• Journal of Korea Water Resources Association
• /
• v.45 no.11
• /
• pp.1107-1119
• /
• 2012

The objectives of this study are to develop the flow nomograph for real-time flood forecasting and to assess its applicability in restored Cheonggye stream. The Cheonggye stream basin has the high impermeability and short concentration time and complicated hydrological characteristics. Therefore, the flood prediction method using runoff model is ineffective due to the limit of forecast. Flow nomograph which is able to forecast flood only with rainfall information. To set the forecast criteria of flow nomograph at selected flood forecast points and calculated criterion flood water level for each point, and in order to reflect various flood events set up simulated rainfall scenario and calculated rainfall intensity and rainfall duration time for each condition of rainfall. Besides, using a rating curve, determined scope of flood discharge following criterion flood water level and using SWMM model calculated flood discharge for each forecasting point. Using rainfall information following rainfall scenario calculated above and flood discharge following criterion flood water level developed flow nomograph and evaluated it by applying it to real flood event. As a result of performing this study, the applicability of flow nomograph to the basin of Cheonggye stream appeared to be high. In the future, it is reckoned to have high applicability as a method of prediction of flood of urban stream basin like Cheonggye stream.

• International Journal of Highway Engineering
• /
• v.8 no.1 s.27
• /
• pp.99-106
• /
• 2006

During the dry periods, many types of pollutant are accumulating on the paved surface by vehicle activities. Particularly, the highways are stormwater intensive landuses because of high imperviousness and high pollutant mass emissions from vehicles. The accumulated pollutants in highways are washed-off during a rainfall event and are highly contributing on water quality of receiving water bodies. The stormwater runoff from the highways are containing various pollutants such as metals, oil & grease and toxic chemicals originated from vehicles. Therefore, this research is performed to find pollutant characteristics in the magnitude of statistical pollutant concentrations during storm periods. During the monitoring periods, the first-flush phenomenon is visibly occurred on most storm events, which is confirmed from hydro- and pollute-graphs. The 95% confidence intervals of washed-off pollutant concentration are ranged to 154.7-257.1 mg/L for 755,138.9-197.6 mg/L for COD, 3.5-6.4 mg/L for oil & grease, 6.3-9.2 mg/L for TN and 2.3-3.31 mg/L for TP. The first flush effect is mostly occurred within initial 30 min of storm duration.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.7
• /
• pp.548-553
• /
• 2017

The aim of this study was to develop a low impact development design technique that can be applied in the land use planning stage and verify quantitatively the effects of non-point pollution reduction. For this purpose, the low impact development design elements that can be applied in the land use planning stage were derived and applied to an actual site, and the non-point pollution reduction effect was analyzed using the LIDMOD2 program. The analysis showed that the permeability rate of the land use plan using low impact development decreased by 19.8% compared to the existing land use plan. In addition, annual surface runoff decreased by 19.0% and annual infiltration increased by 164.1%. In the case of non-point pollution, the annual loading, T-N, T-P, and BOD decreased by 18.7 ~ 22.8%. Therefore, compared to the existing land use plan, the land use plan using low impact development has a considerably large effect of reducing the non-point pollution without changing the floor area according to each application. Therefore, to maximize the reduction effect of non-point pollution, it will be necessary to establish a related plan by applying the low impact development technique from the land use planning stage to the existing LID facility-oriented plan.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.18 no.1
• /
• pp.95-107
• /
• 2016

Ground water is one of important parameters in the designs of underpass structures because urban areas are characterized by soil ground which is relatively permeable than rock ground and a high level of ground water due to low elevation. Therefore, it is important properly to predict variations of the ground water when they can affect underpass structures. In this study, a series of numerical analyses are performed to predict the variations of ground water levels considering the degree of surface imperviousness and LID(Low Impact Development) application. In turn the stability of underground structure is assessed using predicted ground water level. The results show that an increase in the impervious surface area decreases the ground water level. The application of permeable pavement as a LID facility increases the ground water level, improving the infiltration capacity of rainfall into the ground. Seasonal variations of the ground water level are also verified in numerical simulation. The results of this study suggest that reasonable designs of underpass structures can be obtained with the suitable prediction and application of the ground water level considering the surface characteristics.

