• Journal of The Korean Society of Agricultural Engineers
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• v.52 no.4
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• pp.1-10
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• 2010

In this study, two estimation equations for preparing stream data for distributed storm runoff model were developed by analyzing the nonlinear relation between upstream flow-length and stream width, and between upstream flow-length and stream bed-slope. The equations for stream cell were tested in Chungjudam watershed (6,661 $km^2$) using KIMSTORM. Six storm events occurring between 2003 and 2008 were selected for the model calibration and verification before the test of equations. The average values of the Nash-Sutcliffe model efficiency (ME), the volume conservation index (VCI), the relative error of peak runoff rate (EQp), and the difference of time to peak runoff (DTp) were 0.929, 1.035, 0.037, and -0.406 hr for the calibrated four storm events and 0.956, 0.939, 0.055, and 0.729 hr for the two verified storm events respectively. The estimation equations were tested to the storm events, and compared the flood hydrograph. The test result showed that the estimation equation of stream width reduced the peak runoff and delaying the time to peak runoff, and the estimation equation of stream bed-slope showed the opposite results.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.E
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• pp.33-46
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• 1990

Abstract Over 700/0 of the rural land area in Korea is mountainous and small watersheds provide most of the water resources for agricutural use. To provide an appropriate tool for the agricultural water resource development project, SNUA2, a mathematical model for simulating the physical processes governing the precipitation-runoff relationships and predicting the storm and long-term runoff quantities from the small mountainous watersheds was developed. The hydrological characteristics of small mountainous watersheds were reviewed to select appropriate theories for the simulation of the runoff processes, and a deterministic and distributed model was developed. In this, subsurface flows are routed by solving Richard's two dimensional equation, the dynamics of soil moisture contents are simulated by the consideration of phenological factors of canopy plants and surface flows are routed by solving the kinematic wave theory by numerical analysis. As a result of an application test of the model to the Sanglim watershed, peak flow rates of storm runoff were over-estimated by up to 184.2%. The occurence time of peak flow and total runoff volume of storm runoffs simulated were consistent with observed values and the annual runoff volumes were simulated in the error range of less than 5.8%.

• 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.

• Proceedings of the Korea Water Resources Association Conference
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• 2012.05a
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• pp.976-976
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• 2012

The applicability of a distributed rainfall-runoff model for large river basin flood forecasts is analyzed by applying the model to the Nakdong River basin. The spatially explicit hydrologic model was constructed and calibrated by the several storm events. The assimilation of the large scale Nakdong River basin were conducted by calibrating the sub-basin channel outflow, dam discharge in the basin rainfall-runoff model. The applicability of automatic and semi-automatic calibration methods was analyzed for real time calibrations. Further an ensemble distributed rainfall runoff model has been developed to measure the runoff hydrograph generated for any temporally-spatially varied rainfall events, also the runoff of basin can be forecast at any location as well. The results of distributed rainfall-runoff model are very useful for flood managements on the large scale basins. That offer facile, realistic management method for the avoiding the potential flooding impacts and provide a reference for the construct and developing of flood control facilities.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.4
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• pp.89-98
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• 1990

The objectives of this study are to develop a deterministic, distributed, and event - oriented hydrologic watershed model and to test the applicabilities of the model to small watersheds. The resulting model SRAFEM, Storm Runoff Analysis by Finite Element Method, is capable of simulating storm runoff from small watersheds using two - dimensional overland flow and one - dimensional channel flow components by. kinematic approximations and finite element method. Two small watersheds were selected and the applicability of the model was tested. The test results showed that the mean simulation errors for runoff volume and peak flow were 13.9% and 19.1 % for Yeonwha watershed. They were 42.8% and 8.0% for Banweol watershed, respectively.

• Water for future
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• v.25 no.3
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• pp.97-104
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• 1992

The distributed hydrologic models are widely applied to estimate the storm-runoff with spatial variability in watershed characteristics and rainfall pattern. This study was aimed to introduce the event-oriented storm runoff model using finite element method, and to try it's applicability on small watershed. Yeonwha watershed was selected and 14 storm events in 1991 were used for the finite element model, and the simulation results were compared with hydrologic quantities.

• Water for future
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• v.26 no.1
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• pp.81-91
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• 1993

In this paper, a moving storm in the real watershed was simulated using a distributed model. Macks Creek Experimental Watershed in Idaho, USA was selected as a target watershed and the moving storm of August 23, 1965, which continued from 3:30 P.M. to 5:30 P.M., was utilized. The rainfall intensity of the moving storm in the watershed was temporally varied and the storm was continuously moved from one place to the other place in a watershed. Furthermore, runoff parameters, which are soil types, vegetative cover percentages, overland plane slopes, channel bed slopes and so on, are spatially varied. The model developed in the previous paper was utilized as a distributed model for simulating the moving storm. In the model, runoff in a watershed was simulated as two parts which are overland flow and channel flow parts. The good agreement was obtained between a simulated hydrograph using a distributed model and an observed hydrograph. Also, the conservations of mass are well indicated between upstream and downstream at channel junctions.

• Journal of Korean Society on Water Environment
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• v.24 no.2
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• pp.180-184
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• 2008

A distributed hydrologic model of an urban drainage area on Bugok drainage area in Oncheon stream was developed and combined with a optimization method to determine the optimal location and number of best management practices (BMPs) for storm water runoff reduction. This model is based on the SCS-CN method and integrated with a distributed hydrologic network model of the drainage area using system of 4,211 hydrologic response units (HRUs). Optimal location is found by locating HRU combination that leads to a maximum reduction in peak flow at the drainage outlet in this model. The results of this study indicate the optimal locations and numbers of BMPs, however, for more exact application of this model, project cost and SCS-CN reduction rate of structural facilities such infiltration trench and pervious pavement will have to be considered.

• Water for future
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• v.29 no.6
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• pp.131-139
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• 1996

The main goal of this study is a rainfall-runoff analysis using atopographically-based distributed model. It consists of two parts: one is a direct runoff submodel and the other is a baseflow submodel. The direct runoff submodel is a distributed model which routed through the drainage networks with a kinematic wave model. The baseflow submodel is considered as a lumped system. This model makes it possible to take the effect of areal and temporal distribution of storm into accout.

• Journal of The Korean Society of Agricultural Engineers
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• v.55 no.1
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• pp.9-15
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• 2013

This study is to evaluate the parameter behavior of VfloTM distributed rainfall-runoff model by applying 3 kinds of rainfall interpolation methods viz. Inverse Distance Weighting (IDW), Kriging (KRI), and Thiessen network (THI). For the 1,544 $km^2$ Dongcheon watershed of Nakdong river, the model was calibrated using 4 storm events in 2007 and 2009, and validated using 2 storm events in 2010. The model was calibrated with Nash-Sutcliffe model efficiency of 0.97 for IDW, 0.94 for KRI, and 0.95 for THI respectively. For the sensitive parameters, the saturated hydraulic conductivity ($K_{sat}$) for IDW, KRI, and THI were 0.33, 0.31, and 0.43 cm/hr, and the soil suction head at the wetting front (${\Psi}_f$) were 4.10, 3.96, and 5.19 cm $H_2O$ respectively. These parameters affected the infiltration process by the spatial distribution of antecedent moisture condition before a storm.