NPSP Tree Canopy Action Group Update - October 2026

From Madeleine St Johnston-Romano (Group Convenor) - NPSP Tree Canopy Action Group (Facebook)

We’ve all noticed our street trees suffering during dry summers; their wilting, their sunburn, and sometimes even withering, worries us deeply. Alarmists, they call us, when we express our concern, but we know that a plentiful tree canopy provides us with shade and gives us cool; it cuts glare and drops the temperature by as much as 2 to 3 degrees, even on a lethal day. And some days are lethal, here, in our part of the world: a walk outside for a newborn on a 32-degree day, during the sun’s peak hours, may risk its life; the same walk, little matter the hour, on a 43-degree day may end its life. In Adelaide, we need air-conditioning to get through the summer, and the more canopy we have, the less it costs us. Clearly, it is clever to care about trees.

In May, I asked Council for supplementary water, however, as I’ve discovered since, watering trucks are of little benefit to mature trees. How then to get our street trees the water they need to survive this summer’s drought? In the short term, we need to rally our community to, among other things, water its gardens and its verges, but we also need to think about long-term solutions, get people talking about them, and vote for them at the upcoming Council election. Now, one of the long-term solutions is tree-inlets, 1,000+litre tanks that sit under kerb-side trees and collect and disburse rainwater. What rainwater, you might well ask: We are after all possibly facing at least 2 years of drought.

Adelaide gets a steady average of 500mm a year rainfall, with a minimum of 300mm during dry periods, and is plenty enough for our needs. Why then are our trees and gardens under such stress? Answering the last question explains why tree-inlets, and other new urban design technology, like permeable paving, are such amazing, cost-efficient solutions, and so to that, I now turn.

Since the last century, the prevailing view among civil engineers has been that dry soil provides a solid foundation for urban development, so governments have focussed on draining on away our rainwater. As it turns out, this practice is very misguided: we now have 85% run off, and low permeability, subsidence issues like cracking foundations and lifting paving, invasive roots, falling trees, and so on, are all the result. Tree-inlets, which capture rainfall, help to stabilising the soil and prevent ground movement. So, caring for street trees in ways that will really help them, for the long term, also means addressing some of the most expensive, distressing issues that attach to owning a home in our council area, along with also reducing our water bills and great stress on our reservoirs. Clearly then, it is wise to care for trees!