Road edge treatments for stormwater reuction and street tree health

FUNDING SOURCE: Office of Living Victoria, Melbourne Water, City of Monash (2013-2015)

RESEARCHERS: Stephen Livesley , Andrew Coutts (Monash).

Ari et al_city of MonashOVERVIEW: Trialing, testing and promotion of simple, cost effective kerb and nature strip treatments to maximise benefits for local stormwater reduction, street tree health and their capacity to influence urban microclimates to enable large scale implementation for maximum benefit. In four residential streets in the City of Monash we are installing two forms of kerb modification to divert road runoff into aggregate filled WSUD trenches  in nature strips to increase soil moisture contents. This can greatly supplement moisture available to stressed trees during periods of summer drought, as well as potentially increase tree growth, canopy development and overall resilience.

Lophostemun confertus_OakleighTwo residential streets are in sandy loams soils, and two streets are located in clay loam soils. Two streets are planted with native, evergreen Lophostemum confertus (Brush Box), one with exotic deciduous, Ulmus parvifloria (Chinese Elm) and one with exotic, deciduous Pyrus calleryana (Callery Pear).Pyrus_callyerana_Hughesdale

Soil moisture profiles (30, 50, 70 and 90 cm) are being continuously monitored within the WSUD trench, and between the trench and the tree stems so as to track differences between treatment trees and control trees in soil water contents and movement. Pre-dawn leaf water potential is measured monthly as is stem diameter. Monash University is continuously monitoring the street microclimate to determine vapour pressure deficit conditions.

The project outcomes will be cost-effective guidelines for simple retro-fitting of WSUD to residential nature strips, requiring minimal maintenance for quantified storm-water runoff reductions and street tree growth and resilience gains.