• Title/Summary/Keyword: river basin

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An Analysis of the Transition Time between Dry and Wet Period in the Han River Basin (한경유역에서의 건기와 우기의 변이기간 분석)

  • Lee, Jae-Su
    • Journal of Korea Water Resources Association
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    • v.33 no.3
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    • pp.375-382
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    • 2000
  • The surface hydrology of large watershed is susceptible to several preferred stable states with transitions between stable states induced by stochastic fluctuations. This comes about due to the close coupling of land surface and atmospheric interaction. An interesting and important issue is the duration of residence in each mode. In this study, mean transition tunes between the stable modes are analyzed for the Han River Basin. On the basis of historical data, the nonlinear water balance model is calibrated for the Han River Basin. The transition times between the stable modes in the model are studied based on the stochastic representation of the physical processes and on the calibrated model parameters. This study has implications for prediction of the transition time between stable modes or residence times, that is, the time the system spends in a given stable modes, since this would be equivalent to predicting the duration of drought or wet conditions.

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Re-evaluation of comprehensive flood management plan for the Yeongsan river basin using Robust Decision Making (로버스트 의사결정을 이용한 영산강유역 종합치수계획 재평가)

  • Kang, Dong-Heon;Kim, Young-Oh;Park, Junehyeong
    • Journal of Korea Water Resources Association
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    • v.50 no.2
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    • pp.99-109
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    • 2017
  • This research adopted a Robust Decision Making framework to re-evaluate four alternative strategies proposed by the Comprehensive Flood Management Plan for the Yeongsan River Basin report (MLTM, 2005) considering uncertainties of future floods under condition of climate change. To reflect the uncertainties, multiple sets of future flood scenarios were used with three uncertainty factors: the change in rainfall intensity based on the RCP climate change scenarios and the changes in the temporal and the spatial flood distributions. With combinations of these factors, 216 plausible flood scenario sets were generated and the performances of the four alternatives under different future states were evaluated. From the results, the most robust alternative among the strategies was identified. Moreover, the key factors which made the tested alternatives poor were discovered through assessment of the uncertainty factors. This information can provide detailed insights to decision makers and can be utilized to overcome alternatives' potential vulnerabilities by modifying the strategy to be more robust.

A Study on Recognition of Land Acquisition for Ecology Restoration Project in Ecological and Landscape Conservation Area of Donggang River Basin. (동강유역 생태·경관보전지역 내 매수토지 생태복원사업 인식도 연구)

  • Li, Lan;Koo, Bon-Hak
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.20 no.4
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    • pp.15-28
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    • 2017
  • A protected area means a space designated and protected by law from development pressure and environmental pressure. It is mainly designated to protect specific ecosystems, natural landscapes, and cultural resources from irrational development (or damage), and involves policies of the public sector such as central and local governments. The United Nations Educational, Scientific and Cultural Organization (UNESCO) has conducted conservation and restoration projects for preserving natural ecosystems and genetic resources. In order to conserve the ecosystem in the protected area, national and public organizations purchase private land and use it ecologically; in addition, ecological restoration project is carried out for the purpose of creating waterside ecological belt or preserving ecosystem. Land acquisition refers to the land where highly influenced by the water quality and need to restore, and purchased by negotiating with the landlord. Although the nation and public institution carried out ecosystem restoration project for partial purchase land in order to conserve ecosystem, it is below the expected effect due to lack of comprehensive management system and have some problems in restoration project and unification of management institutions. Land acquisition in Donggang River Basin Ecological Conservation area is initiated in 2005 for creating income of local residents and ecological restoration. However, the lack of overall management and awareness resulted in poor vegetation growth and poor response by local residents due to terrain exposure. As such, there is insufficient research on the current situation and systematic integrated management although the number of land acquisition is increasing year after year. Futhermore, overall recognition and follow-up monitoring of eco-restoration are still inadequate. Therefore, the survey on the awareness of the purchase land ecosystem restoration project is necessary for the efficient restoration project and establishment of the management strategy for land acquisition in the future. Therefore, in this study, we provide fundamental materials on further research projects by carrying out research on the awareness of ecological restoration projects in the Donggang River basin ecological preservation area.

