D4RUNOFF NBS Library: https://d4runoff.eu/resources/

Filter strips are uniformly graded and gently sloping strips of grass or other dense vegetation that are designed to treat runoff from adjacent impermeable areas by promoting sedimentation, filtration and infiltration. The runoff flows as a sheet across the filter strip at sufficiently low velocities that allows treatment processes to take place effectively. They are normally used as pretreatment component before swales, bioretention systems and trenches. Filter strips are most suitable for treating stormwater discharge from roads and highways, roof downspouts, very small parking lots, and pervious surfaces.