Instrumentation and modelling of stormwater trees to determine their hydrological performance in a future climate

Abstract

Stormwater trees are nature-based solutions for stormwater management. Often, the infiltration capacity of existing roadside trees is improved to increase collection of runoff from neighbouring streets and sidewalks. Stormwater trees are considered as a pertinent stormwater control measure in highly urbanised areas, but the contribution of the tree (evapotranspiration) to the water balance remains unclear due to measurement challenges. This extended abstract presents preliminary data from a starting PhD project, aimed at continuously monitoring five stormwater trees and two control trees for water level in an infiltration trench, soil water content and matric potential in the tree pit, and sap flow to characterize the water balance. The seven trees have been progressively equipped since December 2024, with the latest equipped in June 2025. By the conference, several months of data from all trees will be available. This data will be used to calibrate a stormwater tree model in HYDRUS, with a preliminary version to be presented at the conference. A later objective is to assess the hydrological performance of stormwater in future climates using downscaled climatic projections.