• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.4
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• pp.69-75
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• 2014

We investigated flood control capacity of 484 agricultural reservoirs with storage capacity of over 1 million $m^3$ in South Korea. In general, agricultural reservoir secures flood control capacity by setting up limited water level during flood season from late June to mid-September. The flood control capacity of an agricultural reservoir during flood season can be divided into stable flood control capacity during non-flood season, stable flood control capacity associated with limited water level, and unstable flood control capacity associated with limited water level. In general, the flood control capacity significantly (P < 0.001) increased with reservoir capacity irrespective of type of spillway. The unstable flood control capacity accounted for about 20 % of reservoir capacity in the uncontrolled reservoirs. The study reservoirs showed flood control capacity of 0.60-65 billion (B) $m^3$ and stable flood control capacity of 0.43-47 B $m^3$, depending on the upper and lower limited water levels during the flood season. The stable flood control capacity of the gated reservoirs (0.29-0.33 B $m^3$) was about two times than that of reservoirs with uncontrolled spillways (0.14 B $m^3$). The ratios of stable flood control capacity to reservoir capacity for agricultural reservoirs range from 21 to 23 %, similar to that for Daecheong multipurpose dam. Moreover, the reservoirs with over 100 mm ratio of flood control capacity to watershed area accounted for 38 % of total gated reservoirs. The results indicate that many agricultural reservoirs may contribute to controlling flood in the small watersheds during the flood season.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.1
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• pp.91-95
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• 2014

During a flood season, Bo region could be easily exposed to flood due to increase of ground water level and the water drain difficulty even the water amount of Bo can be managed. GFI for the flood risk is measured by mean depth to water during a dry season and minimum depth to water and tangent degree during a flood season. In this paper, a forecasting model of the target variable, GFI and predictors as differences of height between ground water and Bo water, distances from water resource, and soil characteristics are obtained for the dry season of 2012 and the flood season of 2012 with empirical data of Gangjungbo and Hamanbo. Obtained forecasting model would be used for keep the value of GFI below the maximum allowance for no flooding during flooding seasons with controlling the values of significant predictors.

• Environmental Engineering Research
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• v.15 no.4
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• pp.197-205
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• 2010

Recent years have witnessed increasing interest in wetland constructions in Korea as a flood control measure during the flood season and for consideration of the ecology during the non-flood season. In this study, hydraulic and hydrologic analyses were performed on a wetland construction plan for use as an alternative sustainable flood defense during the flood season, as well as a wetland that can protect the ecosystem during the non-flood season. The study area was the basin of the Topyeong-cheon stream, which is a tributary of the Nakdong River, including the Upo wetland, which is registered in the Ramsar Convention and the largest inland wetland in Korea. Wetlands were to be constructed at upstream and downstream of the Upo wetland by considering and analyzing seven scenarios for their constructions to investigate the effect of flood control during the flood season; it was found the best scenario reduced the flood level by 0.56 m. To evaluate the usefulness of the constructed wetlands during the non flood season, the water balance in the wetlands was analyzed, with the best scenario found to maintain a minimum water level of 1.3 m throughout the year. Therefore, the constructed wetlands could provide an alternative measure for flood prevention as well as an ecosystem for biodiversity.

• Journal of Ocean Engineering and Technology
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• v.23 no.4
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• pp.25-31
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• 2009

To predict pollutants during the flood and dry season in Gwangyang Bay, the net-fluxes and pollutant material budgets of COD, T-N, and T-P were calculated in Gwangyang Bay using a 2-D hydrodynamic model. Calculating the net-flux for each area in Gwangyang Bay showed that the net-fluxes in regions IV, V, and VII were increasing, but those of regions II, III, and VI were decreasing. In budget calculations for COD, T-N, and T-P in Gwangyang Bay, it was estimated that during the dry season the COD is approximately 1.6 times higher than during the flood season. The T-N during the flood season is approximately 7 times higher than during the dry season. However, the material budget for T-P in Gwangyang Bay predicted that it is almost nonexistent. Moreover, the central part of Gwangyang Bay (Region IV) has the highest material budget of overall pollutants.

• Journal of Korea Water Resources Association
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• v.57 no.5
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• pp.359-369
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• 2024

Korea prepares for potential floods by designating June 21st to September 20th as the flood season. However, many dams in Korea have suffered from extreme floods caused by different climate patterns, as in the case of the longest consecutive rain of 54 days in the 2020's flood season. In this context, various studies have tried to develop novel methodologies to reduce flood damage, but no study has ever dealt with the validity of the current statutory flood season thus far. This study first checked the validity of the current flood season through the observation data in the 21st century and proved that the current flood season does not consider the effects of increasing precipitation trends and the changing regional rainfall characteristics. In order to deal with these limitations, this study suggested seven new alternative flood seasons in the research area. The rigid reservoir operation method (ROM) was used for reservoir simulation, and the long short-term memory (LSTM) model was used to derive predicted inflow. Finally, all alternatives were evaluated based on whether if they exceeded the design discharge of the dam and the design flood of the river. As a result, the floods in the shifted period were reduced by 0.068% and 0.33% in terms of frequency and duration, and the magnitude also decreased by 24.6%, respectively. During this period, the second evaluation method also demonstrated that flood decreased from four to two occurrences. As the result of this study, the authors expect a formal reassessment of the flood season to take place, which will ultimately lead to the preemptive flood response to changing precipitation patterns.

