Enhanced grass swales are vegetated open channels designed to convey, treat and store stormwater runoff. Enhanced swales will calculate the volume of surface ponding and infiltration throughout the swale. Users have options for designing enhanced dry or wet swales. Enhanced dry swale are designed with an additional storage layer, and water could be infiltrated from surface and then seepage to a native soil layer. Otherwise, in wet swale, water could penetrate from surface ponding layer to native layer without a storage layer. Key features for swale designs are shown in the diagram below.

Parameter Name Description Default Value
Surface Area Ponding
DEPTH Maximum depth of bioswale surface ponding area (m) 0.3
CHECK DAM DEPTH The depth of check dam 0.3
WIDTH Width of bioswale surface ponding area (m) 1
LENGTH Length of bioswale surface ponding area (m) 1
LEFT SIDE SLOPE Horizontal: Vertical left-side slope of bioswale (3:1) 3
RIGHT SIDE SLOPE Horizontal: Vertical right-side slope of bioswale (3:1) 4
SURFACE SLOPE Slope in the direction of the flow path (m/m) 2
Storage Layer
DEPTH Depth of the storage layer (m) 1
POROSITY Fraction of storage layer that is made up of spaces (pores) between particles 0.4