Development of a Flash Flood Confidence Index from Disaster Reports and Geophysical Susceptibility

Abstract

The analysis of historical disaster events is a critical step towards understanding current risk levels and changes in disaster risk over time. Disaster databases are potentially useful tools for exploring trends, however, criteria for inclusion of events and for associated descriptive characteristics is not standardized. For example, some databases include only primary disaster types, such as ‘flood’, while others include subtypes, such as ‘coastal flood’ and ‘flash flood’. Here we outline a method to identify candidate events for assignment of a specific disaster subtype—namely, ‘flash floods’—from the corresponding primary disaster type—namely, ‘flood’. Geophysical data, including variables derived from remote sensing, are integrated to develop an enhanced flash flood confidence index, consisting of both a flash flood confidence index based on text mining of disaster reports and a flash flood susceptibility index from remote sensing derived geophysical data. This method was applied to a historical flood event dataset covering Ecuador. Results indicate the potential value of disaggregating events labeled as a primary disaster type into events of a particular subtype. The outputs are potentially useful for disaster risk reduction and vulnerability assessment if appropriately evaluated for fitness of use.

Evaluating the usefulness of VGI from Waze for the reporting of flash floods

“…Relative to other natural hazards in the US, there is a paucity in observational data for flash floods 13 . Compared to other flood types, historical records for flash floods are more likely to have significant gaps 14 , 15 . However, recent advances in unified flood and flash-flood data systems highlight the need for additional data sources to supplement reporting systems 16 .…”

Multiform flood risk in a rapidly changing world: what we do not do, what we should and why it matters

“…While in certain locations misrepresentation of subtype risk could be low, this is likely to be the case only in areas where there is risk of one, and only one, subtype of flood. However, even in the areas where current climatic and socioeconomic conditions lead to one, and only one, subtype occurring, it is possible that both future flood risk of a different subtype may be present, and other subtypes of floods may have occurred in the past (which could influence the subtype assignment of historical flood records of events labeled only as 'flood') [40].…”

Flood susceptibility mapping in the Bilate catchment, Ethiopia

“…The TWI is inextricably related to the slope and upstream, contributing an orthogonal area per unit width to the flow direction. It is a real element (Kruczkiewicz et al 2021) for the occurrence of floods, which spatially expresses the variation in the wetness of a basin. This index is generated to indicate the amount of water contained in each pixel of the region (Zhao et al 2022) (Equation ( 1)):…”

“…This may be a way to cope with the current flood mapping gaps, decrease the data dependency requirements, and promote hydraulic modelling and remote sensing applications. The scarcity of data in the Bilate catchment further limits its simulation (Kruczkiewicz et al 2021).…”