물관리 취약성과 물안보 전략 I

Abstract

Potential Consequences to Climate Change and Water Management Strategy I Climate change has begun to affect the management of water resources due to increased temperatures, and changes in evaporation, precipitation, and runoff. These changes will also have a direct and indirect impact on sources of fresh water, altering both supply & demand, and water quality. Although many uncertainties still remain about the extent and impact of climate change, it is imperative to assess scientific understanding of the impact of climate change on natural and managed water systems and evaluate the capacity and the vulnerabilities therein when considering policy implications and directions. In this study we developed the concept of “National Water Security” after reviewing the recent literature on water security and climate change policy in developed countries, assessed the impact of climate change on water resources, and evaluated the vulnerability of the national water supply system. Finally, we presented national adaptation strategies that reduce the risk of adverse outcomes through actions that increase the resilience of water management systems to climate change stressors. The concept of “National Water Security” was developed upon review of recent research on water security, environmental laws in Korea, and climate change policies in developed countries. The definitions of water security from international organizations usually include three components - ①sustainable access to ②adequate quantity and ③acceptable quality of water for people and the environment. Environmental laws such as the "Basic Environmental Policy Act" in Korea are aimed at ①prevention of environmental pollution and concomitant damages, ②conservation of ecosystem diversity, ③appropriate management and preservation of the environment, ④comfortable and sound lifestyle for the public. Furthermore, the vulnerability of water sectors to climate change was emphasized. By reviewing the foregoing ideas, we proposed the concept of “National Water Security” as denoting a “ontinuous supply of water of adequate quantity and quality for the public to lead a comfortable and sound life, as well as the protection of society and the environment against the impact of climate change.” We also delineated the key components of ‘National Water Security’ as follows - ①securing sources of fresh water, ②protection against floods and droughts, ③mitigation of greenhouse gases, ④improvement of water quality, ⑤conservation of the aquatic ecosystem, ⑥resolution of water conflicts, and ⑦establishment and implementation of appropriate policies. The impact of climate change on water resources was assessed. Statistical techniques were used to evaluate trends in temperature and precipitation vis-？-vis changes in climate. Larger variations in precipitation appeared in the summer, fall, spring and winter, in descending order. A decreasing trend was evident in fall and winter in the Geum, Yeongsan, and Nakdong river basin. Conversely, summer precipitation was found to be increasing in the east and west coast region. The analysis of long-term precipitation and the elasticity of stream flow, which provides a measure of the sensitivity of stream flow to changes in rainfall, indicates that the Nakdong river basin has significant value compared to other major river basins. Seasonal analysis revealed that the Nakdong, Seomjin, and Yeongsan river basin have high elasticity in the springtime. It can be deduced from trend and elasticity analysis that water resource management will be more difficult in the future due to increased risk of droughtsand flood. Drought conditions in winter and spring will cause deterioration of water quality due to a decrease in stream flow. 17 GCMs' simulations of the climate in Korea in the late 20th century were examined. In order to compare global models with observations, observed spatially averaged temperature and precipitation were calculated using 24 gauging stations from 1971-2000. CSIRO (Mk3.0) was selected as future climate data due to its optimal reproducibility in precipitation. GCM simulations were converted to regional scale data using the statistical downscaling method known as MSPG (Multi-Site Precipitation Generator) in order to apply rainfall-runoff like SWAT and TANK to the case study areas of the Nakdong river basin. The assessment of climate change impact on water resource study areas included the Byeongsung watershed and other watersheds-with-dams like Andong, Imha, Hapcheon, Namgang, and Milyang. The study scope was divided into three periods from 2010-2040, 2041-2070, and 2071-2100. Climate change based on the A1B scenario affects stream flow not only in the summer but also in autumn as well. These phenomena were much more pronounced in “A1B”(2010-2040), “A1B”(2041-2070), “A2”(2010-2040). The analysis of watersheds-with-dams among regional runoff estimates for 34 river locations in the Nakdong river basin were performed with the A1B scenario. Annual stream flow increases from 2011-2040 were quite notable. These increases mostly contributed to stream flow during the flood season (from June to August). Decreases were also found in the dry season from 2041-2070 and 2071-2100. The impact of climate change makes