• Journal of Korean Society of Environmental Engineers
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• v.36 no.1
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• pp.58-66
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• 2014

Water pollution problems of urban rivers due to the urbanization and industrialization have been the subject of public attention. In particular, considering the fact that the characteristics of water cycle of each basin change dramatically through the development of new towns, a large number of concerns about future water quality have been raised. However, reasonable measures to predict future water quality quantitatively have not been presented by this moment. In this study, by the linkage of annual unit load generation based on long-term monitoring results of the ministry of environment (MOE) to a semi-distributed rainfall runoff model, SWMM (Storm Water Management Model), we proposed a new methodology to estimate future water quality macroscopically and testified it to verify its applicability for the estimation of future water quality of a small watershed at G new town. As a result of the estimation using Y-EMC (Yearly based Event Mean Concentration), future water quality were simulated as BOD 18.7, T-N 16.1 and T-P 0.85 mg/L respectively which could not achieve the grade III of domestic river life guidance and these criteria could be satisfied by the reduction of domestic wastewater discharge load by over 80%. The results of this study are shown to be utilized for one of basic tools to estimate and manage water quality of urban rivers in the course of new town developments.

• Proceedings of the Korean Society of Environment and Ecology Conference
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• 2003.10a
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• pp.105-126
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• 2003

In Korea most of annual rainfall is concentrated in several episodic heavy rains during the season of summer monsoon and typhoon. Because of uneven rainfall distribution many dams have been constructed in order to secure water supply in dry seasons. The Han River system has the most dams among Korean rivers, and the river is a series of dams now. Reservoirs need different strategy of water quality control from river water. Autochthonous organic matter and phosphorus should be the major target to be controlled in lakes. In this Paper some problems are discussed that makes efforts of water quality improvement ineffective in lakes of Korea, even after the substantial investment to wastewater treatment facilities.1) Phosphorus is the key factor controlling eutrophication of lakes and the reduction ofphosphors should be the major target of water treatment. However, water quality management strategy in Korea is still stream-oriented, and focused on BOD removal from sewage. Phosphorus removal efficiency remains as low as 10-30%, because biological treatment is adopted for both secondary treatment and advanced treatment. The standard for TP concentration of the sewage treatment plant effluent is 6 mgP/l in most of regions, and 2 mg/l in enforced region near metropolitan water intake point. TP in the effluents of sewage treatment plants are usually 1-2 mg/1, and most of plants meet the effluent regulation without a further phosphorus removal process. The generous TP standard for effluents discourages further efforts to improve phosphorus removal efficiency of sewage treatment. Considering that TP standard for the effluent is below 0.1 mg/l in some countries, it should be amended to below 0.1 mg/l in Korea, especially in the watershed of large lakes.2) Urban runoff and combined sewer overflow are not treated, even though their total loading into lakes can be comparable to municipal sewage discharges on dry days. Chemical coagulation and rapid settling might be the solution to urban runoff in regard of intermittent operation on only rainy days.3) Aggregated precipitation in Korea that is concentrated on several episodic heavyrains per year causes a large amount of nonpoint source pollution loading into lakes. It makes the treatment of nonpoint source discharge by methods of other countries of even rain pattern, such as retention pond or artificial wetland, impractical in Korea.4) The application rate of fertilizers in Korea is ten times as high as the average ofOECD countries. The total manure discharge from animal farming is thought to be over the capacity of soil treatment in Korea. Even though large portion of manure is composted for organic fertilizer, a lot of nutrients and organic matter emanates from organic compost. The reduction of application rate and discharge rate of phosphorus from agricultural fields should be encouraged by incentives and regulations.5) There is a lot of vegetable fields with high slopes in the upstream region of the HanRiver. Soil erosion is severe due to high slopes, and fertilizer is discharged in the form of adsorbed phosphorus on clay surface. The reduction of soil erosion in the upland area should be the major preventive policy for eutrophication. Uplands of high slope must be recovered to forest, and eroded gullies should be reformed into grass-buffered natural streams which are wider and resistant to bank erosion.

• The Korean Journal of Ecology
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• v.28 no.1
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• pp.45-53
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• 2005

Urban stream is an important place supporting urban ecosystem. This study was carried out to clarify the role of Jungrangchun for wintering waterbirds in Seoul. We monitored the fluctuation of waterbirds population using our census data (1997/98 winter) and pervious census data (the Ministry of Environment and National Institute of Environmental Research $1999{\sim}2004$). Wintering behaviours of common teals (Anas crecca) were also observed to understand the habitat use of waterbirds in this area. As a result of this, Jungrangchun was an important place to support $3,004\sim8,237$ wintering birds, mainly dabbling ducks and diving ducks. The population of diving ducks showed high annual fluctuation whilst the population of dabbling ducks regularly used this area every year The maximum number of waterbirds foraged and rested in late January and late February. In daily use, the number of waterbirds increased on afternoon and rapidly increased after sunset. It is assumed that waterbirds used this area not only as a nocturnal feeding site but also daytime feeding site. Thus, this result suggest that Jungrangchun is important for not only the daily use but also the nocturnal use of wintering waterbirds. The number of diving ducks was increased with low temperature and high wind speed. Therefore, this area was also a shelter of diving ducks on chilly and windy day.

