• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.2
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• pp.15-26
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• 2015

The purpose of this paper is to develop a software tool, PGA-CC (Projection of hydrology via Grid-based Assessment for Climate Change) to evaluate the present hydrologic cycle and the future watershed hydrology by climate change. PGA-CC is composed of grid-based input data pre-processing module, hydrologic cycle calculation module, output analysis module, and output data post-processing module. The grid-based hydrological model was coded by Fortran and compiled using Compaq Fortran 6.6c, and the Graphic User Interface was developed by using Visual C#. Other most elements viz. Table and Graph, and GIS functions were implemented by MapWindow. The applicability of PGA-CC was tested by assessing the future hydrology of South Korea by HadCM3 SRES B1 and A2 climate change scenarios. For the whole country, the tool successfully assessed the future hydrological components including input data and evapotranspiration, soil moisture, surface runoff, lateral flow, base flow etc. From the spatial outputs, we could understand the hydrological changes both seasonally and regionally.

• The Journal of Engineering Geology
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• v.10 no.3
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• pp.263-272
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• 2000

The main objective of this study is to simulate the rainfall-runoff relationship of the Ohwon rivet basin. For the this study, we used GIS technique and HMS(Hydrological Modeling System). In this study, watershed itself and geometric factors of watershed are extracted from DEM by using a GIS technique. The scanned data of topographical map with scale of 1:50,000 in the Ohwon river basin is used to this study and it is converted to DEM data. The parameters of Hydrological Modeling System as watershed area(A), river length, SCS Curve Number(CN) etc. are extracted by using the GIS technique in the Ohwon Basin. Extracted parameters are applied to the Hydrological Model System, then the paramenters optimized by the observed data and rainfall data. Then, the optimized parameters and Hydrological Modeling System are applied to the study area for the simulation of rainfall-runoff relationship. With the resultn of this study, GIS technique is useful to the extraction of watershed characteristics factors and Hydrological Modeling System is successful to the simulation of rainfall-runoff relationship.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.6
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• pp.103-111
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• 1995

Drought index calculation based on the principal hydrological parameters, such as rainfall and reservoir storage, can estimate the duration and intensity of drought in irrigation reservoirs. It is difficult to build up a drought criteria since the conditions change variously by the reliability of rainfall. Because of the increasing water demands, it is urgent to prepare a generalized positive countermeasure to overcome drought. Water demands can at calculated but the estimation of drought characteristics, and the effective water management method can be established. The purpose of this study is to obtain a drought index and build up a data-base on the reservoir basins for establishing the fundamental hydrological data-base. This Index can observe the behavior of the WSI(Water Supply Index) and the component indices. The results summarized through this study are as follows. 1. WSI value of zero does not correspond to 100% in average due to the skewness in the probability distributions. 2. WSI is not a linear index; that is, given change in terms of water volume or percentage of average does not result in a proportional change on the WSI scale. 3. WSI is not always between the reservoir and the rainfall index in magnitude. This is only true if the component indices are of opposite sign. If they are of the same sign, the SWSI will often have a mangitude greater than either of the component indices. This is easily understood, because the concurrence of extreme values of the same sign for the two components is rarer than the occurrence of extreme values for either of the two components individually.

• Journal of Korean Society on Water Environment
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• v.27 no.5
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• pp.587-596
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• 2011

The interest in hydrological modeling has increased significantly recently due to the necessity of watershed management, specifically in regards to lumped models, which are being prosperously utilized because of their relatively uncomplicated algorithms which require less simulation time. However, lumped models require empirical coefficients for hydrological analyses, which do not take into consideration the heterogeneity of site-specific characteristics. To overcome such obstacles, a distributed model was offered as an alternative and the number of researches related to watershed management and distributed models has been steadily increasing in the recent years. Thus, in this study, the feasibility of a grid-based rainfall-runoff model was reviewed using the flood runoff process in the Han River basin, including the ChungjuDam, HoengseongDam and SoyangDam watersheds. Hydrological parameters based on GIS/RS were extracted from basic GIS data such as DEM, land cover, soil map and rainfall depth. The accuracy of the runoff analysis for the model application was evaluated using EFF, NRMSE and QER. The calculation results showed that there was a good agreement with the observed data. Besides the ungauged spatial characteristics in the SoyangDam watershed, EFF showed a good result of 0.859.

