기후변화 대응을 위한 적정 하천공간 확보방안 II

Abstract

Sustainable Spatial River Planning for Climate Change(II) When we examine the observation data for the past 100 years, we see that climate changes are occurring more rapidly today than would be if caused only by natural phenomena. Due to such changes, temperatures are rising, and as the deviation in rainfall grows, so do the frequency and the magnitude of disasters. In particular, as the river spaces such as washlands and wetlands that function as buffer zones against flooding of rivers become converted into farmlands and new urban landscapes as a factor of rapid urbanization, the risk of disasters in these areas is further accelerated. Structural efforts have been forwarded to stop the floods by reinforcing the embankments as a measure for preventing disasters and reducing damages in these areas. But when extreme flooding that exceeds the design flood amount occurs, as in the case of Typhoon Morakot in Taiwan recently, the current structural countermeasures appear to be limited in effectiveness. To deal with such a situation, the advanced countries in Europe as well as the USA and Japan are seeking a strategy of reducing disaster damages through eco-friendly restoration and spatial expansion of river apace. Also, they are turning these river space into specialized zones considered to be a key factor in bringing life, nature, and culture together into a harmonious relationship. Following such a trend, the flood water levels over a period of 500 years for the Nakdong River basin were examined. A comparative analysis was done on the necessary costs of population relocation following the secure of the river space and embankment work. As an eco-friendly measure for reducing flood damages, a proposal was made to secure horizontal river space through creation of retention basin adjacent to rivers and restoration of wetlands as well as old river channels. In addition, a river space planning strategy that links together these environmental elements with local culture and educational resources was proposed. In this second-year study, the current river management system and the current state of usage and management of waterfront zone are examined in order to propose a more specific mid- to long-term river space securing plan. Based on this, the definition and the scope of a river space were established. By introducing various measures for securing a river space and applying these in a model area, a securing strategy of river space based on a consideration of water control as well as ecological and cultural aspects was proposed. In addition, the principal agent for implementation which are needed in drawing up a mid- to long-term plan for securing river spaces was proposed. Also, a step-by-step approach plan as well as a way to construct a governance for integrated management are suggested. After these stages, we arrived at the following conclusions. First, numerous wild animals and vegetation, including endangered species, were found from the investigation results of the river space within 2km of both banks not only within, but also outside the protected area. The habitats and the eco-bridges of wild animals and vegetation were shown to be damaged because of industrialization and urbanization. For the environmental restoration of the damaged river spaces, there is a need for a river space securing strategy based on an environmental assessment by each river space that goes beyond the restrictions at the regulatory level. As for the current state of river usage and management, problems lie in the lack of connectivity between the river improvement and the river restoration among the branches of the government. This is due to the approach separating the river management focused to the river control and the river environment work focused on restoration. Although such work promotes administrative efficiency and convenience, it is judged to be inappropriate for managing rivers based on an integrative consideration of water utilization and control as well as water quality and ecology. Second, the outlines of the definition and the scope of an appropriate river space which includes water control in addition to water quality and ecology were established. In this study, a river space is defined as a space that includes, in a wide sense, the diverse functions of a river such as water utilization and control, environment, ecology, culture, economy, and tourism, as well as indirectly related cities, farming villages, nature, and artificial assets on the river periphery. The scope of such a river space can be prescribed depending on the functional, environmental, and place characteristics with the goal of securing and managing a river space. That is, when the goal is water control, the scope can be proposed to include the reinforced flood management zone and flood-risk area beyond the river zone; from the aspect of water quality and ecology preservation, it can be adjusted to include the waterfront zone, the legally protected environment, and ecology zone; and in cases where the goal is to invigorate the local economy, cultural and tourist attractions should be included. Third, by introducing various river space securing plans, including land purchase and lease options, based on an examination of the related literature and cases, we proposed a river space securing strategy reflecting aspects of water control as well as ecology and culture. The domestic current river space securing method mainly depends on purchasing land ownership. The land purchase system, however, requires enormous costs, and because agreements with the owners do not proceed smoothly, land purchases are completed sporadically, leading to management difficulties. In the case of advanced countries overseas, diverse land securing measures such as development right, noncropping system of farmland, and regional conservation right are utilized for effective land management and eco-friendly land use. Through these practices, they are searching for multifaceted approaches to overcome the limitations of resources and reduce procedural frictions. In this study, a flexible land lease policy was proposed through establishing a concept that can induce restriction of development without direct purchase with ownership rights. In terms of dealing with the rapid climate change in the long-term, this study promoted natural holding of flooding through the inundation of agricultural land, as an alternative disaster relief policy, an insurance system compensating for the consequent damages. In particular, the Gumi upstream region of the Nakdong River basin was chosen as a target area, and river analysis was done on the flood water level reduction effect due to the water flow holding in the secured horizontal space for flooding over a period of 500 years. Based on this, a land purchase and a insurance system were compared. In addition, the study presented the possibility of river space utilization from the aspects of ecology, culture, and water-friendly area development at the Weondong Wetlands area where the Miryang and the Nakdong Rivers meet. For this, a multifaceted land purchase, noncropping system of farmland, and development right were considered. Fourth, the study established the evidence and the principal agent for implementation needed in drawing up a mid- to long-term level river space securing plan, prepared a step-by-step approach plan, and presented a way to construct governance for integrated management in addition to a management and utilization plan for a secured river space. In this study, the need for a comprehensive river project plan that considers water control, water quality and ecology was also discussed. For this, in the long term, this study proposed a consultative group for implementing the river management work. This group can be made up of experts, local residents, and the branches of the government. In terms of river management, a general water environment assessment index was proposed as the indicator for current conditions evaluation and ex post facto monitoring; in terms of river utilization, a multifaceted utilization plan with the inherent characteristics of a river space was presented. This study presented the conceptual and physical scope of a river space and sought to examine the issues that need to be considered when establishing policy and drawing up plans through a comprehensive approach for determining the development type, and the plan for securing river spaces that deal with climate changes as well as for establishing a river space securing plan and its implementation procedure. At a time when the functional significance of a river in dealing with climate change is gaining attention, there is a need to bring greater attention to the unique attributes of these areas based on the environmental value of river spaces and promote the creation of areas that can contribute to water utilization and control, ecology, culture and local economy. To this end, priority should be given to role sharing and cooperation based on the characteristics of a river rather than to the division of labor by the work of each agency, and based on a consultative body, the opinions of local experts and residents should be actively incorporated. A multifaceted plan for securing, utilizing, and managing river spaces must be established with such opinions as a basis. The results of this study can be utilized as basic research material for providing a framework of green growth through sustainable water environment management and for establishing policy as well as drawing up plans for securing river spaces in relation to the government's task of achieving national water security based on water resources planning and management in preparation for future climate changes.