• Korean Journal of Ecology and Environment
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• v.46 no.4
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• pp.471-487
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• 2013

This review paper was written to provide background information as well as future application for aquatic ecologists interested in using stable isotope. Stable isotope techniques has proved to be an extremely useful to elucidate a lot of environmental and ecological problems. Stable isotopes have been used as possible tracers to identify sources, to quantify relative inputs in a system. When utilized carefully, stable isotope tools provides apparent advantages for the scientists to find out the processes of material cycles in various environments and energy flows in natural ecosystems.

• Journal of Environmental Science International
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• v.22 no.5
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• pp.555-562
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• 2013

Jeju Island, the heaviest raining area in Korea, is a volcanic Island located at the southernmost of Korea, but most streams are of the dry due to its hydrological/geological characteristics different from those of inland areas. Therefore, there are limitations in applying the results from the mainland to the studies on stream run-off characteristics analysis and water resource analysis of Jeju Island. In this study, the SWAT(soil & water assessment tool) model is used for the Hwabuk stream watershed located east of the downtown to calculate the long-term stream run-off rate, and WMS(watershed modeling system) and HEC-HMS(hydrologic modeling system) models are used to figure out the stream run-off characteristics due to short-term heavy rainfall. As the result of SWAT modelling for the long-term rainfall-runoff model for Hwabuk stream watershed in 2008, 5.66% of the average precipitation of the entire basin was run off, with 3.47% in 2009, 8.12% in 2010, and root mean square error(RMSE) and determination coefficient($R^2$) was 496.9 and 0.87, respectively, with model efficient(ME) of 0.72. From the results of WMS and HEC-HMS models which are short-term rainfall-runoff models, unless there was a preceding rainfall, the runoff occurred only for rainfall of 40mm or greater, and the run-off duration averaged 10~14 hours.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.2
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• pp.87-99
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• 1992

The types of dam-break have been classified as instantaneous and gradual failure. Equations for estimating the peak outflow have been derived respectively as a metric unit. New dimensionless routing curves have been deveoloped based on the distance parameter which has been used in SMPDBK and hydro-geometric characteristics of dams and reservoirs in Korea. These suggested curves can be used for any case of the flow of supercritical or subcritical. The computed peak flowrate shows the trend of decreasing dependence on the Froude numbers as it increases. These curves are applied to Hyogi dam. and the results have good agreements with the data observed in the peak discharges, peak elevations and flood travel time. The simplified dam-break model in this study would contribute effectively to forecast the dam-break flood in this country with minimum informations in a short time.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.213-213
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• 2011

남강은 낙동강에 유입되는 지류 중 가장 큰 하천으로서 낙동강 하류의 수질에 매우 큰 영향을 미치고 있다. 남강댐은 저수 용량에 비해 유역면적이 주요 저수지들에 비하여 월등하게 크므로 홍수시 순간적으로 다량의 유량 및 오염물질이 방류되어 낙동강에 유입되는 특성을 가지고 있다. 남강댐은 서북측에서 유입되는 경호강과 남쪽에서 댐축과 가까이 유입되는 덕천강이 공간적으로 멀리 떨어져 있음으로 인해, 주요 유입물질이 유입되는 시기에 횡방향 및 종방향으로 농도차이를 나타내고 있으며, 과거에 설치되었던 댐이 수중에 존재함으로 인해 국지적인 정체현상이 발생하고 있다. 남강은 현재 경남권은 물론, 거제 및 부산권의 용수원을 공급하거나 예정으로 있으므로 수질관리에 가장 큰 우선순위를 두어야 한다. 남강댐의 합리적인 수질관리를 위해서는 호 내의 공간적 시간적 수질변화에 대한 이해와 수질변화 여건에 있으며 이용되는 만큼 호 내의 정밀한 유체거동 해석이 필수적이다. 본 연구에서는 남강댐의 수리-수질 특성을 진단하고 예측하기 위하여 3차원 수리동역학 모델인 EFDC와 수질모델인 WASP을 연계하여 사용하였다. 유량 경계조건은 한국수자원공사 및 국가수자원관리 종합 정보시스템(WAMIS)의 남강댐 운영 자료를 바탕으로 남강댐의 유입량과 유출량 자료를 작성하였다. 남강으로 유입되는 지천 및 호 내의 수온, SS 및 수질농도 등은 환경부의 물환경정보시스템의 월 측정자료를 사용하였으며, 기상조건은 진주 기상대의 자료를 사용하였다. 본 연구에서 가용한 입력자료를 이용하여 남강댐의 수리 및 수질 및 부유물질 특성을 모의하였으며 EFDC-WASP 모델을 이용하여 성공적인 보정이 가능한 것을 확인하였다. 그러나 자세한 분석과 대책을 수립하기 위해서는 남강댐의 유입 수질 및 유량 자료에 대한 실질적인 모니터링이 수행되는 것이 필요하다고 판단된다.

• Journal of Korea Water Resources Association
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• v.47 no.12
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• pp.1213-1225
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• 2014

The development of bars and sediment sorting processes in the braided channels with the mixed grain sizes are investigated experimentally in this study. The sediment in the steep slope channels discharges with highly fluctuation. However, it discharges with relatively periodic cycles in the mild slope channels. The characteristics and amplitudes of the dominant bars are examined by double fourier analysis. The dimensionless sediment particle size decreases as the longitudinal bed elevation increases. However, the size increases as the longitudinal bed elevation decreases. As the dimensionless critical tractive force in the surface layer ratio to the force in the subsurface layer increases, the surface geometric mean size of sediments and the dimensionless sediment particle size decrease. This means that coarse matrix is formed with the dimensionless tractive force by the sediment selective sorting.

