Prabhasri I. Herath (Australia)
Australian National University
Fenner School of Environment & Society, College of Science
Prabhasri’s research admires nature as a vital component of life and an integral part of cities. Incorporating ecosystem concepts in cities helps resolve many consequences and absorb multiple environmental and thermal shocks in the urban system while providing economic and aesthetical values. Her current research project focuses on sustainable, resilient and liveable cities; adapting cities to extreme and excess heat by strategic mitigation planning with Nature-based Solutions (NbS). The studies mainly focus on Australian cities, that are highly vulnerable to severe heatwaves and assess their capabilities of implying NbS or green infrastructure to make cities liveable and resilient.

Presenter of 1 Presentation

 Conference Calendar

EFFECTIVENESS OF GREEN URBAN SURFACES TO MITIGATE EXCESS HEAT DURING HEATWAVES.

Session Name
0480 - Academic Sessions - Resilient 06: Nature-based solutions linked to urban design and resilient urban development (ID 72)
Session Type
Academic Sessions
Date
02/24/2022
Session Time
09:30 AM - 10:40 AM
Room

Hall B

Presenter
Lecture Time
09:30 AM - 09:40 AM

Abstract

Abstract Body

Heatwaves create the second-largest number of deaths from Australian natural disasters. Human thermal comfort is a priority in heatwaves along with the undue burden on energy demand. The heatwave impacts for cities could be intense due to energy budget changes with the urbanization process and Urban Heat Island (UHI) effect. This paper investigates the effectiveness of green surfaces during heatwave events by arguing the city will perform better with more greener for excess heat.

The study was conducted in the City of Melbourne during the well-documented four heatwave events in 2009 (28-30 Jan), 2014 (14-16 Jan) and 2019 (2 events; 6-8 Dec and 28-30 Jan). The Air Pollution Model (TAPM), coupled with UCLEM urban canopy scheme was used to simulate heatwave events with 1 Km resolution. The existing urban surfaces were modified with green surfaces such as urban trees and green roofs. Urban tree ratio was changed in the Central Business District (CBD) as 0%, existing (15%) and 5% increase (20%) in the scenarios of T1, T2 (baseline for the whole study-BSL) and T3, respectively. Green roofs were performed as 50%, 70% and 90% as G1, G2 and G3 (0% in BSL). Both surface parameters were combined in C1 (5% increased canyon trees with 50% green roofs), C2 (5% increased canyon trees with 70% green roofs), and C3 (5% increased canyon trees with 90% green roofs).

From the compared results with BSL (T2), C3 performed the best maximum and minimum temperature (Tmax and Tmin) reduction for all heatwaves (except Tmax in 2014 – G3 performed effectively). For 3-day averaged temperatures (heatwaves exist for 3 or more days), the temperature reduction from C3 was ranged from 1.2 to 2.8°C for Tmin, while Tmax rangedfrom 0.4 to 0.8°C. Therefore, we emphasis green surfaces in cities as potential mitigation strategies to drop the day and night-time temperatures in heatwave events. However, only urban trees distributed in canyons and urban parks cannot cool the temperatures effectively, and we propose combined strategies for the best cooling effectiveness.

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