Street trees in urban environments suffer from a severe limit of space available for plots. This combined with conventional drainage systems that take water away from the site lead to limitations on the health, growth and potential development of the trees. The impermeable environment exacerbates the already disturbed, deoxygenated and contaminated soil conditions by requiring surface compaction of these small spaces.

Trees in urban environments can also adversely affect adjacent infrastructure. As the tree grows, the roots seek out sources of water and grow along this path. These sources can be located under roads, inside pipes or adjacent to housing. These roots cause cracking of the road pavement, pipes and footings and can cause heaving of the footpath and gutter. This is a major concern to councils as the funds required to remove the roots and reinstate the damaged area are significant.

A field research project has commenced that will trial systems that harvest road runoff (for "irrigation" of street trees) and provide water quality and quantity benefits, reducing the impacts of stormwater on receiving environments. A controlled "irrigation" system will encourage the tree roots to grow towards the distribution source and away from the adjacent infrastructure. This will direct the roots to grow parallel to the roadways and houses, with the ultimate goal of keeping the roots within the strip of land between the roadway and the footpath.

Further Reading:

Stormwater Harvesting Trials for 'Irrigation' of Street Trees and Water Quality and Quantity Improvement