• Title/Summary/Keyword: Topographical Cross Section

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The Analysis of Flood in an Ungauged Watershed using Remotely Sensed and Geospatial Datasets (II) - Focus on Estimation of Flood Inundation - (원격탐사와 공간정보를 활용한 미계측 유역 홍수범람 해석에 관한 연구(II) - 침수 피해면적 산정을 중심으로 -)

  • Son, Ahlong;Kim, Jongpil
    • Korean Journal of Remote Sensing
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    • v.35 no.5_2
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    • pp.797-808
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    • 2019
  • This study evaluated the applicability of spacebourne datasets to the flood analysis in an ungauged watershed where is no discharge measurements. The Duman River basin of North Korea was selected as a target area which was flooded by recent Typhoon Lionrock. Topographical parameters for flood analysis were estimated from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM). GDEM includes the shortcomings of information on river cross-section, and conducted 2 dimensional flood analysis when considering virtual river cross-section and not considering it. As a result of comparative analysis, an error occurs in the inundation area and depth, but when used carefully, it is considered that the satellite image can be used for creating flood hazard map and utilizing information for response and preparation.

The Restoration Effect of Deltacon Method in Coastal Erosion (Deltacon공법을 통한 해안 침식지의 복구 효과 연구)

  • Han, Bong-Ho;Park, Seok-Cheol;Lee, Poong
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.20 no.6
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    • pp.35-50
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    • 2017
  • This study is to see the recovery effect of the Deltacon method by investigating the amount of sand deposition, the topographical cross section and the vegetation structure; and to derive the effective recovery method of coastal erosion area. The target areas of this study include Jinri coastal dune, Bajireum coastal dune and Seopori coastal dune in Deokjeok-do Island, Ongjin-gun, Incheon. In order to assess the current status of the coastal erosion area recovery, the soil profile structure map was prepared on the site and then the amount of sand deposition within 1m was calculated indoors. The vegetation recovery status of the costal erosion area was assessed via the analyses of the topographical profile structure and the plant community structure, and we aim to derive the effective recovery plan of the Deltacon method with the results. With the Deltacon method, structures with ductile material, special non-woven fabric bags filled with soil and vegetation can be performed therefore the structuralstability and prevention of sand erosion can be achieved. The amounts of sand deposition of Bajireum coastal dune, Seopori costal dune and Jinri costal dune were calculated $0.98{\sim}2.54m^3$, $1.02{\sim}2.96m^3$, and $0.27{\sim}0.75m^3$, respectively, and it is considered that the costal erosion recovery is actively performed for Bajireum costal dune and Seopori costal dune. The analysis results of vegetation structures by topography show that the installation of the send collecting net in steep areas has been highly effective and the Deltacon-constructed target areas have been restored to vegetation and the costal dune, which is similar to the natural dune. The investigation of the plant community structure in Deokjeok-do Island costal dune, Incheon displayed similar research results of the existing costal dune flora and confirmed the emergence of Lathyrus japonicus, Carex kobomugi, Elymus mollis, Vitex rotundifolia, and Calystegia soldanella and others. In order to carry out further effective recovery with the Deltacon method, improvements to rootage of herbaceous vegetation are needed in areas without foredune herbaceous vegetation, and continuos maintenance & management monitoring of connected windbreak forest to costal dunes are also necessary.

The Application of SQL in Terrain Information Analysis for Route Design (도로 설계를 위한 지형정보 해석에 있어서 SQL의 응용)

  • Kang, Joon-Mook;Yoon, Hee-Cheon;Lee, Hyung-Seok;Lee, Sung-Soong
    • Journal of Korean Society for Geospatial Information Science
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    • v.3 no.2 s.6
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    • pp.29-42
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    • 1995
  • Route design in topographical plane map brings many problems in efficiency and requires much time and labor by hand Recently, the active studies of efficient route design method using 3-D terrain information are being developed according to increasing concentration on GSIS. In order to analyze terrain information for route design efficiently, this study presents objective and overall datum by applying SQL in construction and analysis of database and the possibility of three-dimensional terrain information analysis, This study generates 3-D base map on topographical map of scale 1:5,000 and acquires terrain information that have various thematic map data; contour, land use, roadway, and drange. This is a study on the application of SQL in route design and construction of the terrain information that linked by graphic datum of completed topographical map and attributed datum of database. As the result of this study, we can produce promptly and efficiently design datum of profile annotation, cross section, and volume computations to the preliminary route for route design and apply this efficient method to route design by understanding visual DTM which is composed of the roadway and the natural scene after design.

