• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2015년도 학술발표회
• /
• pp.173-173
• /
• 2015

The flood water level in tidal river is determined by the joint effects of flood discharge and tidal water levels at downstream boundary. Due to the variable tidal boundary conditions, the evaluated design water levels associated with a certain flood event can be significantly different. To avoid determining of design water levels just by a certain tidal boundary condition and remove the influence of variability in boundary condition from the evaluation of design water levels, a probabilistic approach is considered in this study. This study focuses on the development of a method to evaluate the realistic design water levels in tidal river with taking into account the combined effects of river discharge and tidal level. The flood water levels are described by the joint probability of two driving forces, river discharge and tidal water levels. The developed method is applied to determine design water levels for the tidal reach of the Han River. An unsteady flow model is used to simulate the flow in the reach. To determine design water levels associated with a certain flood event, first, possible boundary conditions are obtained by sampling starting times of tidal level time series; then for each tidal boundary condition, corresponding peak water levels along the channel are computed; and finally, design water levels are determined by computing the expectations of the peak water levels. Two types of tides which are composed by different constituents are assumed (one is composed by $M_2$, and the other one is composed by $M_2$ and $M_2$) at downstream boundary, and two flood events with different maximum flood discharges are considered in this study. It is found that (a) the computed design water levels with two assumed tides have no significant difference for a certain flood event, though variability of peak water levels due to the tidal effect is considerably different; (b) tidal effect can reach to the Jamsil submerged weir and the effect is obvious in the downstream reach of the Singok submerged weir; (c) in the tidally affected reach, the variability of peak water levels due to the tidal effect is greater if the maximum flood discharge is smaller.

• 한국수자원학회:학술대회논문집
• /
• 한국수자원학회 2023년도 학술발표회
• /
• pp.519-519
• /
• 2023

Estuarine dams are a recent and global phenomenon. While estuarine dams can provide the benefit of improved freshwater resources, they can also alter estuarine processes. Due to the wide range of estuarine types and estuarine dam configurations, the effect of estuarine dams on estuaries is not well understood in general. To develop a systematic understanding of the effect of estuarine dam location and freshwater discharge interval on a range of estuarine types (strongly stratified, partially mixed, periodically stratified, and well-mixed), this study used a coupled hydrodynamic-sediment dynamic numerical model (COAWST) and compared flow, sediment transport, and morphological conditions in the pre- and post-dam estuaries. For each estuarine type, scenarios with dam locations at 20, 55 and 90 km from the mouth and discharge intervals of a discharge every 0.5, 3, and 7 days were investigated. The results were analyzed in terms of change in tide, river discharge, estuarine classification, and sediment flux mechanism. The estuarine dam location primarily affected the tide-dominated estuaries, and the resonance length was an important length scale affecting the tidal currents and Stokes return flow. When the location was less than the resonance length, the tidal currents and Stokes return flow were most reduced due to the loss of tidal prism, the dead-end channel, and the shift from mixed to standing tides. The discharge interval primarily affected the river-dominated estuaries, and the tidal cycle period was an important time scale. When the interval was greater than the tidal cycle period, notable seaward discharge pulses and freshwater fronts occurred. Dams located near the mouth with large discharge interval differed the most from their pre-dam condition based on the estuarine classification. Greater discharge intervals, associated with large discharge magnitudes, resulted in scour and seaward sediment flux in the river-dominated estuaries, and the dam located near the resonance length resulted in the greatest landward tidal pumping sediment flux and deposition in the tide-dominated estuaries.

• 대한토목학회논문집
• /
• 제32권1B호
• /
• pp.1-7
• /
• 2012

본 연구에서는 준 2차원 수치모형인 GSTARS를 이용하여 형산강의 하상변동모의에 적합한 최적 유사량공식을 산정하고자 하였다. 모형의 검보정을 위한 유사량, 하상재료 및 하천지형자료를 현장조사를 통해 취득하였다. 현재까지 널리 적용되는 유사량 공식들에 대하여 장기하상변동 모의결과의 실측치에 대한 평균오차, 상대오차, 평균제곱오차, 상대제곱근오차, 불일치율, 그리고 Nash-Sutcliffe 효율계수를 비교한 결과, Laursen(1958)공식이 형산강의 장기하상 변동을 모의하기 위한 가장 적합한 유사량공식으로 판단되었다.

