• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.6
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• pp.562-575
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• 2023

In an effort to improve water quality, the South Korean government has implemented measures to increase seawater circulation in Saemangeum Lake. We analyzed the effect of increasing the frequency of seawater circulation based on salinity levels and bottom water exchange in the lake, using an environmental fluid dynamics code model. When the sluice gate opening and shutting frequency increased from once to twice per day, the internal water level of Saemangeum Lake increased by up to ~0.7 m. The salinity increased by 2.12 psu near the western breakwater and decreased by 1.18 psu near the freshwater inlet. We analyzed the extent of bottom water exchange using a particle tracing method and observed that the residual rate of particles shallower than 5 m in water depth decreased by 2.52% in Case 2 (opening and shutting twice per day) compared to Case 1 (opening and shutting once per day). This indicates that increasing the frequency of sluice gate opening and shutting would promote enhanced bottom water exchange. Consequently, the increased salinity and bottom water exchange associated with increased seawater circulation are expected to improve water quality in Saemangeum Lake.

• Journal of Environmental Science International
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• v.18 no.9
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• pp.1027-1033
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• 2009

For the assesment of pollutant loads, a monitoring has been conducted to identify hydrologic conditions and water quality of the Oenam watershed in Juam Lake, and the SWAT model integrated with GIS was applied to the watershed and evaluated for its applicability through calibration and verification using observed data. For the model application, digital maps were constructed for watershed boundary, land-use, soil series, digital elevation, and topographic input data of the Oenam watershed using Arcview. The observed runoff was 832.8 mm while the simulated runoff was 842.8 mm in 2003. The model results showed that the simulated runoff was in a good agreement with the observed data and indicated reasonable applicability of the model. In terms of nutrient load, the simulation results of T-N, T-P showed a similar trend to observed values. The observed T-N load was 10.8 kg/ha and the simulated T-N load was 7.6 kg/ha while the observed T-P load was 0.21 kg/ha and the simulated T-P load was 0.18 kg/ha. In general, SWAT model predicted observed runoff and loads of T-N and T-P after calibration with observed data in acceptable range. Overall, SWAT model was satisfactory in estimation of nutrient pollutant loads of the rural watershed.

• Proceedings of the Korea Water Resources Association Conference
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• 1993.07a
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• pp.491-500
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• 1993

• Proceedings of the Korea Water Resources Association Conference
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• 1993.07a
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• pp.519-526
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• 1993

• Journal of Wetlands Research
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• v.13 no.3
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• pp.707-720
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• 2011

For the lake case, the detention phenomenon of water body occurs and stays for a long time. Especially, following the layer of water depth direction, the lake body and water quality problems are different from the water quality of river. So according to time, the stream and water quality can be simulated by the 3-Dimensional Model, which can divide water layer for reservoir or lake. The water quality simulation result will become more reliability. For this study, the 3-Dimension Model - EFDC was used to simulate water quality of Unam reservoir in the Sumjin Dam. The HEC-GeoHMS and HEC-HMS Rainfall - Runoff Model based on GIS were used to estimate long-term runoff, and input data was constructed to the observed water level, meteorological data, water temperature, T-N and T-P. In order to apply the EFDC model, water depth was divided into 3 layers and 5,634 grids were extracted. After constructing the grid net, the water quality change of Unam reservoir in time and space was simulated. Overall, long term runoff simulation reflected the actual observed runoff well, through the water quality simulation, according to the pollution factors, the behavior characteristics can be checked, and the simulated water quality can be properly reflected. The function of EFDC has been confirmed, which water quality can be properly simulated. In the near future, to establish countermeasures for Intake Facilities of Watershed and Management, this support which some basic tools can be applied is in expectation.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.217-217
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• 2015

