Impact of successive rainfall events on the dynamic relationship between vegetation canopies, infiltration, and recharge in engineered urban green infrastructure systems

Soil surface crusts have been extensively studied in arid and semi‐arid regions, but not in the context of engineered urban green infrastructure (GI) systems, especially in temperate environments. Raindrop impulses can break up larger soil aggregates into smaller particles, dispersing them from their original position, and contributing to the formation of a crust at the soil surface. Crusts, in turn, can reduce infiltration and increase both runoff and the soil's susceptibility to erosion. Vegetation canopies can help to mitigate crust formation by dissipating some of the drops' kinetic energy, though the extent of protection provided by the plants has not been studied in GI systems. This paper presents laboratory research conducted using a rainfall simulator to determine the ability of artificial vegetation canopies to minimize soil crust formation, in comparison with a bare soil control. The mechanical resistance of the soil surface to penetration was measured after each of the 22 different simulated rain events. Over the experiment, the percent change in penetration resistance increased by 83.5% and 148%, in vegetated and bare soil control boxes, respectively. The bare soil control box also displayed statistically significant (p < .001) increase in the duration of post‐storm ponding, compared with the control vegetated box, suggesting a reduced infiltration rate. These results suggest that vegetation canopies can play a key role in protecting the soils found in GI systems from raindrop impact.