• Journal of the Korean GEO-environmental Society
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• v.24 no.12
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• pp.31-38
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• 2023

In this study, runoff characteristics analysis was conducted as a basic research to establish a forecasting and warning system for flood risk areas in small mountainous basins in South Korea. The Danyang 1 Bridge basin located in Danyang-gun, Chungcheongbuk-do was selected as the study basin, and the watershed characteristic factors were calculated using Q-GIS based on the digital elevation model (DEM) of the basin. In addition, nine heavy rainfall events were selected from 2020 to 2023 using hydrometeorological data provided by the National Water Resources Management Comprehensive Information System. HEC-HMS rainfall-runoff model was used to analyze the runoff characteristics of small mountainous basins, and rainfall-runoff model simulation was performed by reflecting 9 heavy rainfall events and calculated basin characteristic factors. Based on the rainfall-runoff model, parameter optimization was performed for six heavy rain events with large error rates among the simulated events, and the appropriate parameter range for the Danyang 1 Bridge basin, a small mountainous basin, was calculated to be 0.8 to 3.4. The results of this study will be utilized as foundational data for establishing flood forecasting and warning systems in small mountainous basin, and further research will be conducted to derive the range of parameters according to basin characteristics.

• Journal of the Korean Association of Geographic Information Studies
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• v.18 no.2
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• pp.174-189
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• 2015

The objective of this study was to reconstruct spatial information using the results of the investigation and evaluation of the health of the living organisms, habitat, and water quality at the investigation points for the aquatic ecosystem health of the Nakdong River basin, to support the rational decision making of the aquatic ecosystem preservation and restoration policies of the Nakdong River basin using spatial analysis techniques, and to present efficient management methods. To analyze the aquatic ecosystem health of the Nakdong River basin, punctiform data were constructed based on the position information of each point with the aquatic ecosystem health investigation and evaluation results of 250 investigation sections. To apply the spatial analysis technique, the data need to be reconstructed into areal data. For this purpose, spatial influence and trends were analyzed using the Kriging interpolation(ArcGIS 10.1, Geostatistical Analysis), and were reconstructed into areal data. To analyze the spatial distribution characteristics of the Nakdong River basin health based on these analytical results, hotspot(Getis-Ord Gi, $G^*_i$), LISA(Local Indicator of Spatial Association), and standard deviational ellipse analyses were used. The hotspot analysis results showed that the hotspot basins of the biotic indices(TDI, BMI, FAI) were the Andong Dam upstream, Wangpicheon, and the Imha Dam basin, and that the health grades of their biotic indices were good. The coldspot basins were Nakdong River Namhae, the Nakdong River mouth, and the Suyeong River basin. The LISA analysis results showed that the exceptional areas were Gahwacheon, the Hapcheon Dam, and the Yeong River upstream basin. These areas had high bio-health indices, but their surrounding basins were low and required management for aquatic ecosystem health. The hotspot basins of the physicochemical factor(BOD) were the Nakdong River downstream basin, Suyeong River, Hoeya River, and the Nakdong River Namhae basin, whereas the coldspot basins were the upstream basins of the Nakdong River tributaries, including Andong Dam, Imha Dam, and Yeong River. The hotspots of the habitat and riverside environment factor(HRI) were different from the hotspots and coldspots of each factor in the LISA analysis results. In general, the habitat and riverside environment of the Nakdong River mainstream and tributaries, including the Nakdong river upstream, Andong Dam, Imha Dam, and the Hapcheon Dam basin, had good health. The coldspot basins of the habitat and riverside environment also showed low health indices of the biotic indices and physicochemical factors, thus requiring management of the habitat and riverside environment. As a result of the time-series analysis with a standard deviation ellipsoid, the areas with good aquatic ecosystem health of the organisms, habitat, and riverside environment showed a tendency to move northward, and the BOD results showed different directions and concentrations by the year of investigation. These aquatic ecosystem health analysis results can provide not only the health management information for each investigation spot but also information for managing the aquatic ecosystem in the catchment unit for the working research staff as well as for the water environment researchers in the future, based on spatial information.

