• KIEAE Journal
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• v.13 no.5
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• pp.89-96
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• 2013

Green roofs can reduce surface water runoff, provide a habitat for wildlife moderate the urban heat island effect, improve building insulation and energy efficiency, improve the air quality, create aesthetic and amenity value, and preserve the roof's waterproofing. Green roofs are mainly divided into three types : intensive, simple-intensive, and extensive. Especially, extensive roof environment is a harsh one for plant growth; limited water availability, wide temperature fluctuations, high exposure to wind and solar radiation create highly stressed environment. This study, aimed at extensive green roof, was carried out on the rooftop of the library at Seoul Women's Univ. from October to November, 2012 and from March to August, 2013. To suggest the most effective vegetation model for biodiversity and heat island mitigation, surface temperatures were monitored by each vegetation model. We found that herbaceous plants of Aster sphathulifolius, Aceriphyllum rossii and Belamcanda chinensis, shrub of Syringa patula 'Miss Kim', Thymus quinquecostatus var. japonica, Sedum species can mixing each other. Among them, the vegetation models including Sedum takesimense, Aster sphathulifolius, Thymus quinquecostatus var. japonica was more effective on the surface temperature mitigation, because the species have the tolerance and high ratio of covering, and also in water. Especially, in the treatment of bark mulching, they helped to increase the temperature of vegetation models. In the case of summer, temperature mitigation of vegetation models were no significant difference among vegetation types. Compared to surface temperature of June, July and August were apparent impact of temperature mitigation, it shows that temperature mitigation are strongly influenced by substrate water content.

• Ecology and Resilient Infrastructure
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• v.3 no.2
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• pp.80-91
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• 2016

Diverse types of meteorological disasters that are frequently occurring at the present time, such as urban flooding, draught, heat waves, or tropical nights do not only cause casualties and property damages but also make it difficult to preserve the natural environment of the city. That is why Low Impact Development or Green Infrastructure has recently received lots of attention as a means to minimize meteorological disasters, adapt to climate change and to leave a better urban environment for the next generation. As of now, Korea's low impact development and green infrastructure technology are standing at the stage of incubation or demonstration. Both central and provincial governments have accelerated the updating of laws and regulations, which allows us to turn the Gray City with Gray Infrastructure that only uses water into a Green City with Green Infrastructure that manages the water. To spread and distribute such a notion in a systemic way, it requires new technology development tailored to Korea, verification of technology, and maintenance of related technological standards, cooperation with other industries, training & promotion, and the participation of citizens.

• Journal of Korean Society on Water Environment
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• v.36 no.5
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• pp.405-422
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• 2020

Land use change by urbanization has significantly affected the hydrological process including the runoff characteristics. Due to this situation, it has been becoming more complicated to manage non-point source pollutions caused by rainfall. In order to effectively control non-point sources, it is necessary to identify the reduction efficiency of the various management method based on land use characteristics. Thus, the purpose of this study is to analyze the reduction efficiency of non-point source pollution management practices targeting three different watersheds with the different land use characteristics using the Soil and Water Assessment Tool (SWAT). To do this, the vulnerable subwatersheds to non-point source pollution occurrence within each watershed were selected based on the streamflow and water quality simulation results. Then, considering the land use, low impact development (LID) or best management practices (BMPs) were applied to the selected subwatersheds and the efficiency of each management was analyzed. As a result of analysis of the non-point source pollution reduction efficiency, when LID was applied to urban areas, the average reduction efficiencies of SS, NO₃-N, and TP were 5.92%, 4.62%, and 10.35%, respectively. When BMPs were applied to rural areas, the average reduction efficiencies of SS, TN and TP were 35.45%, 4.37%, and 10.16%, respectively. The results of this study can be used as a reference for determining appropriate management methods for non-point source pollution in urban, rural, and complex watersheds.

• Journal of the Korean Society of Hazard Mitigation
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• v.8 no.3
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• pp.105-115
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• 2008

Urbanization results in increased runoff volume and peak flowrate and shortening in time of concentration, which may cause frequent flooding downstream. There are various types of flow retardation methods including detention ponds, retention ponds, and infiltration ponds. In general, hydrologic models to design the detention pond are classified into planning model and design model. This study is comparing and analyzing of planning model to design the detention pond in urban area. Detention ponds data of Disaster Impact Assessment Report on 22 sites were analyzed to investigate proper planning models in this study. From this research, following conclusions are derived, 1) In case of on-line detention pond, Lee model(1991) is the best planning model and similar to real storage volume. 2) In case of off-line detention pond, Abt and Grigg model is much more proper model compared to other models.

• Journal of Korea Water Resources Association
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• v.54 no.2
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• pp.71-80
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• 2021

In recent years, the possibility of flooding due to the increase in the incidence of high-frequency rainfall due to abnormal rainfall and the increase in concentrated torrential rain is increasing. Also, the amount of rainwater runoff is increasing due to the increase of the impermeable layer in the city due to the concentration of population due to urbanization and concentration of development. Due to the characteristics of the developed city, it is located in the vicinity of rivers and in the lowlands. For the analysis of inundation in water, using XP-SWMM, which can analyze stormwater pipelines and surface flows, and FLO-2D models that can track flood-sluice curves and rainfall-spill curves, based on hydraulic and hydrological analysis. Inundation analysis was conducted and comparative review was conducted. The patterns of flooding of the two models were compared, and a model suitable for domestic flooding was selected.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.2
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• pp.126-135
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• 2015

