• Journal of Environmental Science International
• /
• v.27 no.6
• /
• pp.371-381
• /
• 2018

Multifunctional weirs constructed through the Four Major Rivers Restoration Project are operated as management water levels. The purpose of this study was to evaluate the effect of water level in the main stem on the tributary water level according to multifunctional weir operation, because the operation of multifunctional weirs for water level management influences the drainage of tributaries. In this study, water level pressure gauges were installed and spatial and temporal water quality was observed. The LOcally Weighted Scatterplot Smoothing (LOWESS) technique was applied to the Nakdong River and the Baekcheon Junction, both upstream of the Gangjeong-Goryeong weir, in order to analyze water quality trends. When considering the overall analysis and observations, it was found that the water quality forecasting point located at the Baekcheon estuary point should be transferred to the Dosung Bridge, which is located upstream of the Sunwon Bridge.

• Journal of Ecology and Environment
• /
• v.39 no.1
• /
• pp.71-80
• /
• 2016

The main goal of this study is to develop a multi-metric fishway assessment model (M_m-FA) and evaluate the efficiency of fishway. The M_m-FA model has three major fishway components with nine metrics: structural characteristics, hydraulic/hydrologic features, and biological attributes. The model was developed for diagnosing and assessing fishway efficiency and tested to Juksan Weir at the Yeongsan River Watershed. Structural characteristics of fishway included slope of the fishway (M₁), ratios of fishway width to stream width (M₂), and the proportion of orifice clogging and orifice size (M₃). Hydraulic/hydrologic characteristics included depth of fishway entrance head (M₄), depth of exit tail (M₅), and current velocity of inner fishway (M₆). Biological characteristics included fish species ratio of inner fishway to upper-lower weir (M₇), fish length distribution (M₈), and the proportion of migratory fish species to the total number of species (M₉). Overall, the assessment of fishway efficiency showed the total score of the M_m-FA model was 25 in the Juksan Weir, indicating "good condition" by the criteria of the five-level classification system. The M_m-FA model may be used as a key tool for the assessment of fishway efficiency, especially on the 16 weirs constructed for the "Four Rivers Restoration Project" after a partial calibration of M_m-FA model.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.6A
• /
• pp.337-345
• /
• 2012

A model test is performed to investigate the dynamic behavior of truss type lift gate which is being constructed by the four major rivers project. The gate dimensioned 40 m in width, 9m in height is scaled with the ratio of 1:25 and is made of acryl panel and supplemented weight by lead in the concrete test flume dimensioned 1.2 m in width, 0.5 m in height and 30m in length. Firstly natural frequencies of the model gate are measured and compared with the numerical results for the calibration. The amplitudes of the vibration are measured under the different gate opening, upstream water level conditions. Also models with bottom angle $20^{\circ}$, $35^{\circ}$ and $50^{\circ}$ are tested and compared to find out a proper shape of bottom structure which minimizes the gate vibration. These test results presents a basic data for the guide manuals of gate management and a design method to reduce the gate vibration of truss type lift gate.

• Journal of Soil and Groundwater Environment
• /
• v.15 no.2
• /
• pp.47-54
• /
• 2010

Although the demands for the dredging work have been increasing due to social and industrial reasons including national plan for restoration of four major rivers, environmental standards or management guidelines for the dredged river sediment are limited. The suggested environmental standard for the beneficial use of dredged river sediment consists of two levels, recyclable and concern, and includes eight contaminants such as metals and organic contaminants. The systematic approach to remediate dredged river sediment is also suggested. The system consists of both washing and stabilization processes with continuous multi particle separation. In the early stage, the sediments are separated into two particle sizes. The coarse-grained sediment over 0.075 mm, generally decontaminated with less trouble, follows normal washing steps and is sent for recycling. The fine-grained sediments under 0.075 mm are separated again at 0.025 mm. The particles bigger than this second separation point are treated in two ways, advanced washing for highly contaminated sediments and stabilization for less. The lab test results show that birnessite and apatite are most effective stabilizing agents among tested for Cd and Pb. The most fine residues, down-sized by continuous particle separation, are finally sent for disposal. The system is tested for metals in this study, but is expected to be effective for organic contaminants included in the environmental standard, such as PAH and PCE. The feasibility test on the field site will be followed.

