• Title/Summary/Keyword: Basin-overlap method

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Flood Simulation for Basin-Shaped Urban Watershed Considering Surface Flow (분지형 도시유역에서의 노면류를 고려한 침수모의)

  • Ahn, Jeonghwan;Cho, Woncheol;Jung, Jaehee
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.34 no.3
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    • pp.841-847
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    • 2014
  • Urban runoff models have been continuously developing with concerns for urban flood. Recently, models that be able to quantitatively analyze surface inundation caused by overflowed water from storm sewer were also developed by coupling 1-dimensional sewer model and 2-dimensional surface flow model. However, only overflowed water from storm sewer can be analyzed by the models have been developed until now. They are limited to be not able to analyze surface inundation caused by surface runoff that could not flow into the storm sewer. In order to overcome the limitation, basin-overlap method was devised adding a dummy 1-dimensional sewer layer to the model, so it can consider the efficiency of inflow to the storm sewer system. XP-SWMM 2011 is applied for urban runoff model and the flood event occurred on July 27, 2011 in basin-shaped Sadangcheon watershed is chosen for study inundation event. According to simulation results basin-overlap method reappear the observed inundation event more precisely than traditional method. This results suggest that drainage system has to be improved for reducing inundation caused by surface runoff and would be used as considerations for planning an urban basin design magnitude.

The Analysis of Soil Seed Bank at Major Wetlands in Nakdong River Basin and Central Korea (낙동강 일대와 중부 지역 주요 습지의 토양종자은행 분석)

  • Ju, Eun Jeong;Kim, Jae Geun
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.12 no.5
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    • pp.77-91
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    • 2009
  • The purpose of this study is to define the species composition of the soil seed banks at major wetlands in Nakdong river basin and central korea and to investigate how soil seed banks relate to aboveground vegetation and soil texture. In 2005, we sampled seed banks at Baksil reservoir, Jillal marsh, Deapyeng marsh, Hwapo marsh, Upo marsh and Junam reservoir in Nakdong river basin and Osan stream and Amsa-dong in Seoul. The soil seeds were estimated with the emergence method from April to October. Total numbers of species at the seed banks were 33 at Baksil, 18 at Daepyeong, 35 at Jillal, 56 at Upo, 32 at Hwapo, 47 at Osan stream, 54 at Amsa waterside, 31 at Amsa meadow. The species diversity in the soil seed banks of Upo marsh was the highest as 0.95. The community overlap index that compares aboveground with underground vegetation is high in the Upo marsh (0.34), Jilla marsh (0.36), and Osan stream (0.27). Soil texture affected distribution of 8 species, Lindernia procumbens, L. attenuata, Arenaria serpyllifolia, Juncus effusus, Persicaria thunbergii, Eragrostis multicaulis, Cyperus nipponicus, Scirpus fluviatilis. Considering the social and cultural values, soils at Amsa meadow, Hwapo marsh and Osan stream have worth to use for wetland restoration.

한강하류지형면의 분류와 지형발달에 대한 연구 (양수리에서 능곡까지)

