• Journal of Environmental Impact Assessment
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• v.24 no.2
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• pp.163-174
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• 2015

Urbanization caused various environmental problems like destruction of natural water cycle and increased urban flood. To solve these problems, LID(Low Impact Development) deserves attention. The main objective of LID is to restore the water circulation to the state before the development. In the previous studies about the LID, the runoff reduction effect is mainly discussed and the effects of each techniques of LID depending on rainfall types have not fully investigated. The objective of this research is to evaluate the effect of LID using the quantitative simulation of rainwater runoff as well as an amount of infiltration according to the rainfall and LID techniques. To evaluate the water circulation of LID on the development area, new land development areas of Hanam in South Korea is decided as the study site. In this research, hydrological model named STORM is used for the simulation of water balance associated with LID. Rainfall types are separated into two categories based on the rainfall intensity. And simulated LID techniques are green roof, permeable pavement and swale. Results of this research indicate that LID is effective on improvement of water balance in case of the low intensity rainfall event rather than the extreme event. The most effective LID technique is permeable pavement in case of the low intensity rainfall event and swale is effective in case of the high intensity rainfall event. The results of this study could be used as a reference when the spatial plan is made considering the water circulation.

• Journal of Wetlands Research
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• v.16 no.3
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• pp.423-429
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• 2014

Due to high imperviousness rates of the roads, various pollutants originated from vehicle activities and air depositions are accumulated on the road surfaces. The washed-off pollutants can deteriorate the water quality and destroy the aqua-ecosystems with their toxicity. Usually the roads are paved with asphalt and concrete, which can affect on the pollutant concentrations with different frictional forces. Therefore, this research is performed to evaluate the influences of different pavement type on discharged concentrations of pollutant. The results shows the first flush phenomenon was occurred on both pavement types. However, peak concentrations are higher in concrete pavement areas than asphalt pavement because concrete pavement has high contact area with vehicles. The EMCs(Event Mean Concentration) also shows high values in concrete paved roads. As a result of this research, it can be concluded the pavement type is also one of the important affecting factors on pollutant emissions from the roads.

• Journal of Korea Water Resources Association
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• v.45 no.1
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• pp.39-52
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• 2012

Surface-subsurface interactions are an intrinsic component of the hydrologic response within a watershed. In general, these interactions are considered to be one of the most difficult areas of the discipline, particularly for the modeler who intends simulate the dynamic relations between these two major domains of the hydrological cycle. In essence, one major complexity is the spatial and temporal variations in the dynamically interacting system behavior. The proper simulation of these variations requires the need for providing an appropriate coupling mechanism between the surface and subsurface components of the system. In this study, an approach for modelling surface-subsurface flow and transport in a fully intergrated way is presented. The model uses the 2-dimensional diffusion wave equation for sheet surface water flow, and the Boussinesq equation with the Darcy's law and Dupuit-Forchheimer's assumption for variably saturated subsurface water flow. The coupled system of equations governing surface and subsurface flows is discretized using the finite volume method with central differencing in space and the Crank-Nicolson method in time. The interactions between surface and subsurface flows are considered mass balance based on the continuity conditions of pressure head and exchange flux. The major module consists of four sub-module (SUBFA, SFA, IA and NS module) is developed.

• Journal of Korea Water Resources Association
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• v.51 no.10
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• pp.929-939
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• 2018

In North Korea, hydropower which occupies about 63% of power generation is a major electric power source, and North Korea has many advantages in the geographical for developing hydroelectric power. In this study, Information on the basin and dam capacity for 33 potential development site of hydroelectric dam was analyzed using DEM, and potential annual power generation was estimated by applying results of long-term runoff simulation with MWSWAT model for recent 30-year. The potential annual power generation at 33 dam was estimated to be about 28% of the current hydroelectric power in North Korea. In addition, a priority of dam development in each province was assessed by estimating the scale of an industry and prospecting the population change in the future. And a priority for dam development within the province was estimated based on the dam capacity and the potential annual power generation. The priority of each province was ranked in order of Pyeongannamdo, Hamgyungnamdo, Hamgyungbukdo, Hwanghaebukdo, Pyeonganbukdo, Jagangdo, Ryanggangdo, Hwanghaenamdo, and Gangwondo. The results of this study can be used as an initial review data for advancing to hydropower development project in North Korea.