• Magazine of the Korean Society of Agricultural Engineers
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• v.17 no.3
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• pp.3848-3859
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• 1975

The author attempted to find most suitable formulas for probable rainfall intensities with analysis and consideration for characteristics of rainfall intensities according to the short and long period return periods at Cheong-Joo district. Above mentioned formulas induced by this study can be contributed to the credibility of runoff estimation for urban sewerage system, drainage works in small catchment area and embankment works in the rivers. The results of this study are summarized as follows: 1 Calculation values by Gumbel-Chow method were selected as a mean values for the calculation of probable rainfall intensities according to return periods in the short period. 2. Calculations for probable rainfall intensities for long period are based upon to the result by Iwai's method. Talbot type, {{{{I= {a} over {t+b} }}}} is confirmed as a most suitable formula for probable rainfall intensities among calculation methods in the short periods at Cheong-Joo district. 4. Specific coefficient method, I24=RN24${\beta}$N was selected as a means of calculation for suitable formulas of probable rainfall intensities according to return periods in case of long period. 5. Runoff estimation with high credibility by rational formula can be anticipated by establishment for the most suitable probable rainfall intensities at Cheong-Joo district.

• KCID journal
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• v.1 no.2
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• pp.22-28
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• 1994

The calculation method for the Drought index based on the principal hydrological factors, such as precipitation, reservoir storage and river discharge, can estimate the duration and intensity of drought. It is not easy to establish an universal criteria o

• KCID journal
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• v.4 no.2
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• pp.48-61
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• 1997

Drought index calculation method using principal hydrological factors, such as precipitation amount and reservoir storage ratio, can estimate the duration and the intensity of drought. It is not easy to establish an universal criteria of drought, since th

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.340-343
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• 2001

The main objective of this study is to simulate design flood discharge of the Sungjoo basin. GIS and HEC-HMS were used in this study. GIS technique can extract various hydrological factors from D.E.M(Digital Elevation Model) and the parameters extracted from each watershed were applied to the HEC-HMS. As a result of this study, GIS technique is useful to tile extraction of watershed characteristics factors and HEC-HMS is successful in tile simulation of design flood discharge.

• Wind and Structures
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• v.8 no.6
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• pp.389-406
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• 2005

The results of reference wind speed calculation in Croatia as a base for the revision of the Croatian standards for wind loads upon structures are presented. Wind speed averaged over 10 minutes, at 10 m height, in a flat, open terrain, with a 50-year mean return period is given for 27 meteorological stations in Croatia. It is shown that the greatest part of Croatia is covered with expected reference wind speeds up to 25 m/s. Exceptions are stations with specific anemometer location open to the bura wind which is accelerated due to the channelling effects of local orography and the nearby mountain passes where the expected reference wind speed ranges between 38 m/s and 55 m/s. The methodology for unifying all available information from wind measurements regardless of the averaging period is discussed by analysing wind speed variability at the meteorological station in Hvar.

• Journal of Korea Water Resources Association
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• v.41 no.10
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• pp.1009-1021
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• 2008

In this study, 4 indices of hydraulic & hydrological, geomorphological, eco & environmental, social effect and 38 items are selected to calculate impact range of downstream of dam. The Analytic Hierarchy Process(AHP) was applied to determine the priority of impact range calculation indices and items. As results of indices valuation, hydraulic & hydrological effect is the first priority, the second is eco & environmental, next are geomorphological and social effect. As results of items valuation, the design flood of dam is the first priority, the second is the natural flood & design flood of channel, next are the design flood rate of channel, drainage area and back water level caused by downstream of dam. In the case of Daechung dam, impact ranges were estimated 47.21 km in terms of the design flood of dam, 45.71 km of the design flood rate of channel, 13.94 km of the drainage area.