Evaluating Porous Pavement for the Mitigation of Stormwater Impacts

Abstract

Urban stormwater management is one of the biggest challenges facing modern cities. The current stormwater networks are likely to be insufficient under continuous urbanisation and the development of residential areas in addition to increases in rainfall intensity, especially in areas with relatively high slopes, which may thus be subject to flooding. This study aimed to mitigate the overflow rate of the selected case study area using a pervious inlets pavement technique based on porous asphalt concrete pavements with a reservoir layer. The current stormwater network system of the Al-Yarmouk quarter (located at the centre of Karbala City, Iraq) was evaluated by exposing it in simulation to a rainfall intensity equivalent to the 5-year return period and applying storm and sanitary analysis (SSA) and GIS software. The simulation results showed that constructing 50% of the road surface area (5% of the total studied area) with porous asphalt concrete with air voids of about 20% and variable reservoir thicknesses, could reduce water runoff entering the network significantly. Moreover, placing 240 mm, 328 mm and 400 mm of No.75 aggregate layer within reservoir depths would result in further mitigations of surface runoff quantity by about 15%, 30%, and 45%, respectively. A reservoir depth of 240 mm was found to reduce flooding quantities and times by about 71% and 18.29%, respectively, while creating a 328 mm reservoir depth under the porous asphalt results in quantity and time reductions of about 98.5% and 81%, respectively. No surface flooding was observed when reservoir depth was changed to 400 mm.