• Journal of Wetlands Research
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• v.20 no.3
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• pp.235-242
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• 2018

The function of vertical subsurface flow wetlands can potentially be reduced with time due to clogging and are often assumed to be occurring when ponding and overflow is observed during rainfall. To investigate their clogging potential, three pilot-scale vertical subsurface flow (VSF) wetland systems were constructed employing woodchip, pumice, and volcanic gravel as main media. The systems received stormwater runoff from a highway bridge for seven months, after which the media were taken out and divided into layers to determine the amount and characteristics of the accumulated clogging matters. Findings revealed that the main clogging mechanism was the deposition of suspended solids. This is followed by the growth of biofilm in the media which is more evident in the wetland employing woodchip. Up to more than 30% of the clogging matter were found in the upper 20 cm of the media suggesting that this layer will need replacement once clogging occurs. Moreover, no signs of clogging were observed in all the wetlands during the operation period even though an estimation of at least 2 months without clogging was calculated. This was attributed to the intermittent loading mode of operation that gave way for the decomposition of organic matters during the resting period and potentially restored the pore volume.

• Journal of Korea Water Resources Association
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• v.51 no.12
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• pp.1261-1271
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• 2018

This study evaluates the applicability of the classification rule of hydrological soil group proposed by Lee et al. (2018) with its application to three river basins (Jungmuncheon, Cheonmicheon, and Hancheon) in Jeju Island. The CN values are estimated as results of this application to these three basins, which is then compared with those estimated by applying the conventional three methods. Additionally, previous studies related with the classification of soil groups of Jesu Island, such as the infiltration and rainfall-runoff analysis, are reviewed to evaluate how the resulting hydrological soil groups vary depending on the adopted classification method.. Summarizing the results is as follows. (1) Comparison result of the hydrological soil groups of Jeju Island with respect to the classification method shows that the soil group B is dominant in the application of Lee et al. (2018). However, it is hydrological soil groups C and D in the application of Hu and Jung (1987), hydrological soil groups A and C in the application of Jung et al. (1995), and hydrological soil group D in the application of RDA (2007). (2) In all the applications of Lee et al. (2018) to three selected river basins in Jeju Island, the CN valuse are found to be smaller than those by other conventional three methods.. Lastly, (3) The evaluation results of previous studies related with the classification of hydrological soil groups analysis in Jeju Island shows that the CN value in the Jeju Island may be smaller than those estimated by conventional three methods, also the initial loss higher than 0.2S.

• Journal of Korea Water Resources Association
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• v.53 no.12
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• pp.1193-1201
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• 2020

This study aims to develop a regression model that estimates a low-flow index that can be applied to ungauged basins. A total of 30 midsized basins in South Korea use long-term runoff data provided by the National Integrated Water Management System (NIWMS) to calculate average low-flow, average minimum streamflow, and low-flow index duration and frequency. This information is used in the correlation analysis with 18 basin factors and 3 climate change factors to identify the basin area, average basin altitude, average basin slope, water system density, runoff curve number, annual evapotranspiration, and annual precipitation in the low-flow index regression model. This study evaluates the model's accuracy by using the root-mean-square error (RMSE) and the mean absolute error (MAE) for 10 ungauged, verified basins and compares them with the previous model's low-flow calculations to determine the effectiveness of the newly developed model. Comparative analysis indicates that the new regression model produces average low-flow, attributed to the consideration of varied basin and hydrologic factors during the new model's development.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.6D
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• pp.1019-1023
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• 2006

The slope information based on DEM is very useful for urban planning, landscape, road design and water resource areas such as rainfall-runoff and soil erosion estimation. The resolution of slope, which is from DEM, can be variously decided by an application fields and the kinds of modeling method. In particular, the more decreased resolution makes the more decreased slope value because of the increased horizontal distance. This study presents slope evaluation method by aggregation method based on discharge and Manning's velocity equation to advance the loss of slope information in according to the resolution, and then applied it to calculate topographic factors of soil erosion model. As a result, conventional method shows 34.8% errors but aggregation method shows 12.6% errors. This study selected up-, middle-, and downstream region in watershed and analyzed the capability of aggregation method in order to estimate the influence of topographic characteristics. As a result of estimation, aggregation method shows more advanced results than conventional method. Therefore, the slope evaluation method by aggregation method can improve efficiently the loss of slope information in according to the variation of resolution in water resource area such as rainfall-runoff model.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.2B
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• pp.225-231
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• 2006

