It is necessary to determine an optimal design frequency for establishing stable flood control against frequent flood disasters. Depending on the importance of river and regional characteristics, design return periods are suggested from at least 50 years up to 200 years for river design. However, due to the wide range of applications, it is not desirable to reflect the geographical and flood control characteristics of river. In this study, Bayes theory was applied to seven evaluation factors to determine the optimal design return period of rivers in Chungcheongnam-do; urbanization flooded area, watershed area, basin coefficient, slope, water system and stream order, range of backwater effect, abnormal rainfall occurrence frequency. The potential flood damage (PFD) capacity was estimated considering climate change and the appropriate design return period was determined by analyzing the capacity of each district. We compared the design return periods of 382 rivers in Chungcheongnam-do with the existing design return periods. The number of rivers that were upgraded from the existing return period were 65, which have relatively large flooding areas and have large PFDs. Whereas, the number of rivers that were downgraded were 169.
본 연구는 최근 빈번히 발생하는 홍수재해에 대비하고 안정적인 치수대책 수립을 위하여 공학적 판단에 근거한 하천의 적정 설계빈도 결정방안을 제시하였다. 지방하천의 설계빈도는 하천의 중요도 및 지역특성에 따라 최소 50년부터 최대 200년까지 설정되고 있으나, 적용범위가 넓어 하천의 지형적, 치수적 특성을 제대로 반영하지 못하는 실정이다. 본 연구에서는 지방하천의 적정 설계빈도를 결정하기 위하여 7개의 평가인자(시가화 침수면적, 유역면적, 형상계수, 하도경사, 수계 및 하천차수, 배수영향구간, 이상강우 발생빈도)에 대하여 베이즈 이론을 적용하여 가중치를 산정하였다. 또한, 기후변화를 고려한 홍수피해잠재능을 산정하였고, 시군구별 잠재능을 구분하여 적정 설계빈도를 결정하였다. 충청남도 382개 지방하천에 대하여 현행 설계빈도의 적정성을 평가하였다. 382개의 현행 하천설계빈도보다 상향되는 하천은 65개 하천으로 상대적으로 시가화 침수면적이 크게 산정되고 홍수피해잠재능이 큰 지역의 하천이며, 하향되는 하천은 169개로 분석되었다.
- Birks, C. J., Pickles, M. L., Bray, C. W. and Taylor, K. (1992). Standards of service for flood defence: a framework for planning and monitoring, Kluwer Academic, Dordrecht, Boston.
- Chungcheongnam-do (2015). Chungcheongnam-do river basin planning manual (in Korean).
- Chungcheongnam-do (2017). Determination frequency of proper design of stream in Chungcheongnam-do (in Korean).
- De Ronde J. G. (1998). “Risk assessment and management of potential flooding in the Netherlands.” Floodplain Risk Management: Proceedings of an International Workshop on Floodplain Risk Management, Hiroshima, 11-13 November 1996 edited by S. Fukuoka, Balkema, Rotterdam.
- JICE (Japan Institute of Construction Engineering). (2000). Comprehensive strategy for floodplain management.
- Kim, C. S. and Suh, M. S. (2009). “Change-point and change pattern of precipitation characteristics using bayesian method over South Korea from 1954 to 2007.” Korean Meteorological Society, Vol. 19, No. 2, pp. 199-211 (in Korean).
- Kim, D. H. (2018). Determination of design frequency of local rivers considering disaster condition, Master Thesis, Kangwon National University, Korea (in Korean).
- Min, B. M. (2010). Estimation of the potential flood damage for flood safety evaluation of Young-San River Basin, Ph.D. Dissertation, Chosun University, Korea (in Korean).
- MOLIT (Ministry of Land, Infrastructure and Transport) (2000). Water vision 2020 (in Korean).
- MOLIT (Ministry of Land, Infrastructure and Transport) (2008a). Guidelines for calculating the potential risk of urban flood damage and the design frequency of the watershed (in Korean).
- MOLIT (Ministry of Land, Infrastructure and Transport) (2008b). Guidelines for establishing a comprehensive watershed flood control plan (in Korean).
- MOLIT (Ministry of Land, Infrastructure and Transport) (2016). Commentary of rivers design standard (in Korean).