• Journal of the Korean Association of Geographic Information Studies
• /
• v.10 no.1
• /
• pp.158-168
• /
• 2007

This study analyzed the reduction efficiency to a debris barrier planed with the Office of Forestry and local provinces among diverse measurements for the diminution of high-density turbid water and soil erosion of Soyang reservoir. As the analysis of soil erosion of Soyang river basin applying rainfall data (2005) and GIS database, soil erosion is estimated as 4,819,494 ton. Also, in the analysis of unit soil erosion, Chugok-, Jaun-, and Ohang stream shows high value comparing with other watersheds. Debris barrier watersheds are extracted as the center of 94 debris barrier points using GIS spatial analysis. As the analysis of soil erosion and sediment delivery ratio (SDR) of debris barrier watershed, the reduction efficiency of soil erosion of debris barrier of 2005 is analyzed as 6.8%, that is 330,203 ton. Also, the reduction efficiency of soil erosion of debris barrier of 2005 increases as 10.5%, that is 506,783 ton, when the locations of debris barrier are changed into the high soil erosion area over 5,000 ton.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.64 no.1
• /
• pp.65-77
• /
• 2022

Due to muddy water from the highland fields upstream of Soyangho Lake, the Mandae, Gaa, and Jawoon have been redesignated as NPS management areas. This study aims to evaluate the adequacy and supplementation points of the implementation plan by analyzing the operation status of muddy water generation and reduction facilities through on-site investigations by NPS management area to achieve the effective nonpoint pollution reduction goal in the implementation of the implementation plan established in 2020. The SS load calculated based on the survey results from July to October 2019 from 2017 showed a decreasen in 2019 compared to 2017. Both and the Jawoon were analyzed to have decreased. However, the amount of precipitation also decreased by about 27%, so it was judged that the effect of the reduction project was not significant. As a result of the detailed investigation of abatement facilities, about 86% of the 793 facilities installed in the management area were evaluated as 'good'. As a result of a detailed investigation by subwatersheds, subwatersheds 105 and 106 in the Mandae were analyzed as apprehensive subwatersheds. appeared to fall. In addition, it was analyzed that the effect of reducing muddy water in the Mandae district was insufficient due to the high ratio of leased farmers, lack of efforts to reduce turbid water in leased farmland, conversion to annual crops, and neglect of bare land. In the case of Gaa district, although the abatement facilities are concentrated in the upstream, muddy water was also found to be severe.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.391-391
• /
• 2022

상수도관은 시간이 경과됨에 따라 노후화가 진행되고 탁수 및 적수문제를 일으킬 가능성이 높아진다. 현재 우리나라는 전체 상수도관 중 경과년수를 초과한 노후 상수도관이 많은 부분을 차지하고 있기 때문에 개선이 시급한 실정이다. 하지만 전체 상수도관을 교체하는 것은 막대한 예산이 필요하기 때문에 현실적으로 어려운 문제이므로 상수도관의 적수 및 탁수 위험도 분석을 통하여 상수도관의 교체 또는 개량 우선순위를 결정하고 개선사업을 실시하는 것이 필요하다. 본 연구에서는 적수 및 탁수발생을 일으키는 인자들을 도출하였다. 먼저, 박리위험도와 퇴적위험도로 분류하여 적수와 탁수의 발생 위험도를 분석하였다. 퇴적위험도의 인자에는 평균유속지수, 정체지수, 관경지수, 경과년지수, 그리고 관길이지수를 적용하였고 박리위험도의 인자에는 유속차이지수, 유향변화지수, 영향범위지수, 관길이지수, 그리고 수충격지수를 적용하여 위험도분석을 수행하였다. 적용 지역은 인구 85만명의 중도시이며 4개동에 걸쳐서 위험도분석을 진행하였고 퇴적위험도가 높은 관과 박리위험도가 높은 관을 선정할 수 있었다. 또한 결과분석을 통해 박리위험도와 퇴적위험도 모두 높은 관을 선정할 수 있었다. 박리위험도와 퇴적위험도의 인자들 중에서 유속 관련지수의 경우 박리위험도에서는 유속이 빠를수록 위험도가 높고 퇴적위험도에서는 느릴수록 위험도가 높기 때문에 박리와 퇴적위험도가 모두 높다는 것은 수질문제를 일으킬 가능성이 매우 높은 관으로 판단할 수 있다. 같은 지역(동)에서 박리위험도와 퇴적위험도를 분석한 결과, 최근 개발된 경관년수가 오래되지 않은 지역의 경우는 박리위험도와 퇴적위험도의 최대값과 최소값의 차이가 3배 정도 되는 것으로 나타났다. 하지만 경과년수가 오래된 지역의 경우는 박리위험도의 경우, 가장 높은 관의 박리위험도가 가장 낮은 위험도와 7배 이상이 차이가 났고 퇴적위험도의 경우 약 10배 이상 차이가 나는 것으로 나타났다. 이는 경과년수에 의한 차이뿐만 아니라 인구감소나 인구고령화로 인해 낮 시간 수도사용량이 매주 적어서 발생하는 것으로 판단된다. 향후 본 연구결과를 적용하여 상수도의 적수 및 탁수 발생 위험도가 높은 관로를 선정하고 이에 대한 집중적인 관리감독을 진행한다면 상수도 수질문제로 인한 민원을 대폭 줄일 수 있을 것으로 판단된다.

• Journal of Korea Water Resources Association
• /
• v.55 no.11
• /
• pp.931-939
• /
• 2022

In Korea, about two-thirds of the precipitation is concentrated in the summer season, so the problem of turbidity in the summer flood season varies from year to year. Concentrated rainfall due to abnormal rainfall and extreme weather is on the rise. The inflow of turbidity caused a sudden increase in turbidity in the water, causing a problem of turbidity in the dam reservoir. In particular, in Korea, where rivers and dam reservoirs are used for most of the annual average water consumption, if turbidity problems are prolonged, social and environmental problems such as agriculture, industry, and aquatic ecosystems in downstream areas will occur. In order to cope with such turbidity prediction, research on turbidity modeling is being actively conducted. Flow rate, water temperature, and SS data are required to model turbid water. To this end, the national measurement network measures turbidity by measuring SS in rivers and dam reservoirs, but there is a limitation in that the data resolution is low due to insufficient facilities. However, there is an unmeasured period depending on each dam and weather conditions. As a sensor for measuring turbidity, there are Optical Backscatter Sensor (OBS) and YSI, and a sensor for measuring SS uses equipment such as Laser In-Situ Scattering and Transmissometry (LISST). However, in the case of such a high-tech sensor, there is a limit due to the stability of the equipment. Therefore, there is an unmeasured period through analysis based on the acquired flow rate, water temperature, SS, and turbidity data, so it is necessary to develop a relational expression to calculate the SS used for the input data. In this study, the AEM3D model used in the Water Resources Corporation SURIAN system was used to improve the accuracy of prediction of turbidity through the turbidity-SS relationship developed based on the measurement data near the dam outlet.

• 한국해양학회지
• /
• v.30 no.4
• /
• pp.262-270
• /
• 1995

A comparative study to understand the changes in physical and sedimentological natures was carried out in the Keum Estuary before and after the gate-close of Keum River weir. After closing of weir-gate maximum tidal current speed decreased about 30∼40% compared with that of the previous gate-opening period. Water masses also represent vertical stratifications both on water salinity and water transparency. The Keum Estuary seems to be changed from the well-mixed type estuary during the gate-opening period to the "partially-mixed type" and/or "salt-wedge type" estuary after the closing of weir-gate. The concentrations of suspended matter range 10∼100 mg/l in surface waters after the gate-close of Keum River Weir, representing about 1/4 to 1/3 decrease than those during the gate-close of Keum River Weir, representing about 1/4 to 1/3 decrease than those during the gate0opening period. Such decrease of suspended mater appears to be due to the decrease in the resuspension of bottom sediments, and also due to the vertical stratification of water masses that prevented the upward diffusion of turbid bottom waters. It is, therefore, expected that the depositional environment of Keum Estuary has been changing into the low energy conditions after the closing of weir gate, resulting in the rapid deposition of fine suspended matters within the Keum Estuary.

