• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.96-96
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• 2021

수문기상인자 중 하나인 증발산량은 수자원 계획 및 관리 시 고려되며, 특히 물수지 모형 등의 입력자료로 활용된다. 우리나라를 포함한 각국 기상청 및 국제기구에서는 직접 관측이 아닌 FAO56 Penman-Monteith(PM)을 통해 증발산량을 산출하고 있다. FAO56 PM 방법은 복사(radiation), 대기온도(air temperature), 습도(humidity), 풍속(wind speed) 등의 기상인자로부터 기준증발산량(reference evapotransipiration)을 추정하며, 상대적으로 높은 정확성을 보여준다. 그러나 FAO56 PM 방법은 많은 기상인자를 요구하므로 미계측 유역을 포함한 일부지역에 대한 증발산량 자료 구축이 어려운 실정이다. 또한, 기준증발산량의 특성이 시간에 따라 변화하므로 비정상성(nonstationary)을 고려한 분석이 요구된다. 본 연구에서는 온도인자 기반의 대체모형(surrogate model)을 개발하여 기준증발산량의 비정상성을 고려하고자 한다. 한강유역에 위치한 관측소를 대상으로 모형을 개발하였으며, 시간에 따라 변동하는 기준증발산량의 특성을 고려하기 위해 Bayesian 추론기법을 통해 매개변수를 시간에 따라 추정하였다. 또한, 본 연구에서는 대체모형으로 산정된 증발산량을 활용해 가뭄지수인 EDDI(evaporative demand drought index)를 제시하였다. 가뭄 모니터링 및 조기 경보 안내를 위해 개발된 EDDI를 활용하여 기존 가뭄보다 빠르게 진행되는 초단기 가뭄(flash drought)를 평가하였다. 본 연구에서 개발된 모형은 미계측 지역에서도 적용이 가능하므로 수자원분야에서 활용성이 높을 것으로 사료된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.277-277
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• 2020

연속 측정된 수위자료를 유량자료로 환산하는 방법중의 하나인 수위-유량관계곡선식은 국내에서 널리 사용된다. 현장에서 측정된 유량자료로 개발되는 수위-유량관계곡선식(이하 곡선식)은 일반적으로 측정성과의 정확도가 그 정도를 좌우하지만, 개발과정에서 개발자의 주관적인 판단에 의해 좌우되기도 한다. 정확한 곡선식을 개발하기 위해 개발자는 수리학적 특성(수위-${\sqrt{Q}}$, 수위-유속, 수위-단면적 등)을 검토하고, 수문학적 특성(상하류 관계, 유출분석 등)을 검토하여 최종 곡선식을 결정하게 된다. 이러한 여러 검토들 중에 수위-${\sqrt{Q}}$ 검토는 비록 정성적인 검토임에도 불구하고 곡선식의 구간분리, 기간분리, 성과의 이상유무, GZF(Gauge Height of Zero flow) 등을 확인할 수 있는 방법으로 실무에 많이 이용된다. 대부분의 곡선식은 측정성과를 기반으로 개발되어 내삽부분에서는 그 정확도가 상당히 높다고 할 수 있지만 외삽부분은 구간분리의 위치, GZF 등에 따라 큰 차이를 보일 수 있다. 그러나 기존의 수위-${\sqrt{Q}}$ 에 의한 정성적인 검토는 개발자의 숙련도에 따라 곡선식의 정확도가 좌우되는 경향이 있다. 본 연구에서는 수위-${\sqrt{Q}}$ 검토의 이론적 배경을 살펴보고 일본 곡선식의 사례를 응용하여 수위-${\sqrt{Q}}$ 검토의 정량화를 시도하였다. 또한 보다 객관적인 구간분리 위치 결정 및 GZF산정의 방법을 제시하여 개발과정에서의 오류를 최소화 할 수 있고 이는 정확한 유량자료의 생산으로 이어질 것으로 기대된다.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.11 no.1
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• pp.11-20
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• 2006

The Nakdong Estuary is complex water system, where sea water and fresh water meet each other. It has undergone the significant change of its environmental conditions since the construction of the Nakdong River Barrier in 1987. Prior to its construction, mixing and circulation processes in the Nakdong Estuary was dominated by tidal current. However, after the dam construction, those processes were greatly altered by the artificial control of the fresh river water discharge. In this paper, the influence of opening and closing the floodgate of Nakdong River on the outflow behavior of estuarine water from the Nakdong Estuary is analyzed in detail.