• Korean Journal of Agricultural Science
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• v.37 no.2
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• pp.285-293
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• 2010

To secure instream flow at the Yudeung urban stream reach of Daejeon city in South Korea, Yudeung upstream diversion was designed with total water storage of $59{\times}10^4m^3$, and the upstream Seongol reservoir was planned to raise the bank with various sizes. Downstream streamflows were simulated by considering outflows from upstream diversion and reservoir, and after then flow durations were analyzed and compared with flows of no reservoir condition. In case of no diversion or reservoir upstream, flow durations were $1^{st}$ flow of $84.72m^3/s$, $95^{th}$ flow of $2.10m^3/s$, $185^{th}$ flow of $0.92m^3/s$, $275^{th}$ flow of $0.42m^3/s$, and $355^{th}$ flow of $0.31m^3/s$. In case of upstream diversion, flow durations were $1^{st}$ flow of $94.38m^3/s$, $95^{th}$ flow of $2.96m^3/s$, $185^{th}$ flow of $1.22m^3/s$, $275^{th}$ flow of $0.50m^3/s$, and $355^{th}$ flow of $0.35m^3/s$. The increase flow rates were $0.04m^3/s$ in $355^{th}$ flow, $0.08m^3/s$ in $275^{th}$, and $0.30m^3/s$ in 185th. In case of Seongol reservoir with effective storage capacities of $365{\times}10^4m^3$, $544{\times}10^4m^3$, $750{\times}10^4m^3$, and $992{\times}10^4m^3$, flow durations were $85.5{\sim}83.9m^3/s$ on $1^{st}$ flow, $2.85{\sim}2.57m^3/s$ on $95^{th}$ flow, $1.16{\sim}1.27m^3/s$ on $185^{th}$ flow, $0.64{\sim}0.99m^3/s$ on $275^{th}$ flow, and $0.56{\sim}0.94m^3/s$ on $355^{th}$ flow. The increase flow rates were $0.25{\sim}0.63m^3/s$ in $355^{th}$ flow, $0.22{\sim}0.57m^3/s$ in $275^{th}$, and $0.24{\sim}0.35m^3/s$ in $185^{th}$. The more the sizes of upstream reservoirs increased, the $1^{st}$ and $95^{th}$ flows decreased in which coefficients of determination were 0.92, 0.99, respectively and the $185^{th}$, $275^{th}$, and $355^{th}$ flows increased in which coefficients of determination were 0.93 to 0.99.

• Journal of the Korean Association of Geographic Information Studies
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• v.22 no.2
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• pp.133-151
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• 2019

This study aims to analyze cold air characteristics in the watershed areas and to suggest strategies for utilizing them in urban ventilation corridor plans. For this purpose, the Jungnangcheon watershed and Uijeongbu-si in the northern part of Gyeonggi province, and Anyangcheon watershed as well as Yangjaecheon Tancheon watershed and Gwacheon-si in the southern part were selected as study areas. We used KALM (Kaltluftabflussmodell), a cold air simulation model developed in Germany and identified both the cold air flow and the height of cold air layer generated during 6 hours at night. Uijeongbu City is located on the main stream of the Jungnangcheon watershed, and the local cold air from the southern outskirts is an important part of Uijeongbu-si's overall ventilation corridor planning. In addition, the cold air generated in the vicinity of Mt. Sapae flows into the central business district near the city hall and plays a major role in regulating the thermal environment of the city. But, the cold air flows in the eastern part of Uijeongbu-si was not smoothly. The cold air flow generated in the east of Gwanak Mountain and in the west of Cheonggye Mountain was the most active in the northern part of Gwacheon-si. This flow is also a major ventilation corridor in Anyangcheon watershed as well as Yangjaecheon Tancheon watershed. But, the southern part where the cold air flow is not smooth is planed to be developed as 'Gwacheon Knowledge Information Town Public Housing District', so rapid development is expected in the future. Hence, it is suggested that an additional ventilation corridor plan should be established based on the detailed local wind flow analysis.