The objective of this study was mainly to evaluate the water resources potential of Lake Tana Basin (LTB) by using Soil and Water Assessment Tool (SWAT). From SWAT simulation of LTB, about 5236 km2 area of LTB is gauged watershed and the remaining 9878 km2 area is ungauged watershed. For calibration of model parameters, four gauged stations were considered namely: Gilgel Abay, Gummera, Rib, and Megech. The SWAT-CUP built-in techniques, particle swarm optimization (PSO) and generalized likelihood uncertainty estimation (GLUE) method was used for calibration of model parameters and PSO method were selected for the study based on its performance results in four gauging stations. However the level of sensitivity of flow parameters differ from catchment to catchment, the curve number (CN2) has been found the most sensitive parameters in all gauged catchments. To facilitate the transfer of data from gauged catchments to ungauged catchments, clustering of hydrologic response units (HRUs) were done based on physical similarity measured between gauged and ungauged catchment attributes. From SWAT land use/ soil use/slope reclassification of LTB, a total of 142 HRUs were identified and these HRUs are clustered in to 39 similar hydrologic groups. In order to transfer the optimized model parameters from gauged to ungauged catchments based on these clustered hydrologic groups, this study evaluates three parameter transfer schemes: parameters transfer based on homogeneous regions (PT-I), parameter transfer based on global averaging (PT-II), and parameter transfer by considering Gilgel Abay catchment as a representative catchment (PT-III) since its model performance values are better than the other three gauged catchments. The performance of these parameter transfer approach was evaluated based on values of Nash-Sutcliffe efficiency (NSE) and coefficient of determination (R2). The computed NSE values was found to be 0.71, 0.58, and 0.31 for PT-I, PT-II and PT-III respectively and the computed R2 values was found to be 0.93, 0.82, and 0.95 for PT-I, PT-II, and PT-III respectively. Based on the performance evaluation criteria, PT-I were selected for modelling ungauged catchments by transferring optimized model parameters from gauged catchment. From the model result, yearly average stream flow for all homogeneous regions was found 29.54 m3/s, 112.92 m3/s, and 130.10 m3/s for time period (1989 - 2005) for region-I, region-II, and region-III respectively.

• Water Engineering Research
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• v.2 no.4
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• pp.209-218
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• 2001

Generation of evaporation data generally assists in planning, operation, and management of reservoirs and other water works. Annual and monthly evaporation series were generated for King Fahad Dam Lake in Bishah, Saudi Arabia. Data was gathered for period of 22 years. Tests of homogeneity and normality were conducted and results showed that data was homogeneous and normally distributed. For generating annual series, an Autoregressive first order model AR(1) was used and for monthly evaporation series method of fragments was used. Fifty replicates for annual series, and fifty replicates for each month series, each with 22 values length, were generated. Performance of the models was evaluated by comparing the statistical parameters of the generated series with those of the historical data. Annual and monthly models were found to be satisfactory in preserving the statistical parameters of the historical series. About 89% of the tested values of the considered parameters were within the assigned confidence limits

• Journal of Korean Society of Water and Wastewater
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• v.14 no.2
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• pp.174-180
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• 2000

In this study two water quality models, widely used in Korea, WASP5 and SWRRB were applied to Lake Paldang. The simulated results were compared with the measured data. The simulation results using WASP5 showed that this model could reasonably predict the concentrations of $NO_3$-N, Organic N, and Organic P. In order to investigate the effect of pollution by non-point source SWRRB was simulated and the concentrations of nutrients were predicted. The results from WASP5 and SWRRB are not directly comparable because their input data are different and output values are differently presented. Therefore, if these two simulation models were applied simultaneously, many valuable data and information could be obtained due to their own applicabilities and advantages.

• Proceedings of the Korean Geotechical Society Conference
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• 2002.10a
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• pp.491-498
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• 2002

The rubble base in the seadike structure is construct with rubble-mound of big size for stability of seadike against a tidal current velocity at the closing. The permeability gives an effect to stability of seadike a lot in The case which rubble base is founded long with a lake direction like objective area of this study. The permeability of the rubble base produced in the model test regarding filling condition and materials of the rubble base, It applied the result which it tests in seepage analysis and it analyzed a stability of piping, In this study, it diminishes the permeability of the rubble base to respect, the pit soil more the dredge soil is effective and it was analyzed with the fact that it increases the stability of lake direction slope against the piping.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.4
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• pp.177-188
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• 1993

Model parameters of the WASP4 applied to Lake Paldang were estimated. The methodology is based on grouping water quality constituents and relevant parameters and successively estimating each group of parameters by a trial-and-error procedure. Chlorophyll a, nitrogen cycles, phosphorus cycles, BOD and DO were simulated at the complexity level 4. A water budget analysis using the monthly records of reservoir inflows and outflows in 1989 and 1990 was made to determine seasonally-averaged flowrates at model boundaries. Estimated flowrates were used, together with the seasonal average of water quality measurements in 1989 and 1990 for the calibration and verification, respectively, of the model. Grouping water quality constituents and associated parameters proved to be efficient in estimating a number of model parameters. From the results of model calibration and verification, it was found that quantitative evaluations of nonpoint and benthic sources of organic matters are essential. Benthic sources near the entrance of the Kyeongancheon were the most significant.