Numerical Assessment of Green Infrastructure Influence on Hydrologic Effectiveness in a Suburban Residential Development.

Applying green infrastructure measures helps to retain water in the land during wet periods, which in turn makes it more available during periods of drought. Water retention reduces the volume of rainwater that transforms into surface runoff, allowing for the increase in the intensity of evapotranspiration and infiltration, which helps to establish a catchment with a balanced hydrologic cycle that's effectively more resistant to the consequences of climate change. With increasing popularity of introducing low impact development (LID) solutions in highly urbanised catchments characterised by a high runoff coefficient, it is important also to reduce rainwater runoff in residential areas with lower density of housing. This work presents a numerical assessment of green infrastructure (green roofs, raingardens, permeable paving and rainwater harvesting) performance in increasing retention in a catchment area consisting of single-family houses. The numerical model of potential residency in Ożarów, Poland was developed in SWMM 5.2. software, replicating local conditions with input infiltration data collected through on site and laboratory testing, as well as data gathered during a period of registering local evaporation and precipitation conditions. After running a series of simulations of three rain events, varying in their duration and intensity, the model was enhanced with green infrastructure solutions by the utilisation of LID Controls option in SWMM. With rainfall simulations resulting in varying rainwater outflow hydrographs and with differences in the volume of collected rainwater outflow, the results of LID application were consistent with the reduction of the peak rainwater outflow (reduction rate 61.90-67.99%), as well as the decrease in rainwater outflow volume (reduction rate 61.17-62.12%). This research promotes the hydrologic effectiveness of introducing green infrastructure in low density housing establishments. [ABSTRACT FROM AUTHOR]