4대강살리기사업 사후환경영향조사 분석,평가 및 개선방안 연구(A study on environment monitoring of 4 major rivers project)

This study aims to analyze post-environmental effects evaluation conducted during the construction and changes and performance of water environment in accordance with the projects of the 4 major rivers project. It also aims to establish monitoring method for water quality and water ecological system and to construct DB and GIS for effective and comprehensive management of water environment for the future. In addition, it attempts to improve the effectiveness of post-environmental effects evaluation currently researched and analyzed and contribute to establish and operate long-term monitoring systemrequired to manage water environment in major rivers in Korea. This study targeted each area of the restoration projects of 4 major rivers and analyzed water quality and water ecological system of the evaluation reports until 2012.It also apprehended current status of the project by analyzing and organizing information and data of pertinent water environment research projects. In addition, it has suggested continual water environment monitoring (draft) after the completion of the project. After conducting analysis on the reports of the project, it has been suggested that the reports were not properly managed since there have repeatedly been errors every year. It has been confirmed that urgent establishment of improvement measure and in-depth post-environmental effects evaluation by experts are needed. In 2012 when most of the process of revitalizing Han River has completed, BOD value has been increased compared to before the project. Deterioration in water quality has also been observed in water ecological health evaluation project. Close monitoring is required whether to determine that deterioration in water quality is temporary due to a large-scale improvement project or derived from structural problem caused by changes in environment. It has been confirmed that the number of migratory birds has sharply been reduced compare to before the project. In 2012 when most of the process of revitalizing Han River has completed, wetland area in the region was found to be reduced about 29.5%. It can be inferred that the significant reduction in wetland area and habitat and activities of migratory birds are highly related. It has been found that wetland in river basin has weakened in its role after the project since most of the legally protected birds inhabit in wetland has no longer been detected at monitoring.As restoration project of Nakdong River has simultaneously been conducted throughout the whole areas of the mainstream, water quality of the mainstream of Nakdong River has been deteriorated. While water quality at upper region has been reduced to class II in terms of BOD, there has not been noticeable change in middle and lower stream. In 2011 when intensive dredging process was conducted, most of the regions except upper region of Nakdong River were rapidly deteriorated to class III. It suggests that continual disturbance has been occurred for the whole year. After restoration project of Nakdong River, 44.8% of wetland has been reduced. While the number of clams in winter in Haepyung, Gumi; Hwawon, Daegu and Geumho region, which are closely related regions with Nakdong River project, has been decreased, it has been increased in lower region of Nakdong river after the project. Looking at the results found in post-environmental effects evaluation of Geungang River project, water quality in 2010 and 2011, when intensive project were conducted, has been increased in terms of BOD. As the number of migratory birds in 2009 to 2012, which was the period of the project, reported to be reduced, close evaluation is required to determine the relationship between rapid decrease and the project. It has been confirmed that 33.4% of wetland in 1-10 area has been reduced due to the project.In the case of Youngsan River project, water quality has been deteriorated in general based on BOD. It suggests that there were no improvement effect on water quality in the mainstream of Youngsan River, rather it is deteriorating. It has been observed that 52.6% of wetland in 1-8 area has been decreased due to the project. While it is hard to find out the relationship between decreased migratory birds and the project at this point, it is needed to find out the reason by closely monitoring the birds. In order to determine the effect of 4 major rivers project on water environment, changes in water environment after the project has been compared to before. However, looking at the long-term perspective, current post-environmental effects evaluation should be reviewed. For national projects such as 4 major rivers project, post-environmental effects evaluation system should be modified so that it could confirm the long term effect and outcomes of the project. There should not be a problem if positive effects after the project were to be confirmed, or else, new restoration plan has to be established. It is possible to conduct post-environmental effects evaluation within the project, it is more desirable to form a separate organization to monitor and evaluate outcome given the importance of the project. It could be operated to the extent of improving existing evaluation or combining existing long-term monitoring research project. It is advisable to run long-term monitoring program for water environment through separate organization or dedicated department.