it even more difficult to operate reservoir systems due to uncertainties in reservoir inflow. However, it must be noted that there are numerous uncertainties in such multiple-step analysis used to convert climate information from GCM-based future climate projections to hydrologic information. Climate change vulnerability was evaluated for water supply systems, whose sources are mostly rivers and reservoirs. Major parameters for the climate change vulnerability index were extracted from statistical data on the national water supply system through delphi analysis with water supply experts. The results showed that the water source's quantity and quality, and the water treatment facility's adaptation ability appear to be important parameters when assessing climate change vulnerability for the water supply system. Using the developed index parameter, all water supply systems were scored relatively on climate change vulnerability. The results showed that urban areas including Seoul and six metropolitan cities have low vulnerability, whereas small inland counties and rural coastal regions had very high vulnerability. This is further confirmed by the positive relationship between the number of public complaints on the water supply system and regional population density. In addition, energy usage in the water supply system was investigated to assess climate change mitigation efforts. Total electricity use for the water supply system in Korea in 2007 reached 2.68 billion kWhs, which was 0.73% of total consumption levels in Korea. Most electricity was used for intake and water treatment facilities for 0.2~0.4 2kWh/ton and less than 0.2kWh/ton, respectively. Furthermore, local county water supply systems have low efficiency in energy use compared to Seoul, six metropolitan cities, and K-Water. As stated earlier, local county water supply systems are relatively vulnerable to climate change. Therefore, intensive investments and efficient asset management must be implemented for local county water supply systems. Key strategies for national water security were developed in light of the foregoing results on the impact of climate change on water resources and vulnerabilities within the water management system. First, water related climate change research should be strengthened within all government run water management programs. In particular, climate change adaptation efforts regarding water management within the government remain insignificant. One of the main reasons for this is the lack of confidence in methodologies for climate change assessment. Accordingly, reliable, scientific assessment methods must be developed for more in-depth and integrated analysis of future climate change. To reduce vulnerability through appropriate investments,and to promote adaptation practices in water management, the following research areas need to be emphasized: 1) Assessing climate change induced vulnerability and development of promotion strategies for the water industry. 2) Continuous monitoring and sharing of information on scientific understanding of climate change as well as its socio-economic impact, and derivation of applicable measures. 3) Assessment of water quality impact on surface water 4) Assessing climate change induced vulnerability to the groundwater system 5) Changing water use for public, industry, agriculture, electricity, and asset management 6) Development of policies and management strategies to better account for the water and energy nexus for climate change mitigation Second, it is necessary to devise a better institutional system for water management to adapt to climate change. The new institutional system for water management should have multiple functions, including: (1) top down development and allocation of water resources in large watersheds, and (2) bottom up ecological restoration and eco-friendly use of water resources. It is also necessary to develop various alternatives through various scenarios for effective water management, so that objective information on various alternatives can be provided to policy makers. Thirdly, adaptation strategies based on impact assessment need to be developed for water resources management. Water resources management will be more difficult in the future due to increases in drought and flood risk. Drought conditions in winter and spring will cause deterioration of water quality due to decreases in stream flow. The impact of climate change makes it even more difficult to operate reservoir systems due to the uncertainty of reservoir inflow. Accordingly, water supplies, disaster preparation, and quality management must be done on a regional and object-oriented basis. To this end, hydrometerological, geographical and water quality information should be incorporated to accurately simulate runoff and deduce recommended reservoir operations, while forecasting water quality of reservoirs and streams in a basin. Finally, it is necessary to develop evaluation systems for water management and stimulus policies for the water industry. An object evaluation index should be developed to accurately assess the impact of climate change on water management so that reasonable and efficient investments and asset management can be pursued for increased growth in water related industry.