LID facilities like bio-retention cells is applied to manage stormwater. LID concept becomes an important part in
stormwater management, and the clear understanding of hydrologic performance and hydrologic impact on the
corresponding catchment has been needed. In this study, the application of flow duration curves as design strategy is
investigated. Bio-retention cells like many LID facilities are installed to reproduce natural hydrologic processes. In this
study, the attempt to determine the size of a bio-retention cell is carried out to satisfy the flow duration criteria. From
the results, it is shown that “5 mm * the area of a target catchment” which is the current facility design capacity is
valid for the drainage area with 20-30% impervious rate. In the 100% impervious catchment where LID facilities are
typically installed, the design capacity to intercept stormwater of approximately 47 mm depth is required to reproduce
natural flow duration curves. This means that about 11% of the target catchment area should be allocated as a
bio-retention cell. However, the criteria of the design capacity and facility surface area should be set at the possible
implementation conditions in reality, and site-specific hydrologic characteristics of a target catchment should be
considered.