• 한국농공학회지
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• 제21권1호
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• pp.13-23
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• 1979

The predictien of a design flood hydrograph at a particular site on a river may be based on the derivation of a discharge or stage hydrograph at an upstream section, together with a method to route this hydrograph along the rest of the river. In order to limit this investigation to cases where the assumption like uniform rainfall may be reasonably valid, the derivation of unit hydrographs has been limited to catchment with an area less than 500 km2. Consequently, flood routing methods provide a useful tool for the analysis of flooding in all but the smaller catchment, particularly where the shape of the hydrograph as well as the peak value is required. The author, therefore, will introduce here a flood routing method on the open channel with a peak discharge of the catchment area concerned. The importance of being able to route floods accurately is also reflected in the large number of flood routing method which have been developed since the year 1900. There are the modified puls method, Steinberg method, Goodrich method, Ekdahl method, Tatum's mean continuously Equation, wisler-Brater method, Muskingum, chung, and Muskingum-cunge (M-C) method and so on. The author will try to introduce a flood routing method which is revised Muskingum-cunge method. In calculating flood routing by the M-C method, whole variable parameters on the river were assumed to almost uniform values from the upstream to the downstream. In the results, the controlled flood rates at the 40km downstream on the river is appeared to decrease 22m$^3$/sec or 12 percent of the peak flood 170m$^3$/sec.

• 한국수자원학회논문집
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• 제32권4호
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• pp.427-435
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• 1999

Clark 모형은 홍수수문학에서 널리 이용되는 합성단위유량도 추정을 위한 모형이다. 본 연구에서는 미계측유역에 Clark 모형을 적용하기 위한 매개변수 추정기법을 고안하여 적용하였다. 모형의 시간-면적유하곡선은 해석적인 방법으로 유도하였으며 모형을 무차원화 하였다. 도달시간의 계산을 위하여 지형학적 자기상사성을 이용한 공식을 적용하였으며 저류상수는 유역의 시간특성의 상사성 공식을 이용하여 추정하였다. 제안된 모형의 타당성을 검토하기 위하여 동곡의 실측자료와 모형의 결과를 비교한 결과 비교적 잘 일치되는 경향을 보여주었다.

• 물과 미래
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• 제14권4호
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• pp.27-34
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• 1981

The design flow of the urban strom drainage systems has been assessed largely on a basis of empirical relations between rainfall and runoff, and the rational formula has been widely used for the cities in our country. In order to estimate it more accurately, the urban runoff simulation model based on the RRl method has been developed and applied to the sample basin in this study. The rainfall hyetograph of the design stromfor the design flow has been obtained by the determination of the total rainfall and the temporal distributions of that rainfall. The total rainfall has been assessed from the empirical formula of rainfall intensity and the temporal distribution of that rainfall determined on the basis of Huff's method from the historical rainfall data of the basin. The virtual inflow hydrograph to each inlet of the basin has been constructed by computing the series of discharges in each time increment, using design strom hyetograph and time-area diagram. The actual runoff hydrograph at the basin outlet has been computed from the virtual inflow hydrographs by developing a relations between discharge and storage for the watershed. The discharge data for verification of the simulated runoff hydrograph are not available in the sample basin and so the sensitivity analysis of the simulation model has not been possible. The peak discharge for the design of drainage systems has been estimated from the computed runoff hydrograph at the basin outlet and compared to thatl obtained form the rational formula.

• Water Engineering Research
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• 제2권4호
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• pp.219-229
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• 2001

Synthetic unit hydrograph equations for rainfall run-off characteristics analysis and estimation of design flood have long and quite frequently been presented, the Snyder and SCS synthetic unit hydrograph. The major inputs to the Snyder and SCS synthetic unit hydrograph are lag time and peak coefficient. In this study, the methods for estimating lag time and peak coefficient for small watersheds proposed by Zhao and McEnroe(1999) were applied to the Kum river basin in Korea. We investigated lag times of relatively small watersheds in the Kum river basin in Korea. For this investigation the recent rainfall and stream flow data for 10 relatively small watersheds with drainage areas ranging from 134 to 902 square kilometers were gathered and used. 250 flood flow events were identified along the way, and the lag time for the flood events was determined by using the rainfall and stream flow data. Lag time is closely related with the basin characteristics of a given drainage area such as channel length, channel slope, and drainage area. A regression analysis was conducted to relate lag time to the watershed characteristics. The resulting regression model is as shown below: ※ see full text (equations) In the model, Tlag is the lag time in hours, Lc is the length of the main river in kilometers and Se is the equivalent channel slope of the main channel. The coefficient of determinations (r$^2$)expressed in the regression equation is 0.846. The peak coefficient is not correlated significantly with any of the watershed characteristics. We recommend a peak coefficient of 0.60 as input to the Snyder unit-hydrograph model for the ungauged Kum river watersheds

• 대한토목학회논문집
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• 제33권4호
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• pp.1361-1375
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• 2013

Lee et al. (2011)이 제시한 목감천 유역의 하천복원 설계절차에 근거하여 수리구조물의 설계와 관련 있는 설계홍수량을 산정에 있어 비정상성을 고려하여 산정하였다. 본 연구의 목적은 목감천 유역에서 비정상성을 고려한 새로운 설계홍수량을 제안하기 위함이다. 설계홍수량 산정방법인 설계-호우단위도법과 직접 홍수빈도해석법을 적용하였으며, 각각의 방법에 사용되는 빈도분석은 NCAR (National Center for Atmospheric Research)에서 개발된 extRemes 모형을 통하여 비정상성을 고려하였다. 직접 홍수빈도해석의 방법은 유량으로부터 직접 빈도해석을 수행한다는 점에서 신뢰성이 기대되지만, 설계-호우단위도법보다 다소 과소 추정되었다. 따라서 가장 크게 산정된 설계호우-단위도법의 100년 빈도 설계홍수량을 목감천 유역의 설계홍수량으로 결정하였다.

