• Title/Summary/Keyword: Hydrodynamic Runoff Model

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Application of a Method Estimating Grid Runoff for a Global High-Resolution Hydrodynamic Model (전지구 고해상도 수문모델 적용을 위한 격자유량 추정 방법 적용 연구)

  • Ryu, Young;Ji, Hee-Sook;Hwang, Seung-On;Lee, Johan
    • Atmosphere
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    • v.30 no.2
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    • pp.155-167
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    • 2020
  • In order to produce more detailed and accurate information of river discharge and freshwater discharge, global high-resolution hydrodynamic model (CaMa-Flood) is applied to an operational land surface model of global seasonal forecast system. In addition, bias correction to grid runoff for the hydrodynamic model is attempted. CaMa-Flood is a river routing model that distributes runoff forcing from a land surface model to oceans or inland seas along continentalscale rivers, which can represent flood stage and river discharge explicitly. The runoff data generated by the land surface model are bias-corrected by using composite runoff data from UNH-GRDC. The impact of bias-correction on the runoff, which is spatially resolved on 0.5° grid, has been evaluated for 1991~2010. It is shown that bias-correction increases runoff by 30% on average over all continents, which is closer to UNH-GRDC. Two experiments with coupled CaMa-Flood are carried out to produce river discharge: one using this bias correction and the other not using. It is found that the experiment adapting bias correction exhibits significant increase of both river discharge over major rivers around the world and continental freshwater discharge into oceans (40% globally), which is closer to GRDC. These preliminary results indicate that the application of CaMa-Flood as well as bias-corrected runoff to the operational global seasonal forecast system is feasible to attain information of surface water cycle from a coupled suite of atmospheric, land surface, and hydrodynamic model.

Predicting Dynamic Behaviors of Highway Runoff using A One-dimensional Kinematic Wave Model (일차원 kinematic wave 모형을 이용한 고속도로 강우 유출수의 동적 거동 예측)

  • Kang, Joo-Hyon;Kim, Lee-Hyung
    • Journal of Korean Society on Water Environment
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    • v.23 no.1
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    • pp.38-45
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    • 2007
  • A one-dimensional kinematic wave model was used to calculate temporal and spatial changes of the highway runoff. Infiltration into pavement was considered using Darcy's law, as a function of flow depth and pavement hydraulic conductivity ($K_p$). The model equation was calculated using the method of characteristics (MOC), which provided stable solutions for the model equation. 22 storm events monitored in a highway runoff monitoring site in west Los Angeles in the U.S. were used for the model calculation and evaluation. Using three different values of $K_p$ ($5{\times}10^{-6}$, $10^{-5}$, and $2{\times}10^{-5}cm/sec$), total runoff volume and peak flow rate were calculated and then compared with the measured data for each storm event. According to the calculation results, $10^{-5}cm/sec$ was considered a site representative value of $K_p$. The study suggested a one-dimensional method to predict hydrodynamic behavior of highway runoff, which is required for the water quality prediction.

Hydrodynamic Analysis at Nakdong River Confluences (낙동강 주요 합류부에서의 동역학적 수리해석)

  • Han, Kun Yeun;Kim, Ji Sung;Yang, Seung Ho
    • Proceedings of the Korea Water Resources Association Conference
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    • 2004.05b
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    • pp.908-911
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    • 2004
  • The purpose of this study is to investigate the applicability of the two dimensional model in natural rivers. In this study, two dimensional unite element model, SMS, is used to simulate a complex flow along with the sediment movements in the natural river. The RMA-2 model embeded in SMS is used to simulate flow phenomena and SED-2D model is employed to simulate sediment transport. The model is applied to the confluence zone of the Gam River and mouth of Nakdong River. For model calibration, the result of the unsteady flow analysis is compared with the Typhoon 'Rusa' data. In addition, the runoff analysis was conducted for the determination of the project flood and the flood forecasting. The simulation results presented the characteristics of two dimensional flow with velocity vector and flow depth. The sediment transport characteristics are shown in terms of sediment concentration as well as bed elevation change. Accordingly, the SMS model in this study turned out to be very effective tool for the simulation of the hydrodynamic characteristics under the various flow conditions and corresponding sediment transports in natural rivers.

