• Journal of Korea Water Resources Association
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• v.33 no.3
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• pp.365-374
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• 2000

This paper is to present the determination of the optimal Joss rate parameters and urnt bydrographs from the observed single rainfall-runoff event using optimization models coupled with a stochastic technique for the global solution. Two kinds of the linear program models are formulated to derive the optimal unit hydrographs and loss rate parameters for gaged basins; one mimmizes the summation of the absolute residual between predlCted and observed runoff ordinates and the other, the maximum absolute residuaL Multistart algorithm which is one or stochastic techniques for the global optimum is adopted to perturb the parameters of the loss rate equations. Multistart efficiently searches the feasIble region to identify the global optimlUll for loss rate parameters, which yields the optimal loss rate parameters and unit hydrograph for Kostiakov's, Plulip's, and Horton's equation. The unique unit hydrograph ordinates for a gIven rainfall-runoff event iS exclusrvely obtained WIth $\Phi$ index, but unit hydrograph ordinates depend upon the parameters [or each loss rate equations. The parameters of Green-Ampt's are determined through a trial and error method. In this paper the single rainfall-nmoff event observed from a watershed is considered to test the proposed method. The optimal unit hydrograph herein found has smaller deviations than the ones reported previously by other researchers.

• Water for future
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• v.7 no.2
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• pp.92-98
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• 1974

The DAD for Nakdong River Basin is studied on the basis of qselected storms (1916~1970) by WMO Standard method. The maximum DAD BAlue for a storm period of 24hrs assuming that the basin area is estimated as about $2,500\textrm{km}^2$ comes out to be 153mm. The investigation appears to be supporting a conclusion that the Horton's formula is also applicable to this basin.

• Journal of the Korean GEO-environmental Society
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• v.21 no.12
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• pp.23-28
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• 2020

As a result of a suite of laboratory tests undertaken to suggest a rational method for the estimation of infiltration capacity, it is found that the infiltration rate tends to increase as the soil unit weight decreases while it tends to increase as the rainfall intensity increases. Comparative analyses for infiltration curves employing the reduction constant of initial infiltration capacity (α coefficient) that was suggested in this study has reasonably captured the time dependent variation of infiltration capacity. Consequently this study has presented an experimental model for the estimation of infiltration capacity to improve the Horton infiltration capacity curve that has been widely used for estimation of the infiltration capacity and amount of infiltration for its application to sandy soils.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.4 no.4
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• pp.37-48
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• 1984

The yield-line analysis is used for earring out the limit analysis of reinforced concrete slabs which are for example like those of vertical walls of tanks subjected to the loads of hydrostatical type. It is considered both isotropic and orthotropic reinforcement using the coefficient of orthotropy with different edge conditions. The yield-line analysis is carried out by using the vertical work method and four collapse mechanisms including the fan mechanisms which is more realistic than over diagonal mechanisms is considered. It is found that the fan mechanisms are more complicated than ever simple diagonal mechanisms which have used for the orthotropically reinforced concrete slabs subjected to hydrostatic pressures. Especially Horton's study is extended in this study, and they are formulated to the constrained multi-variables nonlinear optimization problems, which are solved by the Rosen-Brock Hillclimb Procedure Program and are more critical.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.10 no.1
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• pp.99-108
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• 1990

A Synthetic Unit Hydrograph Method was investigated for representation of the effective rainfall-direct runoff hydrograph by using a Geomorphologic Instantaneous Unit Hydrograpb(GIUH) proposed by Gupta et al(1980). The response function of the basin was assumed to be the two-parameter gamma probability density function. The physical parameters of the response function(Nash Model) was determined by using the regression eqs. were parameterized in terms of Horton order ratios and the relations between the basin lag time and time-scale parameter. The capability of the Synthetic Unit Hydrograph to the real basin was tested for the Pyungchang river basin and Wi Stream basin, and its capability to reproduce the hydrologic response was investigate and compared with the Moment Method and the Least Square Method used incomplete gamma function. The representation of the peak flow, the time to peak and the hydrographs the derived Synthetic Unit Hydrograph were tested on some obseved flood data and showed promising, and it was approved to be used for prediction of the ungaged basins.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.12 no.4_1
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• pp.97-106
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• 1992

