• Title, Summary, Keyword: Runoff

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Rainfall-Runoff Analysis of a Rural Watershed (농촌유역의 강우-유출분석)

  • Kim, Ji-Yong;Park, Ki-Jung;Chung, Sang-Ok
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.93-98
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    • 2001
  • This study was performed to analyse the rainfall and the rainfall-runoff characteristics of a rural watershed. The Sangwha basin($105.9km^{2}$) in the Geum river system was selected for this study. The arithmetic mean method, the Thiessen's weighing method, and the isohyetal method were used to analyse areal rainfall distribution and the Huff's quartile method was used to analyse temporal rainfall distribution. In addition, daily runoff analyses were peformed using the DAWAST and tank model. In the model calibration, the data from June through November, 1999 were used. In the model calibration, the observed runoff depth was 513.7mm and runoff rate was 45.2%, and the DAWAST model simulated runoff depth was 608.6mm and runoff rate was 53.5%, and the tank model runoff depth was 596.5mm and runoff rate was 52.5%, respectively. In the model test, the data from June through November, 2000 were used. In the model test, the observed runoff depth was 1032.3mm and runoff rate was 72.5%, and the DAWAST model simulated runoff depth was 871.6mm and runoff rate was 61.3%, and the tank model runoff depth was 825.4mm and runoff rate was 58%, respectively. The DAWAST and tank model's $R^{2}$ and RMSE were 0.85, 3.61mm, and 0.85, 2.77mm in 1999, and 0.83, 5.73mm, and 0.87, 5.39mm in 2000, respectively. Both models predicted low flow runoff better than flood runoff.

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RUNOFF ANALYSIS BY SCS CURVE NUMBER METHOD

  • Yoon, Tae-Hoon
    • Korean Journal of Hydrosciences
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    • v.4
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    • pp.21-32
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    • 1993
  • The estimates of both runoff depth and peak runoff by the basin runoff curve numbers, which are CN-II for antecedent moisture condition- II and CN -III for antecedent moisture condition-III, obtained from hydrological soil-cover complexes of 26 watersheds are investigated by making use of the observed curve numbers, which are median curve number and optimum curve number, computed from 250 rainfall-runoff records. For gaged basins the median curve numbers are recommended for the estimation of both runoff depth and peak runoff. For ungaged basin, found is that for the estimate of runoff depth CN-II is adequate and for peak runoff CN-II is suitable. Also investigated is the variation of the runoff curves during storms. By the variable runoff curve numbers, the prediction of runoff depth and peak runoff can be improved slightly.

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The Sensitivity Analysis of Parameters of Urban Runoff Models due to Variations of Basin Characteristics (I) - Development of Sensitivity Analysis Method - (유역특성 변화에 따른 도시유출모형의 매개변수 민감도분석(I) -민감도분석방법의 개발-)

  • Seo, Gyu-U;Jo, Won-Cheol
    • Journal of Korea Water Resources Association
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    • v.31 no.3
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    • pp.243-252
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    • 1998
  • In this study, the new dimensionless values were defined and proposed to determine the parameters of urban runoff models based on the relative sensitivity analysis. Also, the sensitivity characteristics of each parameter were investigate. In order to analyze the parameter sensitivities of each model, total runoff ratio, peak runoff ratio, runoff sensitivity ratio, sensitivity ratio of total runoff, and sensitivity ratio of peak runoff were defined. $$Total\;runoff\;ratio(Q_{TR})\;=\;\frac{Total\;runoff\;of\;corresponding\;step}{Maximum\;total\;runoff}$$$$Peak\;runoff\;ratio(Q_{PR})\;=\;\frac{Peak\;runoff\;of\;corresponding\;step}{Maximum\;peak\;runoff}$$$$Runoff\;sensitivity\;ratio(Q_{SR})\;=\;\frac{Q_{TR}}{Q_{PR}}$$ And for estimation of sensitivity ratios based on the scale of basin area, rainfall distributions and rainfall durations in ILLUDAS & SWMM, the reasonable ranges of parameters were proposed.

