• Journal of The Korean Society of Agricultural Engineers
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• v.65 no.6
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• pp.37-49
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• 2023

Rainfall data is one of the most important data in hydrologic modeling. In this study, the impacts of spatial resolution of precipitation data on hydrological responses were assessed using SWAT in the Santa Fe River Basin, Florida. High correlations were found between the FAWN and NLDAS rainfall data, which are observed weather data and simulated weather data based on observed data, respectively. FAWN-based scenarios had higher maximum rainfall and more rainfall days and events compared to NLDAS-based scenarios. Downstream areas showed lower correlations between rainfall and peak discharge than upstream areas due to the characteristics of study site. All scenarios did not show significant differences in base flow, and showed less than 5% of differences in high flows among NLDAS-based scenarios. The impact of resolution will appear differently depending on the characteristics of the watershed and topography and the applied model, and thus, is a process that must be considered in advance in runoff simulation research. The study suggests that applying the research method to watersheds in Korea may yield more pronounced results, and highlights the importance of considering data resolution in hydrologic modeling.

• Journal of Environmental Science International
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• v.13 no.7
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• pp.637-643
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• 2004

A new method of automatic recording raingauge is developed to measure rainfall with 0.01mm resolution. This use two different signals to measure rainfall more accurately compare than other raingauges. One is weight of the tipping bucket with rainfall amount and the other is pulse from tipping bucket reverse. New method applied 1 mm tipping bucket mechanism and install loadcell under tipping bucket mechanism for measuring rainfall weight. Loadcell measure weight of rainfall until 1 mm with 0.01 mm resolution and more than 1 mm than bucket reverse and pulse signal generate, after that loadcell measure weight again. The validation of new instrument was examined in the room 65 mm/hour rainfall rate total 53 mm range. There is below than 1 % error of absolute rainfall amount and 0.01 mm resolution. The field test of instrument was carried out by comparing its measured values with values recorded by weight type and standard type on June 1 2003 at Terrestrial Environmental Research Center at Tsukuba University in Tsukuba of Japan, when it has recorded total amount of 40.58 mm rainfall by standard raingauge and new raingauge recorded 41.032 mm. Same rainfall intensity pattern observed in field observation with weight type raingauge. Rainfall intensity between weight type and Lee-A type raingauge reached 0.9947 correlation in 3 minute average.

• Environmental Engineering Research
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• v.22 no.2
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• pp.162-168
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• 2017

Rainfall is one of the most important phenomena of the natural system. In Bangladesh, agriculture largely depends on the intensity and variability of rainfall. Therefore, an early indication of possible rainfall can help to solve several problems related to agriculture, climate change and natural hazards like flood and drought. Rainfall forecasting could play a significant role in the planning and management of water resource systems also. In this study, univariate Seasonal Autoregressive Integrated Moving Average (SARIMA) model was used to forecast monthly rainfall for twelve months lead-time for thirty rainfall stations of Bangladesh. The best SARIMA model was chosen based on the RMSE and normalized BIC criteria. A validation check for each station was performed on residual series. Residuals were found white noise at almost all stations. Besides, lack of fit test and normalized BIC confirms all the models were fitted satisfactorily. The predicted results from the selected models were compared with the observed data to determine prediction precision. We found that selected models predicted monthly rainfall with a reasonable accuracy. Therefore, year-long rainfall can be forecasted using these models.

• 한국방재학회:학술대회논문집
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• 2008.02a
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• pp.101-104
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• 2008

In this study, rainfall adjust and forecasting using artificial neural network(ANN) which includes a correlation coefficient is application in Seoul region. It analyzed one-hour rainfall data which has been reported in 25 region in seoul during from 2000 to 2006 at rainfall observatory by AWS. The ANN learning algorithm apply for input data that each region using cross-correlation will use the highest correlation coefficient region. In addition, rainfall adjust analyzed the minimum error based on correlation coefficient and determination coefficient related to the input region. ANN model used back-propagation algorithm for learning algorithm. In case of the back-propagation algorithm, many attempts and efforts are required to find the optimum neural network structure as applied model. This is calculated similar to the observed rainfall that the correlation coefficient was 0.98 in missing rainfall adjust at 10 region. As a result, ANN model has been for suitable for rainfall adjust. It is considered that the result will be more accurate when it includes climate data affecting rainfall.

• Membrane and Water Treatment
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• v.10 no.1
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• pp.45-55
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• 2019

Climate change has significantly affected the rainfall characteristics which can influence the pollutant build-up and wash-off patterns from the catchment. Therefore, this study explored the influence of varying rainfall characteristics on urban and agricultural runoff pollutant export using statistical approaches. For this purpose, Mann-Kendall and Pettitt's test were applied to detect the trend and breakpoint in rainfall characteristics time series. In addition, double mass curve and correlation analysis were used to drive the relationship between rainfall-runoff and pollutant exports from both catchments. The results indicate a significant decreased in total rainfall and average rainfall intensity, while a significant increased trend for antecedents dry days and total storm duration over the study periods. The breakpoint was determined to be 2013 which shows remarkable trend shifts for total rainfall, average rainfall intensity and antecedents dry days except total duration. Double mass curve exhibited a straight line with significant rainfall-runoff relationship indicates a climate change effect on both sites. Overall, higher pollutant exports were observed at both sites during the baseline period as compared to change periods. In agricultural site, most of the pollutants exhibited significant (p< 0.05) association with total rainfall, average rainfall intensity and total storm duration. In contrast, pollutants from urban site significantly correlated with antecedent dry days and average rainfall intensity. Thus, total rainfall, average rainfall intensity and total duration were the significant factors for the agricultural catchment while, antecedents dry days and average rainfall intensity were key factors in build-up and wash-off from the urban catchment.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.451-454
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• 2003

