• Ecology and Resilient Infrastructure
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• v.9 no.1
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• pp.1-14
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• 2022

The total maximum daily load (TMDL) implemented in Korea mainly manages the mainstream considering a single common pollutant and river discharge, and the river system is divided into unit watersheds. Changes in the water quality of managed rivers owing to the water quality management in tributaries and unit watersheds are not considered when implementing the TMDL. In addition, it is difficult to consider the difference in the load of pollutants generated in the tributary depending on the conditions of the water quality change in each unit watershed, even if the target water quality was maintained in the managed water system. Therefore, it is necessary to introduce the total maximum load management at tributaries to manage the pollution load of tributaries with a high degree of pollution. In this study, the HSPF model, a watershed runoff model, was applied to the target areas consisting of 53 sub-watersheds to analyze the effect of water quality changes the in tributaries on the mainstream. Sub-watersheds were selected from the three major areas of the Paldang water system, including the drainage basins of the downstream of the South Han-River, Gyeongan stream, and North Han-River. As a result, BOD ranged from 0.17 mg/L to 4.30 mg/L, and was generally high in tributaries and decreased in the downstream watershed. TP ranged from 0.02 mg/L - 0.22 mg/L, and the watersheds that had a large impact on urbanization and livestock industry were high, and the North Han-River basin was generally low. In addition, a pollution source reduction scenario was selected to analyze the change in water quality by the amount of pollution load discharged at each unit watershed. The reduction rate of BOD and TP according to the scenario changes was simulated higher in the watershed of the downstream of the North Han-River and downstream and midstream of the Gyeongan stream. It was found that the benefits of water quality reduction from each sub-watershed efforts to improve water quality are greatest in the middle and downstream of each main stream, and it is judged that it can be served as basic data for the management of total tributaries.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.11
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• pp.795-802
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• 2013

According to the increase of impervious area due to the town development, the rate of infiltration generally lessens and that of runoff rises during wet weather events. And it is concerned that its impacts on water quality for the downstream water bodies due to the change of rainfall runoff patterns may also increase. To cope with these issues, LID (Low Impact Development) techniques which try to maintain the characteristics of rainfall runoff regardless of the town development have been introduced actively. However, the behaviors of each LID technique for rainfall runoff and pollutant loads is not understood sufficiently. In this study, considering the applications of some LID techniques, several sets of simulations using a distributed rainfall runoff model, SWMM-LID, have been conducted for D town whose development is progressing. As the results of the simulations, the rates of infiltration/storage have been decreased from 78% in the case before the town development to 15% after the development and increased again by 24% with LID techniques such as porous pavement, rain barrel and rain garden. The rates of runoff have been increased more than three times from 20% in the case before the development to 74% after the development, and they have also been decreased to 66% by the adoption of LID techniques. It has been simulated that porous pavement is more effective than others in the view point of the reduction of runoff and rain barrel is more attractive for the management of pollutant loads (TSS, BOD, COD, T-N and T-P). Therefore, if some LID techniques should be selected for the a new town, it could be concluded that some techniques with better infiltration functions are recommendable for the control of runoff, and ones with larger storage functions for the management of pollutant loads.

• Korean Journal of Ecology and Environment
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• v.33 no.4 s.92
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• pp.366-373
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• 2000

Toxin production and low digestibility of cyanobacteria are known to cause low exploitability of cyanobacteria by zooplankton. In this study, we compared relative tolerance and compatibility of zooplankton taxa in eight eutrophic lakes, exposed to frequent cyanobacterial blooms, uring the summer season of 1999. Microcystis, Anabaena, Oscillatoria and Phormidium were common cyanobacteria in all lakes. with relatively lower $NO_3-N$ concentration (<0.2 mgN/l) and TN/TP ratio (<20), compared with other lakes where colonial cyanobacteria dominated. Rotifers were dominant zooplankton in most lakes, and among them, Keratella, Polyarthra and Hexathra were common. The laboratory feeding experiment showed that relative copepods that greatly decreased (90%) after 4 day when cyanobacteria were used as the food source of zooplankton, while rotifers gradually increased with the change of dominant taxa from Keratella through Pompholyx to Monostyla. These results suggest that rotifers may be capable of coexisting with cyanobacteria by exploiting them for the food source.