• 한국농공학회지
• /
• 제38권1호
• /
• pp.90-97
• /
• 1996

In Korea, total sediment discharge of a river has been estimated simply by using certain sediment transport formulas including, among others, Einstein's formula. Those formular, however, are known not to be reliable enough for the result calculated by them to be used directly to river planning and management. Therefore, the study used the Modified Einstein Procedure to the estimation of total sediment discharge, because this method is reliable estimated by measurement. Here, measurement of sediment discharge used depth integrating method. The major results obtained from the study for estimation by depth integrating method of sediment discharge in Naeseong stream are as follow; 1 The sedeiment characteristics of Naeseong stream are; The distribution of sediment grain size shows that silt and clay are 55% and sand is 45%. and the bed load sediment grain size is constituted that sand contained with the grain size from O.062mm to 2.0mm is 80% 2. The sediment rating formulas derived from the regression analysis between the sediment discharge and flow discharge are; Seogpo-Gyo : Qs=$0.017 \times 10^{-4} Q^{2.352}$, where discharge is l0cms $0.074 \times 10^{-4} Q^{2.066}$, where discharge is l0cms

• 대한토목학회논문집
• /
• 제31권4B호
• /
• pp.309-314
• /
• 2011

하류수위의 영향을 받는 하도 내 조절수문의 경우 조절수문의 기하학적 형상은 물론 상 하류 수위에 따라 방류특성이 변화하므로 효율적 수위조절 및 수자원 관리를 위해서는 정확한 개도별 방류능 산정이 요구된다. 최근 4대강 살리기 사업으로 인하여 보의 건설과 함께 조절수문이 많이 설치되고 있으나 국내에서는 조절수문 개도에 따른 방류형태 분류기준 및 방류능 산정에 대한 연구를 찾아보기 힘든 실정이다. 따라서 본 연구에서는 특정 조절수문에 대한 수리모형실험을 통하여 방류형태(자유위어, 수중위어, 자유오리피스, 수중오리피스)를 판단할 수 있는 주요 인자를 찾고 분류기준을 검토하여 조절수문 운영을 위한 기초자료를 제시하였다. 게이트 개도높이와 상류수심의 비($h_g/h_1$), 하류수심과 게이트 개도높이의 비($h_3/h_g$)와 하류수심과 상류수심의 비($h_3/h_1$)를 하도 내 조절수문의 개도 및 상 하류 수위에 따른 방류형태를 판단할 수 있는 주요 인자로 선정하고 방류형태 분류기준 값을 제안하였다. 또한 본 연구에서 유도된 각 방류형태별 유출계수 및 방류능 산정공식으로 예측된 유량과 모형에서의 실측유량을 비교하여 연구결과의 적용성을 검증하였다.

• 상하수도학회지
• /
• 제12권3호
• /
• pp.81-90
• /
• 1998

The purpose of this study was to analyze the effect of the groin which was constructed in the down stream of urban river for the prevention of sedimentation on the improvement of the water quality. We studied on the groin in the downstream of Taehwa River constructed to keep the navigation depth of Ulsan day, and used the measured data of the water quality and river discharge. In order to analyze the charge of the water quality due to the groin Que12E model was applied, and BOD and DO was examined. The analysis showed that removal of the groin would not have significant effect on the improvement of the water quality, rather, interception of the pollution source coming into the upstream of the groin would be more influential on the improvement of the water quality. Therefore, It was concluded that to improve the water quality in mild bottom slop of tidal river, interception of the pollution source and river maintenance discharge should precede.

• 한국농공학회지
• /
• 제23권4호
• /
• pp.46-52
• /
• 1981

The aim at this study has the stochastic hydrological analysis for the annual mean discharge and monthly discharge which were observed at Lobith of River Rhine in the Netherlands from 1901 to 1972. After this study was analysed by computer IBM 370 and Hewlett Parkard 9800, the results were as follows; 1.When 72 data was divided into two groups of subsample data as 36 data, they do not have their properties to be non-homogeneous and inconsistent due to F-test and t-test. 2.The credit limits of the serial correlation coefficient was fluctuated $\pm$0. 231 which was shown in Fig. 3. at significant level 99% by Anderson's test. 3.The correlogram at short term was shown to be no short-term persistence as Fig. 3. 4.Since the correlogram at long term has displayed that Hurst's coefficient was 0.6144 between 0.6 and 0.7, it was to be no long-term persistence. 5.The stochastic model with annual discharge of this River Rhine was shown with $\chi$t=2195+483. 8 $\varepsilon$t as $\chi$t=$\mu$+oet and $\varepsilon$t=$_1$ø$\varepsilon$t-$_1$+ζt where t=1,2,3,..., ζt is an independent series with mean zero and variance (1-ø2), $\varepsilon$t is the dependent series, and 4' is the parameter of the model. 6.The serial correlation coefficient of monthly discharge was explained as $\chi$$_1$ = 0.34 . sin(6-$\pi$t+$\pi$) as Fig.4. and the River Rhine has no large fluctuation and smoothly changed during that time.

