==Determine the active storage depth of the practice==
==Determine the active one dimensional (1D) water storage depth of the practice==
* Step 4: Identify the active storage depth, d<sub>a</sub> of the practice<br>
* Step 4: Identify the active water storage components of the practice<br>
For practices without an underdrain, the active storage depth equals the total depth of the practice:
For practices without an underdrain, the active storage components include the surface ponding, mulch and filter media depths (i.e. total depth of the practice, d<sub>T</sub>: