Variability of Infiltration Rates at Selected Green Infrastructure Sites in New York City

Green infrastructure is a cost-effective, resilient approach to managing wet weather impacts and provides many additional benefits. In New York City, Green Infrastructure (GI) is designed to effectively capture stormwater runoff at the source, thereby reducing combined sewer overflow (CSO) – a leading cause of water quality problem in urban areas. The infiltration rate is the most important measurement of a soil’s capacity to capture stormwater in a GI system. The objectives of this research are to examine the variability of infiltration rates at different sites and within a site, and to investigate the factors that contribute to such variability. Field variables such as vegetation and root density were noted. Surface soil samples were collected and analyzed for moisture, organic content, bulk density and texture. Linear correlation and Principal Component Analysis (PCA) were performed to examine the relationships between these variables and infiltration rates. The surface infiltration rates varied significantly (5–20 cm/h) among sites as well as at different locations within the same site. The effect of surface capping is minimal at most sites. There is no significant correlation between infiltration rates and single soil properties, except for that between bulk density and Ksat. PCA analysis suggests that multiple inter-related soil properties and field variables that affect infiltration rates. Soil texture and organic content appear to be the most important variables that control other properties and infiltration rates at the sites included in this study. © 2021, The Author(s), under exclusive license to Springer Nature Switzerland AG.