Distribution of Clay Minerals in Soils on the Northern Drainage Basin of the Nakdong River (낙동강 북부 배수유역의 토양 점토광물 분포)

  • Lee, Bong-Ho;Jeong, Gi-Young
    • Journal of the Mineralogical Society of Korea
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    • v.21 no.4
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    • pp.349-354
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    • 2008
  • Semiquantitative mineralogical analysis of clays in soils was performed to understand the distribution of clay minerals in relation to bedrock lithology on the northern basin of the Nakdong River. The soils developed on the granitic bedrocks have high contents of kaolinite and smectite. mite was the major clay mineral in the soils from sedimentary bedrocks, with minor kaolinite, smectite, and intergrade (interstratified chlorite-smectite or hydroxy-interlayed vermiculite) clay minerals. Illite and kaolinite contents of the soils from metamorphic and volcanic bedrocks fall between those of the soils from the granitic bedrocks and those of the soils from the sedimentary bedrocks. The clay mineralogy of the soils depends on the compositions of bedrock minerals and their susceptibility to chemical weathering. The weathering of plagioclase resulted in the high kaolinite content of the soils derived from granitic bedrocks, while the soils derived from sedimentary bedrocks are abundant in residual illite.

Water Supply Performance Assessment of Multipurpose Dams Using Sustainability Index (지속가능성지수를 이용한 다목적댐의 용수공급 이행도 평가)

  • Lee, Gwang-Man
    • Journal of Korea Water Resources Association
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    • v.47 no.5
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    • pp.411-420
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    • 2014
  • The water resources sustainability is becoming an important issue in consideration of hydrologic uncertainty by global warming and climate change. This study is to assess the water supply performance for the major multipurpose dams using sustainability index. Parameters, mostly utilized in water resources system assessment, are selected in respect of applicability and flexibility, and those parameters are used as a variable of the composite index. In practice, the composite index including reliability, resiliency, vulnerability and maximum deficit are applied to 15 multipurpose dams and 4 major basins. And to conclude, Daechungdam in the Geum river basin and Imhadam, Hapchondam and Namgangdam in the Nakdong river basin show low sustainability comparing with other dams. The Nakdong river basin needs to develop alternatives to improve water supply stability because it indicates the most poor sustainability level.

A Study on TOPMODEL Simulation for Soil Moisture Variation (TOPMODEL의 토양수분 변동성 모의에 관한 연구)

  • Kim, Jin-Hun;Bae, Deok-Hyo;Jang, Gi-Hyo;Jo, Cheon-Ho
    • Journal of Korea Water Resources Association
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    • v.35 no.1
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    • pp.65-75
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    • 2002
  • The objectives of this study are to analyse model-based soil moisture variations depending on model parameters m and $T_0$ and to evaluate the model performance for the simulation of soil moisture variations by the comparison of observed groundwater levels and model-driven soil moisture amounts and observed and simulated river discharges at the basin outlet. The selected study area is the Pyungchang IHP river basin with outlet at Sanganmi station and the summer flooding events during '94-'98 are used for the analysis. As a result, soil moisture holding capacity is increased according to increase the parameter m that represents effective groundwater depth. This phenomenon is especially dominant when higher m and $T_0$ values are used. The qualitative comparison of computed base flow and observed groundwater level shows that the base flow peaks are reasonably simulated and the decreasing limbs of hydrograph are mainly caused by base flows. It is concluded that TOPMODEL can be used effectively for simulating basin-averaged soil moisture variations in addition to river flow generations.

Development of vulnerable period assessment method for efficient groundwater resources management in upstream of Nakdong river basin using entropy method (엔트로피 방법을 이용한 낙동강 상류 지역의 지하수자원 관리 취약시기 평가 방법 개발)

  • Kim, Il Hwan;Lee, Jae-Beom;Yang, Jeong-Seok
    • Journal of Korea Water Resources Association
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    • v.51 no.9
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    • pp.761-768
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    • 2018
  • Groundwater resources are becoming depleted due to climate change factors and non climate change factors. In order to effectively groundwater resources management, we developed a method for evaluating vulnerable periods of groundwater resource management in watershed areas. The watershed based vulnerability assessment was conducted independently of the evaluation of vulnerable areas and vulnerable periods for sub watersheds. The vulnerable area evaluation index was standardized and applied to the independent vulnerable period index each region. It was applied to Bonghwa-gun, Andong-si, Yecheon-gun, Mungyeong-si and Sangju-si in the upstream of the Nakdong river basin. As a result, the Sangju-si's August was the most vulnerable at 0.278, and Andong-si was assessed to be vulnerable to groundwater resource management during 8 months of the year in study area. Using the developed method, we can find efficient management method considering the time and regional of groundwater resources.

