Measuring and mapping the impact of buffer width on riparian microclimate temperatures

Vegetation and water bodies are being utilized as tools to cool the local environment and combat intense heat events through water evaporation and vegetation evapotranspiration, shading, and modification of air movement. This study analyzes the magnitude, spatial and diurnal variability of cooling experienced in 20 m, 40 m and 80 m wide riparian zones compared to an unvegetated site along South Creek in southwest Sydney, Australia. Air temperature sensors were placed across the width of the buffer extending into adjacent grass fields, measuring at hourly intervals over the summer of 2022-2023. LiDAR data was used along three 5 km reaches to map the riparian zone, buffer width, and riparian cooling using a simple kriging interpolation. Vegetated buffer zones were 5-7 °C cooler with more consistent daily maximum temperatures and diurnal variation. Buffer width had little impact on the magnitude of cooling, with the 20 m riparian buffer showing the largest temperature reduction likely due to enhance airflow and river cooling, however the cooling effect of larger buffers extended further beyond the riparian canopy while covering a larger total area. These findings help understand how varying buffer widths can be implemented in urban design to combat the urban heat island effect.