• Journal of Forest and Environmental Science
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• 제34권4호
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• pp.293-303
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• 2018

Sumber Jaya (54,194 hectares) is a district in West Lampung, Indonesia, located at the upper part of Tulang Bawang watershed. This watershed is one major water resource for Lampung Province, but has become a focal point of discussion because of the widespread conversion of forestland to coffee plantations and human settlements which lead to environmental and hydrological problems. This research aimed to evaluate Sumber Jaya watershed affecting by rapid land use change using hydrological methods as a base for watershed management. Nested catchment structure consisted of eight sub-catchments was employed in this research to assess scaling issues of land use change impacts on rainfall-runoff connections. Six tipping bucket rain gages were installed on the hill slopes of each sub-catchment and Parshall flumes were installed at the outlets of each sub-catchment to monitor stream flow. First, unit hydrograph that expressed the relationship of rainfall and runoff was computed using IHACRES model. Second, unit hydrograph was also constructed from observations of input and response during several significant storms with approximately equal duration. The result showed that most of the storm flow from these catchments consisted of slow flow. A maximum of about 50% of the effective rainfall became quick flow, and only less than 10% of remaining effective rainfall which was routed as slow flow contributed to hydrograph peaks; the rest was stored. Also, comparing peak responses and recession rates on the hydrograph, storm flow discharge was generally increased slowly on the rising limb and decreased rapidly on the falling limb. These responses indicated the soils in these catchments were still able to hold and store rain water.

• 한국수자원학회논문집
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• 제46권5호
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• pp.547-558
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• 2013

설계홍수량 산정 시 일반적으로 활용하는 합성단위도법에 대한 개선안을 제시하였다. 본 연구에서는 합성단위도의 형태를 결정짓는 첨두 비유량과 첨두시간의 결정을 위하여 첨두수문량과 유역의 지형공간적 형상계수간의 회귀분석을 시행한 결과, 유역의 단순 공간적 기하요소보다는 형상계수의 결정계수가 뚜렷이 높았으며, 유역의 지형특성영향을 독립적으로 검토할 경우 결정계수가 0.52~0.69에 그쳤으나, 지형특성이 조합된 형상계수를 이용하여 민감도분석을 해보면 결정계수가 0.73~0.81로 개선된 결과를 확인할 수 있었다. 일반적으로 단위도를 적용할 수 있는 적합한 유역의 면적은 대략 500~700 $km^2$이라 볼 때, 이러한 영역에서 유역유출모의를 통한 본 연구의 합성단위도를 검증한 결과, 특이값이 발생하는 유역을 제외하고 본 연구결과의 상대오차가 1.7~29.0%(평균 11.6%)의 수준을 보여주었다. 합성단위도법 적용에 관한 기존사례(KICT, 2000)는 상대오차가 35.0~64.9%(평균 46.7%)를 보여주어 본 연구의 제안식이 기존에 비하여 개선된 결과를 보여주고 있다.

• 산업기술연구
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• 제21권B호
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• pp.223-232
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• 2001

This study is finding the most appropriate model of kangwondo watershed. To synthesize each hydrograph, It is found to several parameters which are used in existing hydrographes. then the synthestic hydrograph is compared and investigated with many hydrographes of the rivers in kanwondo. These methods, Nakayasu, Clark, SCS are used to calculate the run-off of this watershed. When the calculated run-off is compared with real rating-curves, then it is found that the SCS method using the Clark's concentrantion time is the best way on this area having large watershed, long river length and gentle water slope, the Nakayasu method is more suitable on this area having small watershed, short river length and steep water slope. Also it is founded from analyzing run-off hydrographes, peak run-off and peak time that the Clark's method applied Kirpich's concentration time way is suitable in the area of kangwondo.

• 물과 미래
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• 제18권3호
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• pp.265-270
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• 1985

The prediction of a design-flood hydrograph at a particular site on a river may be based on the derivation of discharge or stage hydrograph at an upstream section, togeater with a method to route this hydrograph along the rest of river. On the other hand, flood routing methods provide a useful tool for the analysis of flooding in all but the smaller catchment, and these methods are largely stored into hydrological method and hydraulic method. Although the Muskingum Method as a hydrological method ignores dynamic effects on the flood wave, Muskingum-Cunge Method based on hydraulic method is possible to improve the method so that it gives a good approximation to the solution of the linear convective-diffusion equation. This is made on the basis of the finite diffeience equation for the Muskingum Method. In the study, the outflows predicted by Muskingum-Cunge Method are campared with the observed outflows of the Pyung Chang River.

• 한국수자원학회논문집
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• 제30권4호
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• pp.327-334
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• 1997

본 연구는 우리나라의 2개 하천지점에서 홍수 수문곡선 유도에 이용된 탱크모형의 매개변수를 검정하여 향후 상기 모형들이 관련 하천의 홍수예·경부에 직접 이용되도록 하는데 있다. 선정된 지점은 금강의 공주와 영산강의 나주지점이며 모형의 검정 결과 영산강의 겨우 영산강 유역개발 2단계 수문조사에서 유도된 모형의 매개변수가 비교적 타당하였으나 금강의 경우 대청 다목적댐 타당성 조사보고서에 수록된 모형의 매개변수에 10-1을 곱함으로서 실측치와 거의 일치하는 홍수 수문곡선을 얻을 수 있었다.