• Journal of Korean Society on Water Environment
• /
• v.34 no.5
• /
• pp.537-547
• /
• 2018

Sediment discharge by rainfall runoff affects water quality in rivers such as turbid water, eutrophication. In order to solve various problems caused by soil loss, it is important to establish a sediment management plan for watersheds and rivers in advance. However, there is a lack of sediment data available for estimating sediment discharge in ungauged basins.. Thus, reasonable research is very important to evaluate and predict the sediment discharge quantitatively. In this study, cluster analysis was conducted to classify gauged watersheds into hydrologically homogeneous groups based on the watershed characteristics. Also, this study suggests a method to efficiently predict the sediment discharge for ungauged basins by developing and evaluating the SDR equations based on the PA-SDR module. As the result, the SDR equations for the classified watersheds were derived to predict the most reasonable sediment discharge of ungauged basins with 0.24 % ~ 10.89 % errors. It was found that the optimal parameters for the gauged basins reflect well characteristic of sediment movement. SDR equations proposed in this study will be available for estimating sediment discharge on ungauged basins. Also it is possible to utilize establishing the appropriate sediment management plan for integrated management of watershed and river in Korea.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2023.05a
• /
• pp.482-482
• /
• 2023

상수도관은 사용년수가 경과함에 따라 노후화가 진행되며, 노후화된 상수관은 내부적으로 부식, 이물질 퇴적, 균열 등의 현상이 발생하게 되고, 이는 결국 수질문제로 연결되어, 탁수사고 발생 확률증가의 주요 원인이 되고 있다. 국내 상수도관의 경우 매설년수의 증가로 인해 내구연한이 도래한 상수관망의 비중이 점차 증가하고 있으며, 2019년 서울시 문래동 수질사고, 2019년 인천 붉은 수돗물 사고, 2022년 안양 동안구 탁수사고, 2022년 여수시 웅천 탁수사고 등 관의 노후화로인한 탁수 사고가 빈번하게 발생되고 있어 수도 사용자에게 불편함을 끼치고 있다. 현재 정수장 및 상수관망에 설치된 탁도계를 통해 수질에 대한 감시를 진행하고 있지만, 경제적인 문제로 인해 모든 상수도관에 탁도계를 설치하기에는 현실적으로 불가능하며, 제한적인 탁도계의 개수를 통해 수질에 대한 감시 및 관리를 진행하고 있는 실정이다. 이러한 상황으로 인해 탁수사고 발생 시 발생 원인분석 및 최초 발생위치 결정이 쉽지 않으며, 보수 보강을 통한 상수도관의 정상화까지 오랜 시간이 걸리게 된다. 이에 본 연구에서는 상수관망에서 탁수 발생 시 최초 발생 위치를 결정할 수 있는 기법을 개발하였으며, 이를 실제 상수도관망에 적용하여 탁수발생 파이프를 탐지하였다. 탁수사고 발생 시 실측된 수질 데이터의 부족으로 인해 임의의 파이프에서 탁수가 발생하였다고 가상의 탁수 발생시나리오를 가정하였으며, 완전혼합농도식을 통해 관망에 설치된 탁도계의 NTU(Nethelometric Paultity Unit) 농도를 계산하여 가상의 탁수발생 시나리오를 상수도관망에 적용하였다. 이후, 역추적 계산기법을 통해 파이프의 초기 NTU 농도를 변화시켜주며 관망내 설치된 탁도계의 NTU 농도를 계산하였으며, 가상 시나리오를 적용하여 계산된 탁도계의 NTU 농도와 역추적 계산법을 적용하여 계산된 탁도계의 NTU 농도의 Percentage Error를 비교/분석하여 탁수 발생 파이프를 탐지하였다. 분석결과, 가상 시나리오의 최초 탁수발생 파이프와 역추적 계산법을 적용하여 탐지한 최초 탁수발생 파이프의 위치가 일치하는 것으로 나타났다. 본 연구에서 개발된 역추적계산을 통한 탁수발생 파이프 탐지기법을 실제 관로 교체사업에 활용한다면 파이프의 개선 우선순위를 보다 명확하게 판단할 수 있으며, 더 나아가 상수도 관망의 유지관리에 활용하여 경제적이고 효율적인 상수관망 시스템관리를 할 수 있을 것으로 판단된다.

