• Title/Summary/Keyword: Geum River

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Determine the return period of flash floods by combining flash flood guidance and best fit distribution

  • Duong, Ngoc Tien;Kim, Jeong-Bae;Bae, Deg-Hyo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2020.06a
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    • pp.362-362
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    • 2020
  • Flash flood is a dangerous weather phenomenon, affecting humans and the economy. The identification, forecast of the changing trend and its characteristics are increasingly concerned. In the world, there have many methods for determining the characteristics of flash floods, in which flash flood guidance (FFG) is a fast, effective and widely used method. The main source of flash floods is short-term rainfall. In this study, we used the data of cross-sectional measurement at the tributaries and the hourly rain data from the automatic rainfall measurement stations in the Geum river basin. Besides, we use a combination of the flash flood guidance and the best fit distribution function to estimate the repeatability of flash floods for head-water catchments in Geum river basin. In which, FFG determines the threshold of rainfall for flash floods. The study has determined the best hourly rainfall distribution function for the Geum river basin and estimated the maximum rainfall of 1hr according to the return periods.

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stimation of River Maintenance Water in the Geum River Watershed (금강유역의 하천유지유량 산정)

  • 안상진;김종섭
    • Water for future
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    • v.24 no.1
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    • pp.83-92
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    • 1991
  • The purpose of this paper is to estimate river maintenance water of the main gauging stations in Geum river watershed. The estimation methods of river maintenance water are classified into two categories : views of supply and demand. The definition of river main-tenance water in this paper, is the maximum value between mean drought flow and environmental conserving flow. In order to estimate river maintenance water, the mean drought flow estimated at the upstream of the Daecheong Dam but the downstream of the Daecheong Dam estimated mean drought flow and water quality control flow use of QUAL2E Model. In result, a mean drought flow showed large value at the Gong ju and Gyu am station as the downstream of the Daecheong Dam. The river maintenance water is 33.82$m^3$/sec at the Gong ju station, 51.51$m^3$/sec at the Gyu am station. Therefore, an estimation of the river maintenance water in the Geum River watershed concluded suitability which is determined mean drought flow.

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Analysis of influence on water quality and harmful algal blooms due to weir gate control in the Nakdong River, Geum River, and Yeongsan River (낙동강, 금강 및 영산강 가동보 운영이 수질 및 녹조현상에 미치는 영향 분석)

  • Seo, Dongil;Kim, Jaeyoung;Kim, Jinsoo
    • Journal of Korea Water Resources Association
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    • v.53 no.10
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    • pp.877-887
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    • 2020
  • A 3-Dimensional hydrodynamic and water quality model was applied to evaluate the effects of weir gate operations on water quality and harmful algal bloom (HAB) occurrences at selected locations in the Nakdong River, Geum River, and Yeongsan River. For the Geum River and Yeongsan River, when the gates are left open, annual and summer Chl-a and HABs were decreased at upstream locations, Sejong Weir and Seungchon Weir, but summer average concentrations of Chl-a and HABs were increased at downstream locations, Baekje Weir and Juksan Weir. For the open scenario, the reduced hydraulic residence time in the upper stream areas of the Geum River and Yeongsan River would allow less available time for nutrient consumption that would result in higher dissolved inorganic phosphorus concentrations followed by higher algal growth in the downstream areas. However, in the case of the Nakdong River, both annual and summer Chl-a and HABs were increased in all locations for the open scenario. This condition seems to be resulted in due to increased light availability by reduced water depths. Changes in Chl-a and HABs occurrences due to the water gate control in the study sites are different due to differences in physical, chemical, and biological conditions in each location.

Phosphorus and Suspended Solid Loading in Lake Yongdam (용담호 소유역별 인 및 부유물질 유입부하량 산정)

  • Kwon, Sang-Yong;Kim, Young-Geel;Yih, Won-Ho;Kim, Bom-Chul;Heo, Woo-Myung
    • Korean Journal of Ecology and Environment
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    • v.38 no.3 s.113
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    • pp.322-333
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    • 2005
  • Total phosphorus (TP) and suspended solids (SS) were measured in the discharge waters from 5 drainage basins of Lake Yongdam, from April, 2002 till March, 2004. The responses of SS and TP to rainfall were analyzed and their loadings into Lake Yongdam were calculated. The inflowing rivers into Lake Yongdam were the Juja River, the Jeongja River, the Jinan River, the Geum River and the Guryang River. Among these rivers Jinan River showed the highest TP that fluctuated very much according to the flow rate. TP and the flow rates (Q) of each river showed positive correlations with empirical relationsip of $TP\;=\;6.32Q^{0.30}$ for the Juia River, $TP\;=\;8.58Q^{0.49}$ for the Jeongia River, $TP\;=\;307.92Q^{0.10}$, for the Jinan River, $TP\;=\;17.91Q^{0.47}$, for the Geum River, $TP\;=\;20.11Q^{0.53}$ for Guryang River. In April 2002 ${\sim}$ March 2003, phosphorus loadings from the Juja River, the Jeongja River, the Jinan River, the Geum River and the Guryang River were calculated to be 3,677, 11,430, 36,412, 89,651, and 42,226 kgP ${\cdot}$ $yr^{-1}$ respectively. And the specific loadings from the Juja River, the Jeongia River, the Jinan River, the Geum River and the Guryang River were calculated to be 0.3, 2.9, 13.6, 9.3, and 13.0 kgP ${\cdot}$ $km^{-2}$ ${\cdot}$ $yr^{-1}$ respectively. In April 2002 ${\sim}$ March 2004, the suspended particles loading from the Juja River, the Jeongia River, the Jinan River, the Geum River and the Guryang River were 673, 1,232, 4,232, 30,902, 80,202 ton ${\cdot}$ $yr^{-1}$ respectively. The Guryang River showed the largest contribution of SS loading.

