• Journal of The Korean Society of Agricultural Engineers
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• v.62 no.6
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• pp.97-109
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• 2020

The objective of this study was to assess spatial variation of the target water quality criteria and excess rate in Nakdong river basin after the Total Maximum Daily Loads (TMDLs). For this, 41 total water quality monitoring stations were selected BOD and T-P data were collected from 2003 to 2019. The annual average water quality of BOD and T-P were calculated and compared with the target water quality for each stations by peroid. As a result of analyzing the BOD, Kumho A, Nakbon F, Namgang D, Miryang B, Wicheon B and Hoecheon A exceeded the target water quality criteria for two consecutive times. For T-P, Nakbon N, Naeseung B, Miryang A, Hwanggang A and Hoecheon A exceeded the target water quality criteria twice in a row. In the case of T-P, the target water quality excess rate was relatively low after the TMDLs implementation compared to before the TMDLs implementation. However, in the case of BOD, there was no difference in the target water quality excess rate before and after TMDLs. As a result, the overall annual average water quality shows a decreasing trend, but it is necessary to manage the water quality for the Nakdong river basin that exceed the target water quality.

• Journal of the Korean Association of Geographic Information Studies
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• v.12 no.3
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• pp.21-34
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• 2009

Usually in flood flow problems, one-dimensional approach does not provide the required details of complex flow phenomena such as the flow in braided rivers and river junction. In this study, two-dimensional finite element mesh is constructed using DEM and GIS tool, and applied to RMA-2model. The purpose of this study is to investigate the applicability of the two dimensional model in natural rivers and to analyze characteristics of river flow due to the change of cross section. For model calibration, the result of unsteady flow analysis was compared with the observed data. Accordingly, the SMS model in this study prove to be very effective and reliable tool for the simulation of hydrodynamic characteristics under the various flow conditions.

• Journal of Wetlands Research
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• v.21 no.3
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• pp.215-223
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• 2019

In this study, we analyzed the water quality characteristics of major tributaries of Nakdong River through statistical analysis such as correlation analysis, principal component and factor analysis, and cluster analysis. Organic matter and nutrients are highly correlated, and are high in spring and autumn, and seasonal water quality management is required. Principal component and factor analysis showed that 82% of total variance could be explained by 4 principal components such as organic matter, nutrients, nature, and weather. BOD, COD, TOC, and TP items were analyzed as major influencing factors. As a result of the cluster analysis, the four clusters were classified according to seasonal organic matter and nutrient pollution. Kumho River watershed showed high pollution characteristics in all seasons. Therefore, effective management of water quality in tributary streams requires measures in consideration of spatio-temporal characteristics and multivariate statistical techniques may be useful in water quality management and policy formulation.

• Journal of Environmental Health Sciences
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• v.22 no.2
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• pp.25-31
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• 1996

The species of four heavy metals (Cr, Cu, Ni and Pb) associated with sediments (viz exchangeable, carbonates, reducible, organic and residual fractions) were determined with respect to the particle sizes and depths at four locations of the lower Kumho river. In the exchangeable fraction, 3.7~19.52% of Ni and 2.8~14.81% of Pb were found, and in the carbonates fraction 2.12~19.43% of Ni and 1.39~15.42% of Pb were found. The reducible fraction retained about 8.66~44.93% of Cr, 0.41~9.79% of Cu, 17.38~35.74% of Ni and 9.5~44.89% of Pb. In the organic fraction about 0~21.06% of Cr, 2.95~35.74% of Cu, 0~14.66% of Ni and 0~10.65% of Pb were found. The residual fraction retained about 52.6~83.53% of Cr, 63.86~86.39% of Cu, 39.66~66.16% of Ni and 39.97~71.75% of Pb. The order of release or mobility of heavy metals was Ni > Pb > Cr > Cu. Mobile fraction of heavy metals by particle sizes (1.0~0.5 mm and 0.5~0.25 mm) was found to be higher in particle sizes 1.0~0.5 mm than that of 0.5~0.25 mm. The release or mobility of heavy metals by depths (0~5 cm, 5~10 cm and 10~15 cm) was found to be higher in the upper sediments than in the lower sediments, except Cu.