• Journal of Wetlands Research
• /
• v.14 no.2
• /
• pp.159-168
• /
• 2012

Stormwater runoff affects the quality of surface water and groundwater due to the nonpoint sources (NPSs) of pollutants that it carries during storm events. Typically, urbanized areas experience high pollutant mass emission because of paved roads and other areas which are all highly impervious. For this reason, proper identification of the levels of pollutants from the watershed area is important to pass the Ministry of Environment of the Republic of Korea's water quality standards in rivers and streams. This research was conducted in order to determine and quantify the different constituents present in stormwater runoff generated from highly impervious areas in Cheonan City, Korea. Also, the average event mean concentration (EMC) of stormwater runoff from paved areas was compared with EMCs of other countries to determine the possible causes of its occurrence. In addition, the occurrence of first flush phenomenon was studied in order to find the first flush criteria to be used on the design of best management practices. The results show the pollutant concentration of stormwater runoff was higher than other countries due its landuse and relatively small size of catchment area. During the first 30 minutes of the rainfall events, occurrence of first flush phenomenon was highly evident. Several factors affected the pollutant concentrations in the stormwater such as landuse type, geographic and topographic characteristics,catchment area and amount of rainfall. This research can provide guidance in achieving an effective NPS pollution management applicable to highly urbanized areas in the future.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.40 no.2
• /
• pp.145-156
• /
• 2020

The climate change occurring all over the world increases the risk, specially in urban area, Accordingly, rainwater pumping station expansion is required than before. In order to increase the efficiency of the rainwater pumping station, the analysis of flow characteristics in the pump sump is needed for vortex control. Many efforts have been made to illuminate the vortex behavior using PIV, but any reliable results have not been obtained yet, because of the limitations in image capturing and dependency of measured velocity values on the interrogation area and time interval used for velocity calculation. In this study, therefore, experiments were carried out to find out the limitation of PIV and estimate the validation of the velocity values associated with the analysis parameters such as interrogation area, time interval, grid size. For the experimental condition used in this study, the limitation of PIV and the effects of parameters on the velocity estimation are presented.

• Journal of Korean Society of Environmental Engineers
• /
• v.34 no.1
• /
• pp.23-31
• /
• 2012

Measures against non-point sources pollution in Saemangeum watershed should be established to control water quality of Saemangeum lake, because non-point sources pollution discharge portions of BOD (Biological Oxygen Demand) and TP (Total Phosphorous) in the watershed were 68.4 and 61.4%, respectively. In this study, target regions for the non-point sources pollution control were selected to apply BMP (Best Management Practices) for the agricultural area of Saemanguem watershed in terms of TP that caused eutrophication at the lake. Target regions were selected by the NPSI (Non-point source index) that was calculated by the total 12 indexes at the steps of non-point source production, emission and outflow. Weights of the indexes were determined by the watershed management experts oriented AHP (Analytic Hierarchy Process) analysis. The target region was selected at the unit of Korean basic administrative district 'Dong/Li'. At the results of NPSI calculations through the GIS (Geographical Information System) tools, two sets of 5 regions were selected in the Man-kyung River and Dong-gin River. The main reason for the selected target regions was livestock activity in the district. The results of this study can be useful for implementing the reduction projects of agricultural non-point sources pollution to control water quality in Saemangeum lake.