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Analysis of Precision of Interpolation of Reservoir bed Through Comparison of Data Acquired by Using UAV and Echo Sounder (UAV와 Echo Sounder 취득 자료의 비교를 통한 저수지 하상의 공간 보간별 정확도 분석)

  • Roh, Tae-Ho
    • Journal of the Korean Association of Geographic Information Studies
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    • v.23 no.3
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    • pp.85-99
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    • 2020
  • Reservoir is an important infrastructure of our society because it can store immense amount of water for various usages - manufacturing, agriculture, drinking, power generation, tourism etc. For maintenance of reservoir, various efforts in administrative and technological aspects are periodically conducted and monitoring the conditions of reservoir bed is the first priority for maintenance of reservoir. To check the conditions of reservoir bed, we measured depth of reservoir by using echo sounder, which is relatively reliable, prior to discharging of stored water and surveyed topography of reservoir by using UAV after discharging of water. Then, we conducted interpolation of measured depth of water by means of inverse distance weighting interpolation, Kriging interpolation, minimum curvature interpolation and radial basis function interpolation and calculated the volume of reservoir for each interpolation method. We compared the calculated volume of reservoir with the volume of water calculated by UAV after discharging of water and found the following results: First, as results of the above processes, we found that the Kriging interpolation was 97% correct in measurement of the volume of reservoir. Second, as results of comparison of differences between topographical areas and interpolated areas after selection of cross section for comparison, Kriging interpolation was found to have the most similar configuration with the topographical configuration by showing the least difference in the area of cross section. Therefore, it is determined that the optimal modeling of reservoir bed with the water depth data measured by echo sounder shall provide basic information for efficient maintenance of reservoir.

The Change of Riverside Vegetation by Construction of Ecological Stream in Suwoncheon, Gyeonggi Province (경기도 수원천 생태하천 복원사업 이후 식생변화 연구)

  • Choe, Il-Hong;Han, Bong-Ho;Ki, Kyong-Seok
    • Korean Journal of Environment and Ecology
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    • v.24 no.6
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    • pp.723-734
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    • 2010
  • This study aims to analyze the change in vegetation for 10 years after the construction, targeting Suwoncheon, the first domestic ecological stream construction project. As for the section for the study, the section from Gyeonggi bridge to Youngyeon bridge, the first restoration project section, was targeted. The research districts consisted of 3 districts depending on topographical structure. Investigation check cosisted of cross-sectional topographical structure, vegetation status and the structure of herbaceous plant community. As for the cross-sectional topographical structure of the stream, the width of entire stream was 26.5~28.0m and water channel is 10~20m. The area for hydrophilic space was securing spacious riverside. Upper stream of reservoir beam was shallow and slow in reservoir area above weir. Lower stream of reservoir beam, the width of water channel was narrow and ripples were formed. Among species, 9 plants were planted and 6 species plants including Salix gracilistyla, Phragmites communis and Zoysia japonica were planted at the time of construction. In the water side, there were 2 species, such as Zoysia japonica and Trifolium repens, etc, still remained after seeding at the time of constrcution. The planted plants which were observed through this investigation, were 2 species such as Festuca arundinacea and Dactylis glomerata. Apart from the planted plants, arid climate herbaceous plant such as Setaria viridis and Artemisia princeps var. orientalis formed power and the naturalized species variously emerged in 15 species. For revetment, natural stone stacking method was condicted and Salix gracilistyla, Aceriphyllum rossii, etc were planted. But all the planted plants disappeared and now it was covered with Equisetum arvense and Humulus japonicus. It was because that the base for growth and development of the plants was not constructed at the time of restoration in a way of attaching natural stones onto the concrete base. In the water channel, various wetland species including Typha orientalis, Acorus calamus var. angustatus and Phragmites communis, etc, were planted but only Salix gracilistyla, Phragmites communis and Zizania latifolia remained. As for species of the autochthons, Persicaria thunbergii was dominant. In the lower stream of reservoir beam, Humulus japonicus formed forces. In the hydrophilic space, it was necessary to direct the landscape of in-stream vegetation in cosideration of users. For this, planting Miscanthus sacchariflorus in a community was proposed. In the upper stream of reservoir beam, suplementary screen seeding was necessary so that Zizania latifolia, Typha orientalis and Phragmites communis can fit the depth of water. In the Lower stream of reservoir beam, it was necessary to constantly manage Humulus japonicus so that the wetland autochthons species, such as Phragmites communis and Persicaria thunbergii can establish power more stably.

