Using frequency ratio model for flood susceptibility mapping of Mandaue City, Cebu

Abstract

Floods cause damage to the global economy and environment, leading to the loss of lives;
therefore, identifying flood-vulnerable locations is essential for complete flood risk
management. As a highly dense and low-lying city, Mandaue City in Cebu, Philippines, easily
gets flooded during heavy downpours leading to heavy traffic and damages in the area. This
study utilized a geospatial approach to generate a flood susceptibility map of the city using the
frequency ratio (FR) model. The flood susceptibility analysis considered eight flood
conditioning factors: elevation, slope, Topographic Wetness Index (TWI), curvature, river
density, land use, Normalized Difference Vegetation Index (NDVI), and rainfall. The FR model
results exhibited high accuracy, with an AUC value of 0.902. Five percent of the city falls under
high hazard classification, encompassing industrial, commercial, and critical facilities.