• Journal of the Korean Association of Geographic Information Studies
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• v.8 no.2
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• pp.10-20
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• 2005

The change of stream creation has a very sensitive effect on runoff analysis model using the divergence characteristic of stream. Therefore, in this study, the threshold area of stream creation was examined the change characteristic of topographical parameters. The subject basin of the research was the upper basin of the Kumho water gage station which is located in the middle of the Kumho river. The 1:25,000 numerical geography which was constructed $10{\times}10m$ mesh was used. The range of investigation of topographical parameters are number of stream order, length, area, slope, basin relief, sinuosity ratio, drainage density and total stream length etc. It was found from the result of analysis that the threshold value of 1st order stream has a very big effect on topographical parameters of basin. It was found that the threshold area of stream creation was under $0.10km^2$, the parameters showed a big change but showed a very small change over $0.10km^2$.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.629-636
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• 2010

According to the spatial movements of the Nak-dong river watershed, the changes in heavy metal concentrations were simulated by WASP7.3. The risk assessment was performed using the predicted data of WASP7.3. The target heavy metal was manganese (Mn). In the simulated manganese data of WASP7.3, the average concentration by regions was from 0.03 mg/L to 0.07 mg/L. It is lower than drinking water standard in korea. The risk assessment was presented that it was high at the junction of Nak-dong river and Kumho river. It was influenced by the discharge of industrial complexes and large cities which were located in the junction. In comparison of drinking water standard and predicted data of WASP7.3 risk assessment, whole watershed was also low level at predicted data. However, to keep the similar risk value ($10^{-7}$) in adults and children anywhere, it requires the additional treatment of the point source discharges. It was also reflected by regions. Through this study, it was possible to evaluate heavy metal influence in unattainable monitoring regions and to estimate heavy metal addition and reduction by locations. Therefore, the outcomes of WASP7.3 can connect with the risk assessment and it can evaluate the safety of human by regions.

• Journal of the Korean Association of Geographic Information Studies
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• v.2 no.3
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• pp.23-34
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• 1999

This study proposed the possibility of GIS to analyze stream physiographic characteristics of river basin which is important control factor in complex water management. Based on five 1:25,000 topographic maps which cover Yengchon Dam area locates upper area of Kumho River, this study analyzed the characteristics using Arc/Info(UNIX) GIS. Comparing its results and those from the existing method using digital planimeter, it could conclude as follows; First, as the results of the analysis of hypsometric curve of Yeungchon Dam area, it has the topographic characteristics of youth and maturity. And the landform of Yengchon Dam area has developed with regularity when Horton's three laws on the morphology of stream is applied. Second, the possibility of applying GIS to data management and utilization is sufficient even if it requires long time to construct topographic attribute data. Finally, a further research is needed on watershed direction with landform for the purpose of analyzing water source management and topographic property effectively.

• Journal of Korean Society for Geospatial Information Science
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• v.20 no.1
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• pp.109-116
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• 2012

The effect of the grid resolution on the hydrodynamic simulation has been investigated by using CCHE2D and EFDC. Since a high resolution of the grid results in the increase of computation time, an appropriate grid resolution should be selected by considering the efficiency of simulation according to the objectives of projects. In order to understand the effect of grid resolution and determine the optimal grid resolution, several cases with different lateral grid resolutions have been simulated for the reach of Nakdong river at the confluence of Kumho river for the floods in 2006. Orthogonal curvilinear grids for the domain have been constructed from the survey products at the sections with the longitudinal interval of 20 m. Area-elevation curve and the comparison of simulated results with measured stage at the specific station have been used to check the effect of grid resolution. From the results, the existence of optimal grid resolution has been observed, which ensure both efficiency of computation and certainty of results.

