be safely utilized as a representative value for the area. Also the effect of elevation on the precipitation has a minor significance in the small area where the elevation difference is less than 200m. The methodology developed by Soil Conservation Service for determination of runoff value from precipitation is applied to find the suitability of the method to Korean river basin. The soil cover complex number or runoff curve number was determined by comsidering the type of soil, soil cover, land use and other factors such as antecedent moisture content. The average values of CN for Kyung An and Mushim river basins were found to be 63.9 and 63.1 respectively under AMC II, however, values obtained from soil cover complex were less than those from total precipitation and effective precipitation about 10-30%. It may be worth to note that an attention has to be paid in application of SCS method to Korean river basin by adjusting 10-30% increase to the value obtained from soil cover complex. Finally, the design flood hydrograph was consturcted by employing unit hydrograph technique to the dimensionless mass curve. Also a stepwise multiple regression was performed to find the relationship between runoff and API, evapotranspiration rate, 5 days antecedentprecipitation and daily temperature.

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DEM Extraction from LiDAR DSM of Urban Area (도시지역 LiDAR DSM으로부터 DEM추출기법 연구)

  • Choi, Yun-Woong;Cho, Gi-Sung
    • Journal of Korean Society for Geospatial Information Science
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    • v.13 no.1 s.31
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    • pp.19-25
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    • 2005
  • Nowadays, it is possible to construct the DEMs of urban area effectively and economically by LiDAR system. But the data from LiDAR system has form of DSM which is included various objects as trees and buildings. So the preprocess is necessary to extract the DEMs from LiDAR DSMs for particular purpose as effects analysis of man-made objects for flood prediction. As this study is for extracting DEM from LiDAR DSM of urban area, we detected the edges of various objects using edge detecting algorithm of image process. And, we tried mean value filtering, median value filtering and minimum value filtering or detected edges instead of interpolation method which is used in the previous study and could be modified the source data. it could minimize the modification of source data, and the extracting process of DEMs from DSMs could be simplified and automated.

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Physical Habitat Simulation Considering Stream Morphology Change due to Flood (홍수에 의한 하도변형을 고려한 물리서식처 모의)

  • Lee, Sungjin;Kim, Seung Ki;Choi, Sung-Uk
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.3
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    • pp.805-812
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    • 2014
  • This study investigates the impact of morphological change on the physical habitat simulation. For this, CCHE2D model is used for the hydraulic analysis including the morphological change, and the physical habitat suitability is assessed with habitat suitability curves. The model is applied to a 2.5km long reach downstream of the Goesan Dam, from Sujeon Bridge to Daesu Weir. Flow data of discharge and stage in July, 2006 are used in the computation. The numerical model is verified by means of comparison with the measured water surface elevation data, and the variation of the river bed is not verified in this study. Adult Zacco platypus is chosen for the dominant species. Physical habitat simulations result in composite habitat suitability and weighted usable area for drought, low, normal, and averaged-wet flows. The simulation results indicate that the composite suitability index increased at reaches right downstream of the Sujeon Bridge and around the bend. This also increased weighted usable area by 5.4-11.3%.

Development of Stochastic-Dynamic Channel Routing Model by Storage Function Method (저류함수법에 의한 추계동역학적 하도홍수추적모형의 개발)

  • Bae, Deok-Hyo;Jeong, Il-Mun
    • Journal of Korea Water Resources Association
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    • v.33 no.3
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    • pp.341-350
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    • 2000
  • The objectives of this study are to develop a state-space form of stochastic dynamic storage function routing model and to test the model performance for real-time flow forecast. The selected study area is the main Han River starting from Paldang Dam site to Indogyo station and the 13 flood events occurred from 1987 to 1998 are selected for computing model parameters and testing the model performance. It was shown that the optimal model parameters are quite different depending on Hood events, but the values used on field work also give reasonable results in this study area. It is also obvious that the model performance from the stochastic-dynamic model developed in this study gives more accurate and reliable results than that from the existing deterministic model. Analysis for allowable forecast lead time leads that under the current time step the reasonable predicted downstream flows in 5 hours time advance are obtained from the stochastic dynamic model on relatively less lateral inflow event in the study area.

