A new version of DRAINS is available that allows users to define IL-CL subcatchment areas into three categories: Effective Impervious Area (EIA), Remaining Impervious Area (RIA) and Pervious Area (PA).

RIA is routed through PA, allowing a more rational treatment of Initial and Continuing Losses, and lets you clearly specify different losses for impervious and pervious surfaces. It also provides clear definition of Total Impervious Area (TIA) considered in a catchment.

Refer to the DRAINS Help system for more information.