Artificial lawns exhibit increased runoff and decreased water retention compared to living lawns following controlled rainfall experiments

Abstract

Artificial lawns are an increasingly popular alternative to their living counterparts, but their environmental impacts are undocumented. The hydrological impacts of artificial (synthetic polymer) grass were investigated in comparison to living grass in a series of controlled rainfall experiments, representing daily short rainfall events of different volumes (750 mL, 1000 mL, 1250 mL). Two varieties of artificial grass with varying pile height (short vs long) were compared with a living grass control. Infiltration was measured as drainage (total, initial and delayed) and retention. Significant differences in runoff were observed across all treatments, demonstrating that both types of artificial grass displayed greater volumes and proportion of runoff than living grass, and that long artificial grass had significantly greater runoff than short artificial grass. Living grass was also significantly better at retaining water and delaying drainage compared to both artificial grasses, while retention performance varied between short and long artificial grass. Other aspects of drainage were more complicated, with short grass installations generally draining fastest. Plastic thatch and grass fibres were also shed from the artificial grass installations during the experiments and were carried in the runoff. Further experimentation is required to explore the wider implications of such hydrological responses, but the potential impacts on runoff in particular should be considered when replacing living lawns with their artificial counterparts.