• Title, Summary, Keyword: Namhan River

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Delivered Pollutant Loads of Point and Nonpoint Source on the Upper Watershed of Lake Paldang - Case Study of the Watershed of Namhan River and Gyeongan Stream (팔당호 상류유역의 점·비점오염원 유달부하 특성 - 남한강·경안천 수계를 대상으로)

  • Park, Ji Hyoung;Kong, Dong Soo;Min, Kyung Sok
    • Journal of Korean Society on Water Environment
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    • v.24 no.6
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    • pp.750-757
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    • 2008
  • This study is conducted to characterize and evaluate delivered pollutant loads of point and nonpoint source on the upper watershed of lake paldang. The study area consists of 12 watersheds in Namhan-river and Kyungahcheon, which are approximately 80% of total area of Namhan-river and Kyungahcheon. Based on daily delivered loads from watersheds, 61% of $BOD_5$, 81% of T-N and 70% of T-P were from nonpoint sources, suggesting that delivered loads of nonpoint pollutants be crucial to water quality. On the other hand, 78% of $BOD_5$, 92% of T-N and 87% of T-P as delivered load were from nonpoint sources in an upper watershed of Namhan-river, while 48% of $BOD_5$, 70% of T-N and 57% of T-P as delivered load were from nonpoint sources in a lower watershed of Namhan-river, suggesting higher dependency of point sources than upper watershed of Namhan-river. In the characteristic of delivered loading pollutants from point and nonpoint pollution sources, delivered load of nonpoint pollutants differed significantly by seasonal flow, and as though discharged load of point pollutants were yearly uniform, delivered load of point pollutants was found to be flow-dependent because its delivery ratio was changed.

The Vegetational Diagnosis for the Ecological Rehabilitation of Stream - In case of the Forest Communities, Soil in Namhan river - (하천의 생태적 복원을 위한 식생학적 연구 - 남한강 육상식물, 토양을 중심으로 -)

  • Myung, Hyun
    • Journal of Environmental Science International
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    • v.18 no.1
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    • pp.113-127
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    • 2009
  • This study was designed to present a river model with an aim at restoring the ecosystem and improving the landscape along the urban rivers on the basin of the Namhan river, a core life channel for the National Capital region. The revelation of botanical status, transition trend and correlation of plants might lead to providing the urban river restoration projects and ecological river formation projects with basic data for a model of ideal aquatic ecology and landscape. The outcomes of this study could be summed up as follows: 1. Communities of Juglans mandshurica, Cornus controversa and Fraxinus mandshurica constitute the main portion of flora at or around uppermost branch streams of the River Namhanis harbored mainly in and around small brooks 2. Typical terrestrial forest communities formed around the River Namhan are composed mainly of Larix leptolepis, Pinus rigida, planned forestation of Pinus koraiensis, Quercus acutissima, Quercus variabilis and Pinus densiflora. 3. The analysis into terrestrial environment of plant communities showed a high content of $P_2O_5$, typical communities found in the artificially disturbed land Finally, it seems also desirable to continue to make every exertion to explore the relationship between fluvial and terrestrial ecologies with a purport of building up a model of natural streams in urban area based on the surveyed factors for plant life, forest communities, soil and landscape and, moreover, on the forecasting for overall influences derived from the relation upon the ecosystem.

Assessment of Water Quality in the Lower Reaches Namhan River by using Statistical Analysis and Water Quality Index (WQI) (통계분석 및 수질지수를 이용한 남한강 하류 유역의 수질 평가)