• Journal of the Korean Institute of Landscape Architecture
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• v.36 no.6
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• pp.43-54
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• 2009

This study attempted to develop a model for selecting sites for ecologically effective, multi-functional wetlands during the environmental and ecological planning stage, prior to land use Planning. This model was developed with an emphasis upon the creation of a water circulation system for a newly-created city, dispersing and retaining the run-off that is increased due to urbanization and securing spaces to create wetlands that can promote urban biodiversity. A series of Precesses for selecting sites for wetland restoration and creation - watershed analysis, selection of evaluation items, calculation of weights, reparation of thematic maps and synthesis - were incorporated into the model. Its potentials and limitations were examined by applying it to the recently-planned WiRae New Community Development Area, which is located in the Seoul metropolitan region. At the watershed analysis stage, the site was divided into 13 sub-catchment areas. Inflow to watersheds including the area was $3,020,765m^3$ Run-off before and after development is estimated as $1,901,969m^3$ and $1,970,735{\sim}2,039,502m^3$, respectively. The total storage capacity required in the development area amounts to $68,766{\sim}137,533m^3$. When thematic maps were overlapped during the selection stage for wetland sites, 13 sub-catchment areas were prioritized for wetland restoration and creation. The locations and areas for retaining run-off showed that various types of wetlands, including retaining wetlands (area wetlands), riverine wetlands (linear wetlands) and pond wetlands (point wetlands), can be created and that they can be systematically connected. By providing a basic framework for the water circulation system plan of an entire city, it may be used effectively in the space planning stage, such as planning an urban eco-network through integration with greet areas. In order to estimate reasonable run-off and create an adequate water circulation system however, a feedback process following land use planning is required. This study strived to promote urban changes in a positive direction while minimizing urban changes in negative forms.

• Korean Journal of Ecology and Environment
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• v.38 no.2 s.112
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• pp.225-236
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• 2005

The protection of public health In wastewater reclamation and reuse is one of the most important issues. Monitoring data of Escherichia coli were collected from paddy rice plots in 2003 and 2004 experiments. Five treatments were used and each one was triplicated to evaluate the changes of E. coli: surface water, biofilter effluent (secondary level), UV-disinfected water and pond treatment. Microbial risk was quantified to assess human health risk by exposure to E. coli in paddy rice plots, which were irrigated with reclaimed wastewater. Beta-Poisson model was used to estimate the microbial risk of pathogen ingestion that may occur to farmer and neighbor children. Monte-Carlo analysis (10,000 trials) was used to estimate the risk characterization of uncertainty. In the following analysis, two scenarios were related to the reduction of risk against direct ingestion and exposure times. Scenarios A and B were assumed that the risk was 1,000 and 10,000 times lower than direct ingestion.'Golfers were assumed to be 0.001 L of reclaimed water by contact with balls and their cloths. Opportunity of contact in paddy rice field with pathogens was more frequent than handing golf balls, because of agricultural activity was practiced in ponded water in paddy rice culture. As a result of microbial risk assessment using total data of experimental period, risk value of E. coli in 2003 and 2004 experiment ranged from $10^{-5}$ to $10^{-8}$ and $10^{-4}$ to $10^{-8}$, respectively. The risk values in biofilter effluent irrigation was the highest, which is $10^{-4}$ in 2003 and $10^{-5}$ in 2004 experiments with scenario A. Ranges of $10^{-6}$ to $10^{-8}$ were considered at reasonable levels of risk for communicable disease transmission from environmental exposure and the risk value above $10^{-4}$ was considered to be attributable to the risk of infection. Irrigation with UV-disinfected water in the paddy field during the agricultural Period showed significantly lower microbial risk than others, and their levels of risk value were within the range of actual paddy rice field with surface water.

• Korean Journal of Ecology and Environment
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• v.51 no.1
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• pp.105-123
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• 2018

Currently, satellite images act as essential and important data in water resources, environment, and ecology as well as information of geographic information system. In this paper, we will investigate basic characteristics of satellite images, especially application examples in water resources. In recent years, researches on spatial and temporal characteristics of large-scale regions utilizing the advantages of satellite imagery have been actively conducted for fundamental hydrological components such as evapotranspiration, soil moisture and natural disasters such as drought, flood, and heavy snow. Furthermore, it is possible to analyze temporal and spatial characteristics such as vegetation characteristics, plant production, net primary production, turbidity of water bodies, chlorophyll concentration, and water quality by using various image information utilizing various sensor information of satellites. Korea is planning to launch a satellite for water resources and environment in the near future, so various researches are expected to be activated on this field.

