A New Flood Index for Use in Evaluation of Local Flood Severity: A Case Study of Small Ungauged Catchments in Korea¹

Abstract

Ahn, Jae Hyun and Hyun Il Choi, 2013. A New Flood Index for Use in Evaluation of Local Flood Severity: A Case Study of Small Ungauged Catchments in Korea. Journal of the American Water Resources Association (JAWRA) 49(1): 1‐14. DOI: 10.1111/jawr.12025 Abstract: The aim of this article is to develop a new index measuring the severity of floods in small ungauged catchments for initial local flood information by the regression analysis between the new flooding index and rainfall patterns. Although a rapid local flood caused by heavy storm in a short period of time is now one of common natural disasters worldwide, such a sudden and violent hydrologic event is difficult to forecast. As local flooding rises rapidly with little or no advance warning, the key to local flood forecasting is to quickly identify when and where local flooding above a threshold is likely to occur. The new flooding index to characterize local floods is measured by the three normalized relative severity factors for the flood magnitude ratio, the rising curve gradient, and the flooding duration time, quantifying characteristics of flood runoff hydrographs. The new flooding index implemented for the two selected small ungauged catchments in the Korean Peninsula shows a very high correlation with logarithm of the 2‐h maximum rainfall depth. This study proposes 30 mm of rainfall in a 2‐h period as a basin‐specific guidance of precaution for the incipient local flooding in the two study catchments. It is expected that the best‐fit regression equation between the new flooding index and a certain rainfall rate can provide preliminary observations, the flood threshold, and severity information, for use in a local flood alert system in small ungauged catchments. Editor's note: This paper is part of a featured series on Korean Hydrology. The series addresses the need for a new paradigm of river and watershed management for Korea due to climate and land use changes.

Resiliencia, vulnerabilidad y sustentabilidad de sistemas socioecológicos en México

“…La vulnerabilidad puede descomponerse en: exposición, sensibilidad y resiliencia. El primero se refiere a eventos potencialmente catastróficos que tienen una frecuencia, duración y magnitud y que suceden en un contexto biogeofísico dado (Ahn y Choi, 2013;Messner y Meyer, 2006;Soares, Murillo, Romero y Millán, 2014;Tucker, Eakin y Castellanos, 2010;Wong y Zhao, 2001) y en una población con una capacidad de mitigación definida (López-Marrero, 2010;Messner y Meyer, 2006;Tucker et al, 2010;Vergara-Tenorio et al, 2011). La sensibilidad, mide cómo las condiciones socioecológicas existentes les permiten a los individuos o a las comunidades absorber cambios generados por fenómenos catastróficos (Adger, 2006;Burton y Lim, 2001;Gallopín, 2006;O'Brien, Sygna y Haugen, 2004;Smit y Pilifosova, 2001).…”

User-oriented hydrological indices for early warning systems with validation using post-event surveys: flood case studies in the Central Apennine District

“…In general, precipitation indices are applied for flash flood prediction, since a negligible contribution of infiltration processes is assumed for small catchments (Reed et al, 2007;Hurford et al, 2012;Ahn and Il Choi, 2013). Moreover, Alfieri et al (2012) highlighted that precipitation-based indices are preferable over uninstrumented rivers.…”

“…Given the complexity of the topic, many authors have recognized that effective design of early warning systems (EWSs) is a key element for fostering forecast skills and improving resilience to natural hazards (Basha and Rus, 2007;Alfieri et al, 2011Alfieri et al, , 2012Kundzewicz, 2012;Krzhizhanovskaya et al, 2012;Mysiak et al, 2013;Corral et al, 2019). In this framework, scientists in different fields have to deal with the effective development of robust new techniques and analyses.…”

The extreme runoff index for flood early warning in Europe

“…On the other hand, the large data requirement limits the current implementation of early warning systems at continental scale to just a few cases, the European Flood Awareness System (EFAS, see e.g., Thielen et al, 2009) being a prominent example for Europe. In poorly gauged areas, a simplified option to monitor and forecast floods is by linking them to extreme rainfall occurrences (e.g., Lalaurette, 2003;Hurford et al, 2012;Ahn and Il Choi, 2013). This assumption is widely accepted for surface water flooding events and flash floods due to short and intense rainfall events in small-size catchments.…”