We will learn how to model water quality and LIDs in VO in two exercises.

tutorial – LIDs and Water Quality Single-Event Model (this tutorial)
tutorial – LIDs and Water Quality Continuous Model

This exercise will focus on single-event model. It covers the basic work flow to add water quality calculations and LIDs to a VO model. This is an advanced modeling exercise and assumes users know how to build a single-event simulation, so we will be starting with an existing model and focus only on water quality and LIDs.

Please download the attachment for practicing and viewing results.
tutorial – LID

Water quality calculations are done using a simplified mass balance approach. All water quality features in VO follow these simple rules:

  • Phosphorus and TSS loading are constants, so all runoff from a catchment will have the same concentration of TSS and TP based upon the assigned land use. Only the assigned land use is used to calculate concentrations of TP and TSS.
  • TP and TSS removal rates are user defined, VO does not calculate water quality treatment based on the characteristics of the LIDs, it is up to the user to research and provide justification for the values they assign.
  • VO assumes that all runoff which is infiltrated has 100% TP and TSS removal because it is no longer part of the surface water system.
  • VO assumes that all runoff which overflows an LID or reservoir is untreated.
  • VO will reduce the TSS and TP concentrations based on the user defined removal efficiency rates for all runoff which leaves the LID through a subdrain or through an outflow.