• Proceedings of the Korea Water Resources Association Conference
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• 2009.05a
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• pp.1678-1682
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• 2009

IRWMS(Integrated Real time Water Management System)은 우리나라의 수자원 운영환경에 부합하도록 하천유역에 수자원 통합관리 개념을 도입한 실시간 물관리 의사결정지원 시스템이다. 국내 기술로 개발하여 실무에 적용함으로써 수자원 이용 효율을 극대화하고 선진국 수준의 수자원 관리기술을 확보하기 위한 방안으로 개발되어졌다. 이러한 물관리 시스템 구축을 위해서는 통합 유역에 적합한 모형의 선택과 이수, 치수, 수질 관리 모델의 통합 방안, 해당 유역특성을 반영한 시스템 구성 방법, 각각의 모형의 입,출력 자료의 관리 및 실무에 적용하기 용이한 GUI 구성 등을 고려하여야 한다. 물관리 시스템은 GIS 기반의 해석모형과 웹기반의 정보, 지식 전달 시스템, 수문자료 관리를 위한 DB시스템 등으로 구성되어져 있으며 SOBEK, RIBASIM, MIKE BASIN, WEAP 등 다양한 물관리 시스템들은 각각의 개발 시기나 쓰임에 따라 해석모형과 DB의 사용유무 등 여러 기능들을 차별화하여 구성하고 있다. RIBASIM(RIver BAsin SIMulation)의 경우 다양한 해석모형 들을 각각의 과정에 따라 사용하고 있으며 CMT(Case Management tool), CAT(Case Analysis Tool)라 불리는 기능들을 통하여 각각의 과정을 순차적으로 진행하고 분석하고 있으며 자사의 수문DB관리 프로그램, 수질, GIS도구 등과 연동하여 사용되고 있다. MIKE BASIN의 경우 ArcGIS의 EXTENSION으로 강력한 GIS기능과 비쥬얼한 화면 구성을 그 특징으로 가지고 있다. IRWMS는 강우유출모형과 댐군 저수지 연계 운영모형, 수질모형으로 구성되어져 있으며 DB와의 연동을 통하여 실시간으로 의사결정자들이 의사결정을 지원하며 실무진 중심의 GUI구성을 통하여 실용성을 중심에 두었다. IRWMS는 금강, 낙동강의 구축사례에서 보듯이 실시간 운영으로 수자원 관리 실무진의 사용에 그 주안점을 두었지만 차후 범용화와 상기에서 언급한 여러 국내외 시스템들의 장점을 받아들인다면 각각의 유역특성에 맞는 다양한 활용으로 수자원기술의 선진화에 크게 기여를 할 것이다.

• Journal of Environmental Science International
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• v.26 no.8
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• pp.939-953
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• 2017

For the development of flow duration curves for the management of 41 Total Maximum Daily Load (TMDL) units of the Nakdong River basin, first, an equation for estimating daily flow rates as well as the level of correlation (correlation and determination coefficients) was extrapolated through regression analysis of discrete (Ministry of Environment) and continuous (Ministry of Land, Infrastructure and Transportation) measurement data. The equation derived from the analysis was used to estimate daily flow rates in order to develop flow duration curves for each TMDL unit. By using the equation, the annual flow duration curves and flow curves, for the entire period and for each TMDL unit of the basin, were developed to be demonstrated in this research. Standard flow rates (abundant-, ordinary-, low- and drought flows) for major flow duration periods were calculated based on the annual flow duration curves. Then, the flow rates, based on percentile ranks of exceedance probabilities (5, 25, 50, 75, and 95%), were calculated according to the flow duration curves for the entire period and are suggested in this research. These results can be used for feasibility assessment of the set values of primary and secondary standard flow rates for each river system, which are derived from complicated models. In addition, they will also be useful for the process of implementing TMDL management, including evaluation of the target level of water purity based on load duration curves.

• Journal of Korea Water Resources Association
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• v.33 no.4
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• pp.447-459
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• 2000

Since the development of water resources is getting more difficult than ever before because of human-sociological condition, it would be necessary to develop a practically applicable technique for the management of water resources based on demand-side concept that could reduce unusable release for more effective and appropriate allocation of limited water resources. The objective of the study is to develop an optimal reservoir system operation model for water supply and energy augmentation by the combination of water budget analysis method in downstream area by MIP technique. The applicable study of the developed model was carried out and water supply capability of Nakdong river basin was re-evaluated by the developed model. The model has been found successful to guarantee appropriate water supply to the basin by means of deficit-supply management method and also turned out to be more practical tool for an optimal reservoir system operation model than other existing models.

• Journal of Korea Water Resources Association
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• v.50 no.2
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• pp.99-109
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• 2017

This research adopted a Robust Decision Making framework to re-evaluate four alternative strategies proposed by the Comprehensive Flood Management Plan for the Yeongsan River Basin report (MLTM, 2005) considering uncertainties of future floods under condition of climate change. To reflect the uncertainties, multiple sets of future flood scenarios were used with three uncertainty factors: the change in rainfall intensity based on the RCP climate change scenarios and the changes in the temporal and the spatial flood distributions. With combinations of these factors, 216 plausible flood scenario sets were generated and the performances of the four alternatives under different future states were evaluated. From the results, the most robust alternative among the strategies was identified. Moreover, the key factors which made the tested alternatives poor were discovered through assessment of the uncertainty factors. This information can provide detailed insights to decision makers and can be utilized to overcome alternatives' potential vulnerabilities by modifying the strategy to be more robust.