• Journal of Korea Water Resources Association
• /
• v.50 no.3
• /
• pp.181-190
• /
• 2017

Population congestion and increasing porosity caused by urbanization and increasing rainfall intensity are the main reasons for urban inundation damage. In order to reduce the damage to urban flooding, it is necessary to take a inundation analysis model that can be considered the topographic impact (i.e., building and road) and simulate the detailed inundation areas. In this study, Grid based Inundation Analysis Model (GIAM) is developed using a two-dimensional shallow water equations. The study area is Gangnam basin, with a surface area of $7.4km^2$, which includes 5 drainage areas such as Nonhyun, Yeoksam, Seocho 1, 2, and 3. EPA SWMM5 is used for simulating the overflows at each manhole. GIAM model is constructed to allow for simulating a inundation area with 6 m grid size. The inundation analysis is conducted in two heavy rainfall events (Sep. 21, 2010 and July 27, 2011) for the model evaluation. The accuracy of the simulated inundation area is calculated 0.61 and 0.57 at POD index using the historical flooded area report. The developed model will be used as a tool for analyzing the flood prone areas based on rainfall scenario, and a tool for predicting the detailed inundation area in the real-time.

• Journal of Environmental Impact Assessment
• /
• v.31 no.4
• /
• pp.201-213
• /
• 2022

Creation and administration of green space are emphasized to solve the environmental problem and the management of green space in urban area. Urban area with high development pressure faces green space fragmentation, so the planned approach is needed to improve the continuity of green space. However, the current institutional green axis, used to enhance continuity of urban space is merely an abstract concept under the master plan so that is not a consistent framework for urban green continuity providing no detailed information such as position and path. Therefore, in order to consistently manage green space in continuous point of view, it is insufficient not being connected to each individual green space development projects. This study proposes a method for finding the connection path to enhance urban green space continuity. This proposed method consists of two phases. First phase is finding nodes to connect current green space and second is to calculate the least cost path. We calculate connection cost using NDMI (Normalized Difference Moisture Index), impervious ratio and official land cost, applying to Suwon city and potential greening site that was planned in official master plan. According to the results, we confirm a possibility of finding a cost-effective connection path with detailed spatial information instead of unrealistic abstract concepts and discuss worth applying to a legally plan and policy.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.506-506
• /
• 2022

비점오염원에서 배출되는 오염부하량(BOD, T-P)은 점오염원의 2배 이상을 차지하고 있어 비점오염원 관리에 대한 관심이 증대되고 있다. 이에 비점오염원의 효율적 관리를 위한 전략 및 추진과제 마련을 위해 제1차('04-'11), 제2차('12-'20) 비점오염원 관리 종합대책(이하 종합대책)이 수립 및 이행되었다. 이어 2016년 물환경보전법 개정에 따라 종합대책의 수립이 법제화되고 지난 2020년 말 제3차 비점종합대책('21~'25)이 수립되었다. 제3차 비점종합대책은 수질개선이 체감되는 비점오염원 관리라는 비전을 가지며 도시, 농·축산, 산림, 관리기반의 4개 분야에 총 71개의 세부 추진과제를 제시하고 있다. T-P 비점오염배출부하량 5% 감축, 불투수율 감축, 비점오염관리지역개소 확대, 고랭지 흙탕물 관리지역 구역 확장, 지역 거버넌스 구축을 대책의 목표와 각 분야별 관리지표로 제시하고 있다. 물환경보전법 제53조의5와 동법 시행령 제75조의3에 따라 환경부장관은 매년 이행사항을 점검 및 평가하여 그 결과를 비점오염원 관리 정책의 수립 및 집행에 반영해야 한다. 지난 제1·2차 대책의 경우 성과 점검 및 관리를 위한 체계가 부재하여 사업의 실효성 확보에 한계가 있었으며 이에 따라 소관별 이행사항 점검 및 평가체계의 필요성이 제기되었다. 따라서 본 연구에서는 종합대책 이행평가 전략 및 세부 추진체계를 마련하여 효율적인 소관별 이행사항 점검 및 평가를 도모하고자 하였다. 분야별 세부 추진과제는 매년, 대책의 목표와 각 분야별 관리지표는 대책 시행 후 5차년에 점검 및 평가할 수 있도록 구성하였다. 또한 종합대책의 최종 목표 달성 시뮬레이션을 통해 5차년 이후 원활한 평가가 이루어질 수 있도록 하였다. 본 연구에서 마련한 이행평가 체계를 통해 적절한 이행평가 및 효율적인 비점오염원 관리를 도모할 수 있을 것으로 사료된다.