High-resolution pavement material data can improve estimates of water supply from precipitation to street trees

Moreen Willaredt, Dagmar Haase, Alessandro Ossola

Impervious surfaces in urban landscapes strongly influence how precipitation supplies water to trees. Most data on imperviousness are satellite derived restricting our ability to analyze impacts of imperviousness at the scale of single tree catchments: the area covering tree roots. To address this challenge, we compiled a high-resolution dataset for Berlin, Germany, that specifies pavement materials, complementing it with hydrologic properties from the literature. Our approach aims to assess the accuracy of satellite-derived imperviousness in 71,311 tree catchments and analyze infiltration reduction due to the presence of pavement at the local, fine scale. We found substantial disagreement with satellite-derived imperviousness for ≈ 99 % of tree catchments and that satellite-derived data on average underestimates imperviousness by 13.1 %. High-resolution imperviousness correlated with reduced infiltration, yet catchments with similar imperviousness exhibited high variability and even bimodal distributions. These patterns can be explained by the dominant pavement material, highlighting the importance of high-resolution imperviousness data that capture pavement materials when assessing urban stormwater dynamics. In Berlin the mean annual infiltration reduction was 45.9 %, sometimes limiting water availability for Tilia below transpiration demand during the growing season. These results indicate that street trees in paved environments might experience modified climatic and hydraulic regimes decoupled from those dictated by regional climates. Our findings can help refine predictions of tree drought stress and stimulate field studies along imperviousness gradients. The outcomes can inform practice, e.g. tree water management, and climate adaptation strategies in urban planning, such as pavement removal or retrofitting of tree planting sites.