• Journal of Korean Society on Water Environment
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• v.34 no.6
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• pp.591-601
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• 2018

Optimized BMP plans for controlling water quality using the Pareto trade-off surface curve in upper basin of Namgang Dam is proposed. The proposed alternatives consist of BMP installation scenarios in which the reduction efficiency of non-point pollutants is maximized in a given budget. The multi-objective optimization process for determining the optimal alternatives was performed without direct implementation of a watershed model such as SWAT analysis, thereby reducing the time taken. The shortening of the calculation time further enhances the applicability of the multi-objective optimization technique in preparing regional water quality management alternatives. In this study, different types of BMP are applied depending on the land use conditions. Fertilizer input control and vegetative filter strip are considered as alternatives to applying BMP to the field but only control of fertilizer input can be applied to rice paddies. Fertilizer input control and vegetative filter strip can be installed separately or simultaneously in a hydrologic response unit. Finally, 175 BMP application alternatives were developed for the water quality management of the upper river basin of Namgang dam. The proposed application alternative can be displayed on the map, which has the advantage of clearly defining the BMP installation location.

• Journal of Korea Water Resources Association
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• v.56 no.3
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• pp.185-194
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• 2023

There are more than 22,300 small streams distributed nationwide in Korea, and they have various runoff characteristics depending on basin area, topography and land use. For small stream disaster management, establishing detailed design standards suitable for the small streams is important, but most of the formulas currently proposed in the small stream design standard are based on the river design standard aimed at national and local rivers or foreign river design standards. The design-width is an important factor in determining the size of the stream. It is determined by using design-flood discharges or more variables such as design-flood discharges, basin area, slop, etc in the small stream design standard. This study collected various characteristics information such as the design-flood discharges, basin area, river length and river slop, and design-width values from 4,073 small streams distributed in 12 cities and provinces in Korea to suggest the appropriated design-width formula. This study developed two design-width formulas by using the regression analysis which one is using the design-flood discharges and the other is using various variables such as the design-flood discharges, basin area, river length and river slope collected from the small steams. It is expected that both equations developed in here can be used for small stream disaster management, such as improving small stream design standard or establishing a comprehensive small stream maintenance plan.

• Journal of Korean Society on Water Environment
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• v.26 no.6
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• pp.1016-1027
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• 2010

The phosphorus contribution rate on water quality of North and South-Han River, and Gyungan-cheon by effluents from environmental fundamental facilities located in upstream basin of Paldang Lake were analyzed. QUALKO2 model was selected for the analysis of contrubution rate, and was constructed considering the location of the main point sources and all facilities in study area. The pollutant loading rates and arrival rates for each unit-watershed in study area were calculated for model operation. For the calibration and verification of model, 2006 water quality dataset from Ministry of Environment and the effluent loadings of the environmental fundamental facilities were used. Reliability Index (RI) method was used to estimate the validity of the results of calibration and verification. The phosphorous contribution rate(%) for each environmental fundamental facility were analyzed by excepting the effluent loading of the facility. The contribution rate was analyzed for each facility, facility groups separated by each main river and each unit-watershed. The main results of analysis for each facility are as follows; (i) the phosphorous contribution of B1 facility is 50%, which is the highest phosphorous contribution rate among those of nine facilities in the North-Han River Basin; (ii) the highest phosphorous contribution is 55.6% from J facility among eight facilities in the Gyungan Stream Basin; (iii) 40% from E treatment facility is the highest among those of twenty eight facilities in the South-Han River Basin.

• Journal of Korea Water Resources Association
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• v.32 no.5
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• pp.525-535
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• 1999

An optimal unit commitment model for efficient management of water and energy resources in a basin using combined mixed integer programming is developed. The combined mixed integer programming model is able to solve the inconsistency problem that may occur from mixed integer programming models. The technique which enables the use of conditional constraints and either-or constraints in the linear programming is also suggested. As a result of applying the combined mixed integer programming model to Lower Colorado River Basin in United States. the basin efficiency is decreased by 1.53% from the results of the mixed integer programming, while it is increased by 0.67% from the results of the historical operation. It is found that the decreased allowable error between power supplies and demands in the combined mixed integer programming causes the decreased basin efficiency.