• Proceedings of the Korea Water Resources Association Conference
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• 2008.05a
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• pp.194-198
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• 2008

Significant soil erosion and water quality degradation issues are occurring at highland agricultural areas of Kangwon province because of agronomic and topographical specialities of the region. Thus spatial and temporal modeling techniques are often utilized to analyze soil erosion and sediment behaviors at watershed scale. The Soil and Water Assessment Tool (SWAT) model is one of the watershed scale models that have been widely used for these ends in Korea. In most cases, the SWAT users tend to use the readily available input dataset, such as the Ministry of Environment (MOE) land cover data ignoring temporal and spatial changes in land cover. Spatial and temporal resolutions of the MOE land cover data are not good enough to reflect field condition for accurate assesment of soil erosion and sediment behaviors. Especially accelerated soil erosion is occurring from agricultural fields, which is sometimes not possible to identify with low-resolution MOD land cover data. Thus new land cover data is prepared with cadastral map and high spatial resolution images of the Doam-dam watershed. The SWAT model was calibrated and validated with this land cover data. The EI values were 0.79 and 0.85 for streamflow calibration and validation, respectively. The EI were 0.79 and 0.86 for sediment calibration and validation, respectively. These EI values were greater than those with MOE land cover data. With newly prepared land cover dataset for the Doam-dam watershed, the SWAT model better predicts hydrologic and sediment behaviors. The number of HRUs with new land cover data increased by 70.2% compared with that with the MOE land cover, indicating better representation of small-sized agricultural field boundaries. The SWAT estimated annual average sediment yield with the MOE land cover data was 61.8 ton/ha/year for the Doam-dam watershed, while 36.2 ton/ha/year (70.7% difference) of annual sediment yield with new land cover data. Especially the most significant difference in estimated sediment yield was 548.0% for the subwatershed #2 (165.9 ton/ha/year with the MOE land cover data and 25.6 ton/ha/year with new land cover data developed in this study). The results obtained in this study implies that the use of MOE land cover data in SWAT sediment simulation for the Doam-dam watershed could results in 70.7% differences in overall sediment estimation and incorrect identification of sediment hot spot areas (such as subwatershed #2) for effective sediment management. Therefore it is recommended that one needs to carefully validate land cover for the study watershed for accurate hydrologic and sediment simulation with the SWAT model.

• Journal of the Korean Geographical Society
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• v.36 no.4
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• pp.458-473
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• 2001

The classified map of geomorphic surfaces is the most basic data for the geomorphological research. Up to recent days, the traditional methods extracting specific geomorphic surfaces are accomplished by analyzing the aerial photographs and topographical maps, and field works. Also it needs a lot of time and expertness. Furthermore it is difficult to gain the aerial photographs in Korea. Since digital maps in Korean Peninsula are almost completed recently, we tried to extract specific surfaces by analyzing the characteristics of marine terraces based on the level of paleoshoreline and slope analysis on the terrace surface using GIS. However, research used GIS was hardly found up to date, therefore many problems are not be solved yet. The aim of this study is to develop the more efficient and objective method for the extraction and classification of specific geomorphic surfaces by using GIS in Gampo-eup, Gyeongju city, Southeastem Coast in Korea, where a lot of traditional research has already accomplished. For this aim, we have designed the process of extracting specific geomorphic surfaces, chosen the factors that was Gyeongiu city, Southeastem Coast in Korea, where a lot of traditional research has already accomplished. For this aim, we have designed the process of extracting specific geomorphic surfaces, chosen the factors that was suitable for classification of specific geomorphic surface, and presented method of setting up optimum criteria of extraction. As last, effectiveness and problems of these methods were investigated through conincidence rate and error rate.

• Journal of Korea Water Resources Association
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• v.51 no.6
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• pp.481-490
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• 2018

Recently, the spatiotemporal patterns of flood disasters have become more complex and unpredictable due to climate change. Flood hazard map including information on flood risk level has been widely used as an unstructured measure against flooding damages. In order to product a high-precision flood hazard map by combination of hydrologic and hydraulic modeling, huge digital information such as topography, geology, climate, landuse and various database related to social economic are required. However, in some areas, especially in developing countries, flood hazard mapping is difficult or impossible and its accuracy is insufficient because such data is lacking or inaccessible. Therefore, this study suggests a method to delineate large scale flood-prone area based on topographic factors produced by linear binary classifier and ROC (Receiver Operation Characteristics) using globally-available geographic data such as ASTER or SRTM. We applied the proposed methodology to five different countries: North Korea Bangladesh, Indonesia, Thailand and Myanmar. The results show that model performances on flood area detection ranges from 38% (Bangladesh) to 78% (Thailand). The flood-prone area detection based on the topographical factors has a great advantage in order to easily distinguish the large-scale inundation-potent area using only digital elevation model (DEM) for ungauged watersheds.

