Napier Park is a public park to the north west of Melbourne CBD. The 4.2ha park is characterised by plains grassy woodland vegetation. Remnant river red gums dominate, and are distributed across the site. In recent years there has been a dramatic decline in health of the larger trees with obvious signs of stress and mortality. This decline threatens the viability of an important ecosystem which supports a diversity of flora and fauna within the urban setting.

In parallel with the decline in plant health, the greater Melbourne area has experienced a lower than average rainfall for the last 10 years. Land use within the catchment has been transformed from pervious woodland to a typically impervious residential use. The ongoing and prolonged depletion in soil moisture levels has begun to impact species not normally associated with dry weather stress and often not considered in municipal irrigation strategies.

This paper outlines a response to stormwater harvesting with a focus on the irrigation of native indigenous vegetation. This is a new concept in parkland management whereby an integrated hybrid active/passive irrigation system is used to support the natural distribution of native vegetation to reverse the decline in parkland biodiversity and compensate for the recent changed climate. A stormwater harvesting scheme has been designed which diverts water from an existing drain to reintroduce a relic ephemeral flow path which originally flowed through the site. The ephemeral swale will provide water quality treatment to runoff and passive irrigation of adjacent trees prior to conveyance to underground storage.

The project highlights an approach to stormwater which enhances the environment on a number of levels and expands on the current thinking around irrigation of urban environments to include areas of native vegetation previously assumed to be resilient to climate change.