Analysis of changes in cross section and flow rate due to vegetation establishment in Naeseong stream (내성천 하도 내 식생활착에 의한 단면 및 유량변화 분석)

  • Lee, Tae Hee;Kim, Su Hong
    • Journal of Korea Water Resources Association
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    • v.54 no.3
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    • pp.203-215
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    • 2021
  • In the present study, hydrologic data and topographical data from 2010 to 2019 were collected from three gauging stations placed in the watershed of Naeseong stream to determine changes and rates of changes in rainfall, water level & mean velocity, and water level & discharge, together with changes in rates of erosion and deposition at cross-sections of the river. Besides, effects of regulated and non-regulated rivers according to the presence of artificial regulation of flow rate of the river via artificial structure located at Seo stream (Yeongju si (Wolhogyo) station), the tributary free from construction of dams, were compared and analyzed. Results of analyses conducted in the present study revealed vegetational establishment and landforming due to increasing area of vegetational sandbar evolved in the flood plain (intermediate- or high- water level) by the drought sustained from 2013 to 2015. Continuous erosion of river bed was appeared because of narrowed flow area with low water level and increased velocity and tractive force on river bed.

Development of a River Maintenance Management Technology Related with National River Management Data (국가하천관리자료와 연계한 하천유지관리 기술개발)

  • Jo, Myung-Hee;Kim, Kyung-Jun;Kim, Hyun-Jung
    • Journal of the Korean Association of Geographic Information Studies
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    • v.15 no.1
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    • pp.159-171
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    • 2012
  • This study has developed a technology for river basin including the management of the data related with riverbed and the analysis of the riverbed maintenance based on the high-resolution imagery data and LiDAR (Light Detection and Raging) in order to enhance the utilization of river management by using RIMGIS(River Information Management GIS) and to acquire the advanced operation for river management. Using the detailed river topographical map specially designed in the form of LiDAR or high-resolution images, riverbed data and river bank channel information that are dynamically changed were informationized and established in the RIMGIS DB. At this stage, a monitoring techniques that is established in the river management system associated with RIMGIS and minimized the impact of riverbed maintenance (fluctuations) has been studied. In addition, functions and data structure of RIMGIS containing the information of geography and management of the river have been supplemented to make an improvement of the real-time management of the river. Furthermore, a technology that is capable of supplementing RIMGIS has been developed, making it feasible to maintain the river in use of structural method including an structural scheme of cross-section of the river by providing the information of riverbed and cross-section of the river. This is considered to solve an issue of insufficient data on accuracy and based on a lack of information of the river based on the two-dimensional lines, making it feasible to (steadily) improve the function of RIMGIS and to operate management tasks. Therefore, it is highly expected to enhance aforementioned technology of the river information management as a great foundation that maximizes the utilization of the river management to support RIMGIS for the development of national river management data.