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Research on the Sharing of Disaster Information Using Web GIS Technology (Web GIS를 이용한 재해 정보 제공에 관한 연구)

  • 김동문;양인태
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.21 no.2
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    • pp.101-107
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    • 2003
  • Lately, much researches for information management of web GIS base are gone. Specially, disaster Information Management System development of Web-Based for management and offer of disaster information such as flood or earthquake is necessarily necessary for prevention and countermeasure about disaster, disaster information acquisition of interest area. Spatial DB access for plan/analysis/management business of this system should be possible and must become display of disaster information and disaster mapmaking through internet for disaster prevention but research of web GIS base about this field is childhood yet. This research executed research for disaster information offer using HTML and Javascript and ESRI's ArcIMS that is development tools or web GIS. And this research could search disaster information of interest area through various kinds function and offer in display through user selection. Also, topography of interest area could confirm through third dimension topography model who use VRML. And this research could supply disaster information of Chunchon city using various function thorough system of Web-Based.

Cooperation Measures for Agricultural Infrastructure Development in North Korea (북한 농업생산기반조성 현황과 협력 방안)

  • Choe Jin Wook
    • Proceedings of the Korean Society of Crop Science Conference
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    • 1998.10a
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    • pp.134-158
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    • 1998
  • The objectives of this article are to identify the current status of agricultural infrastructure in North Korea and to suggest some cooperation measures among South and North Koreas and international agencies in order to develop the North Korea's agricultural infrastructure. The area of cultivated land in North Korea is 1,992 thousand ha (paddy field: 585 thousand ha: upland: 1,407 thousand ha) in 1997. Major water use facilities in North Korea are 1,900 reservoirs (included 100 big dams), 36,400 irrigation pumping stations, 1,600 drainage pumping stations, and 14'a,000 wells. In addition, there is 'two thousand Ri canal construction project' linking the rivers of Aprok, Daeryong, Daedong, Jaeryong, and Yesong. The unit of paddy land consolidation is about 1 ha which is regarded as rational for agricultural mechanization. The project of 'Darak' upland construction to create small size farmland, which has been carried out since 1976 has been unsuccessful due to the shortage of construction equipment. The area of farmland created by reclamation by 1995 is only 75 thousand ha although the potential project area is at)out 320 thousand ha along the western coast. It is due to the fact that civil engineering technologies and equipments are old and investment funds are insufficient. These are a few suggested areas of cooperation among South and North Korea and international agencies in order to improve North Korea's agricultural infrastructure : i) see land reclamation and land consolidation projects to increase paddy fields for rice production; ii) rehabilitation project in farm land areas devastated by flood; and iii) agricultural water development project which including diagnosing and rehabilitating irrigation and drainage facilities.

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Application of Surface Runoff-River flow Model to Small- and Large-Size Catchment Areas (소유역 및 대유역 홍수유출모형의 적용)

  • Yoo, Dong-Hoon
    • Journal of Korea Water Resources Association
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    • v.36 no.1
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    • pp.87-104
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    • 2003
  • A numerical model of surface runoff and river flow has been applied to small- and large-size catchment areas in order to investigate the physical characteristics of river flow during flood period. Several refinements are made on the existing model SIRG-RS for the ways of rainfall input through surface runoff, river junction treatment and the computation of river flow on steep slope. For the computation of frictional forces, employed is the power law of friction factor which is a function of Reynolds number and relative roughness height. The empirical equation of friction factor is developed using recent field data as well as laboratory data. The refined model has been applied to small-size catchment area as well as large-size catchment area, and the computation results are found in good agreement with the observations in both cases.