• Membrane Journal
• /
• v.30 no.3
• /
• pp.190-199
• /
• 2020

The utilization of multiple water sources becomes important due to the master plan for development of water supply released by Ministry of Environment, Korea in 2018. In this study, therefore, the analysis of comprehensive effect in blending applicable water sources in Daesan where 100,000 ㎥/d seawater desalination plant will be constructed for industrial use was performed. The increase in mixing ratio of other water sources with seawater reduced salinity up to 50%, but negatively impacted the turbid and organic matter. Lab-scale reverse osmosis performance test also found that membrane fouling was exacerbated in blended water condition. The simulation results of reverse osmosis indicated 39% energy saving on average is expected at the one-to-one blending ratio, however, long-term performance test at the pilot-scale plant is highly required to evaluate the inclusive impact of mixing seawater and other water sources.

• Journal of Korean Society on Water Environment
• /
• v.34 no.6
• /
• pp.632-641
• /
• 2018

Algal dynamics is controlled by multiple environmental factors such as flow dynamics, water temperature, trophic level, and irradiance. Underwater irradiance penetrating from the atmosphere is exponentially decreased in water column due to absorption and scattering by water molecule and suspended particles including phytoplankton. As the exponential decrease in underwater irradiance affects algal photosynthesis, regulating their spatial distribution, it is critical to understand the light extinction characteristics to find out the mechanisms of algal dynamics more systematically. Despite the significance, the recent data have been rarely reported in the main stream areas of large rivers, Korea. In this study, the euphotic depths and light extinction coefficients were determined by monitoring the vertical variation of underwater irradiance and water quality in the main channel of Nakdong River near Dodong Seowon once a week during summer of 2016. The average values of euphotic depth and light extinction coefficient were 4.0 m and $1.3m^{-1}$, respectively. The degree of light extinction increased in turbid water due to flooding, causing an approximate 50 % decrease in euphotic depth. Also, the impact was greater than the self-shading effect during the periods of cyanobacterial bloom. The individual light extinction coefficients for background, total suspended solid and algal levels, frequently used in surface water quality modeling, were determined as $0.305m^{-1}$, $0.090m^{-1}/mg{\cdot}L^{-1}$, $0.013m^{-1}/{\mu}g{\cdot}L^{-1}$, respectively. The values estimated in this study were within or close to the ranges reported in literatures.

• Journal of Korean Society on Water Environment
• /
• v.26 no.2
• /
• pp.215-224
• /
• 2010

This study was carried out to estimate effects of sediment reduction with net type sediment settling pond at highland agricultural areas. Flow and sediment monitoring system with rainfall gauge were installed at the study area for real-time monitoring and analysis. It was found that amount and intensity of rainfall events strongly affect sediment yield from the study area. With net type sediment settling pond, it was expected that approximately 61% of sediment could be removed. The correlation between heavy metals and SS were analyzed in this study. $R^2$ values were 0.644, 0.876, 0.945, and 0.928 for Fe, Mn, Al, and Si, respectively. This results indicate that heavy metals also could be removed with net type sediment settling pond. As shown in this study, the sediment settling pond will be an efficient sediment reduction facility at highland agricultural areas. For maximum reduction efficiencies of sediment and other pollutants at agricultural fields, simplified sediment settling pond should be designed and implemented.