Assessment of Rainfall Runoff and Flood Inundation in the Mekong River Basin by Using RRI Model

  • Try, Sophal;Lee, Giha;Yu, Wansik;Oeurng, Chantha
    • Proceedings of the Korea Water Resources Association Conference
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    • 2017.05a
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    • pp.191-191
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    • 2017
  • Floods have become more widespread and frequent among natural disasters and consisted significant losses of lives and properties worldwide. Flood's impacts are threatening socio-economic and people's lives in the Mekong River Basin every year. The objective of this study is to identify the flood hazard areas and inundation depth in the Mekong River Basin. A rainfall-runoff and flood inundation model is necessary to enhance understanding of characteristic of flooding. Rainfall-Runoff-Inundation (RRI) model, a two-dimensional model capable of simulating rainfall-runoff and flood inundation simultaneously, was applied in this study. HydoSHEDS Topographical data, APPRODITE precipitation, MODIS land use, and river cross section were used as input data for the simulation. The Shuffled Complex Evolution (SCE-UA) global optimization method was integrated with RRI model to calibrate the sensitive parameters. In the present study, we selected flood event in 2000 which was considered as 50-year return period flood in term of discharge volume of 500 km3. The simulated results were compared with observed discharge at the stations along the mainstream and inundation map produced by Dartmouth Flood Observatory and Landsat 7. The results indicated good agreement between observed and simulated discharge with NSE = 0.86 at Stung Treng Station. The model predicted inundation extent with success rate SR = 67.50% and modified success rate MSR = 74.53%. In conclusion, the RRI model was successfully used to simulate rainfall runoff and inundation processes in the large scale Mekong River Basin with a good performance. It is recommended to improve the quality of the input data in order to increase the accuracy of the simulation result.

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A Study on the Channel Planform Change Using Aerial Photographs and Topographic Map in the Mangyoung River (영상자료를 이용한 만경강 하도변화에 관한 연구)

  • Hong, Il;Kang, Joon-Gu;Yeo, Hong-Koo
    • Journal of Korea Water Resources Association
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    • v.45 no.2
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    • pp.127-136
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    • 2012
  • River is able to change by various environmental factors. In order to conduct river restoration design, it is necessary to evaluate the stable channel through the analysis of past and present river channels. River evaluation requires various data, such as geometry, hydraulic and hydrology, but there is a lot of difficulty to understand topographical information of river change on time and space due to a lack of past data by domestic conditions. This study was analyzed abandoned channel formation, changes in the vertical-section and cross-section length of rivers, and micro-landform changes etc using an image analysis technique. Purpose of this research is to evaluates the stable channel through a river channel morphology change from past and present river channels image. Mangyoung river was conducted artificial river maintenance through straight channel consolidation form 1920 to 1930 year. In the result river maintenance, mangyoung river length was decreased by 15 km and abandoned channels of six points were made. Since then, weir was continuously increased to control bed slope and use water. Install of weir was to be the reason of changes on channel width, thalweg, vegetated bar, sand bar, water area. Present Mangyoung river show that water area was temporary increased in upper and middle reach because of weir installation. Total sand bar was only decreased in upper channel. The change of vegetated bar and sand bar was slight recently. In this result, Mangyoung river is inferred to reach stabilized channel although there is some difference to the lower reach.

Channel Evaluation for Abandoned Channel Restoration Using Image Analysis Technique (영상분석기법을 이용한 구하도 복원 대상하천의 하도평가)

  • Hong, Il;Kang, Joon-Gu;Kwon, Bo-Ae;Yeo, Hong-Koo
    • Journal of Korea Water Resources Association
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    • v.42 no.5
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    • pp.397-406
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    • 2009
  • River is able to change by various environmental factors. In order to conduct restoration design of abandoned river channels, it is necessary to evaluate the river through the analysis of past and present river channels. River evaluation requires various data, such as geometry, hydraulic and hydrology, but there is a lot of difficulty to understand topographical information of river change on time and space due to a lack of past data by domestic conditions. This study analyzes the changes in past and present river channels and examines the applicability of river channel evaluation through image analysis using aerial photographs and 1918 year's map. Aerial photograph analysis was conducted by applying the image analysis method and GIS analysis method on Cheongmicheon. As a result of this analysis, we have quantitatively identified the form and size of abandoned channels, changes in the vertical-section and cross-section length of rivers, and micro-landform changes. More importantly, we verified that morphological changes in sandbars due to artificial straightening are important data in identifying the state of current river channels. In these results, although image analysis technique has limitations in two-dimensional information from aerial photographs, we were able to evaluate the changes in river channel morphology after artificial maintenance of the river.