• Korean Journal of Ecology and Environment
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• v.42 no.2
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• pp.200-211
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• 2009

A mathematical modeling program called Soil and Water Assessment Tool (SWAT) developed by USDA was applied to Kyongan stream watershed. It was run under BASINS (Better Assessment Science for Integrating point and Non-point Sources) program, and the model was calibrated and validated using KTMDL monitoring data of 2004${\sim}$2008. The model efficiency of flow ranged from very good to fair in comparison between simulated and observed data and it was good in the water quality parameters like flow range. The model reliability and performance were within the expectation considering complexity of the watershed and pollutant sources. The results of pollutant loads estimation as yearly (2004${\sim}$2008), pollutant loadings from 2006 were higher than rest of year caused by high precipitation and flow. Average non-point source (NPS) pollution rates were 30.4%, 45.3%, 28.1% for SS, TN and TP respectably. The NPS pollutant loading for SS, TN and TP during the monsoon rainy season (June to September) was about 61.8${\sim}$88.7% of total NPS pollutant loading, and flow volume was also in a similar range. SS concentration depended on precipitation and pollution loading patterns, but TN and TP concentration was not necessarily high during the rainy season, and showed a decreasing trend with increasing water flow. SWAT based on BASINS was applied to the Kyongan stream watershed successfully without difficulty, and it was found that the model could be used conveniently to assess watershed characteristics and to estimate pollutant loading including point and non-point sources in watershed scale.

• Korean Journal of Ecology and Environment
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• v.36 no.4 s.105
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• pp.467-472
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• 2003

In this study, an algal fence was developed and applied to reduce the input of algal scum into the water intake facility. The effectiveness of vertical algal fences(overlapped three types of meshes, (312 ${\mu}m$ ${\times}$ 375 ${\mu}m$, 390 ${\mu}m$ ${\times}$ 450 ${\mu}m$, and 0,7 cm ${\times}$ 1cm; vertical depth, 1.5 m; length of fence, about 120 m)) was experimentally tested at a water intake facility (Mulgum, lower Nakdong River). The application of the fence resulted in the statistically significant difference of algal biomass between inside and outside of the fence. According to ANOVA test, chi. a concentration in Day-1showed large difference at each depth of 0, 1, 2 m (0.001> p at each depth, n = 16 respectively). Especially large difference was observed at 0 and 1 m depth. However, the fence was only effective for a short period and its efficiency declined by Day-5after the installation. When better maintenance options for the fence are prepared, e.g. mechanical installation and periodic backwashing of the fence, the performance of algal fence may be sustained. In addition, reliable models for bloom prediction are required to provide an advanced indication of the optimal timing for the installation so that effective operation would be achieved.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.4
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• pp.21-29
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• 2014

In terms of quality of life, leisure and health have become important issues with increasing incomes and decreasing working hours in Korea. This study empirically investigates the effects of urban open space on outdoor leisure activities, emphasizing that parks, river banks, and physical activity sites can provide opportunities such as walking, jogging, stretching, and cycling, free of charge to all residents. Based on 2010 sample survey data on leisure activities, multiple regression model as well as hierarchical linear model are estimated, taking account of both individual characteristics on demand and environmental/areal factors on supply side, including open space. Major findings include: first, urban open space significantly increases residents' outdoor leisure activities, second, the effect is more significant for the elderly and third, the effect is more valid for those with relatively low incomes and less education. These results imply that urban open space could be available as a local public good to cope with population aging and to realize health city and social welfare, since this space is not only a leisure place but also public health and welfare facilities.

• Journal of the Korean Association of Geographic Information Studies
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• v.23 no.3
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• pp.174-191
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• 2020

In this study, we analyzed the vulnerable areas of non-point source pollutants and management pollutants and management time by subwatershed curves in the Seohwacheon basin located upstream of Daecheongho. First, in order to create a load duration curve, a long-term flow model SWAT was constructed to create a flow duration curve, and the result was multiplied by the target water quality to create a load duration curve. For the target water quality, monitoring data values measured from November 2017 were used for the management of nonpoint source pollutants in Seohwacheon, and a value corresponding to 60 percentile of the measured data was set as the target water quality. At this time, the target water quality was limited to"slightly good"(II) when the calculated value exceeded"slightly good"(II) of the river living environment standard. The vulnerable areas of non-point source of pollution were selected using the excess rate exceeding the target water quality, and the excess pollutant was judged as a management substance and the management time was selected through seasonal evaluation.