• Journal of Korea Water Resources Association
• /
• v.40 no.11
• /
• pp.841-849
• /
• 2007

This study evaluated the effect of combined rainfall observation of using rain gauge and rain radar. The effect of combined observations is to be evaluated by considering the decrease of measurement error due to combined use of design orthogonal observation methods. As an example, this study evaluated the rain gauge network of the Keum river basin, and showed how the density of rain gauges could be decreased by combining the radar observation. This study applied the researches on sampling error by North and Nakamoto(1989), Yoo et al. (1996) and Yoo (1997), also the simple NFD model for representing the rainfall field. The model parameters were decided using the rainfall characteristics (correlation time and length) estimated using the data collected in the Keum River Basin by 28 rain gauges and the operation rule of radar was assumed arbitrarily. This study considered the rain gauge density criteria provided by WMO(1994) and the rain gauge density installed in the Keum river basin to decrease the rain gauge density under the condition of introducing the radar.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.4
• /
• pp.601-610
• /
• 2021

The tidal current patterns at Keum River Estuary before and after the construction of coastal structures were compared according to the CASES. The depth-integrated and tidal difference treatment applied FLOW2DH numerical model was used for the tidal current predictions. The test conditions consisted of before construction of coastal structures (CASE1), after construction of coastal structures (CASE2), and the addition of watergate operation(CASE1Q and CASE2Q), and present (CASE3). CASE1 showed a stable tidal current pattern, such as a natural estuary. In CASE2, the tidal current velocities and directions of the Keum River Estuary were changed due to the installed coastal structures. In particular, the tidal current velocities of the Gaeya open channel sections (P5~P9) in CASE2 were calculated to be 10~30% larger than that of CASE1. In the case of the Gunsan Inner Harbor (P4), which is closest to the Geum River Estuary, the ebb flow rate was approximately 250~300% faster than that of other CASEs due to the discharge of the watergate operation for 2.7 hours during the ebb of CASE1Q and CASE2Q. This will affect sediment transport, and it is predicted to lead to seabed changes. CASE3 is considered to be entering the stabilization stage according to the simulation of the tidal current velocities and directions of the Keum River Estuary and the surrounding coastal area.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.7 no.3
• /
• pp.121-132
• /
• 1987

The estuarine tide becomes strongly distorted as it propagates into upstream reach of tidal river system common to the west and south coasts of Korea. This distortion can be represented by friction, non-linear advection, interaction with channel geometry and freshwater discharge. In the present paper, the effect of an increased river discharge on tide progressing into the Keum River is evaluated quantitatively by one-dimensional hydrodynamic model. The computed relation between the prevailing discharges and the tide reaching the upper reaches of the river, both its range and its timing has shown that there are good agreement with theoretical inferences of Godin(1985).

• 한국해양학회지
• /
• v.18 no.2
• /
• pp.142-148
• /
• 1983

In order to understand the circulation dynamics of the Keum River estuary, an extensive study was conducted; (i) variability of salinity boundary layer (ii) fluid dynamic characteristics (iii) tides and tidal currents (iv) circulation, diffusion, and dispersion (v) numerical modelling. As first part of this series of work, the salinity data obtained at six sites by using instantaneous profil]ing technique were analyzed in detail. it is found that the amplitude of salinity variation increases toward the upstream direction and its magnitude is greater at neap tide than spring tide. And also duration of salinity boundary layer is much longer during the neap tide than the spring tide, As a result of this study, the Keum River estuary is classified as a typical standing wave type estuary. Finally, we present a schematic diagram for the duration of the salinity boundary layer, which will be useful for further study on flocculation phenomena and sedimentation dynamics.

• Journal of Environmental Health Sciences
• /
• v.35 no.1
• /
• pp.45-52
• /
• 2009

In recent years, pharmaceuticals in the aquatic environment have become a matter of increasing public concern. Environmental risk assessment (ERA), including an exposure assessment, is considered the best scientifically based approach for evaluating the potential effects of pharmaceuticals on ecosystems. Computerized exposure models constitute an important tool in predicting environmental exposures of pharmaceuticals. This paper presents the applicability of an exposure model by comparing measured data of selected pharmaceuticals with predicted environmental concentrations from an exposure model. $PhATE^{TM}$ (Pharmaceutical Assessment and Transport Evaluation) model developed by the Pharmaceutical Research and Manufacturers of America (PhRMA) was adapted to run simulations for the Keum River. A set of 7 pharmaceuticals of high production in Korea was modeled. The PECs generated by the $PhATE^{TM}$ model that were then compared to the measured concentrations. The $PhATE^{TM}$ model predicted concentrations for 7 pharmaceuticals including acetaminophen, acetylsalicylic acid, erythromycin, ibuprofen, lincomycin, mefenamic acid, and naproxen were in good agreement with actual measured concentrations, which demonstrated the utility of $PhATE^{TM}$ as a predictive tool. In conclusion, $PhATE^{TM}$, although it does not intend to accurately represent reality, could be utilized for rapid predictions of the environmental concentrations of pharmaceuticals.

