Relationship between Land Cover and Infiltration Rates in Urban Landscapes

Abstract

Infiltration capacity has a critical impact on runoff models and low impact development stormwater controls. Therefore, the quantification of infiltration rates achieved by stormwater control technologies in urban areas is an important task in determining the possibility of making predictions about infiltration rates based on land use type. In this study a total of 140 trials of infiltration measurements were conducted using a Cornell Sprinkle Infiltrometer at 40 sites distributed between New York City and Philadelphia on different types of stormwater control technologies, permeable urban surfaces, such as porous rubberized safety materials, porous asphalt, porous concrete, vegetated courtyard, tree pits, bioretention facilities, urban parks, porous pavers, and backyards to assess whether statistically significant differences are present between them. The results of the Kruskal-Wallis test showed that there was a highly significant difference (p<0.01) in infiltration capacity of different types of permeable urban surfaces. Moreover, there was highly significant difference between tree pit sites (Kruskal-Wallis, p <0.01). The results also revealed a significant difference between individual tree pits without guards but no significant difference among tree pits with guards. A correlation analysis indicated no significant relationships between measured infiltration rates and specific independent variables (bulk density, antecedent dry period, initial soil moisture content) (Spearmans r. bulk density -0.2 p=0.183, initial soil moisture content-0.189 p=0.209, and antecedent dry hours 0.06 p=0.489). Three different groupings are evident when the ranges corresponding to 95% confidence interval about the median infiltration rate measured for each permeable urban surface category are compared. Porous concrete has the highest infiltration performance among different permeable urban surfaces.%%%%M.S., Environmental Engineering – Drexel University, 2012