Assessment of Urban Flood Inundation Dynamics Using Integrated Rainfall–Runoff and Hydraulic Modeling in Rapidly Developing Secondary Cities

Abstract

Rapid urban growth in secondary cities has intensified flood vulnerability due to land-use transformation and increasing pressure on drainage systems. This study examines flood inundation dynamics using an integrated modeling approach that combines hydrological and hydraulic simulations. Discharge is estimated through rainfall–runoff modeling and subsequently applied in hydraulic analysis to evaluate flood depth and spatial distribution under multiple rainfall scenarios. The findings reveal a substantial rise in peak discharge, accompanied by a faster flow response, as rainfall intensity increases. The extent of inundation expands disproportionately once system capacity is exceeded, particularly in densely populated areas. The results highlight the value of integrated modeling in providing more reliable spatial insights to support adaptive flood management strategies.