• Journal of Environmental Science International
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• v.15 no.3
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• pp.253-260
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• 2006

Groundwater recharge from precipitation is affected by the infiltration from ground surface and the movement of soil water. Groundwater recharge is directly related to the groundwater amount and flow in aquifers, and baseflow to rivers. Determining groundwater recharge rate for a given watershed is a prerequisite to estimate sustainable groundwater resources. The estimation of groundwater recharge rate were carried out for three subwatersheds in the Wicheon watershed and two subwatersheds in the Pyungchang River basin and for the period 1990-2000, using the NRCS-CN method and the baseflow separation method. The recharge rate estimates were compared to each other. The result of estimation by the NRCS-CN method shows the average annual recharge rate 15.4-17.0% in the Wicheon watershed and 26.4-26.8% in the Pyungchang River basin. The average annual recharge rates calculated by the baseflow separation method ranged 15.1-21.1% in the W icheon watershed, and 25.2-33.4% in the Pyungchang River basin. The average annual recharge rates calculated by the NRCS-CN method is less variable than the baseflow separation method. However, the average annual recharge rates obtained from the two methods are not very different, except NO. 6 subwatershed in Pyungchang River basin.

• Proceedings of the Korea Water Resources Association Conference
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• 2001.05a
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• pp.286-291
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• 2001

• Journal of Environmental Science International
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• v.13 no.12
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• pp.1033-1039
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• 2004

The methodology developed by Soil Conservation Service for determination of runoff value from precipitation is applied to estimate the precipitation recharge in the Pyungchang river basin. Two small areas of the basin are selected for this study. The CN values are determined by considering the type of soil, soil cover and land use with the digital map of 1:25,000. Forest covers more than $94{\%}$ of the study area.. The CN values for the study area vary between 47 in the forest area and 94 in the bare soil under AMC 2 condition. The precipitation recharge rate is calculated for the year when the precipitation data is available since 1990. To obtain the infiltration rate, the index of CN and five day antecedent moisture conditions are applied to each precipitation event during the study period. As a result of estimation, the value of precipitation recharge ratio in the study area vary between $15.2{\%}\;and\;35.7{\%}$ for the total precipitation of the year. The average annual precipitation recharge rate is $26.4{\%}\;and\;26.8{\%}$, meaning 377.9mm/year and 397.5mm/year in each basin.

• Water for future
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• v.25 no.3
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• pp.79-86
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• 1992

ARF(Areal Reduction Factor) have been developed and used to convert point I-D-F to areal I-D-F in many countries. In Korea, through ARF was calculated in Han river basin by several researchers, it has limit to apply to other regions \ulcorner 새 low density of rainfall gauge station and shortage of data. In this study ARF has developed in areas of high density of rainfall gauge station, Pyungchang river(han river), Wi stream(nakdong river), and Bochung stream(Guem river) basin by fixed-area method. And coefficient of variation of annual mean precipitation was presented to use ARF in othere areas and its applicability was analyzed.

• Korean Journal of Hydrosciences
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• v.4
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• pp.105-116
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• 1993

Areal Reduction Factor(ARF) has been developed and used to convert point Rainfall intensity-Duration-Frequency(I-D-F) to areal I-D-F in many countries. In Korea, though ARF was estimated in Han river basin by several researchers, it has some limitations to apply to other regions due to low denisity of rainfall gauging station and shortage of data. In this study ARF has been developed in area of relatively high density of rainfall gauging station, i.e., Pyungchang river(Han river), Wi stream(Nakdong river), and Bochung stream(Guem river) basin by geographically fixed-area method. And coefficient of variation of mean annual precipitation was presented to use ARE in other areas and its applicability was analyzed.

• Water for future
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• v.23 no.4
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• pp.421-434
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• 1990

The problems of hydrologic similarity among river basins was analyzed by a geomorphologic response model using Hortons*s ordering scheme. The Nash model was used for deriving the geomorphologic response function, and for the optimization of the responsefunction, imcomplete gamma function andRosso*s regression equation were used. The application of this method was tested on some observed flood data of Pyungchang river basin and Wi Stream basin and Bocheong stream, and predictions of hydrologic response were compared with that of the Moment method. The results show that the proposed model and dimensionless instantaneous unit hydrograph can be used for the runoff analysis of an ungauged basin and the analysis of hydrologic similarity.

• Korean Journal of Hydrosciences
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• v.1
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• pp.1-14
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• 1990

The analytical diffusion model is first formulated and its characteristics are critically reviewed. The flood events during the 1985-1986 flood seasons in the IHP Pyungchang Representative Basin are routed by this model and are compared with those routed by the kinematic wave model. The present model is proven to be an excellent means of taking the backwater effects due to lateral inflow or downstream river stage variations into consideration in channel routing of flood flows. It also requires much less effort and computing time at a desired station compared to any other reliable flood routing methods.

• Journal of Korea Water Resources Association
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• v.43 no.6
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• pp.559-569
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• 2010

This study proposes an empirical method for estimating the concentration time and storage coefficient of a basin using the Nash unit hydrograph. This method is based on the analytically derived concentration time and storage coefficient of the Nash model. More fundamentally, this method recursively searches convergent number of linear reservoirs and storage coefficient of linear reservoir representing the basin given. This method is to overcome the problem of HEC-HMS to use an optimization technique to estimate the basin concentration time and storage coefficient. The proposed method was applied to the Bangrim station of the Pyungchang river basin, also found to estimate physically reasonable values.

• Journal of Korea Water Resources Association
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• v.35 no.1
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• pp.65-75
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• 2002

The objectives of this study are to analyse model-based soil moisture variations depending on model parameters m and $T_0$ and to evaluate the model performance for the simulation of soil moisture variations by the comparison of observed groundwater levels and model-driven soil moisture amounts and observed and simulated river discharges at the basin outlet. The selected study area is the Pyungchang IHP river basin with outlet at Sanganmi station and the summer flooding events during '94-'98 are used for the analysis. As a result, soil moisture holding capacity is increased according to increase the parameter m that represents effective groundwater depth. This phenomenon is especially dominant when higher m and $T_0$ values are used. The qualitative comparison of computed base flow and observed groundwater level shows that the base flow peaks are reasonably simulated and the decreasing limbs of hydrograph are mainly caused by base flows. It is concluded that TOPMODEL can be used effectively for simulating basin-averaged soil moisture variations in addition to river flow generations.

• Journal of Korea Water Resources Association
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• v.32 no.2
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• pp.163-176
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• 1999

Hydrology-based topographical informations generated by GIS techniques could be changed according to the selection of base map, algorithm of extraction, and so on. The purpose of this paper is to investigate the variation of SCS CN extracted by GIS technique and to propose the effective strategy for applying GIS to the rainfall-runoff simulation in ungaged basin. For experimental implementation, GIS spatial data, such as reconnaissance soil map, detailed interpretative soil map, landuse planning map and remotely sensed data(Landsat TM), were collected and generated to calculate the amount of effective rainfall in Pyungchang river basin. In applying SCS Runoff Curve Number to the test basin, the hydrological attribute data were analyzed. In addition, the characteristics of runoff responses according to the selection of GIS spatial data for SCS CN were reviewed. This study shows the applicability of GIS techniques to runoff simulation in ungaged basin by comparing with the measured flood hydrograph. It has been found that the detained interpretative soil map and remote sensing data are appropriate for calculating of SCS CN.