• Journal of Fisheries and Marine Sciences Education
• /
• v.19 no.1
• /
• pp.1-7
• /
• 2007

The purpose of this study was to investigate geochemical characteristics of surface sediments in the Keum river estuary adjacent to coastal area. For this study we collected the 21 surface sediments samples. Mean size of surface samples was $3.24{\sim}6.65{\phi}$ on inner estuary and was $2.15{\sim}3.42{\phi}$ on outside estuary. Surface samples were composed of silt on inner estuary and were composed of sand which was more larger than $4{\phi}$ on outside estuary. Most major elements except CaO, $Na_2O$ showed good relationships between variation of contents and grain size. Contents of $Al_2O_3$, $Fe_2O_3$, MgO, $K_2O$, $TiO_2$, $P_2O_5$ and $M_nO$ were increased predominately owing to the variation of mean size of surface samples. Contents of Co, Cr, Cu, Li, Sr, Zn, La, Ce, Pb, Rb, Nd have a good relationships with grain size but Ba, Th, Sm have not. All of major and minor elements contents except $K_2O$ and Ba were less than world mean contents of shallow surface sediments but apprehend a high pollution possibility on silt sediments in the estuaries.

• Current Research on Agriculture and Life Sciences
• /
• v.17
• /
• pp.31-38
• /
• 1999

Trend of some hydrologic features such as precipitation, runoff and reservoir storage rates in the five great river systems of Han, Nakdong, Keum, Yeongsan and Seomjin river watershed areas were surveyed and analysed. The sample period of Sept. 1994 to Aug. 1998 (four years) was chracterized by unusual climatic features such as El Nino, La Nina and areal terrible storms. And also average values of rainfall and runoff of the priod of 1961 to 1990 (30 years) were surveyed and analysed compared with the sample preiod events for the same river systems. In case of the monthly mean rainfall of the sample period (Sept. 1994 to Aug. 1998 : 48 months) in the five great river systems, 20 months, 19 months, 20 months, 21 months and 18 months in the Han, Nakdong, Keum, Yeongsan and Seomjin river system respectively were higher than monthly average rainfall records of the 30 year records. For the monthly runoff in the same river systems, 7 months, 9 months, 7 months, 11 months and 11 month in the Han, Nakdong, Keum, Yeongsan and Seomjin river systems respectively were higher than the monthly average runoff of the period of 30 years. For the storage rates, most of the dams in the Han river systems were highly stored through the year continuously and Paldang dam was specially higher than the other dams in the same river system. And most of the dams in the other river systems were stored irregularly but getting much better than early time during the 48 months. And special climatic features were not found during the sample period of 48 months, Sept. 1994 to Aug. 1998.

• Water for future
• /
• v.22 no.1
• /
• pp.99-107
• /
• 1989

KEUM River downstream has some characteristics in which the dowunstream is affected with tidal motion, the several tributaries are forming a dendritic river system, and the channel cross-sections are irregular. The flood in this downstream can now be analyzed by the hydrological flood routing methods and under the assumption regarding the dendritic river system as a single reach. In this study the river system was used for the flood routing. The flood records which were measured in 1978 and 1987 were applied for calibration and verification of the unsteady flow model respectively. The results show that the flood at KANG-KYONG station was not affected with the tidal motion when the discharge at KONG-JU station exceeded about 5, 000$m^3$/sec, and that the bottle neck at IP-PO station intercepted the tidal influences.

• Korean Journal of Hydrosciences
• /
• v.2
• /
• pp.85-98
• /
• 1991

This paper is focused on the development of the RIVNET1 model, which is a dynamic wave model, for flood analysis in dendritic river networks with arbitrary cross-sections. This model adopted the $-point implicit RDM and utilized a relaxation algorithim in order to solve the governing equations. The double-sweep method was used to reduce the C.P.U. time to solve the matrix system of the model. This model is applied the analyze flood waves of the Ohid river in the U.S.A. and the Keum river in Korea. The results of analysis obtained from this model are compared with those of the DWOPER and observed data.

• Journal of Korea Water Resources Association
• /
• v.54 no.6
• /
• pp.433-442
• /
• 2021

In order to examine the characteristics of tidal wave from the estuary to upsteam of tidal river, tidal asymmetry was identified based on analysis of the harmonic constants of M2 and M4 tidal constituents in the domestic western coastal regions. As shallow water tide is greatly developed in the estuary, flood dominance in Han River and Keum River, and ebb dominance in Youngsan River are developed. These tidal asymmetries can be reconfirmed by analyzing the tidal current data. Unlike having reciprocating tidal current patterns in Keum and Youngsan estuaries, rotaing tidal current pattern is shown in the Han River estuary due to the complex topography and waterways around Ganghwa Island area. However, when residual current is removed, flood dominance is shown in consistency with the tide data. The tidal asymmetry in the estuary tends to intensify with the growth in shallow water tide as the tidal wave propagates to upstream of tidal river. Energy dissipation, in shallow Han River and Keum River classified as SD estuaries, is very large regarding bottom friction characteristics. On the other hand, the deep Youngsan River, classified as a WD estuary, shows less energy dissipation.