• Journal of Korean Society of Disaster and Security
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• v.11 no.2
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• pp.45-52
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• 2018

This study identifies the cause of the accident and presents a new concept for safe urban stream management by numerical simulating the flood event of Cheonggyecheon on August 17, 2017, using rain data measured through a dense weather observation network. In order to simulate water retention in the CSO channel listed as one of the causes of the accident, a reliable urban runoff model(XP-SWMM) was used which can simulate various channel conditions. Rainfall data measured through SK Techx using SK Telecom's cell phone station was used as rain data to simulate the event. The results of numerical simulations show that rainfall measured through AWSs of Korea Meteorological Administration did not cause an accident, but a similar accident occurred under conditions of rainfall measured in SK Techx, which could be estimated more similar to actual phenomena due to high spatial density. This means that the low spatial density rainfall data of AWSs cannot predict the actual phenomenon occurring in Cheonggyecheon and safe river management needs high spatial density weather stations. Also, the results of numerical simulation show that the residual water in the CSO channel directly contributed to the accident.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.24 no.1
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• pp.37-45
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• 2006

Damage of rivers construction is serious to natural disaster by concentration rainfall in summer. Specially, increase of soil erosion breeds flood calamity of river bed accumulation and pondage decline etc., and erosion increase in upper stream shows in rivers flood of earth and sand, farm land and form of urban district burying. Flood damage investigation through on-the-spot probe until present need effective and scientific modelling techniques because is not efficient. This research wished to examine practical use of monitoring data of high resolution satellite image through satellite image analysis of various space resolution. Research analyzed abstraction possibility of soil disaster information using high resolution satellite image. Also, studied soil disaster damage present condition interpretation practical use possibility through various resolution satellite image analysis, and studied practical use of KOMPSAT image for interpretation of river topography change analysis.

• Journal of Korean Society on Water Environment
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• v.25 no.2
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• pp.311-321
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• 2009

Long-Term Hydrologic Impact Assessment (L-THIA) was modified to improve runoff and pollutant load prediction for Korean watersheds with changes in land use classification and event mean concentration produced from observed data in Korea. The L-THIA model was linked with SCE-UA, which is one of the global optimization techniques, to automatically calibrate direct runoff. Modified L-THIA model was applied to Gumho River Basins to analyze spatial distribution of nonpoint source pollution. The results of model calibration during 1991~2000 and validation during 1981~1990 for direct runoff represented high model efficiency of 0.76 for calibration and 0.86 for validation. As a results of spatial analysis of nonpoint source pollution, the BOD was mainly loaded from urban area but SS, TN, and TP from agricultural area which is mainly located along the stream. Modified L-THIA model improve its accuracy with minimum imput data and application efforts. From this study, we can find out the L-THIA model is very useful tool to predict direct runoff and pollutant loads from the watershed and spatial analysis of nonpoint source pollution.

• Water Engineering Research
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• v.3 no.2
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• pp.85-92
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• 2002

There has been continuous efforts to manage water resources for the required water quality criterion at river channel in Korea. However, we could obtain the partial improvement only for the point sources such as, waste waters from urban and factory site through the water quality management. Therefore, it is strongly needed that the best management practice throughout the river basin fur water quality management including non-point sources pollutant loads. This problem should be resolved by recognizing the non-point sources pollutant loads from the upstream river basin to the outlet of the basin depends on the landuse and soil type characteristics of the river basin using the computer simulation by a distributed model based on the detailed investigation and application of Geographic Information System (GIS). The purpose of this study is consisted of the three major distributions, which are the investigation of spread non-point sources pollutants throughout the river basin, development of the base maps to represent and interpret the input and outputs of the distributed simulation model, and prediction of non-point sources pollutant loads at the outlet of a up-stream river basin using Agricultural Non-Point Sources Model (AGNPS). For the validation purpose, the Seom-Jin River basin was selected with two flood events in 1998. The results of this application showed that the use of combined a distributed model and an application of GIS was very effective fur the best water resources and quality management practice throughout the river basin

• Journal of the Economic Geographical Society of Korea
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• v.20 no.1
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• pp.70-83
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• 2017

Traditionally, economic growth has been uneven over the space. It has also been true for the recovery from social and economic crisis in old industrial areas of the advanced economies. Even if many of such old industrial areas were seriously affected by de-industrialization, some areas have been showing progress, while others have not been so. While interpreting this phenomenon used to be a key issue in economics, main stream liberal economic theorists' explanation was uneven distribution of economic resources, such as raw materials, labour and money. However, some revolutionary economic theorists have brought in the concept of "history" in explaining the phenomenon. Path dependence theorists, for example, interpretate the emergence of different growth paths with the concept of historical accidents. This contrasts to the recent argument of the group of scholars suggesting the concept of "regional resilience," who argue that uneven growth and different growth paths are originated from different regional resilience. This paper introduces the backgrounds, characteristics and utilities of the two theories: path dependence theory and the concept of regional resilience.