• 한국환경과학회지
• /
• 제20권8호
• /
• pp.977-986
• /
• 2011

This study analyzed the characteristics of stormwater runoff in the orchard areas and quantitatively estimated effluence of nonpoint source pollutants for the volume of runoff. Two target areas under vine cultivation were each $2,000m^2$ and $1,800m^2$, located in Gyeongju City. Since grape was the only crop on the target area, the characteristics of stormwater runoff at vineyard could be evaluated independently. A total of 51 rainfall events in the vineyard area during two years(2008-2009) was surveyed, and 19 of them became stormwater runoff, with rainfall ranging 16.5 - 79.7 mm and antecedent dry period of 1-13 days. The pollutant runoff loads by volume of stormwater runoff showed BOD ranging 19.5 - 45.3% in 30% of runoff volume. The average pollution discharge rate was 32.4%, indicating small first flush effect of BOD. The range of SS concentrations was 5 - 52.0% in 10% of runoff volume, showing the average 28.7% of discharge rate, about 3 times more than rainfall effluent. TOC and TN appeared to be similar to the results of BOD, the average discharge rate of 30.9% and 30.6% for TOC and TN, respectively, for 30% of stormwater runoff volume. Average discharge rate of COD and TP in the same runoff volume was 35.1% and 36%, respectively, showing comparatively high discharge ratio. As the targeted vineyard area was permeable land, the pollution load ratio against rainfall-runoff volume appeared to be 1:1, implying no strong first flush effect for all the survey items.

• 한국물환경학회지
• /
• 제22권4호
• /
• pp.666-671
• /
• 2006

Effects of a rainfall event (July 28, 2005) on the hydrochemical characteristics of the Jungrang river, the biggest tributary of the Han river, was investigated. Significant spatial variations in the hydrochemical characteristics were observed. At JR2 location, concentrations of T-N and T-P were relatively low indicating occurrence of active oxidation in the stepped drop structure. At JR3 location, concentrations of Na, K, Cl, $NH_4-N$ and EC were elevated suggesting increased discharge from the nearby waste-water treatment plant and tributaries. The rain event diluted major dissolved ion concentrations in the river by 12~52%. The $NO_3-N$ levels were preserved during the rain then increased about twofold after rainfall, suggesting increased discharge of nitrate-contaminated groundwater. Heavy metals including Cd, Co, Cr, Cu and Pb were not detected in all water samples and the leachates from surface sediment samples. Concentrations of Fe, Mn, Al and Zn were below the Korean Drinking Water Guideline. Results of this study suggested that establishment of water-quality monitoring protocols describing temporal and spatial variations in parameters sensitive to rainfall events, relatively steady factors, and contaminant sources is required.

• 한국물환경학회지
• /
• 제30권2호
• /
• pp.184-198
• /
• 2014

For estimating discharge and pollution loads into the Yeongsan lake, a conceptual watershed model HSPF(Hydrological Simulation Program - Fortran) was applied to the Yeongsan River Basin. Various spatial data set including DEM, watershed boundaries and land uses were used to set up the model for the Yeongsan River Basin that was divided into 45 sub-basins. The model was calibrated and validated for the river discharges, SS, BOD, TN and TP concentrations against the data observed in 2011 at several monitoring stations. The simulation results show good agreement with the observed water flows($R^2$ = 0.46 - 0.97, NSE = 0.70 - 0.96). The simulated concentrations of SS, BOD, TN and TP are also in good agreement with the observed. The total freshwater discharge to the Yeongsan lake is estimated $2,406{\times}10^6m^3/year$ which the Jiseok and Hwangryoung stream contribute as much as 19%, 17% respectively. It is estimated that the total discharges to the Youngsan lake is SS 152,327 ton/year, BOD 15,721 ton/year, TN 10,071 ton/year, TP 563 ton/year. Both water and pollution loads are high in summer, particularly in July, when the monsoon season arrives at the Korean peninsula.