Increase of delivery effect of pollutant loads and surface runoff due to urbanization of catchment area results in serious environmental problems in receiving urban streams. This study aims to develop integrated stormwater management system to assist efficient urban stream flow and water quality control using information from the Storm Water Management Model (SWMM), real time water level and quality monitoring system and remote or automatic treatment facility control system. Based on field observations in the study site, most of the pollutant loads are flushed within 4 hours of the rainfall event. SWMM simulation results indicates that the treatment system can store up to 6 mm of cumulative rainfall in the study catchment area, and this means any type of normal rainfall situation can be treated using the system. Relationship between rainfall amount and fill time were developed for various rainfall duration for operation of stormwater treatment system in this study. This study can further provide inputs of river water quality model and thus can effectively assist integrated water resources management in urban catchment and streams.

• Korean Journal of Ecology and Environment
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• v.34 no.3 s.95
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• pp.215-222
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• 2001

A statistical analysis was performed to evaluate relationships among the pollutant concentrations in non-urban area. The data obtained from two subcatchments in Hwa-Ong watershed during 1999 was used for correlation and regression analyses. Strong correlations were observed among the SS, COD, and TP, while it was not significant with TN. The reason fer weak correlation with TN might be that TN was high in dry-days and runoff in wet-days could not increase enough to change it substantially like in other pollutants. The correlations were stronger for the data in wet-days than in dry-days, and it was influenced by watershed characteristics. While TP-COD showed linear relationship from the regression analysis, SS-TP and SS-COD shelved intrinsically linear relationship between log-transformed TP and COD data and non-transformed SS data. The TP-COD showed strong relationship for all the combinations of monitored data, which implies that these two constituent concentrations varied in a similar pattern. The regression equations reported in the paper might be used to estimate one pollutant concentration from the other in pollutant loading estimates, and its application could be expanded to other non-urban watersheds if their characteristics are not significantly different from the study area. In water quality management projects, rigorous monitoring and its thorough evaluation are recommended to develop more reliable relationships among the pollutant concentrations which could be used in other area.

• Journal of Korea Water Resources Association
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• v.39 no.2 s.163
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• pp.109-120
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• 2006

Permeable pavement and release of treated wastewater into streams can increase streamflow of urban streams for a dry weather period. A SWMM code was modified to have a permeable pavement option. The modified SWMM was applied to continuous simulations of urban runoff from Hakuicheon watershed and it was used to analyse the effect of a permeable pavement installation and the reuse of treated wastewater. A critical error in the pan coefficient multiplication was also corrected in the modification. The analysis results of the reuse of treated wastewater is as follows: The low flow ($Q_{275}$) increases by 1.63 times as much as the current one and the drought flow ($Q_{355}$) increases by 3.57 times as much as the current one. If the impervious area in the Hakuicheon watershed is replaced with the permeable pavement area by 10 percent, the low flow and the drought flow increases by 3 percent and 17 percent, respectively. The results shows the effectiveness of the release of treated wastewater into stream to increase urban streamflow. The permeable pavement installation also play a minor role in the drought flow increase.

• Journal of Korea Water Resources Association
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• v.39 no.11 s.172
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• pp.923-934
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• 2006

In this study, the effects of variability in climate, groundwater withdrawal, and landuse on dry-weather streamflows were investigated by input sensitivity analysis using SWAT (Soil and Water Assessment Tool). Since only dry-period precipitation and daily average solar radiation among climate variables have high correlation coefficients to total flow (TF), sensitivity analyses of those were conducted. Furthermore, an equation was derived from simulation results for 30 years by multiple regression analysis. It may be used to estimate effects of various climatic variations (precipitation during the dry period, precipitation during the previous wet period, solar radiation, and maximum temperature). If daily average maximum temperatures increase, TFs during the dry period will decrease. Sensitivities of groundwater withdrawal and landuse were also conducted. Similarly, groundwater withdrawals strongly affect streamflow during the dry period. However, landuse changes (increasing urbanization) within the forested watershed do not appear to significantly affect TF during the dry period. Finally, a combined equation was derived that describes the relationship between the total runoff during the dry period and the climate, groundwater withdrawal and urban area proportion. The proposed equation will be useful to predict the water availability during the dry period in the future since it is dependent upon changes of temperature, precipitation, solar radiation, urban area ratio, and groundwater withdrawal.

• Journal of Korean Society of Disaster and Security
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• v.14 no.2
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• pp.13-23
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• 2021

This study intended to assess the reliability of topographic data using satellite imaging data. The topographical data using actual instrumentation data and satellite image data were established and applied to the rainfall-leak model, S-RAT, and the topographical data and outflow data were compared and analyzed. The actual measurement data were collected from the Water Resources Management Information System (WAMIS), and satellite image data were collected from MODIS observation sensors mounted on Terra satellites. The areas subject to analysis were selected for two rivers with more than 80% mountainous areas in the Han River basin and one river basin with more than 7% urban areas. According to the analysis, the difference between instrumentation data and satellite image data was up to 50% for peak floods and up to 17% for flood totals in rivers with high mountains, but up to 13% for peak floods and up to 4% for flood totals. The biggest difference in the video data is Landuse, which shows that MODIS satellite images tend to be recognized as cities up to 60% or more in urban streams compared to WAMIS instrumentation data, but MODIS satellite images are found to be less than 5% error in forest areas.