• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.420-431
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• 2010

Simple material budget models were developed to predict the dry season water quality for a river-type reservoir in Paldang, Republic of Korea. Of specific interest were the total phosphorus (TP), chlorophyll ${\alpha}$ (Chl. ${\alpha}$), 5-day biochemical oxygen demand (BOD), and chemical oxygen demand (COD). The models fit quite well with field data collected for 20 years and have enabled the identification of the origins of organic materials in the reservoir. The critical hydraulic load that determines the usability of phosphorus for algal production appeared to be about $1.5m\;d^{-1}$. When a hydraulic load was smaller than the critical value, the concentrations of $Chl.{\alpha}$, COD, and BOD in the reservoir water became sensitive to internal algal reactions such as growth, degradation, and settling. In spite of the recent intensive efforts for organic pollutant removal from major point sources by central and local governments, the water quality in the reservoir had not been improved. Instead, the concentration of COD increased. The model analysis indicated that this finding could be attributed to the continuing increase of the algal production in the reservoir and the allochthonous load from non-point sources. In particular, the concentrations of COD and BOD of algal origin during 2000~2007, each of which is comprised of approximately one half of the total, were approximately 2.5 times higher than those observed during 1988~1994 and approximately 1.3 times higher than those between 1995~1999. The results of this study suggested that it is necessary to reduce the algal bloom so as to improve the water quality of the reservoir.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.221-221
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• 2012

The WRAP-SALT (Water Rights Analysis Package-SALT) simulation includes computation of end-of-month reservoir storage concentrations and mean monthly reservoir outflow concentrations for each month of the simulation. The model computes reservoir storage loads and concentrations based on load balance accounting algorithms and computes concentrations of water released and withdrawn from a reservoir as a function of the volume-weighted mean concentration of the water stored in the reservoir in the current month or previous months. A load budget accounting of the various component load inflows and outflows entering and leaving a reservoir is performed. A time history of storage concentrations computed for previous months is maintained for use in the lag procedure. This study presents computational methods for routing salinity through reservoirs for incorporation into WRAP-SALT simulation routines and methods for determining values for the parameters of the routing methods.

• Journal of Environmental Science International
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• v.8 no.4
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• pp.431-441
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• 1999

In this study, the regional frequency analysis is used to determine each subbasin drought frequency with reliable monthly precipitation and the L-Moments method which is almost unbiased and has very nearly a normal distribution is used for the parameter estimation of monthly precipitation time series in Nakdong river basin. As the result of this study, the duration of '93-'94 is most severe drought year than any other water year and the drought frequency is established as compared the regional frequency analysis result of cumulative precipitation of 12th duration months in each subbasin with that of 12th duration months in the major drought duration. The Linear regression equation is induced according to linear regression analysis of drought frequency between Nakdong total basin and each subbasin of the same drought duration. Therefore, as the foundation of this study, it can be applied proposed method and procedure of this study to the water budget analysis considering safety standards for the design of impounding facilities large-scale river basin and for this purpose, above all, it is considered that expansion of reliable preciptation data is needed in watershed rainfall station.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.7 no.4
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• pp.257-266
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• 2002

To estimate the nitrogen budget and assess the purification function of a tidal flat ecosystem, a field survey was carried out at Hajeon tidal flat in Gomso Bay, the southern part of Byeonsan Peninsula, Chollabuk-do, Korea. A study area of 3.0$\times$4.5 ㎢ was established on the tidal flat and the concentrations of chlorophyll-a, DIN, DON, and TN were measured in the water column during the period of April 17-18, 1999: From the budget analysis, the loss rate of Chl-a was estimated to be -0.05 mg Chl/㎡/hr, which is approximately 7% of that at Issiki tidal flat in Aichi Prefecture, Japan. The lower loss rate of Chl-a in the study area was attributable to the lower standing crop of phytoplankton, the lower temperature that may reduce metabolic rates of biotic components and the lower biomass of macrobenthos in the study area. Over the 13.5 ㎢ of study area, Hajeon tidal flat removed 8.36$\times$10$\^$2/ kg N/day of TN, 5.36$\times$10$\^$3/ kg N/day of PON and 1.62$\times$10$\^$2/ kg N/day of phytoplankton-related PON, showing that the tidal flats may play an important role in removing nitrogen in coastal waters. The removal rate of PON, compared to the removal cost of the existing waste water treatment facilities, indicates that the economic value of the purification function of Hajeon tidal flat (13.5㎢) may be more than that of two large facilities.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.5
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• pp.557-564
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• 2005

The objective of this study is to evaluate a criteria of intercepting capacity and a reduction goal of overflow pollution load in combined sewer system. In the current criteria of intercepting capacity in the domestic sewage facility standard, it is known that three times of peak sewage (Q) in dry period or runoff flow by 2mm/hr is not appropriate since the intercepted flow is estimated by runoff and show different result even in the same watershed. Though a reduction goal of overflow pollution load can be determined from 1) same level of storm-water runoff pollution load in separated storm sewer, 2) less than 5% sewage load in dry weather period, by the domestic sewage facility standard, the simulated results from storm-water model show large differences between two criteria. While it is predicted that sewage pollution load standard three time larger than separated storm sewer standard in high population density and urbanized area, it is shown that separate storm sewer standard larger than sewage pollution load standard in middle population density and developing area. Accordingly, it is proposed that more reasonable intercepting flow and reduction goal of overflows pollution load should be established to minimize discharging pollution load in combined sewer systems. For the purpose, a resonable standard has to be amended by pollution load balance considering the characteristics of a watershed for generation, collection, treatment, and discharging flow.

