• The Journal of Society for e-Business Studies
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• v.20 no.1
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• pp.183-199
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• 2015

Due to the Four Major Rivers Restoration Project, Nakdong River Estuary Barrage's designed flood quantity has been largely increased, and this has caused to construct several drainage gates at the right side of Eulsukdo island to secure the safety of downstream river area. For successful functioning of Nakdong River Estuary Barrage, such as flood control, disaster prevention, and the securing of sufficient water capacity, drainage gates at the both sides of island have to operate systematically and reliably. To manage this under restricted personnel and resources, we have implemented the IOS (Integrated Operation System) by integrating previous facilities and resources via information and communication technologies. The IOS has been designed to have higher availability and fault tolerance to function continuously even with the partial system's failure under the emergency situation like flood. Operators can use the system easily and acknowledge alarms of facilities through its IWS (Integrated Warning System) earlier. Preparing for Integrated Water Resources Management and Smart Water Grid, the architecture of IOS conformed to open system standards which will be helpful to link with the other systems easily.

• Journal of Environmental Science International
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• v.23 no.5
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• pp.839-852
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• 2014

The Ministry of Environment (MOE) has made more effort in managing point source pollution rather than in nonpoint source pollution in order to improve water quality of the four major rivers. However, it would be difficult to meet water quality targets solely by managing the point source pollution. As a result of the comprehensive measures established in 2004 under the leadership of the Prime Minister's Office, a variety of policies such as the designation of control areas to manage nonpoint source pollution are now in place. Various action plans to manage nonpoint source pollution have been implemented in the Soyang-dam watershed as one of the control areas designed in 2007. However, there are no tools to comprehensively assess the effectiveness of the action plans. Therefore, this study would assess the action plans (especially, BMPs) designed to manage Soyang-dam watershed with the WinHSPF and the CE-QUAL-W2. To this end, we simulated the rainfall-runoff and the water quality (SS) of the watershed and the reservoir after conducting model calibration and the model validation. As the results of the calibration for the WinHSPF, the determination coefficient ($R^2$) for the flow (Q, $m^3/s$) was 0.87 and the $R^2$ for the SS was 0.78. As the results of the validation, the former was 0.78 and the latter was 0.67. The results seem to be acceptable. Similarly, the calibration results of the CE-QUAL-W2 showed that the RMSE for the water level was 1.08 and the RMSE for the SS was 1.11. The validation results(RMSE) of the water level was 1.86 and the SS was 1.86. Based on the daily simulation results, the water quality target (turbidity 50 NTU) was not exceeded for 2009~2011, as results of maximum turbidity in '09, '10, and '11 were 3.1, 2.5, 5.6 NTU, respectively. The maximum turbidity in the years with the maximum, the minimum, and the average of yearly precipitation (1982~2011) were 15.5, 7.8, and 9.0, respectively, and therefore the water quality target was satisfied. It was discharged high turbidity at Inbuk, Gaa, Naerin, Gwidun, Woogak, Jeongja watershed resulting of the maximum turbidity by sub-basins in 3years(2009~2011). The results indicated that the water quality target for the nonpoint source pollution management should be changed and management area should be adjusted and reduced.

• Journal of Environmental Policy
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• v.14 no.4
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• pp.45-61
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• 2015

The river environment in Korea has changed significantly after the completion of the Four Major Rivers Project due to the outdated river management methods and thus, it is necessary to modify the current river management process. A typical example of this management is dredging but it is a method that usually results in socio-environmental side effects. Therefore, in order to minimize the socio-environmental impacts of dredging, Korea is currently applying the Environmental Windows, a management practice currently being used in the United States that eliminates the risk of potentially harmful impacts of dredging. The use of statistical methods was suggested to address the issue of data insufficiency and this methodology was applied in the downstream part of the Gangjeong-Goryeong weir located within the Nakdong river basin. The results show that when performing a month of dredging, the optimal period is March whereas the optimal month to start dredging is August in case of an eight-month dredging project. If Korea's flood season is also considered for an eight-month dredging process, then October is the optimal month to start dredging. Non-structural methods such as the Environmental Windows reduce maintenance costs and also bring only short-term side effects to the environment, as opposed to structural methods such as the development of environmentally-friendly dredging machine. Given that few studies have explored this topic in Korea, the findings and suggestions could serve as basic data in studying river dredging in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.33 no.3
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• pp.947-956
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• 2013