• Journal of Korean Society on Water Environment
• /
• v.23 no.6
• /
• pp.863-871
• /
• 2007

Spectroscopic characteristics of river water from four major watersheds in the Ulsan area were measured to examine their potential for estimating water quality parameters. The total 176 river samples were collected from 44 sites of small streams within the watersheds during the year 2006. Spectroscopic characteristics investigated included protein-like fluorescence (FLF) intensity, fulvic-like fluorescence (FLF) intensity, terrestrial humic-like fluorescence (TLF) intensity, UV absorbance at 254 nm, and UV absorbance difference at 220 nm and 254 nm. Protein-like fluorescence intensity showed linear relationships with biochemical oxygen demand (BOD), chemical oxygen demand (COD), total phosphorous (TP) concentrations of the samples with the correlation of 0.784, 0.779, and 0.733, respectively. Due to the UV absorption characteristics of nitrate at 220 nm, UV absorbance difference at 220 nm and 254 nm was selected to represent total nitrogen (TN) concentration. Exclusion of some samples with PLF intensity higher than 5.0 improved the correlation between the UV absorbance difference and TN as demonstrated by the increase of the correlation coefficient from 0.392 to 0.784. Instead, for the samples with PLF intensity lower than 5.0, the highest correlation of TN was achieved with UV absorbance at 254 nm. The results suggest that PLF intensity could be used as the estimation index for BOD, COD, and TP concentration of river water, and as the primary screening index for the prediction of TN using UV absorbance difference. Some BOD-based water quality levels among the river water were statistically discriminated by the PLF intensity. Low p-values were obtained from the t-tests on the samples with the first level and the second level (p=0.0003) and the samples with the second and the third levels (p=0.0413). Our combined results demonstrated that the selected spectroscopic characteristics of river water could be utilized as a tool for on-site real-time monitoring and/or the primary estimation of water quality.

• Journal of Korean Society of Water and Wastewater
• /
• v.29 no.3
• /
• pp.325-335
• /
• 2015

Concerns about water quality in the Nakdong River have been raised because the Nakdong River will change from a lotic environment to a lentic environmental due to the installation of eight weirs to be constructed as part of the Four Major Rivers Restoration Project. The rapid urbanization and industrialization of the middle and the lower reaches of Nakdong River causes the indiscreet discharge of uncleanly living sewage and industrial wastewater. And the water quality of lower reaches of Nakdong River is getting seriously worse. Owing to the water shortage of Nakdong River and the closing of reaches because of the estuary dyke in the dry season, the velocity of a moving fluid is almost accumulated under 0.03m/sec. Then a pollutant is piled up on the bottom of the river. Polluted sediment is formed and nutrition level of water is increased more and more. The eutrophication state propagated to dark brown or green from eutrophication often comes out. Therefore in this study, we measured Chl. a of chlorophyll sensor (YSI6600V2) and aceton extraction through field observation in the Nakdong River and Samrangjin. And we evaluated the reliability of chlorophyll sensor. In correlation analysis between chlorophyll sensor and aceton extraction, it shows high relation in general. And it also shows high relation among the chlorophyll sensor and aceton extraction of the dominant diatom (Skeletonema costatum), Dinophyta (Prorocentrum minimum) in the Nakdong River estuary by laboratory analysis results.

• The Journal of the Korea Contents Association
• /
• v.19 no.12
• /
• pp.299-312
• /
• 2019

This study examined the effect of media and personal frames on readers' attitude towards newspaper articles and on their perceived fairness. Study 1 examined the frame effects with the issue of the Candlelit Protest in 2008 and Study 2 did with the issue of the Four Major Rivers Restoration Project. Results indicated that in both studies two frames had main effects on readers' attitude and yet their interaction was not significant. In both studies, effects of personal frame were partially significant on the perceived fairness of the article, but main effects of media frame and interaction effects between two frames were not significant. These findings demonstrated that readers' attitude towards newspaper articles and on their perceived fairness would be influenced by their headlines and their source along with their content.

