최근 이상기후로 인해 홍수 등 자연재해의 강도 및 빈도가 증가하고 있다. 2002년 태풍 루사, 2003년 태풍 매미 등 집중호우에 따른 대규모 홍수로 인해 인명 및 재산피해의 급격한 증가가 나타났으며, 이는 불규칙한 기상변화에 대한 기존의 방재대책과 홍수예측시스템의 한계를 보여주고 있다. 이러한 이상홍수에 효율적으로 대응하기 위해서는 홍수범람 양상을 정확하게 모의할 수 있는 범람모형을 통해 효과적인 대응방안 마련하는 것이 중요하지만 기존의 홍수범람해석모형은 해석시간의 과다소요 및 해석결과의 정확성 등의 문제가 존재한다. 따라서 본 연구에서는 2002년 8월 집중호우로 인해 붕괴된 낙동강 유역의 백산제를 대상으로 쿼드트리격자를 사용하는 Gerris모형을 이용하여 홍수범람해석을 수행하였으며, 기존의 홍수범람모형 중 비구조격자를 사용하는 FLUMEN모형 및 실제 범람지역과의 비교를 통해 쿼드트리 격자기반 홍수범람모형의 적용성 및 효율성을 판단하고, Gerris모형의 치수경제성분석에 대한 적용성을 판단하였다.
Lately, intensity and frequency of natural disasters such as flood are increasing because of abnormal climate. Casualties and property damages due to large-scale floods such as Typhoon Rusa in 2002 and Typhoon Maemi in 2003 rapidly increased, and it shows the limits of the existing disaster prevention measures and flood forecasting systems
* A thesis submitted to the committee of Graduate School, Chungnam National University in a partial fulfillment of the requirements for the degree of Master of Science in Civil Engineering conferred in February 2013.
regarding irregular climate changes. In order to efficiently respond to extraordinary flood, it is important to provide effective countermeasures through an inundation model that can accurately simulate flood inundation patterns. However, the existing flood inundation analysis model has problems such as excessive take of analysis time and accuracy of the analyzed results. Therefore, this study conducted a flood inundation analysis by using the Gerris model that uses quadtree grid, targeting the Baeksan Levee in the Nakdong River Basin that collapsed because of a concentrated torrential rainfall in August, 2002. Through comparisons with the FLUMEN model that uses unstructured grid among the existing flood inundation models and the actual flooded areas, it determined the applicability and efficiency of the quadtree grid-based flood inundation model and the applicability of the flood control economic analysis of the Gerris model.
The results drawn from the study above is like the following.
1. As the result of conducting a flood inundation analysis, Gerris showed simpler input and output data processing than FLUMEN. In fact, Gerris required approximately 30 minutes and FLUMEN approximately 8 hours for the time of flood inundation analysis, so the flood inundation analysis by quadtree grid shortened more time than the existing unstructured grid.
2. As the result of conducting the flood inundation analysis, a difference occurred in the results of inundation area and inundation depth of the Gerris and FLUMEN models. For only the difference in the area, the FLUMEN model showed closer value to the actual inundation area than the Gerris model, but the Gerris model reflected the form of the actually inundated geographical features well, so it was determined that the results of the flood inundation analysis that used the Gerris model’s quadtree grid were valid.
3. As the results of determining the applicability regarding the flood control economic analysis through the Gerris model, it was difficult to apply to the areas where the inundation depths were less than 1m. However, regarding the areas where the inundation depths were deeper than 1m, since probability of damage is determined based on the inundation depth, it is possible to calculate the damage and probability of damage, and since flood control economic analysis regarding damage by large-scale flood is important, it was determined that the applicability regarding the flood control economic analysis of the Gerris model was valid.
Thus, the quadtree grid of the Gerris model has a huge advantage that it can shorten the time of input and output data processing and flood inundation analysis, and it applied the geographical features relatively correctly. For the analysis results as well, it showed relatively correct results, closer to the actual inundation patterns. It also has an advantage that it can conduct analysis, targeting even larger areas than the FLUMEN model could do, which has limits on the number of grid, so it is judged that it will have high utilization in establishing a flood inundation forecasting system. However, when the areas targeted for analysis become too large, the simulation time will take longer and inefficient results can come. Therefore, in order to apply it to the actual flood inundation forecasting system, sufficient simulation must be performed targeting various areas and flood events so that the basin can be efficiently divided and analysis conducted.
목차
제 1 장 서 론 11.1 연구배경 11.2 연구목적 41.3 연구내용 및 절차 5제 2 장 연구동향 72.1 국외 연구동향 72.2 국내 연구동향 10제 3 장 적용모형의 선정 및 배경이론 143.1. 모형의 선정 153.2 선정 모형의 배경이론 183.2.1 지배방정식 193.2.2 선정모형의 수치해법 273.2.3 사면구조 격자 34제 4 장 대상지역 선정 및 입력자료 구축 384.1 대상지역 개요 384.2 입력자료 구축 및 해석수행방법 404.2.1 수문자료 구축 414.2.2 조도계수 464.2.3 지형자료 구축 및 해석수행방법(Gerris) 484.2.4 지형자료 구축 및 해석수행방법(FLUMEN) 54제 5 장 모형의 적용 및 분석 585.1 모형의 홍수범람해석 결과 585.2 모의결과 비교 및 분석 715.3 치수경제성분석에 대한 적용성 검토 80제 6 장 결론 및 고찰 88참 고 문 헌 90ABSTRACT 98감사의 글 102
