The Impact of the designed urban environment on pluvial flood : a case study of selected locations in Colombo municipal area

Abstract

Pluvial flooding, caused by intense rainfall overwhelming urban drainage capacity, has become an increasing concern in rapidly urbanizing cities. While conventional flood studies often emphasize engineering and hydrological factors, the role of urban design remains underexplored. This research aims to assess the urban design aspects that influence the occurrence and severity of pluvial flooding within the urban context. It investigates how spatial configurations, built form patterns, surface materials, and the integration of natural and artificial drainage systems contribute to surface water accumulation and flow behavior. Through spatial mapping, field observations, and morphological analysis of selected urban areas, the study identifies the design-related characteristics that either exacerbate or mitigate pluvial flood risks. The findings are expected to reveal critical urban form attributes such as street layout, building density, open space distribution, and permeability that affect stormwater dynamics. Ultimately, this research contributes to developing a framework for integrating flood resilience strategies into urban design practices, for supporting more adaptive, and sustainable, urban environment.