• Korean Journal of Ecology and Environment
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• v.52 no.4
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• pp.316-323
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• 2019

This study was carried out to investigate sedimentary environment changes in Nakdong River sediments. For this purpose, sediments at six sites upstream of Gangjeong-Goryung Weir in the middle of the Nakdong River were collected before and after the rainy season. Particles size, IL, TOC, TN, TP, and SRP were analyzed for the sediment environment. The changes in the watershed environment before and after the rainy season (precipitation, discharge, and SS concentration) were investigated. After the rainy season, the amount of precipitation and discharge increased more than three times, and the average concentration of SS in the stream increased more than two times. Fine grained sediment and the concentrations of IL, TOC, TN, TP, SRP were increased after the rainy season. As a result of sediment contamination assessment, IL was 19~68% of the reference value, TN and TP were 21~76% and 21~58% of the reference value. The result showed strong correlation between particle size (Silt+Clay) and organic contents of sediment (IL, TOC, TN, TP and SRP). It is considered that the change of the river watershed environment (precipitation, discharge) is an important factor of the change of sedimentation environment.

• Water for future
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• v.7 no.2
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• pp.107-111
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• 1974

Annual runoff in the Nakdong river basin has been analyzed to find the probability functions of best fit to distribution of historical annual runoff. The results obtained are as follows; (1) Log-normal 3-parameter disrtibution is believed as the probability function of best fit to historical distribution (2) Log-normal 3-parameter disrtibution is believed as the best fit probability function among Log-normal dist-ributions. (3) In the test of goodness of fit, $x^2-test$ shows that probability of $x^2-valus$ in Log-normal 3-parameter distribution is nearly more than 90%. But in the Simirnov-Kolmogorov test, hypotheses for the probability distributions cannot be rejected at significance level 5% & 1%. (4) Among 7 gauging stations, Dongchon & Koryung-Bridge's records show lower fitness to the theoretical probability functions than other 5 gauging station's

• Korean Journal of Hydrosciences
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• v.10
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• pp.17-34
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• 1999

The SSARR model adopting Is(integrated snowband) watershed model is applied to Nakdong River basin for lowflow analysis. The IS watershed model is added to new version of the SSARR which has functions of simulating evapotranspiration, infiltration and lower zone routing. It provieds annual water budget informations as an output file and can be operated by interactive mode. Sensitivity analysis for both cases of high and lowflows was carried out, which becomes the knowledge base for model calibration. Model verification was performed using the relative errors of highflows and absolute errors of lowflows at the control points. Monthly water budget analysis was done by IS watershed model, and is reveals that runoff coefficient is 52.6%.

• Journal of Korean Society of Rural Planning
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• v.11 no.4 s.29
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• pp.47-57
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• 2005

The goal of this research is to evaluate landscape-ecological characteristics of watersheds in the Nakdong River Basin by using Geogaphic Information System (GIS) and landscape indices for integation of spatio-temporal informations and multivariate statistical techniques for quantitative analysis of forest landscape. Fragmentation index and change matrix techniques using factor analysis and grid overlay method were used to efficiently analyze and manage huge amount of information for ecological-environmental assessment (land-cover and forest landscape patterns). According to the results based on the pattern analysis of land-cover changes using the change detection matrix between 1980s and 1990s, addition on 750km$^2$ became urbanized areas. The altered 442.04km$^2$ was agricultural areas which is relatively easy for shifting of land-use, and 205.1km$^2$ of forests became urbanized areas, and average elevation and slope of the whole altered areas were 75m and 4$^{\circ}$. On the other hand, 120km$^2$ of urban areas were changed into other areas (i.e., agricultural areas and green space), and fortunately, certain amount of naturalness had been recovered. But still those agricultural areas and fallow areas, which were previously urban areas, had high potential of re-development for urbanization due to their local conditions. According to the structural analysis of forest landscape using the landscape indices, the forest fragmentation of watersheds along the main stream of the Nakdong River was more severe than my other watersheds. Furthermore, the Nakdong-sangju and Nakdong-miryang watersheds had unstable forest structures as well as least amount of forest quantity. Thus, these areas need significant amount of forest through a new forest management policy considering local environmental conditions.

• Journal of Environmental Science International
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• v.25 no.12
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• pp.1597-1611
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• 2016

A numerical assessment using mesoscale-CFD (computational fluid dynamics) coupled A2C (atmosphere to CFD) model was carried out to analyze the variation of microscopic air flow pattern due to the construction of the Chilgok barrage in the Nakdong River. Scenarios with air flow patterns were classified into pre- and post-construction. The increased width of the river due to the construction of the Chilgok barrage induced obvious changes in moisture and the thermal environment around the river. However, air temperature variation was restricted within an area along the windward side in the numerical assessment. The impact of barrage construction on air temperature tends to be stronger during the nighttime than the daytime. It also stronger during the winter than the summer. In the simulation, the convergence of mesoscale wind is more pronounced after barrage construction than before. This is caused by the change of heat flux pattern induced by the widening of the river. Although this work is a case study with restricted atmospheric stability conditions that has several limitations in the numerical simulations, the impacts of the land-use changes brought about by the construction of the barrage in the river acceptable.