• Journal of Wetlands Research
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• v.15 no.1
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• pp.71-78
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• 2013

An exceptional case of inhabitation of a Sphagnum sp. was firstly confirmed at abandoned paddy terrace (APT) wetland in Ansan. Water sampling for analyzing of physicochemical conditions including nutrients such as NP, $Ca^{2+}$ and $Mg^{2+}$ was performed and the vegetation map for distribution of Sphagnum sp., topographical map, and flora list for companion species were made at field in June 2011. From the results, the Sphagnum sp. in the study site was identified as S. palustre and it covered about 8% of the wetland cover of 3,200 $m^2$. Most distributions of S. palustre were observed at tussock structures as micro-topography by sedges and grasses within a wetland (74%) and the shaded slope area under Pinus densiflora's canopy in wetland boundary (26%). Despite that APT in Ansan is relatively lower wetland in altitude than high moors, the contents of calcium ($0.45{\pm}0.2$) and magnesium ($1.48{\pm}0.6$) ion which are critical limiting factors for Sphagnum spp. were very low levels as well as NP ($PO_4$-P, $0.02{\pm}0.0$; $NO_3$-N, $0.25{\pm}0.3$; $NH_4$-N, $0.06{\pm}0.1$) and it could enable the inhabitation of S. palustre in lower APT.

• Journal of the Korean Institute of Traditional Landscape Architecture
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• v.38 no.4
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• pp.12-24
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• 2020

The purpose of this study is to analyze the influence of the water system on the location, spatial structure, and construction method of Hongju-eupseong, centering on Hongjumok-eupchi. During the Joseon Dynasty, the water system in Hongjumok-eupchi is composed of artificially constructed Seong-an Runnel and ponds based on a branch-shaped natural waterways flowing from south to north and west to east. Compiling the results of various literature records, excavations and analysis of map data, it can be seen that the water system has an important influence on the construction of Hongju-seong. Firstly, Hongju-seong from the Goryeo Dynasty to the late Joseon Dynasty is located using a circular shape of topographical structure and a small erosion basin formed on the inner side of the Hongseongcheon and Wolgyecheon streams without significant change in location. In particular, Wolgyecheon and Hongseongcheon are natural moats, which are harmonized with Sohyangcheon and riverside topographical structures, affecting the location and construction method of Hongju-seong, water related facilities, and the spatial structure of eupseong. It is understood that location characteristic of Hongju-seong reflects the urban location structure harmonized with waterways in ancient China and Korea. Secondly in harmony with the water system and topographic structure of Hongju-seong, it is an important factor in deciding the land use of the town, the arrangement of the town hall facilities and inducing various non-subsidiary measures such as the establishment of embankment forest with a secret function and the closure of the south gate. In addition, artificial drainage facilities such as Seongan runnel and ponds are being actively introduced from early on to protect the walls or towns from flooding of Wolgyecheon. Especially there were typical methods for protecting the walls from water damage such as the Joseon Dynasty stone castle structure that was integrated with saturn(soil wall) in the Goryeo Dynasty, retreating wall in the northern gate area in the late Joseon Dynasty, and the method of constructing wall using korean tile and stone floors between reinforced soil layers in the western and northern wall.

• 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.

• Journal of the Korean Association of Geographic Information Studies
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• v.13 no.4
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• pp.157-169
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• 2010

In this study, the applicability of SRTM(The Shuttle Radar Topography Mission) DEM(Digital Elevation Model) which is one of the remotely sensed shuttle's radar digital elevation was tested for use as the input data in a grid-based rainfall-runoff model. The SRTM DEM and digital topographic map derived DEM(TOPO DEM) were building with 500m spatial resolution for the Chungju-Dam watershed which located in the middle east of South Korea, and stream-burning method was applied to delineate the proper flow direction for model application. Similar topographical characteristics were shown as a result of comparing elevation, flow-direction, hydrological slope, number of watershed cell, and profile between SRTM DEM and TOPO DEM. Two DEMs were tested by using a grid-based rainfall-runoff model named KIMSTORM with 6 storm events. The results also showed no significant differences in average values of relative error for both peak runoff(0.91 %) and total runoff volume(0.29 %). The results showed that the SRTM DEM has applicability like TOPO DEM for use in a grid-based rainfall-runoff modeling.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.5
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• pp.27-39
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• 2004

