• Journal of Environmental Science International
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• v.24 no.4
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• pp.415-424
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• 2015

As global warming has accelerated to weather in recent years, and The frequent floods are creating heavy rains and typhoons followed by considerable damage in Jeju. This study estimated design flood discharges and flood stage in Jeju, considering climate change in connection with RCP scenario, the 5th IPCC Report recently published. It also analyzed the period which might be subject to the risk of flooding in downstream of Oedo Stream. As a result, it has analyzed that there might be a risk of flooding when there were 80 years or more rainfall events in 35 years that rainfall would have increased by 10%, 69 years that 100 years or more heavy rain and rainfall would have increased by 20%, and 104 years that 100 years or more heavy rain and rainfall would have increased by 20%. It is expected that this study results of rainfall increasing trend caused by climate change will be helpful to minimize the damage of floods which will secure the future of Jeju.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.1209-1213
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• 2005

It reflects well feature of slope that is characteristic of city river basin of Pusan local. Process various hydrological datas and basin details datas which is collected through basin basis data. weather satellite equipment(EMS-DEU) and automatic water level equipment(AWS-DEU) and use as basin input data of ILLUDAS model, SWMM model and HEC-HMS model In order to examine outflow feature of experiment basin and then use in reservoir design of experiment basin through calibration and verification about HEC-HMS model. Inserted design rainfall for 30 years that is design criteria of creek into HEC-HMS model and then calculated design floods according to change aspect of the impermeable rate. Capacity of reservoir was determined on the outflow mass curve. Designed imagination reservoir(volume $54,000m^3$) at last outlet upper stream of experiment basin, after designing reservoir. It could be confirmed that the peak flow was reduced resulting from examining outflow aspect. Designing reservoir must decrease outflow of urban areas.

• Journal of the Korean Society of Hazard Mitigation
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• v.10 no.2
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• pp.143-149
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• 2010

The river master plan was established every 10 years in Korea. The basin characteristics of 62 small and medium size rivers of which master plans were recently established during the past three years in Gyeonggi-do were investigated, and design rainfalls and design floods in the past and the latest were compared and analyzed. It was predicted that basin data and flood estimating method changed design flood. The quantitative amount of design floods were analyzed for 6 basins like Gungunchen etc. As the results, the increasing factors of design flood were the application of critical duration time, temporal time of rainfall and the increase of CN value. The decreasing factors of design flood were the application of Huff's rainfall distribution instead of Mononobe one and the ARF. The application of critical duration time increased flood about 60% whereas the application of Huff's rainfall distribution method estimated less flood than Mononobe about 62%. Considering critical duration time and changing rainfall distribution were the most important factors of increasing or decreasing design flood. However, trends of flood variation were differently analyzed by factors in 6 basins because characteristics of topography, weather, hydrology and hydraulic were different, now that correlations were not found between factors and flood variation. Flood variation is evaluated by complex effects of factors so new flood recalculated by reasonable methods should be considered as design flood.

• 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 The Korean Society of Agricultural Engineers
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• v.63 no.3
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• pp.59-73
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• 2021

The purpose of this study is to investigate transition of pumping technology, irrigation water requirement, and unit area drainage discharge at the Pumping station-based Irrigation Associations (PIAs) in South Korea during Japanese colonial period (1910-1945). The PIAs established pumping stations and embankments along rivers for the purpose of irrigation, drainage and flood prevention until the mid-1920s. From the late 1920s after major river improvement projects, newly established PIAs did not include the flood prevention in their purpose of establishment. The design criteria of the irrigation and drainage projects, such as irrigation water requirements, design rainfall, and allowable ponding duration were decided according to the circumstances of PIAs. The gross irrigation water requirement of paddy fields increased from the 1920s to the 1940s, and reached the level of 0.0020 m³/s/ha (19 mm/d) in the 1940s for the fairly good irrigation status in the drought. The great floods of 1930, 1933, and 1934 triggered the increase in drainage discharge in the late 1930s, leading to the unit area drainage discharge of 0.9-2.6 m³/s/km² for natural drainage and 0.3-1.1 m³/s/km² for pump drainage. Therefore, several PIAs near the major rivers could avoid repetitive floods damage.

• Water for future
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• v.12 no.2
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• pp.56-62
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• 1979

Many methods of estimating design floods from rainfall data involve a trial and error procedure to determine the duration of the design rainfall, which is very complicated and time-consuming. In this study, an effort was given to derive an analytical expression for estimating the appropriate duration for use with a particular unit hydrograph. According to the so-derived analytical expression the coordinateds of hvdrograph curve and rainfall curve for the Musim Representative Basin were computed and then plotted on a same scal graph paper on which the critical durations of design rainfall excess of various recurrence intervals were determined by the point of intersection of the tow curves.