Determination of Prior Areas for Livestock Excreta Pollution Survey (가축분뇨실태조사를 위한 우선 조사 대상지역 선정 방안 도출)

  • Ryu, Hong-Duck;Park, Bae Kyung;Chung, Eu Gene;Ahn, Ki Hong;Choi, Won-Sik;Kim, Yongseok;Rhew, Doughee
    • Journal of Environmental Science International
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    • v.24 no.8
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    • pp.1085-1099
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    • 2015
  • The purposes of this study were to suggest the methodology to select prior areas in the environmental pollution survey for livestock excreta (EPSLE) as well as to elucidate the validity of the methodology. In this study, the prior areas in the EPSLE were determined by examining the number of compost facilities categorized according to the three levels of size including the basin, the sub-basin and the watershed, respectively, based on the data from "Annual Nation-wide Pollution Sources Survey (2012)". The results suggested that the list of prior basins were Nakdong, Geum, Youngsan and Han river basins in order. Also, it was examined that the prior sub-basins in the four river basins including Nakdong, Geum, Youngsan and Han rivers were Naesung Stream, Geumgang Gongju, Juam Dam and Namhan Downstream, respectively. The prior watersheds in the sub-basins of Naesung stream, Geumgang Gongju, Juam Dam and Namhan Downstream were Seocheon Downstream, Geum Stream, Gyeombaek Suwipyo and Yanghwa Stream, respectively. The validity of the methodology used in this study was elucidated by analyzing the correlation of the number of compost facilities with the concentrations of T-N and T-P observed in the end-points of sub-basins. The results of correlation analysis showed that the concentrations of T-N and T-P increased with the number of compost facilities. Specifically, there was the stronger correlation between the number of compost facilities and the concentrations of T-N than that for T-P. Consequently, it was proved that the methodology used in this work was valid and rational for the selection of prior areas in environmental pollution survey for EPSLE.

Parameter Sensitivity Analysis of SWAT Model for Prediction of Pollutants Fate in Joman River Basin (조만강 유역의 오염물질 거동 예측을 위한 SWAT 모형의 매개변수 민감도 분석)

  • Kang, Deok-Ho;Kim, Tae-Won;Kim, Young-Do;Kwon, Jae-Hyun
    • 한국방재학회:학술대회논문집
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    • 2008.02a
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    • pp.787-790
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    • 2008
  • The SWAT(Soil and Water Assesment Tool) is a relatively large scale model for the complicated watershed or river basin. The model was developed to predict the effect of land management practices on water, sediment and agricultural chemical yields in large complex watershed with varying soils, land use and management conditions over long periods of time. Usually streams are divided into urban stream and natural stream in accordance with the development level. In case of urban stream, according to urbanization, as impermeable areas are increasing due to the change of land use condition and land cover condition, dry stream phenomenon at urban stream is rapidly progressed. In this study, long term run-off simulations in urban stream are performed by using SWAT model. Especially, the model is applied in small scale water shed, Joman River basin. The optimization by the sensitivity analysis is also performed for the model parameter estimations.

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Atmospheric Circulation of Pacific-Japan (PJ) and Typhoon-induced Extremes in the Nakdong River Basin (PJ 대기패턴과 태풍에 의한 낙동강 유역의 수문학적 극치 사상의 지역적 특성 변화 분석)

  • Kim, Jong-Suk;Yoon, Sun-Kwon;Moon, Young-Il;Lee, Joo-Heon
    • Journal of Korea Water Resources Association
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    • v.45 no.12
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    • pp.1309-1319
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    • 2012
  • The East Asia (EA) region including China, Taiwan, Japan, and Korea are especially vulnerable to hydrometerological extremes during the boreal summer (June-September). Therefore, this study pursued an exploratory analysis to improve better understanding of the potential impacts of the PJ pattern on WNP Tropical cyclone (TC) activity and TC-affected extremes based on the Korean Nakdong River Basin. The results show that during the positive PJ years, the large-scale atmospheric environments tend more favorable for the TC activity than those in the negative PJ years. KP-influenced TCs during the positive (negative) PJ years are likely to occur more southwestward (northeastward), recurve at more northwestward (northeastward) locations, and indicate increase (decrease) in frequency over Korea and Japan. Consequently, TCs making landfall are more exhibited over the southeastern portions of South Korea during the positive PJ years.