The nonpoint source control is based on TPLMS (Total Pollution Load Management System) program. Recently, the Ministry of Environment in Korea has programed TPLMS for 4 major large rivers to improve the water quality in rivers by controling the total pollutant loadings from the watershed area. Usually the urbanization is the main pollutant sources, particularly for nonpoint pollutants, because of high imperviousness and high pollutant mass emissions. The stormwater runoff from urban areas is containing various pollutants such as sediments, metals and toxic chemicals due to human and vehicle activities. Of the various landuses, the highways are highly polluted landuses because of high pollutant accumulation rate by vehicle activities during dry periods. Therefore, this research is achieved to provide pollutant EMCs (Event Mean Concentrations) and mass loadings washed-off from highways during rainfall periods. Five monitoring locations were equipped with an automatic rainfall gage and an flow meter. The results show that the EMC ranges for 95% confidence intervals in highway land use are 45.52-125.76 mg/L for TSS, 52.04-95.48 mg/L for COD, 1.77-4.48 mg/L for TN, 0.29-0.54 mg/L for TP. The ranges of washed- off mass loading are $712.7-2,418.4mg/m^2$ for TSS and $684.1-1,779.6mg/m^2$ for COD.

• Proceedings of the Korea Water Resources Association Conference
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• 2005.05b
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• pp.715-719
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• 2005

현재 우리나라는 1970년대 이후 급속한 경제성장으로 인하여 산업화 및 도시화 현상이 심화되고 있는 실정이며, 이러한 과정에서 불투수층의 증가로 인하여 첨두유출량의 증가, 자연유역에서 도시유역으로 변하면서 유역내 도달시간의 감소 등의 수문학적 특성이 변화로 예기치 못한 홍수로 인하여 피해가 발생하고 있다. 다라서 첨두유출량이 관망으로 전달되는 과정에서 관에 발생하는 부하의 증가로 인하여 내수침수 피해를 입게 되는데, 도시 유역에서의 인구 증가 및 산업활동에 따른 도시 개발로 인한 불투수면적의 증가로 우수유출량이 커지고 있으며, 저지대의 활용이 증대됨에 따라 내수 피해는 더욱 증가되고 있는 실정이다. 이러한 도시 유역의 재배 저감 대책 수립을 위해서는 먼저 실측자료와 도시유출 모형에서 산정된 첨두유출량과의 비교$\cdot$분석하여 최적의 모형을 채택하여야 한다. 또한 채택된 모형으로 적절한 설계 강우량이 선정되어야 하고, 그에 따른 유출량을 정확히 산정하여야 하나, 설계 강우량 산정을 위한 강우의 지속시간의 결정에 대해서 일반적인 기준이 확립되지 못하고 있는 실정이기에 재해 저감 대책 수립에 많은 어려움이 따르고 있다. 이에 본 연구에서는 실측 강우량, 첨두유출량 및 유출총량과 도시지역의 유출량 산정에 사용되어지는 ILLUDAS, SWMM 모형에 모의치와의 비교 연구를 통해 최적의 도시유출모형을 제시하고자 한다. 따라서 실측자료가 있는 서울시 장안$\cdot$뚝섬배수구역의 실측 강우와 펌프장에서 조사된 실측 유량과 ILLUD AS, SWMM 모형에 의해 산정된 유량과의 비교 분석 결과 SWMM 모형에 의한 첨두유량이 실측 첨두유출량과의 오차율에서 장안배수구역은 $21.1\%$, 뚝섬배수구역은 $4.3\%$로 가장 근접한 결과를 나타내었으며, 총 유출량에서도 각각 $7.8\%,\;13.2\%$의 오차율을 가지는 것으로 분석되어 타 모형에 비해 실유량과의 차가 가장 적은 것으로 모의되었다. 향후 도시유출을 모의하는 데 가장 근사한 유출량을 산정할 수 있는 근거가 될 것이며, 도시재해 저감대책을 수립하는데 기여할 수 있을 것이라 판단된다.