Evaluation of LOADEST Model Applicability for NPS Pollutant loads Estimation from Agricultural Watershed (농촌유역의 비점원오염부하 산정을 위한 LOADEST 모델의 적용성 평가)

  • Shin, Min hwan;Seo, Ji yeon;Choi, Yong hun;Kim, Jonggun;Shin, Dongsuk;Lee, Yeoul-Jae;Jung, Myung-Sook;Lim, Kyoung Jae;Choi, Joongdae
    • Journal of Korean Society on Water Environment
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    • v.25 no.2
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    • pp.212-220
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    • 2009
  • In many studies, the Numeric Integration (NI) method has been widely used to calculate pollutant loads from the watershed because it is easy to apply. However, there have been many needs for more accurate pollutant loads estimation method with the restricted number of water quality samples. However, the ESTIMATOR model does not allow the users to define the regression model to explain the measured flow and water quality relationship, indicating the ESTIMATOR model is not flexible. The LOADEST model allows the user to choose the model type from 11 predefined general forms of regression equations. Annual loads of T-N and T-P with the LOADEST model were 0.70 times and 0.84 times of those by NI method, respectively. The coefficient of determination ($R^2$) of the LOADEST regression for the T-N and T-P were 0.92 and 0.72, respectively. This indicates that the load estimation regression model with the LOADEST for the study watershed explains the relationship between the observed flow and water quality data well reasonably well. Based on these findings, we suggest that the LOADEST model estimated regression equation could be used to estimate pollutant loads using the measured flow data for the study watershed.

A Study on the Analysis of Non-point Source Runoff Characteristics and Verification of Unit Pollutant Load Considering Baseflow Runoff (기저유출을 고려한 비점오염 유출특성 분석과 원단위 검증에 관한 연구)

  • Park, Jaebeom;Kal, Byungseok;Lee, Chulgu;Hong, Seonhaw;Choi, Moojin
    • Journal of Wetlands Research
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    • v.19 no.3
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    • pp.279-286
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    • 2017
  • In this study, the characteristics of non-point source pollution runoff and the possibility of using new unit load were investigated by using pollutant load based on monitoring data considering baseflow. For this purpose, the components of hydrograph were separated by using digital filter method and the numerical integration method was applied to calculate the non-point source pollutant load for nine rainfall events in Juwon river in the Geum River basin. As a result of this study, the mean contribution rate of non-point pollutant was 31.34% for BOD, 58.94% for T-N, and 50.42% for T-P and BOD was more influenced by baseflow pollutant. Also, it was analyzed the pollutant load using the new unit load is closer to the observation load than the old unit load. This result implies that it is necessary to manage not only pollutant load due to direct runoff but also pollutant load due to baseflow runoff for efficient water quality management of the watershed.

Water Quality Properties of Tributaries of Daechung Lake, Korea (대청호 유입지천의 수질 특성)

  • Shim, Moo Joon;Yoon, Jae Yong;Lee, Soo Hyung
    • Korean Journal of Ecology and Environment
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    • v.48 no.1
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    • pp.12-25
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    • 2015
  • The tributaries of Daechung Lake play an important role in controlling eutrophication in the lake, which is used for agricultural purposes and as potable water. However, water quality properties were not extensively studied in the tributaries of Daechung Lake. The objectives of this study are to investigate spatial and temporal properties of water quality and to characterize streams which could threaten water quality of Daechung Lake. For this study, water samples were weekly or monthly collected from February 2014 to October 2014 in 9 streams. Water quality parameters analyzed in this study include biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), total nitrogen and phosphorus (TN and TP), suspended solids (SS), and chlorophyll a. Based on temporal distribution and principal component analysis, BOD, COD, TOC, SS, and TP were controlled by not only river discharge that increased during summer due to heavy rain fall, but also due to anthropogenic input (e.g., bridge construction and/or agricultural activity). Dilution is also one of the factors explaining TN and conductivity, both of which decreased with increased discharge. Generally, concentrations of contaminants (BOD, COD, TOC, TN and TP) in the tributaries were higher than those of Daechung Lake. However, pollution load indicated that only the main channel of Geum River and Sook Stream may largely influence lake waters, attributed mostly to their large volumes. This implies that the main channel and Sook Stream are the major influences on the water quality of Daechung Lake.