• Journal of Korean Society of Water and Wastewater
• /
• v.31 no.3
• /
• pp.197-204
• /
• 2017

This study was carried out to apply the UAV(Unmanned Aerial Vehicle) coupled with Multispectral sensor for the algae bloom monitoring in river. The study acquired remote sensing data using UAV on the midstream area of Gum River, one of four major rivers in South Korea. Normalized difference vegetation index (NDVI) is used for monitoring algae change. This study conducted water sampling and analysis in the field for correlating with NDVI values. Among the samples analyzed, the chlorophyll concentration exhibited strong and significant linear relationships with NDVI, and thus NDVI was chosen for algae bloom index to identify emergence aspect of phytoplankton in river. Aerial remote sensing technology can provide more accurate, flexible, cheaper, and faster monitoring methods of detecting and predicting eutrophication and therefore cyanobacteria bloom in water reservoirs compared to currently used technology. As a result, there was high level of correlation in chlorophyll-a and NDVI. It is expected that when this remote water quality and pollution monitoring technology is applied in the field, it would be able to improve capabilities to deal with the river water quality and pollution at the early stage.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2018.05a
• /
• pp.481-481
• /
• 2018

본 연구에서는 4대강 수계 16개 보를 대상으로 보별 오염물질의 정량적인 분석을 통한 수질관리를 목적으로 미공병단에서 개발된 CE-QUAL-W2 모형을 이용하여 보별 유기물(BOD, TOC), 영양염류(TN, TP), 조류생체량(ALG)에 대한 물질수지를 분석하였다. 2013년부터 2017년까지를 분석기간으로 설정하여 각 보 구간에서 상류 보, 지류, 하수종말처리장의 유입부하를 입력조건으로 구성하였으며, 검증된 모델 입력자료 및 출력자료를 바탕으로 각 수질항목에 대한 유입 및 유출부하량을 산정하였다. 또한 월별 및 연간 오염물질의 증감 양을 비교 분석하여 보 구간에서 오염물질의 생산 및 소멸 여부에 대한 평가를 하였다. 조사기간 동안 오염물질의 증감 양은 수계 및 보별, 월별 및 연도별, 그리고 수질항목에 따라 상이한 것으로 나타났다. 5년간 평균 수계별 보 구간으로 유입부하량, 유출부하량에 대한 증감율을 보면 한강수계 3개보의 경우 BOD는 -5.4~3.1%, TN은 -3.9~1.1%, TP는 -6.9~-0.9%, TOC는 -8.1~-2.1%, ALG는 14.4~30.8%를 나타내었으며, 낙동강수계 8개보의 BOD는 -10.3~10.6%, TN은 -12.2~11.4%, TP는 -14.9~21.6%, TOC는 -16.6~2.3%, ALG는 -29.5~30.1%, 금강수계 3개보의 BOD는 -1.6~ -0.5%, TN은 -2.6~-0.9%, TP는 -6.6~-3.9%, TOC는 -5.4~-4.9%, ALG는 3.5~21.5%, 영산강수계 2개보의 BOD는 -0.4~3.1%, TN은 0.6~2.0%, TP는 -9.8~-0.9%, TOC는 -11.4~-10.3%, ALG는 30.3~36.5%로 전반적으로 낙동강수계의 BOD와 TP, 영산강수계의 BOD와 TN을 제외한 오염물질이 보 구간 내에서 침전, 분해 등에 의해 감소하는 것으로 나타났다. 조류생체량은 낙동강의 낙단보와 구미보를 제외한 보 구간 내에서 증가하였으며 특히, 금강과 영산강은 하류로 갈수록 조류생체량이 증가하는 것으로 나타났다.

• Journal of Korea Water Resources Association
• /
• v.54 no.12
• /
• pp.1223-1232
• /
• 2021

In this study, a new analysis method by using a "Discharge Gini Coefficient" is presented to determine the degree of inequality in daily discharge throughout the year. The Discharge Gini Coefficient can be calculated using the area relationship with the cumulative percentage of the daily mode discharge in the ascending order according to the cumulative percentage of the date of occurrence of the daily discharge throughout the year. The Discharge Gini Coefficient is presented as a value between 0 and 1, and the degree of inequality can be divided into 5 levels. The Discharge Gini Coefficient can be used to estimate the discharge stability of the downstream point relative to the upstream point. In addition, it is possible to quantify the influence of each reference discharge on the total inequality. The applicability of the Discharge Gini Coefficient was reviewed using long-term daily discharge data at eight points upstream and downstream of the four major rivers in Korea. The Discharge Gini Coefficient can also be used to analyze the discharge control effect in the downstream by the upstream dam.