In this study, WUA (Weighted Usable Area) was calculated to determine ecological flow at the confluence of Nakdong River and Gumho River by using River2D. To calibrate River2D, simulation results of River2D were compared with calibrated HEC-RAS simulation results and the optimum parameters were determined. After parameter calibration, WUA of Zacco platypus and Zacco temmincki which are dominant species in Nakdong River was calculated with changing upstream flowrate. From the result, WUA is changed according to flowrate and growth stage. In the flowrate-WUA/A graph, ecological flow can be determined as $33.3m^3/s{\sim}39.96m^3/s$ in Nakdong River and $3.6m^3/s{\sim}4.32m^3/s$ in Gumho River. After dredging for Four major rivers restoration project, WUA of Zacco platypus and Zacco temmincki were calculated by using the ecological flow. The results show that WUA after dredging are decreased when compared with undredged condition. WUA of Common carp is 2~3 times bigger than WUA of Zacco platypus and Zacco temmincki at the dredged condition in Nakdong River.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.21 no.4
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• pp.246-258
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• 1988

Semi-quantitative analysis of $less-than-2{\mu}m$ clay minerals in thirty-nine superficial sediments from the Chinju Bay, southern coast of Korea, was made to reveal the distribution, provenance and dispersal pattern of fine-grained sediments. Additional nine samples were also taken from the Choryang Cheon (a river draining the kaolin-rich Hadong area) to investigate the influence of river a discharge. Grain size analysis for the Chinju Bay sediment samples was performed simultaneously as an aid to understand the sediment types and depositional environments. Except for the northeastern part, clayey mud predominates the entire bay. Average relative abundance of the four major clay minerals, I. I., illite, kaolinite, chlorite and smectite, is $55.1\%,\;23\%,\;21.5\%\;and\;0.4\%$, respectively. Although illite dominant clay mineral, the average content is about $10\~20\%$ tourer than that of the nearby continental shelf area. On the contrary, kaolinite content in the bay is about $10\%$ higher than that of the shelf area. Recent clay minerals of the Chinju Bay are mainly derived from the nearby inland area through numerous rivers and streams. Transport from shelf area, however. also seems to be important.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.4B
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• pp.309-314
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• 2011

Analysis of discharge characteristics through control gates at river crossing structures is important for an effective water level control and water resources management. In recent years, many river control structures in four major rivers are under construction but only few researches on discharge characteristics at control gates could be found in Korea. The discharge characteristics depend on both shape of control gates and the effects of downstream water-depth. In this research, classification index for discharge patterns (free weir, submerged weir, free orifice, submerged orifice) through a control gate were reviewed with $h_g/h_1$, $h_3/h_g$, and $h_3/h_1$. Classification criteria of discharge patterns were also suggested. Representative discharge estimation equations for each discharge patterns were adopted and discharge coefficients were developed from a hydraulic model for a specific control gate which will be constructed in Nakdong river. Reliability of the derived discharge equation and coefficients were confirmed by comparisons between the real discharge in a model and the predicted discharge from the results of this research.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.5
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• pp.378-383
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• 2011

