• Journal of Environmental Science International
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• v.24 no.8
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• pp.1065-1073
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• 2015

Urbanization can be significantly affected the hydrologic cycle by increasing flood discharge and heat flux. In order to mitigate these modifications in urban areas, Low Impact Development (LID) technique has been designed and applied in Korea. In order to estimate runoff reduction rate using SWMM LID model, the characteristics of five LID techniques was firstly analyzed for water balance. Vegetated swale and green roof were not reduce flood discharge nor infiltration amount. On the other hand, porous pavement and infiltration trench were captured by infiltration function. The flood reduction rate with LID is substantially affected by their structures and properties, e.g., the percentage of the area installed with LID components and the percentage of the drainage area of the LID components.

• Journal of Korean Society on Water Environment
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• v.27 no.6
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• pp.841-847
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• 2011

In this study, a method to determine the design capacities of nonpoint source (NPS) pollutant treatment facilities in urban areas was suggested. A facility capacity to treat 80 percent of total SS discharge was estimated by 2-year rainfall - runoff - build-up and wash-off simulation at Goonja drainage district in Seoul. For wash-off simulation, four wash-off models (EMC, RC, EXP, and Joo model) were used. As the results, 80 percent of total SS discharge could be treated with only 7.7~31.4% facility capacity of peak flow. The suggested method and results will provide a guideline to determine design capacities of NPS pollutant treatment facility in urban areas.

• Journal of Korea Water Resources Association
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• v.51 no.4
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• pp.347-354
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• 2018

In urban areas, runoff flow is drained through sewer networks as well as surface areas. Therefore, it is very important to consider sewer networks as a component of hydrological drainage processes when conducting urban inundation modelling. However, most researchers who have implemented urban inundation/flood modelling, instinctively simplified the sewer networks without the appropriate criteria. In this research, a 1D-2D fully coupled urban inundation model is applied to estimate the influence of sewer network simplification on urban inundation modelling based on the dendritic network classification. The one-dimensional (1D) sewerage system analysis model, which was introduced by Lee et al. (2017), is used to simulate inlet and overflow phenomena by interacting with surface flow. Two-dimensional (2D) unstructured meshes are also applied to simulate surface flow and are combined with the 1D sewerage analysis model. Sewer network pipes are simplified based on the dendritic network classification method, namely the second and third order, and all cases of pipes are conducted as a control group. Each classified network case, including a control group, is evaluated through their application to the 27 July 2011 extreme rainfall event, which caused severe inundation damages in the Sadang area in Seoul, South Korea. All cases are compared together regarding inundation area, inflow discharge and overflow discharge. Finally, relevant criterion for the simplification method is recommended.

• Journal of Environmental Science International
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• v.20 no.12
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• pp.1553-1560
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• 2011

The study analyzes groundwater balance with regard to the water recharge and discharge which contain urbanization components in Suyeong-gu, Busan. It also verifies the reliability and accuracy improvement on the analysis of the balance. The result of the study is viewed as preliminary data which are useful to develop, utilize and manage groundwater. The average quantity of groundwater recharge is 6,014.1 $m^3$/day in the research area during the last ten year period(from 1998 to 2007). The outflow from drainage areas to rivers and coasts is 149.3 $m^3$/day, the inflow from rivers and coasts to drainage area is 439.9 $m^3$/day. The use of the water is 4,243.0 $m^3$/day. The outflow caused by subway in line No.2 and No.3 through Suyeong-gu and the one by building an underground electric complex is 1,500.0 $m^3$/day. The leakage of water works is 6514.9 $m^3$/day. The inflow and outflow of sewerage is 5082.2 $m^3$/day from groundwater to sewer. The amount of groundwater recharge, the inflow from rivers and coasts to drainage area, and the leakage of water works belong to the amount of groundwater inflow and the total amount is 12,968.9 $m^3$/day. The amount of outflow from drainage area to rivers and coasts, the use of groundwater, outflow by subway and underground electric complex tunnel and the amount of inflow of the water to sewerage belong to the amount of outflow of groundwater and the sum amount is 13,031.5 $m^3$/day. The gap between the amount of inflow and outflow of groundwater is 62.6 $m^3$/day, which is considered to reflect the trend that the short term drop in the amount of rainfall results in the amount of groundwater recharge and that the amount of outflow from drainage area to rivers and coasts decreases.

• Korean Journal of Agricultural Science
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• v.10 no.2
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• pp.371-381
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• 1983

This study is aimed at identifying the economic effects of drainage improvement projects. The total area of poor drainage is equivalent to 170,000ha, 13% of the total area of paddy field in Korea. The development of poor drained paddy is an urgent problem considering the low rate of self-sufficiency of food grain and the limitation of farmer's income increase. Rapid development of Korean economy has brought labor shoriage in rural farming sector. Accordingly farm mechanization is an important agricultural policy to hike labor productivity and to save production costs of rice farming. The expected economic benefits of the drainage improvement project are derived from increasing land productivity, expanding double cropped area and farming the farm mechanization base in paddy fields. The economic and financial rate of return of the project are considered very important decision making criteria for project implementation by resource allocation. Therefore this study covered benefit and cost analysis of the sampled area, the estimated financial rate of returns in $Buy{\check{o}}$ and Jinsung are represented 15% and 51% respectively and the economic rate of returns in both project area are also showing 1% and 26% respectively. The rate of return of the projects has showed an outstanding variance according to the locational and natural characteristics of the project area. As showing the above economic rate of return, $Buy{\check{o}}$ is very low Jinsung is very high. But the financial rate of return of both projects are considered comparatively high. Cosequently, the drainage improvement projects should be promoted from the view point of farm income increase to make narrow the income gap between rural and urban incomes and farm mechanization to solve labor shortage in the rural area.