  • Cho, Yong-Chul;Choi, Hyeon-Mi;Ryu, In-Gu;Kim, Sang-hun;Shin, Dongseok;Yu, Soonju
    • Journal of Korean Society on Water Environment
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    • v.37 no.2
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    • pp.114-127
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    • 2021
  • Water pollution in the lower reaches of the Namhan River is getting worse due to drought and a decrease in water quantity due to climatic changes and hence is affecting the water quality of Paldang Lake. Accordingly, we have used a water quality index (WQI) and statistical analysis in this study to identify the characteristics of the water quality in the lower reaches of the Namhan River, the main causes of water pollution, and tributaries that need priority management. Typically, 10 items (WT, pH, EC, DO, BOD, COD, SS, T-N, T-P, and TOC) were used as the water quality factors for the statistical analysis, and the matrix of data was set as 324 × 10·1. The correlation analysis demonstrated a strong correlation between Chemical Oxygen Demand (COD) and T-P with a high statistical significance (r=0.700, p<0.01). Furthermore, the result of principal component analysis (PCA) revealed that the main factors affecting the change in water quality were T-P and organic substances introduced into the water by rainfall. Based on the Mann-Kendall test, a statistically significant increase in pH was observed in SH-1, DL, SH-2, CM, and BH, along with an increase in WQI in SH-2 and SM. BH was identified as a tributary that needs priority management in the lower reaches of the Namhan River, with a "Somewhat poor" (IV) grade in T-P, "Fair" grade in WQI, and "Marginal" grade in summer.

Investigation on Water Quality Variation Characteristics during Dry Season in Namhan River Drainage Basin (남한강수계 저수기 수질변동 특성에 관한 연구)

  • Lee, H.J.;Kong, D.S.;Kim, S.H.;Shin, K.S.;Park, J.H.;Kim, B.I.;Kim, S.M.;Jang, S.H.;Cheon, S.U.
    • Journal of Korean Society on Water Environment
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    • v.23 no.6
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    • pp.889-896
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    • 2007
  • From the direct outflow of Chungju Dam to the junction of water body and watershed in Paldang lake is the scope of this research. This study performed to investigate the main cause of water quality deterioration and the influenced region in the middle field range of the Namhan river Basin with the onsite measurement of water quality and flow rate simultaneously during spring dry season. The purpose of this study is to find out the time-spatial variation characteristics of water quality and flow rate. Following the flow direction $BOD_5$ and $COD_{Mn}$ concentration increased to the highest value of 3.7 mg/L, 5.9 mg/L at Wolgesa respectively. Chl.a concentration increased to $50mg/m^3$ or so at Kangsang, after that it decreased to $37mg/m^3$ at the junction of Paldang lake. Organic matter concentration variation trend showed similar than that of Chl.a. Also $BOD_5$ concentration tendency was similar to Chl.a in every measuring sites except Paldang lake mixing zone. The major factors of water quality deterioration in Namhan river and Paldang lake during dry season were algal bloom and followed internal production. High phosphorus load from Dalcheon and Seom river caused dry season algal bloom and internal production in transitional zone which was stagnant area in downstream of Namhan river.

Diagnosis of Vegetation for the Ecological Rehabilitation of Streams - The Case of the Namhan River - (하천의 생태적 복원을 위한 식생학적 진단 - 남한강을 중심으로 -)

  • Myung, Hyun;Kwon, Sang-Zoon;Kim, Chang-Hwan
    • Journal of the Korean Institute of Landscape Architecture
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    • v.30 no.5
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    • pp.98-106
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    • 2002
  • This study was designed to present a river model with the aim of restoring the ecosystem and improving the landscape along the urban rivers on the basin of the Namhanl river, a core life channel for the National Capital regin. The revelation of botanical status, transition trend and correlation of plants might lead to providing the urban river restoration projects and ecological river formation projects with basic data for a model of ideal aquatic ecology and landscape. The outcomes of this study could be summed up as follows: 1. The plant communities of river flora found on the basin of the Namhan river could be categorized largely into 39 plant communities 2. Most diverse plants were distributed in the rivers lower reaches such as Unsim-ri where the protected zone of Paldang reservoir for city water borders the body of Jodae swamp where natural streams flow nearby. 3. One of the greatest threats to the biomass of the River Namhan is that the communities of such invasive alien plants as Panicum dichotomiflorum and Ambrosia artemisiifolia var. elatior dominate most parts of the area, a fact that has resulted in a reduced variety of plants and will, sooner or later, be likely to cause an ecological imbalance in the hitherto healthy Aquatic plant life. It is highly advisable to gradually diversify the species of trees and to return the plants bark to their original state since, besides the naturalized plants, plantations afforested with Erigeron canadensis and Erigeron annuus stocks in buckwheat field, Robinia Pseudo-accacia in riverside forest, Pinus rigida in terrestrial forest on the river basin and Larix leptolepis are anticipated to act as interceptors of normal migrations of the fluvial and terrestrial ecosystems. Finally, it seems also desirable to continue to explore the relationship between fluvial and terrestrial ecologies with the purpose of building up a model of natural streams in urban areas based on the surveyed factors for plant life, soil and landscape and, moreover, on the forecasting for overall influences derived from the rotation upon the ecosystem.

