연구보고서
- 저자
- 윤선권 박사
- 작성일
- 2016.01.23
- 조회
- 148
- 요약
- 목차
The understanding and predicting of the seasonal to interannual variations of hydrometeorological data and hydrological data are viewed as a critical consideration for a sustainable future planning. This study investigated the characteristic changes in seasonal precipitation and runoff associated with the conventional cold-tongue (CT) and warm-pool (WP) El Niño phases during spring (MAM; March to May) and summer (JJA; June to September) season for the Korean Han River Basin and its sub-watersheds. During WP El Niño years, rainfall in MAM and its coefficient of variation (CV) were higher than in normal years. Moreover, during conventional CT El Niño years, JJA season tended to be drier than in climatologically normal years, although variability in precipitation during JJA was relatively lower. Data for runoff showed wetter MAM season during both types of El Niño events as compared to long-term normal years and significant changes in runoff during summer under CT El Niño conditions. During WP El Niño years, increased runoff was seen for 95.8% of all basins and this increase was statistically significant for 58.3% of these basins, but variability in runoff was small. Overall, the findings confirm that water resources in the Han River Basin during the MAM and JJA seasons are sensitive to CT/WP El Niño events. Thus, for basins such as these, where seasonal variability and the uncertainty of hydrometeorological data are high, it is necessary to investigate the relationship between climate parameters and hydrologic factors to maintain the stability of the flesh water supply system and allow prediction of water resources management.
Tropical cyclones (TC), also known as typhoons, in the Western North Pacific (WNP) are an important hydrometeorological factor that drives changes in summer rainfall patterns over East Asia (EA). Tropical cyclones in the WNP can affect EA regions either directly or indirectly, and damage from associated extreme rainfall events is gradually increasing. Extreme rainfall can have adverse effects on the structure and function of river ecosystems; therefore, these types of impacts need to be examined more closely. Subsequently, this study examined the characteristics of cyclone activity during cold-tongue (CT) and warm-pool (WP) El Niño events, and analyzed the local characteristics of the corresponding rainfall over the Korean Peninsula (KP) during the summer. The results obtained through comparisons with all typhoons (1966–2007) affecting the KP region indicate that typhoons occurring during CT El Niño years were located in southern areas (14.3°N, 140.6°E), and typhoons occurring during WP El Niño years were located in southeastern areas (14.3°N, 143.2°E). The TC-induced summer rainfall in five major river basins of Korea decreased by -3.94% from normal levels (1966–2007) during CT El Niño years, and increased by 33.92% during WP El Niño years. While the results of this study were based on relatively short-term observations and small sample sizes, the data do suggest that TC activities affect the KP and differences in TC-induced rainfall occur during CT and WP El Niño phases. Such findings may be useful for making mid- to long-term water resources forecasts, preparing flood control and disaster prevention plans, helping communities to adjust to a changing climate, and reducing typhoon-related damages.
In this study, an integrated flood risk index (IFRI) was developed using information on hydrological, socio-economic, and ecological components to assess watershed-based flood hazards and vulnerability in the Korean Han River basin, which is a region where flood disasters frequently occur. In total, this study used 15 indicators to create an IFRI map for the region, and 5 categories of flood risk were distinguished: “very high,” “high,” “medium,” “low,” and “very low.” The results, which were presented in ternary diagrams to illustrate the relative importance of the three different components, show that urban areas in the Korean Han River basin have experienced a decrease of 1.0% in terms of the hydrologic component. However, the socio-economic and ecological components have increased by 3.2% and 4.4%, respectively. In rural areas, an increase of 4.8% was found in the hydrologic component alongside decreases in the socio-economic (1.6%) and ecological (2.2%) factors. In addition, the IFRI map shows that 20.02% of the total area of the Han River Basin was classified as having “very high” or “high” flood risk; the size of this high-risk zone has increased significantly by since 1990. This study also evaluated flood risks according to the different phases of conditions, and the results from the analysis indicate that flood risks were worse during strong cold-tongue (CT) and warm-pool (WP) El Niño years. Further analyses of possible factors that affect the vulnerability and resilience of communities to flood hazards in the Han River basin should be conducted on the basis of this research. Accordingly, the results from this study may provide useful data for reducing flood risks in developing areas that are experiencing.