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Characteristics of Runoff ratio and Pollutant Loading in Rural Watersheds (농촌유역에서의 유달부하량 및 유달율의 특성)

  • 양영민;권순국
    • Proceedings of the Korean Society of Agricultural Engineers Conference
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    • pp.533-540
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    • 1998
  • In this study, to propose the methods predicting water qualities in rural areas, the methods which were based on the runoff ratio, the relationships between the pollutant load(L) and the water runoff(Q), and the relationships between the runoff ratio and the water runoff in Bokha stream watersheds were examined. As a result, we had acquired reliable the values of runoff ratio and the reasonable equations between the pollutant load(L) and the water runoff(Q) in Bokha stream watersheds. And it was noticed that the runoff ratio had tendency of varying directly proportional to the water runoff.

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A study on the flood runoff analysis with TANK MODEL (탱크 모델에 의한 홍수(洪水) 유출량(流出量) 해석(解析)에 관(關)한 연구(硏究))

  • Hong, Chang-sun;Choi, Han-kuy
    • Journal of Industrial Technology
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    • v.3
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    • pp.95-101
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    • 1983
  • This study aims at the determination of the coefficienties of runoff and infiltration affecting runoff. The rating curve is more available than the peak flood runoff to determine flood control plan of flood control reservoir and the volume of hydroelectric power plant, or to make multipurpose dam. In hydrologic analysis and design, it is necessary to develop relations between precipitation and runoff, possible using some of the factors affecting runoff as parameters. In order to calculate the runoff discharge, the runoff process constituting elements are divided to the surface runoff, the subsurface runoff and the groundwater runoff. By comparing the computed hydrograph with the measured hydrograph, determinned the watershed TANK Model constant Varying the tank model constant for approximating the computed hydrograph to the measured hydrograph.

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Long Term Runoff Simulation for Water Balance at Daecheong Basin (대청유역 물수지 분석을 위한 장기 유출모의)

  • Lee, Sang-Jin;Kim, Joo-Cheol;Noh, Joon-Woo
    • Journal of Environmental Science International
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    • v.19 no.10
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    • pp.1211-1217
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    • 2010
  • For an accurate rainfall-runoff simulation in the river basin, it is important to consider not only evaluation of runoff model but also accurate runoff component. In this study long-term runoffs were simulated by means of watershed runoff model and the amounts of runoff components such as upstream inflow, surface runoff, return flow and dam release were evaluated based on the concept of water budget. SSARR model was applied to Daecheong basin, the upstream region of Geum river basin, and in turn the monthly runoff discharges of main control points in the basin were analyzed. In addition, for the purpose of providing the basic quantified water resources data the conceptual runoff amounts were estimated with water budget analysis and the reliability of the observations and the monthly runoff characteristics were investigated in depth. The yearly runoff ratios were also estimated and compared with the observations. From the results of the main control points, Yongdam, Hotan, Okcheon and Daecheong, the yearly runoff ratios of those points are consistent well with data reported previously.

Runoff Analysis and Application of Runoff Model of Urban Storm Drainage Network (도시하수도망에 대한 유출모형의 남용과 유출해석)

  • 박성천;이관수
    • Journal of Environmental Health Sciences
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    • v.22 no.4
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    • pp.33-42
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    • 1996
  • This research is to show the application of runoff model and runoff analysis of urban storm drainage network. the runoff models that were used for this research were RRL, ILLUDAS, and SWMM applicative object basin were Geucknak-chun and Sangmu drainage basin located in Seo-Gu, Kwangju. The runoff analysis employed the design storm that distributed the rainfall intensity according to the return period after the huff's method. The result from the comparative analysis of the three runoff models was as follows The difference of peak runoff by return period was 20-30% at Sangmu drainage area of $3.17 Km^2$, while less than 10% at Geucknak-chun drainage area of $12.7 Km^2$. The peak runoff were similar to all models. At the runoff hydrograph the times between rising and descending points were in the sequence of RRL, ILLUDAS and SWMM, but the peak times were similar to all models. The conveyance coefficient to examine the conveyance of the existing drainage network was 0.94-1.37, which means insecure, in Geucknak-chun drainage basin and 0.69-1.16, which means secure, in sangmu drainage basin.

