• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.149-149
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• 2011

기후변화에 따른 영향으로 태풍 및 집중호우가 증가하고 있으며, 산업발달과 인구의 도시집중 현상이 심화됨에 따라 도시지역의 인명 및 재산 피해가 증가되고 있는 시점이다. 도시화로 인한 불투수면적의 증가는 자연유역에 비해 도달시간이 단축되고 첨두유량을 증가시키게 된다. 또한 도시지역에서 대부분의 우수량은 관거(합류식의 경우에는 하수관거)를 통해 배제되기 때문에 관거 용량 이상의 강우에 대해서는 이를 충분히 배제하지 못하여 도시홍수 피해의 가장 큰 원인으로 작용하게 된다. 즉, 도시유역의 배수시스템 능력이 부족할 경우 큰 피해를 가져올 수 있게 된다. 따라서 이러한 특징을 갖는 지역에서는 도시유출모형을 이용한 침수예측과 이에 따른 효과적인 대책 수립이 필요하다. 본 연구에서는 이러한 도시유출모형 중 ILLUDAS 모형을 이용하여 2010년 9월 집중호우로 피해를 입은 굴포천 유역에 대해 내수침수모의를 실행하고 실측침수심도 자료와 비교하여 효과적인 피해 저감방안에 대해 연구하고자 하였다.

• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.29-29
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• 2023

To mitigate the damaging impacts of floods, accurate prediction of runoff, streamflow and flood inundation is needed. Conventional approach of simulating hydrology and hydraulics using loosely coupled models cannot capture the complex dynamics of surface and sub-surface processes. Additionally, the scarcity of data in ungauged basins and quality of data in gauged basins add uncertainty to model predictions, which need to be quantified. In this presentation, first the role of integrated modeling on creating accurate flood simulations and inundation maps will be presented with specific focus on urban environments. Next, the use of machine learning in producing streamflow predictions will be presented with specific focus on incorporating covariate shift and the application of theory guided machine learning. Finally, a framework to quantify the uncertainty in flood models using Hierarchical Bayesian Modeling Averaging will be presented. Overall, this presentation will highlight that creating accurate information on flood magnitude and extent requires innovation and advancement in different aspects related to hydrologic predictions.

• Journal of Korea Water Resources Association
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• v.54 no.2
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• pp.71-80
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• 2021

In recent years, the possibility of flooding due to the increase in the incidence of high-frequency rainfall due to abnormal rainfall and the increase in concentrated torrential rain is increasing. Also, the amount of rainwater runoff is increasing due to the increase of the impermeable layer in the city due to the concentration of population due to urbanization and concentration of development. Due to the characteristics of the developed city, it is located in the vicinity of rivers and in the lowlands. For the analysis of inundation in water, using XP-SWMM, which can analyze stormwater pipelines and surface flows, and FLO-2D models that can track flood-sluice curves and rainfall-spill curves, based on hydraulic and hydrological analysis. Inundation analysis was conducted and comparative review was conducted. The patterns of flooding of the two models were compared, and a model suitable for domestic flooding was selected.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.157-161
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• 2011

Although many researches have been carried out concerning the watershed division in natural areas, it has not been researched for the urban watershed division. If the boundary between two urban areas is indistinct because no natural distinction or no administrative division is between the areas, the boundary between the urban areas that have the different outlets (multi-outlet urban watershed) is determined by only designer of sewer system. The suggested urban watershed division model (UWDM) determines the watershed boundary to reduce simultaneously the peak outflows at the outlets of each watershed. Then, the UWDM determines the sewer network to reduce the peak outflow at outlet by determining the pipe connecting directions between the manholes that have the multi-possible pipe connecting directions. In the UWDM, because the modification of the sewer network changes the superposition effect of the runoff hydrographs in sewer pipes, the optimal sewer layout can reduce the peak outflow at outlet, as much as the superposition effects of the hydrographs are reduced. Therefore, the UWDM can optimize the watershed distinction in multi-outlet urban watershed by determining the connecting directions of the boundary-manholes using the genetic algorithm. The suggested model was applied to a multi-outlet urban watershed of 50.3ha, Seoul, Korea, and the watershed division of this model, the peak outflows at two outlets were decreased by approximately 15% for the design rainfall.

