Urbanization increases the percentages of impervious area, compared to predevelopment status. This leads to decreases of the water volume infiltrating into soil layers and lack of groundwater. And, this could be problematic in lower watersheds since agricultural water uses for crop growth would be possibly limited. In addition, direct runoff might cause water quality degradation in stream, transporting pollutants on soil surfaces. One such technique to minimize the impact of landuse changes is to apply the low impact development (LID) practice. Basically, LIDs are to maintain impervious area percentages of predevelopment status. They are effective approaches to sustain soil infiltration capacity, there is a need to simulate them prior to LID applications in fields.
Storm Water Management Model (SWMM) provides opportunities to estimate runoff quantity and quality and to evaluate LIDs. However, the model provides seven LID types which are Permeable pavement, Rain gardens, Green roofs, Street planters, Rain barrels, Infiltration trenches, and Vegetative swales. While seven LIDs are allowed in the model, it is often required to evaluate other practices not listed in the model. In the study, it was requested to evaluate eleven LIDs, that are Permeable block paving, Porous grass block paving, Rain cistern, Green roof, Infiltration trench, Harvested rainwater draining, Rain garden, Bio-retention cell, Rain barrel, and vegetative swale.
The objectives of this study are 1) to demonstrate how various LIDs can be applied in SWMM model and 2) to evaluate LIDs for minimization of landuse changes.