• Journal of Korean Society on Water Environment
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• v.26 no.2
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• pp.356-364
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• 2010

The chemical and biological reaction of the aquatic organism is closely related with temperature variation and water temperature is one of the most important factors that should be considered in establishing sustainable reservoir operation scheme to minimize adverse environmental impacts related with dam construction. This paper investigates temperature variation in the downstream of Yongdam Reservoir using sampled data collected from total 8 temperature monitoring stations placed along the main river and the major tributaries. Using KoRiv1, 1-dimensional dynamic water quality simulation model, temperature variation in the downstream of Yongdam Reservoir has been simulated. The simulated results were compared with sampled data collected from May 15 to August 1 2008 by applying two different temperature modeling schemes, equilibrium temperature and full heat budget method. From the result of statistical analysis, seasonal temperature variation has been simulated by applying the equilibrium temperature scheme for comparison of the difference between the reservoir operation and the natural conditions.

• Asian Journal of Business Environment
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• v.10 no.4
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• pp.29-34
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• 2020

Purpose: Town of Woldia, a semi-arid region in the Northern Wollo region of Ethiopia, faces water supply shortage in general, though the town possesses a running stream of clean water throughout the year. This study is aimed at analyzing the possibility of using rainwater for water scarcity and non-potable water needs of the Woldia University. A careful study and analysis have been made to assess the feasibility of using rainwater in place of the tap water supply. Research design and methodology: This study was done inside the main campus of Woldia University located in Woldia town. The runoff water from the roof of buildings was studied, by the time of rainfall in the town. Also, the budget needed for implementing a rainwater harvesting system was calculated. Results: The findings of the study clearly indicates that the requirements of the water to use for flushing, cleaning, and washing toilets in the administrative buildings and classrooms can be satisfied by using rainwater as an alternative to tap water. Conclusion: Based on the results the study finds it is benefitable for the Woldia University to install the rainwater harvesting system at the earliest to solve the water problems prevailing in the current situation.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.469-472
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• 2003

A life cycle cost analysis model for public water supply systems should be different from the ones for other civil and architectural facilities as the operation and the maintenance cost of the water supply systems mainly come from the various mechanical systems and the pipeline systems of the collecting/treating/distributing facilities. This paper presents a cost classification scheme and a life cycle cost analysis model for public water supply systems. A value analysis (VA) procedure that is well suited for practical purposes is also presented. The presented life cycle model and the value analysis procedure were applied to a real world project, and this case study is discussed in the paper. The model and the procedure presented in this study can greatly contribute to the value-oriented design alternative selection, the estimation of the maintenance cost, and the allocation of budget for water supply system construction projects.

• Korean Journal of Construction Engineering and Management
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• v.5 no.2 s.18
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• pp.181-193
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• 2004

A life cycle cost analysis model for public water supply systems should be different from the ones for other civil and architectural facilities as the operation and the maintenance cost of the water supply systems mainly come from the various mechanical systems and the pipeline systems of the collecting/treating/distributing facilities. This paper presents a cost classification scheme and a probabilistic life cycle cost analysis (PLCCA) model for public water supply systems. A value analysis (VA) procedure that is well suited for practical purposes is also presented. The presented probabilistic life cycle model and the value analysis procedure were applied to a real world project, and this case study is discussed in the paper. The model and the procedure presented in this study can greatly contribute to the value-oriented design alternative selection, the estimation of the maintenance cost, and the allocation of budget for water supply system construction projects.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.7
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• pp.57-69
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• 2003

To evaluate nutrient dynamics with different fertilization in paddy field and develop water quality model, mass balance analysis was performed during growing season of 2001-2002 in field experimental plots irrigated with groundwater. As a result of water balance analysis, most of outflow was surface drainage as about half of total outflow and about 500mm was lost by evapotranspiration. The water budget was well balanced. The runoff from paddy field was influenced by rainfall and forced drain. Especially runoff during early cultural periods more depends on the forced drain. As a result of mass balance analysis, most of nutrient was input by fertilization and lost by plant uptake. Significant amount of nitrogen were supplied by precipitation and input from upper paddy field, comprising 12%∼28% of total inflow. Nutrient loading by surface drainage was occurred showing about 15%∼29% for T-N and 6%∼13% for T-P. The response of rice yield with different fertilization was not significant in this study. Water quality model for paddy field developed using Dirac delta function and continuous source was calibrated and validated to surface water quality monitoring data. It demonstrates good agreement between observed and simulated. The nutrient concentration of surface water at paddy field was significantly influenced by fertilization. During early cultural periods when significant amount of fertilizer was applied, surface drainage from paddy field can cause serious water quality problem. Therefore, reducing surface drainage during fertilization period can reduce nutrient loading from paddy fields. Shallow irrigation, raising the weir height in diked rice fields, and minimizing forced surface drainage are suggested to reduce surface drainage outflow.