Run Model
Normal simulation. Provides output time series summarized by storm event for all devices. Both summary and event time series data are available using the ' List ' procedures. Simulations periods can be up to 100 years in length and contain up to 5000 storm events.
Run Traced (Hourly or Daily)
Provides normal simulation. Also provides hourly or daily inflow, outflow, and precipitation time series for a specified device for subsequent display using the ' Charts' procedure. The daily or hourly time series data can also be listed using the ' List' procedures. The flows, loads, and concentrations for all particles and water quality components are listed for the device inflow ( Term 9 ) and device outflow ( Term 10 ).
Traced
output is restricted to about 4 years for
hourly output or 100 years for daily output.
Run Design
Lookup
This routine rescales existing devices to achieve a user-defined removal efficiency for any particle class or water quality component. In order to run this routine, the user must first define a case containing a preliminary design and run it successfully via the 'Run Mode
Designs a device to achieve ~70% or ~85% total suspended solids removal for one user-defined watershed. To use this routine, a case must be defined with at least one watershed & device.
P8 includes a catalogue of prototype designs to achieve total suspended solids removal efficiencies of 70% & 85%, based upon simulation of 5 years of Providence rainfall data (1983-1987). This catalogue was developed and calibrated before the snowmelt routine was added to P8. Application to time series containing snowfall/snowmelt will generally result in designs with lower removal efficiencies. These can be subsequently refined using the Run Design Tune procedure.
Devices are defined based upon type (wetpond, buffer, etc.) & other parameters determining tss removal (mean depth, infiltration rate, slope, Manning's n, etc.). User selects a device prototype from the menu.
To size the device for the specified watershed, device areas are rescaled based upon ratio of device area to impervious watershed area. The procedure does not account for linkage to upstream devices.
This represents an "initial guess" of design requirements for a particular watershed, device type, & tss removal objective. This design can be refined to reflect the particular watersheds and precipitation time series using the 'Run Design Tune' procedure or by manually editing the device parameters.
Run Design
Tune
This routine rescales existing devices to achieve a user-defined removal efficiency for any particle class or water quality component. In order to run this routine, the user must first define a case containing a preliminary design and run it successfully via the 'Run Model' command.
The user specifies the following:
| Option | Description |
| 1- Areas & Volumes |
bottom area, permanent pool area and volume, flood pool area and volume; length (for swales) |
| 2- Volumes |
permanent and flood pool volumes; area fixed; effectively adjusts mean depth |
| 3- Permanent Pool Volumes | permanent pool volume; area fixed; effectively adjusts mean depth |
| 4-Outlet Capacity |
orifice diameter, weir length, drawdown time; specified normal outflow for general device; for ponds & general devices only |
The routine will
not run on devices that do not remove particles (pipes, splitter,
aquifer). Only options 1 and 4 are available for a general device.
An iterative solution is attempted for the device scale factor (multiplier for initial device dimensions), using the Newton-Raphson technique. A maximum of 10 iterations is performed. Solutions are not always feasible.
The user has the option of
saving the results or reseting the device to the intial dimensions.
Run Sensitivity
Tests sensitivity of overall removal efficiency & surface outflow load to each model input value. The user selects a subset of input variables to be tested (watershed, device, both, particles, all).
The user specifies the devices to be considered (at least one), a single variable (particle class or water quality component) and percentage increase to be used in the sensitivity analysis.
Each model input is increased by a fixed percentage (one at a time). In each iteration, the specified percentage change is applied simultaneously to all members of the specified input group (selected devices, all watersheds, all particles/water quality components). The model is re-executed. Effects on removal efficiency & outflow load for each selected device and for the selected particle class/water quality component are tabulated.
Only input values with positive values are tested.
This procedure is especially useful for obtaining perspective on which model inputs have the greatest impact on model predictions & are therefore most important to estimate or measure accurately (Walker,1982 ).