• Journal of Korea Water Resources Association
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• v.45 no.11
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• pp.1157-1168
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• 2012

In this study, we assess changes in water quality trends over time based on certain control measurements in order to identify and analyze the cause of the trend in water quality. The current water pollution in the Nakdong River was analyzed, as it suggests that the significant changes in water quality have occurred in between 2006 and 2010. Based on monthly average data, we have examined for trends of the Nakdong River watershed in water temperature, Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Nitrogen (TN), and Total Phosphorus (TP). Moreover, we have investigated seasonal variation of water quality of sites within the Nakdong River Basin by implementing further analyses such as, Correlation Coefficient, Regression Analysis, Hierarchical Clustering Method, and Time Series Analysis on SPSS. Geology and topography of the watershed, controlled by various conditions such as, climate, vegetation, topography, soil, and rain medium, have been affected by the non-homogeneity. Our study suggests that such variables could possibly cause eutrophication problems in the river. One possible way to overcome this particular problem is to lay up a ship on the river by increasing the nasal flow measurement of the Nakdong River during rainy season. Moreover, the water management requires arranging the measurement of the flow in order to secure the river while the numerous construction projects need to be continuously observed. However, the water is not flowing tributary of the reason for the timing to be flowing in a natural state of river water and industrial water intake because agriculture. Therefore, ongoing research is needed in addition to configuration of all observations.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.6
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• pp.729-736
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• 2015

In this study, It was analyzed to estimate the origin from the collected disposable lighters with the printed company name and telephone number on the surface. Monitoring was done bimonthly from 2 areas of sandbar Coastline of Nakdong River Estuary(Jinu-do, Shinja-do) and 3 areas(Doomo beach, Heungnam beach, Yeocha beach) of Northeastern coast of Geoje-do. As a result of the monitoring, there were 166 lighters collected. Then, the monthly occurrence amount was concentrated in Jun, August. The origin of Disposable lighters that flowed in study area were mostly cause to the Nakdong River basin region and the coastal area where population densities are high.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.74-83
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• 2007

The goal of this study is to establish an integrated watershed hydrologic model for the whole Nakdong River basin whose area is an approximately 24,000 km2. Including a number of watershed elements such as rainfall, runoff, water use, and so on, the proposed model is based on SWAT model, and is used to improve the flow duration curve estimation of ungauged watersheds for Korean Total Maximum Daily Load (TMDL). The model is also used to recognize quantitatively the river flow variation due to water use elements and large dam effluents in the whole watershed. The established combined watershed hydrologic model, SWAT-Nakdong, is used to evaluate the quantified influences of artificial water balance elements, such as a dam and water use in the watershed. We apply two water balance scenarios in this study: the dam scenario considering effluent conditions of 4 large multi-purpose dams, Andong dam, Imha dam, Namgang dam, and Habcheon dam, and the water use scenario considering a water use for stream line and the effluent from a treatment plant. The two scenarios are used to investigate the impacts on TMDL design flow and flow duration of particular locations in Nakdong River main stream. The results from this study will provide the basic guideline for the natural flow restoration in Nakdong River.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.6
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• pp.153-162
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• 2015

In this study, we analyzed the trends of water quality along the main stream in Nakdong river basin using the recent data and seasonal Mann-Kendall test. Monthly averaged values of DO, BOD, SS, COD, TN, and TP from 1989 to 2014 for 14 stations (including 2 TMDLs stations) were used in the study. The trend analysis results showed that BOD and TP at most stations has decreasing temporal trend except a few stations while COD and SS showed increasing trend at most stations. Temporal trends in TN at 8 stations were found to be statistically significant and 5 of them showed increasing temporal trend. Temporally averaged BOD, COD, TN and TP were generally increasing as going downstream and the worst water quality were found at Goryeong and Hyunpung station. Overall, water quality of Nakdong river especially in COD, SS, and TN getting worse in time at most stations and as going downstream.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1400-1404
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• 2010

In this study the flow duration curves and load duration curves for Nakdong river basin are analyzed. The TANK model is used as s hydrologic simulation model whose parameters are estimated from 8-days intervals flow data measured by Nakdong River Water Environment Laboratory. also in this study a Minimum Variance Unbiased Estimator(MVUE) is confirmed that it provides satisfactory load estimate. The Seven-Parameter Log Linear Model for estimating Total Organic Carbon(TOC) and Biochemical Oxygen Demand(BOD) loads in Nakdong river using a MVUE.