  • Park, No-Sik
    • Journal of the Speleological Society of Korea
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    • no.68
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    • pp.23-73
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    • 2005
  • Purpose of study; The purpose of this study is specifically classified as two parts. The one is to attempt the chronological annals of Quaternary topographic surface through the study over the formation process of alluvial surfaces in our country, setting forth the alluvial surfaces lower-parts of Han River area, as the basic deposit, and comparing it to the marginal landform surfaces. The other is to attempt the classification of micro morphology based on the and condition premising the land use as a link for the regional development in the lower-parts of Han river area. Reasons why selected the Lower-parts of Han river area as study objects: 1. The change of river course in this area is very serve both in vertical and horizontal sides. With a situation it is very easy to know about the old geography related to the formation process of topography. 2. The component materials of gravel, sand, silt and clay are deposited in this area. Making it the available data, it is possible to consider about not oかy the formation process of topography but alsoon the development history to some extent. 3. The earthen vessel, a fossil shell fish, bone, cnarcoal and sea-weed are included in the alluvial deposition in this area. These can be also valuable data related to the chronological annals. 4. The bottom set conglometate beds is also included in the alluvial deposits. This can be also valuable data related to the research of geomorphological development. 5. Around of this area the medium landform surface, lower landform surface, pediment and basin, are existed, and these enable the comparison between the erosion surfaces and the alluvial surfaces. Approach : 1. Referring to the change of river beds, I have calculated the vertical and horizontal differences comparing the topographic map published in 1916 with that published in 1966 and through the field work 2. In classifying the landform, I have applied the method of micro morphological classification in accordance with the synthetic index based upon the land conditions, and furthermore used the classification method comparing the topographic map published in 1916 and in that of 1966. 3. I have accorded this classification with the classification by mapping through appliying the method of classification in the development history for the field work making the component materials as the available data. 4. I have used the component materials, which were picked up form the outcrop of 10 places and bored at 5 places, as the available data. 5. I have referred to Hydrological survey data of the ministry of Construction (since 1916) on the overflow of Han-river, and used geologic map of Seoul metropolitan area. Survey Data, and general map published in 1916 by the Japanese Army Survbey Dept., and map published in 1966 by the Construction Research Laboratory and ROK Army Survey Dept., respectively. Conclusion: 1. Classification of Morphology: I have added the historical consideration for development, making the component materials and fossil as the data, to the typical consideration in accordance with the map of summit level, reliefe and slope distribution. In connection with the erosion surface, I have divided into three classification such as high, medium and low-,level landform surfaces which were classified as high and low level landform surfaces in past. furthermore I have divided the low level landform surface two parts, namely upper-parts(200-300m) and bellow-parts(${\pm}100m$). Accordingly, we can recognize the three-parts of erosion surface including the medium level landform surface (500-600m) in this area. (see table 22). In condition with the alluvial surfaces I have classified as two landform surfaces (old and new) which was regarded as one face in past. Meamwhile, under the premise of land use, the synthetic, micro morphological classification based upon the land condition is as per the draw No. 19-1. This is the quite new method of classification which was at first attempted in this country. 2. I have learned that the change of river was most severe at seeing the river meandering rate from Dangjung-ni to Nanjido. As you seee the table and the vertical and horizontal change of river beds is justly proportionable to the river meandering rate. 3. It can be learned at seeing the analysis of component materials of alluvial deposits that the component from each other by areas, however, in the deposits relationship upper stream, and between upper parts and below parts I couldn't always find out the regular ones. 4. Having earthern vessel, shell bone, fossil charcoal and and seaweeds includen in the component materials such as gravel, clay, sand and silt in Dukso and Songpa deposits area. I have become to attempt the compilation of chronicle as yon see in the table 22. 5. In according to hearing of basemen excavation, the bottom set conglomerate beds of Dukso beds of Dukso-beds is 7m and Songpa-beds is 10m. In according to information of dredger it is approx. 20m in the down stream. 6. Making these two beds as the standard beds, I have compared it to other beds. 7 The coarse sand beds which is covering the clay-beds of Dukso-beds and Nanjidobeds is shown the existence of so-called erosion period which formed the gap among the alluvial deposits of stratum. The former has been proved by the sorting, bedding and roundness which was supplied by the main stream and later by the branch stream, respectively. 8. If the clay-beds of Dukeo-bed and Songpa-bed is called as being transgressive overlap, by the Eustatic movement after glacial age, the bottom set conglomerate beds shall be called as being regressive overlap at the holocene. This has the closest relationship with the basin formation movement of Seoul besides the Eustatic movement. 9. The silt-beds which is the main component of deposits of flood plain, is regarded as being deposited at the Holocene in the comb ceramic and plain pottery ages. This has the closest relationship with the change of river course and river beds.

Analysis of Land Use Change within Four Major River Areas Using High-Resolution Air-Photographs: The Case of the Nakdong River Basin (고해상도 항공사진을 이용한 4대강 하천구역 내 토지이용변화 분석 - 낙동강 유역을 사례로)

  • Park, Soo-Kuk;Kim, Jin;Lee, Kil-Jae;Jo, Myung-Hee
    • Journal of the Korean Association of Geographic Information Studies
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    • v.16 no.4
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    • pp.171-188
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    • 2013
  • Landuse changes and cadastral information error categories in the four major river areas were analyzed for the use of policy data as cadastral re-arrangement of national and public lands would be required, using high-resolution air-photographs and cadastral maps before and after the river development. The study sites were the river areas of 40km around four dams of the Nakdong river where their landuses were changed most. As the results, national and public lands reached 79.9% of land parcels and 93.3% of land areas of the study sites similar with those of the four river areas, 84.3% of land parcels and 85.5% of land areas. The landuse classification of the study sites before the four river development was consisted most of 'river'(71.6%) and 'rice field'(12.3%), but after the development the 'river' was reduced to 42.7% and 'park area'(19.6%) including sport fields and 'mixed lots'(20.8%) were increased. Also, 86.7% of land parcels before the development could be reduced after the development if administrative districts and land ownerships were not considered. Cadastral information error categories can be found as cadastral polygon missing, polygon overlap, location and boundary non-coincidence, small polygon generation, and non-coincidence between cadastral boundary and river boundary. Landuse change monitoring method using air-photographs will be useful to analyze landuse state through fast information aquisition and to manage properties of national and public lands such as river areas.