• Current Research on Agriculture and Life Sciences
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• v.24
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• pp.49-53
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• 2006

The objective of this study was to present regression equations between reservoir water quality and land use types of the watersheds. In order to derive regression equations, a multiple linear regression analysis was used using observed data from 88 reservoirs in the Kyungpook Provcince. The measured values of BOD, COD, T-N, and T-P were correlated with the areas of land use types. 23 regression equations were obtained for all the water quality items and watershed sizes. The results showed that 2 regression equations have the multiple correlation coefficient(MCC) above 0.90, 10 regression equations have the MCC values from 0.70 to 0.90, 9 equations have the MCC from 0.40 to 0.70, and 2 equations have the MCC from 0.20 to 0.40. The results of this study can be used to estimate reservoir water quality simply and quickly in the planning phase.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.574-581
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• 2012

It is important to analyze the status of water quality with relation to the stream flow to attain water quality goal more effectively in the unit watersheds for the management of Total Maximum Daily Loads (TMDLs). This study developed a flow duration-water quality distribution graph to figure out water quality appearances on the flow variation and analyzed contributions of water quality observations to the impaired water bodies quantitatively by hydrologic conditions. Factors relating to water quality variation can be analyzed more precisely and assessed on the base of quantified contributions. It is considered that this approach could be utilized to establish a more effective plan for the water quality improvement including the prioritization of pollution reduction options.

• Journal of Korean Society on Water Environment
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• v.28 no.4
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• pp.582-594
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• 2012

A simple ecohydorlogic model that simulates hydrologic components and vegetation dynamics simultaneously based on equations of soil water dynamics and vegetation's growth and mortality is discussed. In order to simulate ungauged watersheds, the proposed model is calibrated with indirected estimated observation data set; 1) empirically estimated annual vaporization, 2) monthly surface runoff estimated by NRCS-CN method, and 3) vegetation fraction estimated by SPOT/VEGETATION NDVI. In order to check whether the model is performed well with indirectly estimated data or not, four upper dam watersheds (Andong, Habcheon, Namgang, Milyang) in Nakdong River watershed are selected, and the model is verified.

• Journal of Korean Society on Water Environment
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• v.29 no.3
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• pp.438-442
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• 2013

According to Geum-River restoration project, given conditions for management of water environment in the Geum-River were changed. Because of those changes, this study was investigated the establishment of water quality standards and water quality target in the Geum-River basin. For management of water environment in the Geum-River, the sub-basins and watersheds are newly divided and the water quality and ecosystem standards in the sub-basins are reestablished. Considering the consistency of water environment policy and legal system, the legal name of sub-basins and watersheds are unified. TMDL (total maximum daily load) should be implemented in the sub-basin where exceeds the water quality standards and the number of water pollutant among the water quality parameters which exceeds the water quality standards are extremely minimized. The water quality target of water pollutant for implementation of TMDL should be established same or higher concentration of water quality standards.

• Proceedings of the Korea Water Resources Association Conference
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• 1989.07a
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• pp.17-30
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• 1989

In this study, more exact runoff phenomina of the watersheds were comprehened and the relationships between geographical factors of the selected watershed and the unit hydrograph characteristic variables representing runoff processes, were also established. Moreover, the estimation of the adequate design flood was presented, which is needed for the design of the hydrologic structures in the ungauged watersheds. And owing to these results, it is considered to be possible to execute the effective flood control projects of the river and the efficient water resources management.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.353-358
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• 1998

GRASS-AGNPS model integrated with GIS was applied to rural watersheds having complex land use characteristics and evaluated for its applicability through calibration using observed data. The analyses of raster encoding accuracy and model behavior to runoff, sediment yields and nutrient loads for different cell-size showed that 150 m cell size indicated reasonable applicability of the model. Simulated runoff was in a good agreement with the observed data and simulated peak runoff rate was larger than the observed data. The sediment yield simulated by modified AGNPS model using irregular cell for forest area were less than that of the regular cell method. In predicting sediment yields, the result showed a different trend at each representative rural watershed. Nutrient loads simulated by the model were significantly different from the observed data.

• Magazine of the Korean Society of Agricultural Engineers
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• v.42 no.6
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• pp.56-62
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• 2000

The NRCS curve number (CN) method has been widely adopted in practice to synthesize runoff hydrographs from small watersheds with complex land use. It may not be valid to apply this model for irrigated paddies, since hydrological characteristics of irrigated rice paddies are not sufficiently considered in CN method. This paper attempts to extend the capability of the well-known SCS TR-20 model to local conditions by formulating a submodel for the runoff-processes in paddies. The modified model was tested with field data from the Baran watershed. The results were in good agreement with field data. It was also applicable to simulate runoff changes resulting from land use changes within the watershed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.26 no.3
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• pp.90-98
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• 1984

In this paper, the anthor made a basic study of the storage function model and examined several constants in applying the storage function model to flood run-off analysis by dealing with the data in the Supyung and Hoyng Syung watershed, the applicabilities of the storage function model are examined by searching this optimum model parameters in two watersheds. The results are summarized as follows, 1) The optimum values of the exponential constants, P, in the storage function model showed to be 0.77 to 0.87 in two watersheds observed, therefore it was confirmed that the storage fumction model was approaching to the surface runoff model. 2) It was confirmed that the interval of variation of the storage constant, K, Showed to be larger than that of the exponential constant, p. 3) Relative erros in the discharge obtained by using the storage function model and the SDFP mothod showed to be 20 and 17 percent respectively to the observed discharge, therefore it was confirmed that the applicability of the storage function model using the SDFP method are excellent for runoff analysis. 4) A simple method is proposed for estimating the lag time in the storage function model.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.E
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• pp.20-32
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• 1990

Abstract This study was conducted to pursue the normalization of frequency distribution by making an approach to the coefficient of skewness to nearly zero through the Box-Cox transformation, to get probable flood flows can be calculated by means of the transformation equation which has been derivated by Box-Cox transformation in the annual maximum series of the applied watersheds. It has been concluded that Box-Cox transfromation is proved to be more efficient than logarithmic, square root and SMEMAX transformation which is based on the trigonometric solution of a right triangle whose three verteces repesent the smallest, median and largest observed values of a population in making the coefficient of skewness nearer to zero. Consequently it is shown that probable flood flows according to the return period based on Box-Cox transformation are closer to the observed data as compared to other methods including SMEMAX transformation and fitted probability distributions such as the three parameter lognormal and the type I extremal distribution for the applied watersheds.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.435-438
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• 2003

Model for estimating daily paddy water requirements was developed to simulate daily streamflow in upstream and downstream. Evapotranspiration in paddy fields was estimated using modified Penman equation. Daily water requirements in paddy fields were calculated from multiplication of paddy area to ponding depth decreased for one day. And model was constructed with a system form user-friendly and almost completely using controls of image, grid, and etc. in Visual Basic 6.0. The developed model was applied to estimate daily agricultural water requirements at 12 small watersheds during 20 years from 1983 to 2002 with paddy field areas of $3,332{\sim}26,422ha$ in small watersheds, and with agricultural water requirements of $37.22{\sim}294.53mcm$ on yearly average.