Analysis of Water Quality Fluctuations in Upstream Namhan River Watershed Using Long-term Statistical Analysis (통계적 경향 분석을 통한 남한강 상류 수계 수질 변동 해석)

  • Byeon, Sang-Don;Noh, Yeon-Jung;Lim, Kyeong-Jae;Kim, Jong-Gun;Kim, Dong-Jin;Hong, Eun-Mi
    • Journal of The Korean Society of Agricultural Engineers
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    • v.62 no.5
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    • pp.15-26
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    • 2020
  • There are fifteen non-point pollution management areas in Korea and three of them (Doam lake, Daegi district and Golji-cheon) are located in the upstream of the Namhan river watershed. Many efforts to reduce non-point sources (NPS) pollution have been conducted, however, water quality pollution in the watershed is still serious. To solve these problems, it is a priority to grasp water quality using statistical techniques. In this study, a trend analysis was conducted to evaluate the effect of NPS management in the watershed. The long-term trends from 1996 to 2018 of water quality properties were analyzed using data collected from the water environment information system. Seventeen monitoring stations were selected along the main stream in Namhan river basin. Monthly water quality properties (BOD, COD, TN, TP, TN/TP ratio, Conductivity, SS and Chlorophyll-a) were collected and analyzed by Mann-Kendall test and LOWESS. The results showed that the Conductivity tended to increase in all regions and was the highest level in Jijangcheon. Organic pollution such as BOD and COD tended to increase in the Jungseon area. SS did not show a large tendency, but it showed high concentration in the Doam watershed. In all regions, 40% of water quality properties showed a tendency to 'UP', 15% of water quality properties tended to 'DOWN', and 46% indicated no tendency. In order to determine the cause of this, additional research and measures for improvement are necessary. This study will be used for the establishment of water quality policy in the future.

Development of Numerical Model for Flood Inundation Analysis in a River with GIS Application

  • Lee, Hong-Rae;Han, Kun-Yeun;Kim, Sang-Ho;Choi, Hyun-Sang
    • Korean Journal of Hydrosciences
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    • v.10
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    • pp.59-72
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    • 1999
  • FIAS(Flood Inundation Analysis System) using Arc/Info is developed and applied to the Namhan River basin. The DWOPER model is revised and expanded to handle simultaneous multiple overtopping and/or breaking, and to estimate the inundated depth and extents. The model is applied to an actual levee overtopping case, which occurred on August 23∼27, 1995 in the Namhan River. Stage hydrographs inside and outside of the levee are compared, then inundated discharges from overbank spilling are computed. The Graphic User interface is developed with AML. Two- and three-dimensional inundation map by Arc/Info are presented. The computed inundation extends agree with observations in terms of inundated depth and flooded area. The FIAS is useful for the analysis of flood hazards and preparation of inundation map for river basins.