• Journal of the Korean earth science society
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• v.22 no.6
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• pp.491-499
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• 2001

Generally, several hydrological characteristics which can be obtained from geographic processing in GIS S/W would be utilized to actual hydrological applications such as landslide stability or drainage analysis. Furthermore, by using practical GIS extension programs, it can be possible that automatic extraction task of those information, which was time-consuming and complex processing, is performed as systematical and automatic processing. In this study, using ArcView GIS S/W and its extensions concerning hydrological processing, some waterflow and surface factors in the area of Yemi sheet scaled 1:50,000 were extracted. Then, assessment of landslide stability, determined by DEM-based variables were carried out in order to investigate practical applicability of extension programs. It is thought that several hydrological factors extracted by this study were significant information to predict field model or hydrological hazardous events. It also reveals that landslide potential is overall stable with stability index mapping and S-A plot, with theoretical basis. This methodology can be applicable to other areas related to hydrological characteristics with measurements in fields.

• The Journal of Engineering Geology
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• v.5 no.3
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• pp.289-300
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• 1995

At the initial stage of the underground reservoir design one should thoroughly consider surface and subsurface hydrology, hydrogeologic characteristics of aquifer system, and the function of cut - off wall because it is linked to the effective management. In this study, three dimensional finite difference model was applied to analyse the function of Ian underground reservoir at Kyungbuk Province. The steady and unsteady state conditions after construction of the underground dam were simulated through the model, and from these results the groundwater budget and the safe yield were determined. The model simulation indicates the infiltration of irrigation water to be one of the major factors of seasonal fluctuation of groundwater level. The recharge rates of irrigation water were estimated as 4.3mm/d during May and June, and 1.7mm/d during July and Agust. Groundwater recharge from the watershed area estimated to about $0.04m^3/s$, almost consistent through the year. In 1984, groundwater discharge through the transverse section of the dam was $0.002m^3/s$ and the optimum yield for two momths(July and Aguest)was $254000m^3$, however, the discharge became $0.013m^3/s$ in1993, implying the failure of cut -off function. without appropaiate of the cut - off wall, optiumum yield during the irrigaton period would be $93, 000m^3$.

• Journal of Wetlands Research
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• v.10 no.1
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• pp.39-47
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• 2008

An eco-washland is increasingly getting attentions as a new alternative plan for management of water resources because of role as flooding control and ecological park without social and ecological side effects. However, there is a lack of study regarding technological development and ecological guidelines to create eco-washland. This study was carried out to suggest ecological guidelines necessary for engineering process to create eco-washland. A study site was the lower reach of Seokjang stream connecting to Yimjin river, a candidate of new eco-washland, and Kumsa area in Namhan river was selected as a reference site. The analysis of ecological characteristics focused on vegetation, fishes, and birds. Major vegetation communities, composed of dominant species such as Salix koreensis, Salix gracylistyla, Miscanthus sacchariflorus, Phragmites communis, etc., formed physical conditions along with other land uses including open water, sandbar, cultivated land, etc. Dominant species of fishes were some species belonging to Cyprinidae and Acheilognathinae, and in case of birds Anser albifrons, Anas platyrhychos, Anas poecilorhyncha belonging to waterbirds and Paradoxornis webbinanus dependent to forest edge were dominantly distributed. The results showed that complex wetland types associated with partially deep water and upland was the optimal eco-hydrological condition of washland. Cyprinidae and Acheilognathinae in case of fish and Egretta spp. (spring season) and Anas spp. (winter season) in case of bird were selected as target species for the these wetland types. Finally, a detail planning criteria to create habitats of these target species were discussed in terms of spawning, breeding, feeding, resting, refuge, nesting, etc.

• Ecology and Resilient Infrastructure
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• v.2 no.4
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• pp.284-290
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• 2015

In this study, two hypotheses were examined to preliminarily verify for the vegetation recruitment and establishment on riparian bars in unregulated rivers; hydrologic regime change and nutrients influx into streams. In order to preliminarily verify the first hypothesis, precipitation patterns were analyzed during a period from March through to May when reeds, the most common riparian vegetation in Korea, germinate and start to grow in riparian areas. The results show that during the last 35 years, the total precipitation during the three-month period decreased by about 15 %, while the total annual one increased by about 15% in Korea. In order to verify the second hypothesis, a preliminary experiment was conducted with a set of two-vegetative flumes for one year. In this experiment, a stream flow with reeds on the riparian sand bars was simulated with a flume with reeds planted on the sand bed and water with a concentration of 3.5 mg of N flowing in the flume for four hours. For comparison, clean water was circulated in the same way in another flume for simulating a stream flow without N. The experimental results show that the growth rate of reeds in N-mixed flow exceeds that in clean water flow by about 30%. The above two results could explain the phenomenon of change in unregulated rivers from white river to green river in Korea, although they were obtained through limited extents of analysis and experiment.