• Land and Housing Review
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• v.3 no.1
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• pp.97-109
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• 2012

For the design of underpass structures, -1.0m(G.L) ground water level guideline for the design of railway, subway, utility tunnel etc, is still being used in Korea. As a result, the underpass structure can be forced by buoyancy, and therefore the in-situ buoyancy anchor method is usually being applied to prevent the uplifting force. For the Yeongjongdo sky city project, the drainage method was applied to remove the buoyancy force. In this study we estimate the efficiency and safety of the applied design and propose the detailed guidelines for standard design and maintenance of the guided drainage technique. Especially, the auxiliary pumping well was operated to maintain the ground water level around the underpass. In the study site, the applied guided drainage method has advantages in both engineering and economic aspects.

• Journal of Korean Society of Water and Wastewater
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• v.35 no.6
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• pp.389-403
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• 2021

In this study, dual drainage system based runoff model was established for W-drainage area in G-si, and considering the various rainfall characteristics determined using Huff and Mononobe methods, the degree of flooding in the target area was analyzed and the risk was compared and analyzed through the risk matrix method. As a result, the Monobe method compared to the Huff method was analyzed to be suitable analysis for flooding of recent heavy rain, and the validity of the dynamic risk assessment considering the weight of the occurrence probability as the return period was verified through the risk matrix-based analysis. However, since the definition and estimating criteria of the flood risk matrix proposed in this study are based on the return period for extreme rainfall and the depth of flooding according to the results of applying the dual drainage model, there is a limitation in that it is difficult to consider the main factors which are direct impact on inland flooding such as city maintenance and life protection functions. In the future, if various factors affecting inland flood damage are reflected in addition to the amount of flood damage, the flood risk matrix concept proposed in this study can be used as basic information for preparation and prevention of inland flooding, as well as it is judged that it can be considered as a major evaluation item in the selection of the priority management area for sewage maintenance for countermeasures against inland flooding.

• Journal of Korea Water Resources Association
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• v.38 no.12 s.161
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• pp.1029-1037
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• 2005

Urban Storm Sewer Optimal Design Model(USSOD) was developed to compute pipe capacity, pipe slope, crown elevation, excavation depth, risk and return cost in the condition of design discharge. Rational formula is adopted for design discharge and Manning's formula is used for pipe capacity. Discrete differential dynamic programming(DDDP) technique which is a kind of dynamic programming (DP) is used for optimization and first order second moment approximation method and uncertainty analysis is also for developing model. USSOD is applied to hypothetical drainage basin to test and verify. After testing the model, it is also applied to Ulsan drainage basin which was developed by Korea Land Cooperation(KOLAND). Comparing the design results of USSOD with those of KOLAND, discharge capacity 0.35 $m^3/sec$, the crown elevation is 0.77m higher and return cost is $9\%$ less than design results of KOLAND, which verify the improvement of USSOD. Layout design model using GIS and optimization including detention or retention effect are needed in the future study.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.1D
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• pp.177-184
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• 2006

This study is to develop a distributed urban flood runoff model that simulates the road runoff and to test the applicability of the model by applying to Pyeongtaek city of $12.2km^2$. To generate the runoff along the runoff, agree burned DEM (Digital Elevation Model) with road networks was suggested and the proper spatial resolution of DEM was identified finer than 15 m. To test the model applicability, 32 points on the road networks were selected and the hydrographs of each point were generated. The test showed reasonable results that increase the road runoff from the high elevation roads to the low elevation roads and the road runoff considering rainwater drainage from the road also showed reasonable results.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.97-97
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• 2020

Flooding in urban areas is caused by heavy rains for a short period of time and drains within 1 to 2 hours. It is also characterized by a small flooding area. In addition, flooding is often caused by various and complex causes such as land use, basin slope, pipe, street inlet, drainage pumping station, making it difficult to predict flooding. Therefore, this study analyzes the effect of each basin characteristic on the occurrence of flooding in urban areas by correlating various basin characteristics, whether or not flooding occurred, and rainfall(Limit Rainfall), and intends to use the data for urban flood prediction. As a result of analyzing the relationship between the imperviousness and the urban slope, pipe, threshold rainfall and limit rainfall, the pipe showed a correlation coefficient of 0.32, and the remaining factors showed low correlation. However, the multiple correlation analysis showed the correlation coefficient about 0.81 - 0.96 depending on the combination, indicating that the correlation was relatively high. In the future, I will further analyze various urban characteristics data, such as area by land use, average watershed elevation, river and coastal proximity, and further analyze the relationship between flooding occurrence and urban characteristics. The relationship between the urban characteristics, the occurrence of flooding and the limiting rainfall amount suggested in this study is expected to be used as basic data for the study to predict urban flooding in the future.