• International Journal of Contents
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• v.12 no.2
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• pp.12-23
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• 2016

This paper presents a novel concept of Disaster Prevention Design (DPD) and its derived subjects and topics for the safety of folk villages in both Korea and Japan. Nowadays, design concepts are focused on 'human-oriented nature' as a whole and this tendency fits to be appropriate for disaster prevention against real dangers of a future society, which is expected to have far more complicated features. On the other hand, convergences have performed with other areas in the field of Information Communication Technology (ICT) so that we can easily find examples like 'the strategy of ICT-based convergence' of the Korean Government in 2014. Modern content designs including UI (user interface) and USN (ubiquitous sensor network) have been developed as one of the representative areas of ICT & UD (universal design) convergences. These days this novel concept of convergence is overcoming the existing limitations of the conventional design concept focused on product and/or service. First of all, from that point our deduced topic or subject would naturally be a monitoring system design of constructional structures in folk villages for safety. We offer an integrated model of maintenance and a management-monitoring scheme. Another important point of view in the research is a safety sign or sign system installed in folk villages or traditional towns and their standardization. We would draw up and submit a plan that aims to upgrade signs and sign systems applied to folk villages in Korea and Japan. According to our investigations, floods in Korea and earthquakes in Japan are the most harmful disasters of folk villages. Therefore, focusing on floods in the area of traditional towns in Korea would be natural. We present a water-level expectation model using deep learning simulation. We also apply this method to the area of 'Andong Hahoe' village which has been registered with the World Cultural Heritage of UNESCO. Folk village sites include 'Asan Oeam', 'Andong Hahoe' and 'Chonju Hanok' villages in Korea and 'Beppu Onsen' village in Japan. Traditional Streets and Markets and Safe Schools and Parks are also chosen as nearby test-beds for DPD based on ICT. Our final goal of the research is to propose and realize an integrated disaster prevention and/or safety system based on big data for both Korea and Japan.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.5
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• pp.139-152
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• 2015

Along with climate change, it is reported that the scale and frequency of extreme climate events show unstable tendency of increase. Thus, to comprehend the change characteristics of precipitation data, it is needed to consider non-stationary. The main objectives of this study were to estimate future design floods for Wonpyeongcheon watershed based on RCP (Representative Concentration Pathways) scenario. Wonpyeongcheon located in the Keum River watershed was selected as the study area. Historical precipitation data of the past 35 years (1976~2010) were collected from the Jeonju meteorological station. Future precipitation data based on RCP4.5 were also obtained for the period of 2011~2100. Systematic bias between observed and simulated data were corrected using the quantile mapping (QM) method. The parameters for the bias-correction were estimated by non-parametric method. A non-stationary frequency analysis was conducted with moving average method which derives change characteristics of generalized extreme value (GEV) distribution parameters. Design floods for different durations and frequencies were estimated using rational formula. As the result, the GEV parameters (location and scale) showed an upward tendency indicating the increase of quantity and fluctuation of an extreme precipitation in the future. The probable rainfall and design flood based on non-stationarity showed higher values than those of stationarity assumption by 1.2%~54.9% and 3.6%~54.9%, respectively, thus empathizing the necessity of non-stationary frequency analysis. The study findings are expected to be used as a basis to analyze the impacts of climate change and to reconsider the future design criteria of Wonpyeongcheon watershed.

• Journal of Korea Water Resources Association
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• v.49 no.8
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• pp.719-729
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• 2016

Extreme events of rainfall has increased mainly from climate change, resulting in more severe floods intensified by land use development. Appropriate estimation of design floods gets more attention to ensuring the safety of life and property in flood-prone areas for hydraulic structures such as dams and levees. In the current study, we reestimated the design flood of the Nam River Dam to adopt the influence of climatic change of hydrometeorological variables including recent datasets of extreme rainfall events. The climate change scenarios of extreme rainfall events in hourly scale that has been downscaled was used in analyzing the annual maximum rainfall for the weather stations in the Nam River Dam basin. The estimates of 200-year and 10,000-year return periods were calculated to provide a design flood and a probable maximum flood case for the Nam River Dam. The results present that the new estimate employing the RCP4.5 and RCP8.5 downscaled data is much higher than the original design flood estimated at the dam construction stage using a 200-year return period. We can conclude that the current dam area might be highly vulnerable and need an enhancement of the dam safety regarding the reduction of damage in Sachen bay from the outflow of Nam River Dam.

• Journal of The Korean Society of Agricultural Engineers
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• v.46 no.6
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• pp.3-10
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• 2004

The fundamental study of hydrologic redesign of Donghwa area located in a sccond tributary of Seomjin river was performed. The amounts of hydrologic design were estimated using the available cumulated hydrology data provided by Korea Agricultural and Rural Infrastructure Corporation (KARICO). The management status of The water resources in Donghwa area was also widely surveyed. The probability rainfalls, probable maximum precipitation (PMP) and probability floods were estimated and subsequently their changes analyzed. The amount of 200 year frequency rainfall with l day duration was 351.1 mm, 2.5 % increased from the original design value, and The PMP was 780.2 mm. The concentration time was reestimated as 2.5 hours from existing 2.4 hours. Soil Conservation Service(SCS) method was used to estimate effective rainfall- The runoff curve number was changed from 90 to 78, therefore the maximum potential retention was 71.6 mm, 154 % increased from the original value. The Hood estimates using SCS unit hydrograph showed 8 % increase from original value 623 $m^3$/s to 674 $m^3$/s and The probable maximum Hood was 1,637 $m^3$/s. Although the Row rate at the dam site was increased, the Hood risk at the downstream river was decreased by the Hood control of the Donghwa dam.