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Dynamic Simulation of Storm Surge and Storm Water-Combine Inundation on the Jeju Coastal Area (폭풍 해일 및 폭풍우로 인한 제주 해안역에서의 동역학적 범람 모의)

  • Lee, Jung-Lyul;Lee, Byung-Gul;Lee, Joo-Yong;Lim, Heung-Soo
    • Proceedings of the Korea Water Resources Association Conference
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    • 2006.05a
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    • pp.1945-1949
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    • 2006
  • A storm-induced coastal inundation model (SICIM) is presented to simulate the flood event during typhoon passage that often results in significant rise in sea-level heights especially in the upstream region of the basin. The SICIM is a GIS-based distributed hydrodynamic model, both storm surge and storm water inundations are taken into account. The spatial and temporal distribution of the storm water level and flux are calculated. The model was applied to Jeju Island since it has an isolated watershed that is easy to handle as a first step of model application. Another reason is that it is surrounded by coastal area exposed to storm surge inundation. The model is still advancing and will be the framework of a predictive early inundation warning system.

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Calculation of Direct Runoff Hydrograph considering Hydrodynamic Characteristics of a Basin (유역의 동수역학적 특성을 고려한 직접유출수문곡선 산정)

  • Choi, Yun-Ho;Choi, Yong-Joon;Kim, Joo-Cheol;Jung, Kwan-Sue
    • Journal of the Korean Society of Hazard Mitigation
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    • v.11 no.3
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    • pp.157-163
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    • 2011
  • In this study, after the target basin was divided into both overland and channel grids, the travel time from center of each grid cell to watershed's outlet was calculated based on the manning equation. Through this process, volumetric discharge was calculated according to the isochrones and finally, the direct runoff hydrograph was estimated considering watershed's hydrodynamic characteristics. Sanseong subwatershed located in main stream of Bocheong basin was selected as a target basin. The model parameters are only two: area threshold and channel velocity correction factor; the optimized values were estimated at 3,800 and 3.3, respectively. The developed model based on the tuned parameters led to well-matching results between observed and calculated hydrographs (mean of absolute error of peak discharge: 3.41%, mean of absolute error of peak time: 0.67 hr). Moreover, the analysis results regarding histogram of travel time-contribution area demonstrates that the proposed model characterizes relatively well hydrodynamic characteristics of the catchment due to effective rainfall.

Estimation of Tritium Concentration in Groundwater around the Nuclear Power Plants Using a Dynamic Compartment Model

  • Choi, Heui-Joo;Lee, Han-Soo;Kang, Hee-Suk;Choi, Yong-Ho
    • Journal of Radiation Protection and Research
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    • v.28 no.3
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    • pp.239-245
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    • 2003
  • Every nuclear power plant measured concentrations of tritium in groundwater and surface water around the plants periodically. It was not easy to predict the tritium concentration only with these measurement data in case of various release scenarios. KAERI developed a new approach to find the relationship between the tritium release rate and tritium concentration in the environment. The approach was based upon a dynamic compartment model. In this paper the dynamic compartment model was modified to predict the tritium behavior more accurately. The mechanisms considered for the transfer of tritium between the compartments were evaporation, groundwater flow, infiltration, runoff, and hydrodynamic dispersion. Time dependent source terms of the compartment model were introduced to refine the release scenarios. Also, transfer coefficients between the compartments were obtained using realistic geographical data. In order to illustrate the model various release scenarios were developed, and the change of tritium concentration in groundwater and surface water around the nuclear power plants was estimated.

Analysis of Microcystis Bloom in Daecheong Reservoir using ELCOM-CAEDYM (ELCOM-CAEDYM을 이용한 대청호 Microcystis Bloom 해석)

  • Chung, Se Woong;Lee, Heung Soo
    • Journal of Korean Society on Water Environment
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    • v.27 no.1
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    • pp.73-87
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    • 2011
  • An abnormal mono-specific bloom of the cyanobacterium Microcystis aeruginosa had developed at a specific location (transitional zone, monitoring station of Hoenam) in Daecheong Reservoir from middle of July to early August, 2001. The maximum cell counts during the peak bloom reached 1,477,500 cells/mL, which was more than 6~10 times greater than those at other monitoring sites. The hypothesis of this study is that the timing and location of the algal bloom was highly correlated with the local environmental niche that was controled by physical processes such as hydrodynamic mixing and pollutant transport in the reservoir. A three-dimensional, coupled hydrodynamic and ecological model, ELCOM-CAEDYM, was applied to the period of development and subsequent decline of the bloom. The model was calibrated against observed water temperature profiles and water quality variables for different locations, and applied to reproduce the algal bloom event and justify the limiting factor that controled the Microcystis bloom at R3. The simulation results supported the hypothesis that the phosphorus loading induced from a contaminated tributary during several runoff events are closely related to the rapid growth of Microcystis during the period of bloom. Also the physical environments of the reservoir such as a strong thermal stratification and weak wind velocity conditions provided competitive advantage to Microcystis given its light adaptation capability. The results show how the ELCOM-CAEDYM captures the complex interactions between the hydrodynamic and biogeochemical processes, and the local environmental niche that is preferable for cyanobacterial species growth.