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Influence of Landuse Pattern and Seasonal Precipitation on the Long-term Physico-chemical Water Quality in Namhan River Watershed (남한강 수계에서 장기 이화학적 수질특성에 대한 토지이용도 및 계절성 강우의 영향)

  • Lee, Ji-Eun;Choi, Ji-Woong;An, Kwang-Guk
    • Journal of Environmental Science International
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    • v.21 no.9
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    • pp.1115-1129
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    • 2012
  • The objective of this study was to analyze long-term annual and seasonal trends of water chemistry on landuse patterns and seasonal precipitation using 72 sampling sites within Namhan River watershed during 2001-2010. Water quality, based on multi-parameters of water temperature(WT), dissolved oxygen(DO), biochemical oxygen demand(BOD), chemical oxygen demand(COD), suspended solids(SS), total nitrogen(TN), total phosphorus(TP), and electric conductivity(EC) varied largely depending on monsoon rain and landuse patterns such as forest, cropland, and residence. Concentrations of BOD and COD as an indicator for organic matter pollution, increased during summer monsoon season at the cropland and residential streams. Values of TN and TP were higher in residential streams than in the forest and cropland streams. In the meantime, DO values had weak relations to the landuse patterns of forest and cropland cover. Water quality was worst in cropland and residential streams, and also most degradated in 4th order streams. Overall, our results suggest that efficient water quality management is required in the cropland and residential landuse streams.

The Dynamic of Phytoplankton Communities and the Biological Water Quality Assessment at Three Artificial Weirs in Downstream of Namhan-river (남한강 3개 인공보의 식물플랑크톤 군집 변동과 생물학적 수질평가)

  • Shin, Hyun-Joo;Lee, Ok-Min
    • Journal of Korean Society on Water Environment
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    • v.30 no.6
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    • pp.612-621
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    • 2014
  • Physicochemical factors and the phytoplankton communities in the downstream area of Namhan-River were investigated from June 2012 to November 2013. We also assessed water quality using biological water quality indices. Total nitrogen was 2.4 mg/L, total phosphorus was 0.04 mg/L, and biological oxygen demand was 1.1 mg/L. This resulted in a level 2 (Ib, good) water quality rating. A total of 259 phytoplankton taxa were classified, consisting of 26 families, two subfamilies, 64 genera, 222 species, 32 varieties, and five formas. Bacillariophyceae dominated during a1l seasons and at all sites. The dominant species were Aulacoseira granulata, Cyclotella meneghiniana, C. stelligera, Melosira varians, Cocconeis placentula var. lineata, Nitzschia palea, N. amphibia, Cymbella minuta, and Achnanthes convergens. The diatom assemblage index for organic pollution values was level A-D, and TDI was level B-D. P-IBI at most sites was at the M (moderate) level, but TSI was at the E (eutrophic) level. Most indices dropped from upstream to downstream.

Numerical analysis of flow and bed change at a confluence of the Namhan River and the Seom River using a two-dimensional model (2차원 수치모형을 이용한 남한강과 섬강 합류부 구간의 흐름 및 하상변동 해석)

  • Park, Moonhyung;Kim, Hyung Suk;Baek, Chang Hyun
    • Journal of Korea Water Resources Association
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    • v.51 no.12
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    • pp.1273-1284
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    • 2018
  • The flow and bed change were analyzed using the CCHE2D model, which is a two-dimensional numerical model, at a confluence of the Namhan River and Seom River where deposition occurs predominantly after the "Four Major Rivers Restoration Project." The characteristic of the junction is that the tributary of Seom River joined into the curved channel of the main reach of the Namhan River. The CCHE2D model analyzes the non-equilibrium sediment transport, and the adaptation lengths for the bed load and suspended load are important variables in the model. At the target area, the adaptation length for the bed load showed the greatest influence on the river bed change. Numerical simulation results demonstrated that the discharge ratio ($Q_r$) change affected the flow and bed change in the Namhan River and Seom river junction. When $Q_r{\leq}2.5$, the flow velocity of the main reach increased before confluence, thereby reducing the flow separation zone and decreasing the deposition inside the junction. When $Q_r$>2.5, there was a high possibility that deposition would be increased, thereby forming sand bar. Numerical simulation showed that a fixed sand bar has been formed at the junction due to the change of discharge ratio, which occurred in 2013.