• Journal of Preventive Medicine and Public Health
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• v.21 no.2 s.24
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• pp.307-319
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• 1988

In order to determine the contents of lead, cadmium and zinc, the tissues of the crussian carp, Carassius carassius, collected from the middle streams of the Nakdong river were examined. During the dry season from 8 to 15, March, 1987, six loci were selected to sample the fish and river water; five of them were the midstreams of the Nakdong river i. e., the vicinities of the Andong dam, the Nakdong bridge, the Waegwan bridge, Gangjung and Gaepori, the other one was the Kumho river around the Paldal bridge(see Fig. 1). The microanalyses of lead and cadmium contents were undertaken by the atomic absorption spectrophotometer(Model IL-551) connected with CTF-IL 655, while that of Zinc by the flame method with IL551 only. The contents of lead and cadmium in water sampled from Gaepori distant from about 30km downward from the junction with the Kumho river were about 1.5 times higher than those from Gangjung distant about 0.5km upward from the junction, and the content of zinc from Gaepori was slightly higher than that from Gangjung. However, the contents of lead and cadmium in water sampled from Gaepori were three fifth of those from the vicinity of Paldal bridge far about 2km upperward from the junction. In the other words, the contents of lead and cadmium in the samples from the vicinity of the Paldal bridge were about 2.5 to 3 times higher than those from the Gangjung and 5 times higher than those from the Andong dam. The contents of the heavy metals in the tissues of Carassius carassius were relatively consistent to those of the aquatic environments where the fish were collected, with higher contents in the tissues of the crussian carp collected from the vicinity of Gaepori and the Paldal bridge which were so much polluted than in those from other loci in upper stream from the junction. And the contents of lead and cadmium in tissues were positively correlated with the age of the fish, however, that of zinc was not. The contents of lead in bone of crussian carp from the vicinity of the Paldal bridge in the group of 0-1 year old fish were similar to those of 4-5 years old fish from Gaepori, and higher than those of 3-4 years old fish collected from the upper stream of the junction. It is likely that fishing from Gaepori and the paldal bridge is not recommended, and all the industrial producers have to pay intensive attention to the water pollution due to the sewage disposal.

• The Korean Journal of Ecology
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• v.22 no.3
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• pp.139-144
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• 1999

In order to clarify ecological survival strategy of Rumex crispus community dominating under contaminated area of lower region of Kumho riverside including Chimsangyo (CS), Paldalgyo (PD), Talseochon (TS) and Kumhogyo (KH), we analyzed the content of heavy metals and inorganic matter and vegetative growth. R. crispus showed rapid formation of community by high growth rate, high T/R ratio and showed maximum T/R ratio at the contaminated area Talseochon. Nitrogen and phosphorus contents in R. crispus showed high value in shoot than that of root. T/R ratio of nitrogen and phosphorus showed 3.1∼3.6 and 1.5∼4.5 for the early growth stage, and 6.7∼17.3 and 3.9∼8.3 for the late one, respectively. The absorbed heavy metals by riot were translocated to shoot, the heavy metal content in shoot higher than those in root of Cu, Zn, Fe, and Pb for 3.6, 1.7, 1.5 and 4.8 times, respectively. Distribution ratio of the heavy metals in each organ showed 61∼85% and 15∼39% for shoot and root, respectively. R. crispus accumulated heavy metals in the order of Fe>Zn>Cu>Pb in shoot, and showed maximum values of Cu, Zn, Fe and Pb for 89.7, 376.6, 2946.1 and 13.2 ㎍/g dw, respectively at Talseochon in April. A physiological and morphological characteristics of R. crispus showed thickened leaf, increased water content above 80% and rapid growth of shoot. R. crispus showed ecological adaptation to the contaminated area by transportation of heavy metals and inorganic matter to shoot, and by accumulation of Ca ion in root.