In the first part of this study, five homogeneous regions in view of topographical and geographically homogeneous aspects except Jeju and Ulreung islands in Korea were accomplished by K-means clustering method. A total of 57 rain gauges were used for the regional frequency analysis with minimum rainfall series for the consecutive durations. Generalized Extreme Value distribution was confirmed as an optimal one among applied distributions. Drought rainfalls following the return periods were estimated by at-site and regional frequency analysis using L-moments method. It was confirmed that the design drought rainfalls estimated by the regional frequency analysis were shown to be more appropriate than those by the at-site frequency analysis. In the second part of this study, LH-moment ratio diagram and the Kolmogorov-Smirnov test on the Gumbel (GUM), Generalized Extreme Value (GEV), Generalized Logistic (GLO) and Generalized Pareto (GPA) distributions were accomplished to get optimal probability distribution. Design drought rainfalls were estimated by both at-site and regional frequency analysis using LH-moments and GEV distribution, which was confirmed as an optimal one among applied distributions. Design rainfalls were estimated by at-site and regional frequency analysis using LH-moments, the observed and simulated data resulted from Monte Carlotechniques. Design drought rainfalls derived by regional frequency analysis using L1, L2, L3 and L4-moments (LH-moments) method have shown higher reliability than those of at-site frequency analysis in view of RRMSE (Relative Root-Mean-Square Error), RBIAS (Relative Bias) and RR (Relative Reduction) for the estimated design drought rainfalls. Relative efficiency were calculated for the judgment of relative merits and demerits for the design drought rainfalls derived by regional frequency analysis using L-moments and L1, L2, L3 and L4-moments applied in the first report and second report of this study, respectively. Consequently, design drought rainfalls derived by regional frequency analysis using L-moments were shown as more reliable than those using LH-moments. Finally, design drought rainfalls for the classified five homogeneous regions following the various consecutive durations were derived by regional frequency analysis using L-moments, which was confirmed as a more reliable method through this study. Maps for the design drought rainfalls for the classified five homogeneous regions following the various consecutive durations were accomplished by the method of inverse distance weight and Arc-View, which is one of GIS techniques.

• Journal of the Korean association of regional geographers
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• v.15 no.2
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• pp.282-291
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• 2009

This research predicts the spatial discord which relates with a restriction using 1915 and 2005 spatial data. In this research, difference of relative spatial density is measured and predicted the discord which relates with an environmental restriction in Pyeongchang. First, research area Pyeonchang's relative crowding degree of the building was strengthened from 1915 to 2005. When classifies a change type, formed the strong hold with new regulation and grew types and at the strong hold where contiguous concentration is progress types, general the influence weakening types and the change almost nil types. The next is the result which analyzes the long and short terms discord for the environmental restriction which is forecast from the research area. That is forecast with the fact that the discord between of development and preservation will be big with long and short terms in Jinbu-Myeon, Pyeongchang-Eup city center angles and 31 national road circumferences. And in Daegwanryeong-Myeon the discord is big short-term but with the fact that the discord will be weakened long-term. Bangrim-Myeon, now the discord is weak but the discord will be strengthened long-term. This result could be applied with fundamental data for weakening the spatial discord of the area.

• Journal of the Korean Association of Geographic Information Studies
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• v.17 no.4
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• pp.28-39
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• 2014

Several studies have been performed globally on the construction of integrated systems that are available for the integrated use of 3D geographic information on terrain and oceans. Research on 3D geographic modeling is also facilitated by the application of Lidar surveying, which enables the highly accurate realization of 3D geographic information for a wide area of land. In addition, a few marine research organizations have been conducting investigations and surveying diverse ocean information for building and applying MGIS(Marine Geographic Information System). However, the construction of integrated geographic information systems for both terrain and oceans has certain limitations resulting from the inconsistency in reference systems and datum levels between two data. Therefore, in this investigation, integrated geospatial information has been realized by using a combined topographical map, after matching the reference systems and datum levels by integration of airborne Lidar data and multi-beam echo sounder data. To verify the accuracy of the integrated geospatial information data, ten randomly selected samples from study areas were selected and analyzed. The results show that the 10 analyzed data samples have an RMSE of 0.46m, which meets the IHO standard(0.5m) for depth accuracy of hydrographic surveys.