• Journal of Korea Water Resources Association
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• v.41 no.5
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• pp.483-489
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• 2008

Recently, we have a growing interest in the washland construction for the function of flood defense in flood season and also as an ecosystem in non flood season. Therefore this study performed the hydraulic and hydrologic analysis for washland construction plan as sustainable flood defense alternative in flood season and wetland application possibility. The study area is Topyoung-cheon basin in Changnyeong-gun, Gyeongnam. A Topyoung-cheon basin includes a Woopo wetland which is the largest nature wetland in Korea and a Topyoung-cheon is ond of the tributaries of Nakdong river. We assume that the artificial washland is constructed in upperstream and downstream of Woopo wetland, and In flood season, the hydraulic analysis for the investigation of the effectiveness of flood level mitigation is performed by HEC-RAS model. Simulation of model is performed from 7 scenarioes of washland construction. As the result in flood season, the flood level is reduced by maximum 0.56 meter as we construct the washlands by 7 scenarios. Also, we performed hydrologic analysis for the investigation of water balance in washland in non flood season using SWAT model. From the result of water balance analysis, we found that the minimum water level of washland was maintained in about 1.3 meter for one year.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.2
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• pp.147-156
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• 2011

The purpose of multipurpose reservoir operation in flood season is to reduce the peak flood at a control point by utilizing flood control storage or to minimize flood damage by controlling release and release time. Therefore, the most important thing in reservoir operation for flood season is to determine the optimal release and release time. In this study, goal programming is used for the optimal reservoir operation in flood season. The goal programming minimizes a sum of deviation from the target value using linear programming or nonlinear programming to obtain the optimal alternative for the problem with more than two objectives. To analyze the applicability of goal programming, the historical storm data are utilized. The goal programming is applied to the reservoir system operation as well as single reservoir operation. Chungju reservoir is selected for single reservoir operation and Andong and Imha reservoirs are selected for reservoir system operation. The result of goal programming is compared with that of HEC-5. As a result, it was found that goal programming could maintain the reservoir level within flood control level at the end of a flood season and also maintain flood discharge within a design flood at a control point for each time step. The goal programming operation is different from the real operation in the sense that all inflows are assumed to be given in advance. However, flood at a control point can be reduced by calculating the optimal release and optimal release time using suitable constraints and flood forecasting system.

• Journal of the Korean Society of Marine Environment & Safety
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• v.17 no.3
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• pp.185-189
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• 2011

To predict the deposition characteristic in the Nakdong river estuary, the material budget of Suspended Solid(SS) was investigated with the amount of Nakdong river discharge being set as dry season and flood season. The results of material budged of SS in dry season and flood season were 60,708 kg/day(inflow) and 306,892 kg/day(outflow), respectively.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.5
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• pp.1690-1707
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• 2021

Precipitation prediction during flood season has been a key task of climate prediction for a long time. This type of prediction is linked with the national economy and people's livelihood, and is also one of the difficult problems in climatology. At present, there are some precipitation forecast models for the flood season, but there are also some deviations from these models, which makes it difficult to forecast accurately. In this paper, based on the measured precipitation data from the flood season from 1993 to 2019 and the precipitation return data of CWRF, ANN cycle modeling and a weighted integration method is used to correct the CWRF used in today's operational systems. The MAE and TCC of the precipitation forecast in the flood season are used to check the prediction performance of the proposed algorithm model. The results demonstrate a good correction effect for the proposed algorithm. In particular, the MAE error of the new algorithm is reduced by about 50%, while the time correlation TCC is improved by about 40%. Therefore, both the generalization of the correction results and the prediction performance are improved.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.211-211
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• 2015

Mekong River is the world's $10^{th}$ longest river and runs through China's Yunnan province, Burma, Thailand, Laos, Cambodia and Vietnam. And Tonle Sap Lake, the largest fresh water body in Southeast Asia and the heart of Mekong River system, covers an area $2,500-3,000Km^2$ in dry season and $10,000-16,000Km^2$ in wet season. As previously noted, the water within Sap river flows from the Mekong River to Tonle Sap Lake in flood season (between June and October) and backward to Mekong River in dry season. Recently the flow regime of Sap River might be significantly affected by the development of large dams in upstream region of Mekong River. This paper aims at basic study about the large scale flood inundation of Cambodia using by CAESAR-Lisflood. CAESAR-Lisflood is a geomorphologic / Landscape evolution model that combines the Lisflood-FP 2d hydrodynamic flow model (Bates et al, 2010) with the CAESAR geomorphic model to simulate flow hydrograph and erosion/deposition in river catchments and reaches over time scales from hours to 1000's of years. This model is based on the simplified full Saint-Venant Equation so that it can simulate the interacted flow of between Mekong River and Tonle Sap Lake especially focusing on the flow direction change of Sap River by season.