산사태 경보를 위한 RTI 모델의 적용성 평가 = A Feasibility Study of a Rainfall Triggeirng Index Model to Warn Landslides in Korea

국문 초록 (Abstract)

우리나라는 여름철 강수량이 연 강수량의 약 70% 이상을 차지하고 일 강우량이 200 mm가 넘는 극한강우가 증가하고 있다. 강우는 산사태를 유발하는 가장 직접적인 인자로서 이를 활용한 산사태 발생 예측 기준을 설정하고 경보를 발령하여 산사태로 인한 피해를 최소화 하는 것이 필요하다. 본 연구에서는 기존의 발생한 산사태이력 중 발생시점 및 장소가 분명한 12개소를 선 정하고 각 지역의 강우데이터를 수집하여 분석하였으며, RTI (Rainfall Triggering Index) 모델에 사용된 각 인자들을 한국의 산 사태 유발 강우특성에 따라 적정성을 검토하여 반영하고 강우강도의 단위시간을 달리한 3가지 모델을 비교하였다. 분석결과, 60-minutes RTI 모델은 3개소에서 산사태 발생 예측에 실패하였으며, 30-minutes RTI 모델 및 10-minutes RTI 모델은 모두 사 전예측 가능하였다. 각 모델별 산사태 발생 경보에 따른 평균 대응시간은 60-minutes RTI model이 4.04시간, 30-minutes RTI model과 10-minutes RTI model은 각각 6.08과 9.15시간으로 단위시간이 짧은 강우강도를 사용한 RTI 모델이 산사태 사전예측 실패 가능성이 적고 보다 긴 대응시간을 확보 할 수 있는 것으로 나타났다. 이를 통해 산사태 발생 예측을 통한 대응시간은 단 위시간을 세분화한 모델일수록 더 많은 시간을 확보 할 수 있음을 알 수 있다. 또한, 단시간 내 발생하는 변동성이 큰 강우강 도 가진 한국의 강우특성을 고려할 때 시간 단위 이하의 강우강도를 적용하는 것이 RTI 모델을 통한 산사태 예측과 조기경보 시스템의 정확도를 높일 수 있을 것으로 판단된다.

다국어 초록 (Multilingual Abstract)

In Korea, 70% of the annual rainfall falls in summer, and the number of days of extreme rainfall (over 200 mm) is increasing over time. Because rainfall is the most important trigger of landslides, it is necessary to decide a rainfall threshold for landslide warning and to develop a landslide warning model. This study selected 12 study areas that contained landslides with exactly known triggering times and locations, and also rainfall data. The feasibility of applying a Rainfall Triggering Index (RTI) to Korea is analyzed, and three RTI models that consider different time units for rainfall intensity are compared. The analyses show that the 60-minute RTI model failed to predict landslides in three of the study areas, while both the 30- and 10minute RTI models gave successful predictions for all of the study areas. Each RTI model showed different mean response times to landslide warning: 4.04 hours in the 60-minute RTI model, 6.08 hours in the 30-minute RTI model, and 9.15 hours in the 10 minute RTI model. Longer response times to landslides were possible using models that considered rainfall intensity for shorter periods of time. Considering the large variations in rainfall intensity that may occur within short periods in Korea, it is possible to increase the accuracy of prediction, and thereby improve the early warning of landslides, using a RTI model that considers rainfall intensity for periods of less than 1 hour.

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