• Journal of Korea Water Resources Association
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• v.48 no.5
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• pp.409-423
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• 2015

In this study the very short-term rainfall forecasting and storm water forecasting using the weather radar data were implemented in an urban stream basin. As forecasting time increasing, the very short-term rainfall forecasting results show that the correlation coefficient was decreased and the root mean square error was increased and then the forecasting model accuracy was decreased. However, as a result of the correlation coefficient up to 60-minute forecasting time is maintained 0.5 or higher was obtained. As a result of storm water forecasting in an urban area, the reduction in peak flow and outflow volume with increasing forecasting time occurs, the peak time was analyzed that relatively matched. In the application of storm water forecasting by radar rainfall forecast, the errors has occurred that we determined some of the external factors. In the future, we believed to be necessary to perform that the continuous algorithm improvement such as simulation of rapid generation and disappearance phenomenon by precipitation echo, the improvement of extreme rainfall forecasting in urban areas, and the rainfall-runoff model parameter optimizations. The results of this study, not only urban stream basin, but also we obtained the observed data, and expand the real-time flood alarm system over the ungaged basins. In addition, it is possible to take advantage of development of as multi-sensor based very short-term rainfall forecasting technology.

• Journal of Korea Water Resources Association
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• v.43 no.3
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• pp.245-256
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• 2010

We study the basic theory and applicability of the WQUAL block in the FFC2Q model and the characteristics of non-point pollutant loads during the early stage of runoff. Study is also performed on selection of the values of the related parameters and their effect on the simulation results. FFC2Q simulation results are compared for verification with the measured data for three rainfall events in the Gunja Subbasin and found to be similar to the measured data in peak-flows, total runoff volumes, total loads, peak concentrations and times of peak concentration. This model thus shows results very close to those applying the SWMM and MOUSE models, even though it uses simplified input data. Related to rainfall distribution, under the condition of Huff 1st quartile distribution the pollutant loads occurred earlier than under other conditions, and in the early stage of rainfall the BOD and COD loads increased faster than the SS loads. The NPS loads were concentrated in the early stage of rainfall and finally reached total loads, so the rainfall after that could not contribute so much to the NPS loads.

• Journal of Korea Water Resources Association
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• v.49 no.7
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• pp.579-588
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• 2016

Changes in precipitation due to climate change is made to induce the local and intensive rainfall, it is increasing damage caused by inland inundation. Therefore, it requires a technique for predicting damage caused by flooding. In this study, in order to determine whether this flood inundated by any route when the levee was destroyed, Which can simulate the path of the flood inundation model was developed for the SIMOD (Simplified Inundation MODel). Multi Direction Method (MDM) for differential distributing the adjacent cells by using the slope and Flat-Water Assumption (FWA)-If more than one level higher in the cell adjacent to the cell level is the lowest altitude that increases the water level is equal to the adjacent cells- were applied For the evaluation of the model by setting the flooding scenarios were estimated hourly range from the target area. SIMOD model can significantly reduce simulation time because they use a simple input data of topography (DEM) and inflow flood. Since it is possible to predict results within minutes, if you can only identify inflow flood through the runoff model or levee collapse model. Therefore, it could be used to establish an evacuation plan due to flooding, such as EAP (Emergency Action Plan).

