Paul is exploring how to optimise the design and monitoring of urban tree systems irrigated passively with stormwater runoff.

Urban forests sustain the health and mental well-being of residents. They provide vital ecosystem services of shading and stormwater reduction through rainfall interception, and microclimate cooling via transpiration, but the ability of urban trees to provide these functions is hampered by a disconnection from water. Rain falls onto hard paved surfaces and instead of infiltrating into the soil and being transpired by trees it becomes stormwater, flowing at high velocities into creeks and rivers causing destabilisation and adding pollutants.

To fix these problems, systems which passively capture and store stormwater in the soil have been developed to allow trees to transpire and grow at a faster rate. The quantities of stormwater being reduced and the extent to which tree health and growth is improved remains poorly understood. Once we know how the systems are performing we can then optimise designs to get the greatest benefit.

My research explores novel methods to evaluate previously installed systems and to design new systems to reduce stormwater runoff to ecologically significant baselines and ensure the health of a broader range of urban tree species.