• Journal of Korea Water Resources Association
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• v.41 no.6
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• pp.619-628
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• 2008

Bank protection is a structure constructed to protect directly embankment breakage and erosion by river flow. Traditionally, the type of bank protection has been decided by practitioner's subjective and empirical judgement, which often causes problems after construction. Recently, however, it becomes important to consider not only physical protection but also environment. Various types of bank protection for environment-friendly river are now available. Thus, there is a need for more objective and quantitative decision method for bank protection work. This study adopts the analytic hierarchy process (AHP) to improve the objectiveness in the decision of bank protection work. Criteria for stability, economy, construction, environment are identified and a standardized process is presented for field application. With the proposed method, one can prioritize various bank protection works and make the optimal decision. We believe that the method can serve as a useful tool for river engineers in practice.

• Water for future
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• v.15 no.2
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• pp.33-39
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• 1982

For the determination of a reservoir capacity Rippl's mass-curve method has long been used with the past river flow data assuming the same flow records will be repeated in the future. In this study the synthetic generation methods of thomas-Fiering type and harmonic analysis were used to synthetically generate 50 years of monthly river inflows to three single-purpose reservoris(Chuncheon, Chungpyong, Hwacheon) and three multi-purpose reservoirs(Soyany, Andon, Daichung). The generated sequences of monthly flows were analyzed based on the range concept, and hence the so-determined ranges for single-prupose and multi-purpose rewervoirs were correlated with the number of monthly flow subseries, resulting an empirical equation of the Feller's type. (1) Single-purpose reservoir $$R_n=2.8357 I\sqrt{n}$$ (2) Multi-purpose reservoir $$R_n=2.5145 I\sqrt{n}$$ where, $R_n$:Range(㎥/S-M) n:periodic(12 months, ……120 months) I:Input mean(㎥/S-M) In Korea, the monthly inflow data generation will be fit to the Thomas-Fiering type, and this paper shows that the periodic range is easily calculated without the Rippl's mass-curve method as shown above formula.

• Journal of Wetlands Research
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• v.13 no.1
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• pp.53-66
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• 2011

We estimated the expected flood damage considering uncertainty which is involved in hydrologic processes and data. Actually, this uncertainty represents a freeboard or safety factor in the design of hydraulic structures. The uncertainty was analyzed using Bootstrap method, and SIR algorithm then the frequency based rainfalls were estimated for each method of uncertainty analysis. Also the benefits for each uncertainty analysis were estimated using 'multi-dimensional flood damage analysis(MD-FDA). As a result, the expected flood damage with SIR algorithm was 1.22 times of present status and Boostrap 0.92 times. However when we used SIR algorithm, the likelihood function should be selected with caution for the estimation of the expected flood damage.

• Journal of Korea Water Resources Association
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• v.40 no.12
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• pp.931-941
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• 2007

Traditionally, the decision of river width has aimed majorly at flood control and good river conveyance. And the river width has been decided by practitioner#s subjective and empirical opinion. Recently, however, there is a need for more objective and thus quantitative decision method for decision of river width considering not only economical aspect but also social or environmental aspect. This study adopts the analytic hierarchy process (AHP) to improve the objectiveness in the decision of river width. Criteria and a standardized process are presented for field application. Using the proposed method, one can prioritize various river width and make the optimal decision. We believe that the method can serve as a useful tool for river engineers in practice.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.271-271
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• 2011

최근의 유출해석은 지리정보체계(GIS, Geographic Information System) 및 지형자료(DEM, Digital Elevation Model 등) 구축의 발달로 대부분 격자 기반의 분포형 강우-유출 모형을 통해 이루어지고 있으며, Rodriguez-Iturbe and Valdes (1979)에 의해 소개된 통계물리학적 접근방법인 지형학적 순간단위도(GIUH)모형 역시 DEM을 기반으로 한 연구가 꾸준히 진행되어 온 실정이다(Maidment, 1993; D'odorico and Rigon, 2003; Di Lazzaro, 2010). 이러한 격자 기반 모형들은 대부분 8방향 최급경사에 기초한 흐름방향도를 기반으로 물의 유동을 표현한다. 8방향법에 의해 결정된 흐름방향도를 이용할 경우 각 격자 중심에서 유역출구 까지의 배수로경로길이를 비교적 쉽고, 빠르게 계산할 수 있다는 장점을 가지나, 공간해상도(격자 규모)에 따라 상이한 결과를 나타내는 것을 예상할 수 있다. 따라서 본 연구에서는 DEM의 공간해상도에 따른 배수경로길이의 통계적 변화양상을 살펴보고, 이로부터 실제 수문사상의 통계적 특성과 Di Lazzaro(2010)의 특성유속산정 공식을 이용해 지표면과 하천의 특성유속을 산정하였다. 산정된 특성유속들을 D'odorico and Rigon(2003)이 제시한 값과 비교함으로써 격자 기반의 GIUH 모형의 적용에 있어서 적정 공간해상도를 찾고자 하였다. 대상유역으로는 국제수문개발계획(IHP, International Hydrological Project)의 금강수계 보청천 유역 중 이평수위국을 출구로하는 소유역을 선정하였으며, DEM의 공간해상도는 수치지형도의 축척을 고려하여 1: 5,000의 경우 5, 10, 15, 20m를, 1: 25,000의 경우 20, 30, 50, 100, 150, 200m로 결정하였다. 분석 결과 격자 형태 GIUH의 특성유속을 산정을 위한 적정 공간해상도는 1:5,000의 경우 5m를, 1:25,000의 경우에는 20～50m의 범위를 적용하는 것이 타당할 것으로 판단된다.