• Journal of Wetlands Research
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• v.22 no.3
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• pp.187-193
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• 2020

The increase in the area of impervious water due to the recent abnormal weather conditions and rapid urbanization led to a decrease in the amount of low current, resulting in an increase in the amount of surface runoff. Increased surface runoff is causing erosion, destruction of underwater ecosystems, human and property damage in urban areas due to flooding of urban river. The damage has been increasing in Korea recently due to localized heavy rains, typhoons and floods. As a countermeasure, the Busan Metropolitan Government will proceed with the creation of the Eco-Delta City waterfront zone in Busan with the aim of creating a future-oriented waterfront city from 2012 to 2023. Therefore, the current urban river conditions and precipitation data were collected by utilizing SWMM developed by the Environment Protection Agency, and the target basin was selected to simulate flood damage. Measures to reduce flood damage in various cases were proposed using simulated data. It is a method to establish a disaster prevention plan for each case by establishing scenario for measures to reduce flood damage. Considering structural and non-structural measures by performing an analysis of the drainage door with a 30-year frequency of 80 minutes duration, the expansion effect of the drainage pump station is considered to be greater than that of the expansion of the drainage door, and 8 scenarios and corresponding alternatives were planned in combination with the pre-excluding method, which is a non-structural disaster prevention measure. As a result of the evaluation of each alternative, it was determined that 100㎥/s of the pump station expansion and the pre-excluding EL.(-)1.5m were the best alternatives.

• Journal of Korea Water Resources Association
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• v.30 no.2
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• pp.177-191
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• 1997

The influences of the space allocation of design rainfall and partition of the subbasin on the characteristics of urban storm runoff was investigated for the 6 drainage basins by applying SWMM model. It show the deviation of -54.68∼18.77% in the peak discharge when we applied the composed JUFF quantiles to the two zones which are divided by upper and lower region of the basin. Then it is compared with the value for the case of using uniform rainfall distribution all over the drainage. Therefore, it would be helpful to decrease the flood risk when we adopt the space distribution of the design rainfall. The effects of the partitioning the drainage on the computing result shows various responses because of the surface characteristics of the each basin such as slope, imperviousness ratio, buy we can get closer result to the measured value as we make the subbasin detailed. If we use the concept of the skewness and area ratio when we determine the width of subbasin, we can improve the computed result even with fewer number of subbasins. We expect reasonable results which close into the measured results in the range of relative error, 25%, when we divide the basin into more than 3 subbasins and the total urban drainage area is less than 10$\textrm{km}^2$.

• Journal of Korea Water Resources Association
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• v.54 no.spc1
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• pp.1107-1118
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• 2021

Climate change brought on by global warming increased the frequency of flood and drought on the Korean Peninsula, along with the casualties and physical damage resulting therefrom. Preparation and response to these water disasters requires national-level planning for water resource management. In addition, watershed-level management of water resources requires flow duration curves (FDC) derived from continuous data based on long-term observations. Traditionally, in water resource studies, physical rainfall-runoff models are widely used to generate duration curves. However, a number of recent studies explored the use of data-based deep learning techniques for runoff prediction. Physical models produce hydraulically and hydrologically reliable results. However, these models require a high level of understanding and may also take longer to operate. On the other hand, data-based deep-learning techniques offer the benefit if less input data requirement and shorter operation time. However, the relationship between input and output data is processed in a black box, making it impossible to consider hydraulic and hydrological characteristics. This study chose one from each category. For the physical model, this study calculated long-term data without missing data using parameter calibration of the Soil Water Assessment Tool (SWAT), a physical model tested for its applicability in Korea and other countries. The data was used as training data for the Long Short-Term Memory (LSTM) data-based deep learning technique. An anlysis of the time-series data fond that, during the calibration period (2017-18), the Nash-Sutcliffe Efficiency (NSE) and the determinanation coefficient for fit comparison were high at 0.04 and 0.03, respectively, indicating that the SWAT results are superior to the LSTM results. In addition, the annual time-series data from the models were sorted in the descending order, and the resulting flow duration curves were compared with the duration curves based on the observed flow, and the NSE for the SWAT and the LSTM models were 0.95 and 0.91, respectively, and the determination coefficients were 0.96 and 0.92, respectively. The findings indicate that both models yield good performance. Even though the LSTM requires improved simulation accuracy in the low flow sections, the LSTM appears to be widely applicable to calculating flow duration curves for large basins that require longer time for model development and operation due to vast data input, and non-measured basins with insufficient input data.