A Synthesis of Unit Hydrograph by a Correlation Analysis between the Basin Characteristics and the Runoff-Characteristics - Han and Geum River Basin - (유역특성과 유출특성간의 상관관계 해석에 의한 단위유량도의 합성 - 한강 및 금강유역 -)

  • 윤용남;선우중호
    • Water for future
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    • v.8 no.1
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    • pp.61-79
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    • 1975
  • An attempt is made to develope a scheme for synthesizing unit hydrograph for any arbitrary small watershed in the Han or Geum River basin, which can be applied in determining various sizes of design flood for flood control prijects. Stage gauging stations, seven in the Han and five in the Geun River basin with rating curves, were selected as subbasins for the analysis. Unit hydrographs of 2-hour duration were derived for several heavy storm events using the storm and the corresponding flood runoff data for each subbasin. The Clark method programmed by the Hydrologic Engineering Center, U.S. Corps of Engineers, was utilized for derivation of instantaneous unit hydrographs which were, in turn, converted into 2-hour unit hydrograph. By averaging the 2-hour unit hydrographs from several storm events a representative 2-hour unit hydrograph was determined for each subbasin and hence a separate derivation of dimensionless unit hedrograph was also possible for the Han and Geum River basins. The physiographic characteristics such as stream length, distance to the centroid of each watershed were correlated with the characteristic parameters of the derived unit hydrograph for the subbasins within two large basins. correlation analyses between the characteristic parameters were also made. These correlation analyses resulted a series of four equations and a dimensionless unit hydrograph for the two large basins, which made it possible to draw a synthetic 2-hour unitgraph for any small watershed within the Han or Geum River basin. A detailed procedure for aplying the derived method for an arbitrary basin is summarized with one sample computation for each of the two basins. A comparison of the actually derived 2-hour unit hydrogrograph and the synthesized one showed a fair agreement. A recommendation is made for the further study.

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Analysis of Flow Duration Characteristics due to Environmental Change in Korea River Basin (우리나라 하천유역 환경변화가 유황특성에 미치는 영향 분석)

  • Lee, Jae-Joon;Kim, Young-Jun
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.1
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    • pp.67-75
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    • 2011
  • The purpose of this study is to evaluate the flow duration characteristics of Nakdong, Seomjin and Geum river due to environmental change. The water level gauging stations of Nakdong, Seomjin and Geum river were selected to analyze the change of flow duration. The construction period of multipurpose dam was considered to analyze flow duration characteristics. As the result of this study, it show that ninety-five day flow, normal flow, low flow and drought flow were increased by multipurpose dam construction at all stations except a Jukpo gauging station. Especially, improved effect of flow duration in downstream part was bigger than that in upstream and midstream part. The coefficients of river regime of Nakdong, Seomjin and Geum river were decreased and also coefficients of flow duration were decreased after the multipurpose dam construction. However decline of coefficient of flow duration was smaller than coefficient of river regime because coefficient of flow duration is less affected by maximum discharge and minimum discharge than coefficient of river regime, It was confirmed that multipurpose dam on upstream and midstream has a useful effect for improving the flow duration characteristics.

Status and Distribution of Riparian Vegetation in the Geum River, Korea (금강 유역의 수변 식생 현황과 분포)

  • Kim, Kee-Dae;Park, Mee-Hwa
    • Journal of Environmental Science International
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    • v.18 no.2
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    • pp.153-167
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    • 2009
  • Riparian vegetation gives basic habitats for animal and other biological organisms. It is one of essential landscapes in river ecosystem. This floral study was conducted to give basic information for management of the Geum river ecosystem. We discovered total 69 plant communities out of 40 sites studied and mean 8 plant communities were analysed per study site. Salix koreensis and Salix subfragilis community were dominant of all communities at tree layer and Salix gracilistyla and Rubus parvifolius were dominant communities at shrub layer. Phalaris arundinacea, Phragmites japonica, Miscanthus sacchariflorus and Artemisia princeps var. orientalis appeared most as perennial grasses and Humulus japonicus, Persicaria thunbergii and Persicaria hydropiper appeared most as annual grasses. Robinia pseudoacacia, Amorpha fruticosa and Bidens frondosa were frequently present as exotic species. Grass communities were higher than tree communities because of human disturbance by artificial banks. The number of species was 182 appeared as 53 families 144 species, 34 varieties and 4 forma and mean species number was 25.5 per site. The most abundant site was Yanggang bridge site (14 vegetation association, 49 species) and the least abundant site was Namdaechon, Muju site (3 vegetation association, 12 species). We suggest that continuous riparian vegetation monitoring should be carried out to manage water environment ecologically.