Total length of stream networks and main stream length vary with topographic map scales, and the stream length of drainage basin on topographic map can be viewed as a fractal. Total length of stream network and main stream length are represented as only stream area ratio($R_a$) based on Horton's laws, thereafter the fractal dimensions of stream network and main stream length are derived as a simple function of stream length($R_L$) and stream area ratios($R_a$) respectively. The derived equations of fractal dimension are applied to Sansung basin in Kum River and compared with the equations already existed. The stream network appeared as space filling with fractal dimension near 2 as map scale increases, while main stream length shows near 1. The results of this study are expected to be helpful in the quantitative analysis of drainage network composition with map scale.

• Water for future
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• v.19 no.2
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• pp.139-148
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• 1986

The hydrologic response function in a small basin is expressed by the distribution function of slope length. The characteristics of topographical factors is represented to the concentration time, and the instantaneous unit hydrograph is derived as a hydrologic rsponse function by application of probobility density function. The averaging process of runoff characteristics within watershed was analyzed for a few small watershed where was split up the small basin itself. The method of calculation of the effective rainfall should play important roles in the transformation process from hydrologic response function to runoff hydrograph. In this paper, the Horton's infiltration quation is used as a method of calculation of effective rainfall, a new response function of runoff process is derived. The $\Phi$-index method and the infiltration method are tested by comparing the observed and estimated values.

• Journal of Korea Water Resources Association
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• v.43 no.11
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• pp.945-956
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• 2010

Practically, the composite roughness coefficient, which is the equivalent roughness coefficient of a cross-section where the wall roughness is not constant along the wetted perimeter, is used to describe the flow conditions in open channels. In this study, it was conducted that the previous formulae was classified according to a weighting factor of the local resistance. The new subsection division method was also developed based on the force-balance concept in each subsection. The accuracy of the proposed method was examined and the applicability and limitation of the 13 existing formulae were analyzed by comparing the calculated with the experimental measured data from Djajadi (2009) and Knight and Macdonald (1979). It was found that Horton's method might underestimate the total conveyance of a composite channel and Lotter's method showed a good agreement between calculated and measured data. However, the proper division method, such as the proposed method based on the Z-method, is required for the application of Lotter's method.

• Journal of Wetlands Research
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• v.7 no.3
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• pp.57-66
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• 2005

This paper is to present the determination of the optimal loss rate parameters and unit hydrographs from the observed single rainfall-runoff event using optimization model. The linear program models has been formulated to derive the optimal unit hydrographs and loss rate parameters for the site of the Su-Jik Bridge in the HwangGuJichen River; one minimizes the summation of the absolute residual between predicted and observed runoff ordinates. In the perturbation stage of parameters the trial and error method has been adopted to determine the loss rate parameters for Kostiakov's, Philip's, Horton's, and Green-Ampt's equation. The unique unit hydrograph ordinates for a given rainfall-runoff event is exclusively obtained with ${\Phi}$ index, but unit hydrograph ordinates depend upon the parameters for each loss rate equations. In this paper the single rainfall-runoff event observed from the sample watershed is considered to test the proposed method. The optimal unit hydrograph obtained by the optimization model has smaller deviations than the ones by the conventional method.

• Journal of Korea Water Resources Association
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• v.54 no.1
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• pp.49-60
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• 2021

This study presents a methodology to estimate two distinct fractal dimensions of natural river basin by using fractal tree concept. To this end, an analysis is performed on fractal features of a complete drainage network which consists of all possible drainage paths within a river basin based on the growth process of fractal tree. The growth process of fractal tree would occur only within the limited drainage paths possessing stream flow features in a river basin. In the case of small river basin, the bifurcation process of network is more sensitive to the growth step of fractal tree than the meandering process of stream segment, so that various bifurcation structures could be generated in a single network. Therefore, fractal dimension of network structure for small river basin should be estimated in the form of a range not a single figure. Furthermore, the network structures with fractal tree from this study might be more useful information than stream networks from a topographic or digital map for analysis of drainage structure on small river basin.