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Estimation of runoff coefficient through impervious covers analysis using long-term outflow simulation (장기유출 모의를 통한 도시유역 불투수율에 따른 유출계수 변화)

  • Kim, Young-Ran;Hwang, Sung-Hwan
    • Journal of Korean Society of Water and Wastewater
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    • v.28 no.6
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    • pp.635-645
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    • 2014
  • The changes of rainfall pattern and impervious covers have increased disaster risks in urbanized areas. Impervious covers such as roads and building roofs have been dramatically increased. So, it is falling the ability safety of flood defense equipments to exist. Runoff coefficient means ratio of runoff by whole rainfall which is able to directly contribute at surface runoff during rainfall event. The application of accurate runoff coefficients is very important in sewer pipelines design. This study has been performed to estimate runoff characteristics change which are applicable to the process of sewer pipelines design or various public facilities design. It has used the SHER model, a long-term runoff model, to analyze the impact of a rising impervious covers on runoff coefficient change. It thus analyzed the long-term runoff to analyze rainfall basins extraction. Consequently, it was found that impervious surfaces could be a important factor for urban flood control. We could suggest the application of accurate runoff coefficients in accordance to the land Impervious covers. The average increase rates of runoff coefficients increased 0.011 for 1% increase of impervious covers. By having the application of the results, we could improve plans for facilities design.

Characteristics of Andong Dam Inflow during Non-rainfall Season

  • Park, Gey-Hwan;Park, Ki-Bum;Chang, In-Soo
    • Journal of Environmental Science International
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    • v.27 no.10
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    • pp.845-851
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    • 2018
  • In this study, the runoff characteristics of the non-rainfall period were examined using daily rainfall data from 1977 to 2017 and the data of runoff into the dam. Results showed that, the mean runoff decreases with longer non-rainfall periods in the Andong dam basin. The correlation coefficient between non-rainfall days and average runoff reaches 0.85. The results of the analysis of the runoff characteristics during the non-rainfall period, based on the preceding rainfall of Andong dam are as follows. The runoff characteristics of the entire non-rainfall period, shows that, for a rainfall of 1.0 mm or less, the runoff height was larger than the rainfall size and the base runoff larger. The correlation between the antecedent rainfall and runoff height was reached as high as 0.9864 in the 30 ~ 50 mm interval of the antecedent rainfall period, and this is the interval where the linearity of rainfall and runoff was at its maximum in the Andong dam basin. The correlation between the antecedent rainfall and the runoff height reached 0.92 for rainfalls of 100.0 mm. However, for rainfalls of 100.0 mm greater, the correlation between the antecedent rainfall and runoff height during the rainfall period was 0.64, which is relatively small. In this study, we investigated the runoff characteristics of the rainfall period in the Andong dam watershed. As a result, it was confirmed that the mean runoff decreased with rainfall duration. The linearity was found to be weak for rainfall events greater than 100.0 mm. The results of this study can be used as data for water balance analysis and for formulating a water supply plan to establish water resource management of Andong dam.

Energy Conservation for Runoff and Soil Erosion on the Hillslope (산지사면의 유출 및 토양침식에 대한 에너지 보존)

  • Shin, Seung-Sook;Park, Sang-Deog;Cho, Jae-Woong;Hong, Jong-Sun
    • Proceedings of the Korea Water Resources Association Conference
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    • pp.234-238
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    • 2008
  • The energy conservation theory is introduced for investigating processes of runoff and soil erosion on the hillslope system changed vegetation condition by wildfire The rainfall energy, input energy consisted of kinetic and potential energy, is influenced by vegetation coverage and height. Output energy at the outlet of hillslope is decided as the kinetic energy of runoff and erosion soil, and mechanical work according to moving water and soil is influenced dominantly by the work rather than the kinetic energy. Relationship between output and input energy is possible to calculate the energy loss in the runoff and erosion process. The absolute value of the energy loss is controlled by the input energy size of rainfall because energy losses of runoff increase as many rainfall pass through the hillslope system. The energy coefficient which is dimensionless is defined as the ratio of input energy of rainfall to output energy of runoff water and erosion soil such as runoff coefficient. The energy coefficient and runoff coefficient showed the highest correlation coefficient with the vegetation coverage. Maximum energy coefficient is about 0.5 in the hillslope system. The energy theory for output energy of runoff and soil erosion is presented by the energy coefficient theory associated with vegetation factor. Also runoff and erosion soil resulting output energy have the relation of power function and the rates of these increase with rainfall.

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