Turbidity Modeling for a Negative Buoyant Density Flow in a Reservoir with Consideration of Multiple Particle Sizes (입자크기 분포를 고려한 부력침강 저수지 밀도류의 탁도 모델링)

  • Chung, Se Woong;Lee, Heung Soo;Jung, Yong Rak
    • Journal of Korean Society on Water Environment
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    • v.24 no.3
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    • pp.365-377
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    • 2008
  • Large artificial dam reservoirs and associated downstream ecosystems are under increased pressure from long-term negative impacts of turbid flood runoff. Despite various emerging issues of reservoir turbidity flow, turbidity modeling studies have been rare due to lack of experimental data that can support scientific interpretation. Modeling suspended sediment (SS) dynamics, and therefore turbidity ($C_T$), requires provision of constitutive relationships ($SS-C_T$) and accounting for deposition of different SS size fractions/types distribution in order to display this complicated dynamic behavior. This study explored the performance of a coupled two-dimensional (2D) hydrodynamic and particle dynamics model that simulates the fate and transport of a turbid density flow in a negatively buoyant density flow regime. Multiple groups of suspended sediment (SS), classified by the particle size and their site-specific $SS-C_T$ relationships, were used for the conversion between field measurements ($C_T$) and model state variables (SS). The 2D model showed, in overall, good performance in reproducing the reservoir thermal structure, flood propagation dynamics and the magnitude and distribution of turbidity in the stratified reservoir. Some significant errors were noticed in the transitional zone due to the inherent lateral averaging assumption of the 2D hydrodynamic model, and in the lacustrine zone possibly due to long-term decay of particulate organic matters induced during flood runoffs.

PREDICTION OF THE TRITIUM CONCENTRATION IN THE SOIL WATER AFTER THE OPERATION OF WOLSONG TRITIUM REMOVAL FACILITY

  • CHOI HEUI-JOO;LEE HANSOO;SUH KYUNG SUK;KANG HEE SUK
    • Nuclear Engineering and Technology
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    • v.37 no.4
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    • pp.385-390
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    • 2005
  • The effect of the Wolsong Tritium Removal Facility on the change of tritium concentration in the soil water was assessed by introducing a dynamic compartment model. For the mathematical modeling, the tritium in the environment was thought to come from two different sources. Three global tritium cycling models were compared with the natural background concentration. The dynamic compartment model was used to model the behavior of the tritium from the nuclear power plants at the Wolsong site. The source term for the dynamic compartment model was calculated with the dry and wet deposition rates. The area around the Wolsong nuclear power plants was represented by the compartments. The mechanisms considered in deriving the transfer coefficients between the compartments were evaporation, runoff, infiltration, hydrodynamic dispersion, and groundwater flow. We predicted what the change of the tritium concentration around the Wolsong nuclear power plants would be after future operation of the tritium removal facility to show the applicability of the model. The results showed that the operation of the tritium removal facility would reduce the tritium concentration in topsoil water quickly.

Phosphorus Cycle in a Deep Reservoir in Asian Monsoon Are3 (Lake Soyang, Korea) and the Modeling with a 2-D Hydrodynamic Water Quality Model [CE-QUAL-W2] (아시아 몬순지역의 대형댐(소양호)에서의 인순환과 2차원모델의 적용)

  • Kim, Yoon-Hee;Kim, Bom-Chul
    • Korean Journal of Ecology and Environment
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    • v.37 no.2 s.107
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    • pp.205-212
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    • 2004
  • Phosphorus cycle was studied in a deep stratified reservoir in summer monsoon area (Lake Soyang, Korea) by surveying phosphorus input from the watershed and the movement of phosphorus within the reservoir. And the spatial and temporal distribution of phosphorus was modeled with a 2-dimensional water quality model (CE-QUAL-W2), Phosphorus loading was calculated by measuring TP in the main inflowing river (the Soyang River) accounting for 90% of watershed discharge. TP of the Soyang River showed a large daily variation with the flow rate. High phosphorus loading occurred during a few episodic storm runoff laden with suspended sediments and phosphorus. Because storm runoff water on rainy days have lower temperature, it plunges into a depth of same temperature (usually below 20m depth), forming an intermediate turbidity layer with a thickness of 20 ${\sim}$ 30 m. Because of stable thermal stratification in summer the intermediate layer water of high phosphorus content was discharged from the dam through a mid-depth outlet without diffusing into epilimnion. The movement of runoff water within the reservoir, and the subsequent distribution of phosphorus were well simulated by the water quality model showing a good accuracy. The major parameter for the calibration of phosphorus cycle was a settling velocity of detritus, which was calibrated to be 0.75 m ${\cdot}$ $day^{-1}$. It is concluded that the model can be a good simulator of limnological phenomena in reservoirs of summer monsoon area.