• Journal of the Korean Geophysical Society
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• v.9 no.4
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• pp.321-331
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• 2006

Recently, runoff characteristics of urban area are changing because of the increase of impervious area by rapidly increasing of population and industrialization, urbanization. It needs to extract the accurate topologic and hydrologic parameters of watershed in order to manage water resource efficiently. Thus, this study developed more precise input data and more improved parameter estimating procedures using GIS(Geographic Information System) and GA(Genetic Algorithm). For these purposes, XP-SWMM (EXPert-Storm Water Management Model) was used to simulate the urban runoff. The model was applied to An-Yang stream basin that is a typical Korean urban stream basin with several tributaries. The rules for parameter estimation were composed and applied based on quantity parameters that are investigated through the sensitivity analysis. GA algorithm is composed of these rules and facts. The conditions of urban flows are simulated using the rainfall-runoff data of the study area. The data of area, slope, width of each subcatchment and length, slope of each stream reach were acquired from topographic maps, and imperviousness rate, land use types, infiltration capacities of each subcatchment from land use maps, soil maps using GIS. Also we gave the management scheme of urbanization runoff using XP-SWMM. The parameters are estimated by GA from sensitivity analysis which is performed to analyze the runoff parameters.

• Journal of the Korean Geographical Society
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• v.41 no.4 s.115
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• pp.404-417
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• 2006

In order to clarify some characteristics of hydrological cycle in the subalpine zone of Mt. Halla, water balance has been analysed using hydrological data of a first-order drainage basin around Mansedongsan and meterological data of Odeung AWS. The experimental basin extends from 1,595 m to 1,645 m in altitude and has an catchment area of 1.34 ha. It is largely underlain by trachybasalt and covered with sasa bamboo and sedges. Hydrological observations were carried out every 20 minutes from April 15 to September 19, 2004. The basin shows the total precipitation of 3,074 m that is 1.6 to 3 times of those in coastal and intermontane regions. Surface runoff amounts to 850 mm that is equivalent to 27.6% of the precipitation. By contrast, evapotranspiration only accounts for 14.2% of the precipitation, and the remnant of 1,790 m penetrates underground through a basement. The basin is located in the subalpine zone and then it has a high rainfall intensity as well as a large rainfall due to frequent orographic precipitation. But surface runoff usually dose not exceed 30% of the rainfall while Percolation demonstrates about 2 times of the runoff. Compared with granite or gneiss basins in Korea Peninsula, the experimental basin is characterized by a higher portion of percolation in water balance. And it is probably related to the highly permeable basaltic lavas in Jeju Island which are also overlain by porous volcanic soils.

• Journal of Korea Water Resources Association
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• v.35 no.3
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• pp.321-330
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• 2002

This study aims at the analysis of the geomorphological instantaneous unit hydrograph model (GIS-GIUH) with geographic information system for the rainfall-runoff analysis of watershed which is ungaged or doesn't have sufficient hydrologic data. The rainfall-runoff analysis was performed in Wi stream(Dongkok, Koro, Miseung, Byeungchun, Hyoreung, Museung) which is a representative experimental river basin of IHP. In the process of analysis of the GIUH model, developed GIS-GIUH model and Rosso-GIUH model were applied the study basin and computed hydrographs by these models were compared with observed hydrograph. The GiS-GIUH model shows more closely to the observed hydrograph than Rosso-GIUH model in the peak discharge of the hydrograph. For the development of the GIS-GIUH model, Gamma function factor N was given by N=3.25( $R_{B}$/ $R_{A}$)$^{0.126}$ $R_{L}$$^{-0.055}$, which is the relation of the watershed geomorphological factor, K was also obtained as K=1.50( $R_{A}$/( $R_{B}$. $R_{L}$))/$^{0.10}$.(( $L_{{\Omega}}$+ $L_{{\Omega}-1}$)/V)$^{0.37}$. As the results of analysis, it was found that GIS-GIUH model can be applied to an ungaged watersheds.eds.