This study was mainly conducted to derive the design drought rainfall by the consecutive duration using probability weighted moments with rainfall in the regional drought frequency analysis. Selecting the drought rainfall series by the consecutive durations of drought observed for the long period all over the regions in Korea, optimal regionalization of the drought rainfall was classified by the climatologically and geographically homogeneous regions. Using the L-moment ratio and Kolmogorov- Smimov test, resonable frequency distribution for the drought rainfall was selected by the regions and consecutive periods of drought. Design drought rainfalls by the regions and consecutive durations were derived and compared by at-site and regional drought frequency analysis using the method of L-moments.

• Journal of The Korean Society of Agricultural Engineers
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• v.58 no.5
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• pp.91-99
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• 2016

High resolution rainfall data at 1-hour or a finer scale are essential for reliable flood analysis and forecasting; nevertheless, many observations, forecasts, and climate projections are still given at coarse temporal resolutions. This study aims to evaluate a chaotic method for disaggregation of 6-hour rainfall data sets so as to apply operational 6-hour rainfall forecasts of the Korean Meteorological Association to flood models. We computed parameters of a state-of-the-art multiplicative random cascade model with two combinations of cascades, namely uniform splitting and diversion, using rainfall observations at Seoul station, and compared statistical performance. We additionally disaggregated 6-hour rainfall time series at 58 stations with the uniform splitting and evaluated temporal transferability of the parameters and changes in multifractal properties. Results showed that the uniform splitting outperformed the diversion in reproduction of observed statistics, and hence is better to be used for disaggregation of 6-hour rainfall forecasts. We also found that multifractal properties of rainfall observations has adequate temporal consistency with an indication of gradually increasing rainfall intensity across South Korea.

• Water for future
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• v.14 no.3
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• pp.47-54
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• 1981

The characteristics of point rainfall for three different durations in Seoul Pusan Taegu and Gwangju have been analysed by the probabilistic ainfall method and the M-year maximum rainfall method. The probabilities that the T-year probabilistic rainfall did not occur during the observation period, compared with the values obtained from the observed data. were smaller than the theoretical values. The averages of the probabilities that the M-year maximum-ten-minute rainfall did not occur in the consequent N-years were larger than the theoretical values, the M-year maximumone hour rainfall were smaller than the theoretical ones, and the M-year maximum daily rainfall nearly agreed with them, and while those of Japan were smaller than the theoretical values. It is recommended from the results that the recorded maximum value should be used as a design value rather than the probabilistic rainfall.

• Journal of Environmental Science International
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• v.32 no.5
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• pp.303-313
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• 2023

In this study, the hydraulic gradient was calculated using the groundwater level and rainfall observed in the Hyogyo-ri area for a year, and the change in the hydraulic gradient according to the rainfall was analyzed. It was found that the groundwater level increased as the rainfall increased in all groundwater wells in the research site, and the groundwater level rise decreased as the altitude of the groundwater well increased. The hydraulic gradient in the research site ranged from 0.016 to 0.048, decreasing during rainfall and increasing after the end of the rainfall. As the rainfall increased, the groundwater level rise in the low-altitude area was more than the high-altitude area, and the hydraulic gradient decreased due to the difference in groundwater level rise according to the altitude. Through this study, it was found that the influence of rainfall is dominant for the fluctuation of the hydraulic gradient in the unconfined aquifer.

• Journal of Korea Water Resources Association
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• v.51 no.1
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• pp.19-33
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• 2018

This study proposed a rainfall-runoff model for the purpose of real-time flood warning in urban basins. The proposed model was based on the shot noise process, which is expressed as a sum of shot noises determined independently with the peak value, decay parameter and time delay of each sub-basin. The proposed model was different from other rainfall-runoff models from the point that the runoff from each sub-basin reaches the basin outlet independently. The model parameters can be easily determined by the empirical formulas for the concentration time and storage coefficient of a basin and those of the pipe flow. The proposed model was applied to the total of three rainfall events observed at the Jungdong, Guro 1 and Daerim 2 pumping stations to evaluate its applicability. Summarizing the results is as follows. (1) The unit response function of the proposed model, different from other rainfall-runoff models, has the same shape regardless of the rainfall duration. (2) The proposed model shows a convergent shape as the calculation time interval becomes smaller. As the proposed model was proposed to be applied to urban basins, one-minute of calculation time interval would be most appropriate. (3) Application of the one-minute unit response function to the observed rainfall events showed that the simulated runoff hydrographs were very similar to those observed. This result indicates that the proposed model has a good application potential for the rainfall-runoff analysis in urban basins.