The policy of total maximum daily load (TMDL) was adopted to manage water pollutants so as to keep the total amount of pollutants in the watersheds within established target water quality. While the TMDL was implemented in all four major river basins, various problems occurred. Even though the corrections for problems were conducted, the role between central and local government was not established exactly. This study was presented to suggest a role between central and local governments for effective implementation of TMDL. When the central government establishes the environmental criteria with water quality standards and pollutants in the main rivers, the local government should establish the level of target pollutants in the watershed. Also, the local government should be continuously implementing the water quality and flowrate monitoring of the tributaries to find out the degree of water quality improvement in the tributaries. Especially, the basic plan of TMDL for the whole watershed should be established by the river basin environmental office at the central government. The local government should be established the implementation plan of TMDL for the watershed where exceeds the established target water quality. The performance assessment of TMDL should be implemented every year to the water quality and flowrate monitoring of the tributaries for satisfaction assessment of target water quality in the watershed by the lower-lever government. The performance assessment report of TMDL included with an analysis of causes for the excess water quality in the watershed should be submitted to the river basin environmental office at the end of the TMDL planning period.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.250-257
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• 2019

Recently, 357 water-friendly space were established near the main streams of the country through the Four Major Rivers Project, which was used as a resting and leisure space for the citizens, and the river environment and ecological health were improved. We are working hard to reduce the number of points and plan and manage the water-friendly space. In particular, attempts are being made to utilize mobile big data to make more scientific and systematic research on the number of users. However, when using mobile big data compared to the existing method of conducting field surveys, it is possible to easily identify spatial user movement patterns, but it is different from the actual amount of use, so various verifications are required to solve this problem. Therefore, this study evaluated the accuracy of estimating the number of users using mobile big data by comparing the number of visitors using mobile big data and the number of visitors using drone for Samrak ecological park located in the mouth of Nakdong River. As a result, in the river hydrophilic district, it was difficult to accurately estimating the usage pattern of each facility due to the low precision of pCELL, and it was confirmed that the usage patterns in the park could be distorted due to the signals stopped at roads and parking lots. Therefore, it is necessary to improve the number of pCELLs in the water-friendly space and to estimate the number of visitors excluding facilities such as roads and parking lots in future mobile big data processing.

• Journal of Wetlands Research
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• v.11 no.2
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• pp.67-76
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• 2009

The contribution of pollutant loadings from non-point source (NPS) to the four major rivers in Korea exceeded 22~37 % of the total loadings in 2004 and is expected to reach 60 % in 2020. Most of NPS loadings are coming from urban areas, especially from paved areas. Because of high imperviousness rate, many types of NPS pollutant are accumulating on the surface during dry periods. The accumulated pollutants are wash-off during a storm and highly degrading the water quality of receiving water bodies. For this reason, the Korean Ministry of Environment (MOE) developed the Total Maximum Daily Load (TMDL) program to protect the water quality by managing the point source and NPS loadings. NPS has high uncertainties during a storm because of the characteristics of rainfall and watershed areas. The rainfall characteristics can affect on event mean concentrations (EMCs), mass loadings, flow rate, etc. Therefore, this research was performed to determine EMCs for rainfall ranges from transportation landuses such as road and parking lot. Two sites were monitored over 45 storm events during the 2006/06 through 2008/10 storm seasons. Mean TSS EMCs decrease as rainfall ranges increase and highest at less than 10mm rainfall. The results of this study can be used to determine the efficient scale of BMP facility considering specific rainfall range.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.27 no.6
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• pp.639-647
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• 2009

In line with the rapid settlement of information society, the demand for geospatial information and its applications are dramatically increasing. The Project of National Geographic Information System(NGIS) is actively on going to meet up-to-dateness and accuracy of geospatial data. It is fact that the public interest in environmental issues is increasing than ever in accordance with the restoration of the four major rivers, core project of Green New Deal Policy, and the event of the Ramsar General Meeting. Because the Nakdong River Estuary is a place of great importance in both aspects of wetland and environment conservation, a variety of researches related to this area are progressing. Although artificial developments and natural phenomena are rapidly changing the topography and ecosystem of this area, the effort to build topographic DB for change monitoring is very slow. This study describes a Lidar surveying project over the restored wetland Eulsukdo, the southermost part of the Nakdong River, to establish precise topographic DB throughout producing 3D topographical maps and wetland classification maps. The results of this study will make a large contribution to the systematic maintenance and management for the restored Eulsukdo wetland.