Rain gardens generally function as a stormwater filter and infiltration practice which can be used to temporarily store, treat and infiltrate runoff. The LID is designed with an engineered soil layer to store and treat runoff which then infiltrates into surrounding native soil. Rain gardens are designed with an overflow and a native soil infiltration rate. Key features for rain garden designs are shown in the diagram below.

Parameter Name Description Default Value
Surface Area Ponding
DEPTH-AREA CURVE Depth area curve for surface ponding area, depth is defined from the bottom of the ponding layer
INFILTRATION RATE (m/hr) The rate at which water on ponding surface enters the engi-neered soil layer 0.5
Engineered Soil Layer
TOTAL POROSITY Fraction of soil that is made up of spaces (pores) between particles 0.463
SEEPAGE Saturated hydraulic conductivity for soils in areas with ponded water, represent the ease at which moisture can move through a soil (m/hour) 0.013
SOIL MOISTURE Initial soil moisture content of the engineered soil layer. (fraction) 0.3