QUAL2K Wizard Field Reference: All Input Parameters Explained
This reference documents every input field in the QUAL2K Web Wizard, based on the EPA QUAL2K parameter definitions. Fields are organized by wizard card. Default values are shown where applicable. For a walkthrough of how to use these fields, see the Getting Started guide.
Card 1: Project Setup Fields
| Field | Key | Units | Default | Description |
|---|---|---|---|---|
| River Name | riverName | — | "" | Name of the river system being modeled |
| Simulation Date | simDate | YYYY-MM-DD | today | Date of the simulation scenario |
| Time Zone | timezone | hours UTC | -5 | UTC offset for solar calculations |
| Calc Step | calcStep | minutes | 11.25 | Numerical integration time step |
| Integration Method | integration | — | Euler | Euler or Runge-Kutta |
| Simulation Type | simType | — | Steady | Steady-state or Diel (24-hour) |
Card 2: Reach Definition
| Field | Key | Units | Range | Description |
|---|---|---|---|---|
| Reach Name | name | — | — | Identifier (e.g., "PR1", "VPR1") |
| Downstream Distance | downstreamDist | km | > 0 | Cumulative distance from headwater |
| Upstream Elevation | upstreamElev | m | ≥ 0 | Elevation at upstream end of reach |
| Downstream Elevation | downstreamElev | m | ≥ 0 | Elevation at downstream end of reach |
| Manning's n | manningN | — | 0.01–0.30 | Roughness coefficient for the channel |
| Bottom Width | bottomWidth | m | > 0 | Width of the channel bottom |
| Side Slope 1 (left) | sideSlope1 | H:V | ≥ 0 | Left bank slope (0 = vertical) |
| Side Slope 2 (right) | sideSlope2 | H:V | ≥ 0 | Right bank slope (0 = vertical) |
Card 3: Headwater
| Field | Key | Units | Range | Description |
|---|---|---|---|---|
| Flow | flow | m³/s | > 0 | Headwater (upstream boundary) flow rate |
| Temperature | temperature | °C | 0–40 | Water temperature at headwater |
| DO | do | mg/L | 0–15 | Dissolved oxygen at headwater |
| CBOD Fast | cbodFast | mg/L | ≥ 0 | Fast carbonaceous BOD |
| CBOD Slow | cbodSlow | mg/L | ≥ 0 | Slow (refractory) BOD |
| Organic N | orgN | μg/L | ≥ 0 | Organic nitrogen |
| NH₄ | nh4 | μg/L | ≥ 0 | Ammonium nitrogen |
| NO₃ | no3 | μg/L | ≥ 0 | Nitrate nitrogen |
| Organic P | orgP | μg/L | ≥ 0 | Organic phosphorus |
| Inorganic P | inorgP | μg/L | ≥ 0 | Inorganic (soluble reactive) phosphorus |
| ISS | iss | mg/L | ≥ 0 | Inorganic suspended solids |
| Conductivity | cond | μmhos | ≥ 0 | Electrical conductance |
| Pathogens | pathogens | cfu/100mL | ≥ 0 | Indicator organisms (E. coli, fecal col.) |
| Alkalinity | alk | mg CaCO₃/L | ≥ 0 | Buffering capacity |
Card 4: Point Sources
| Field | Key | Units | Description |
|---|---|---|---|
| Name | name | — | Source identifier (e.g., "WWTP Effluent") |
| Location | location | km | Distance from headwater where source enters |
| Flow | flow | m³/s | Discharge flow rate (positive = injection) |
| Abstraction | abstraction | m³/s | Water withdrawal flow rate |
| Temperature | temperature | °C | Effluent temperature |
| All WQ fields | (same as HW) | — | Constituent concentrations in effluent |
Card 5: Diffuse Sources
| Field | Key | Units | Description |
|---|---|---|---|
| Name | name | — | Source identifier (e.g., "Agricultural runoff") |
| Upstream Location | upLocation | km | Start of diffuse source zone |
| Downstream Location | dnLocation | km | End of diffuse source zone |
| Flow | flow | m³/s | Total distributed flow over the zone |
| All WQ fields | (same as HW) | — | Constituent concentrations |
Card 6: Kinetic Rate Input Parameters
| Field | Key | Units | Default | Description |
|---|---|---|---|---|
| CBOD fast decay | kdc | day⁻¹ | 0.20 | Fast CBOD oxidation rate at 20°C |
| CBOD slow decay | kdcs | day⁻¹ | 0.01 | Slow CBOD oxidation rate at 20°C |
| Hydrolysis | khc | day⁻¹ | 0.02 | Slow → Fast CBOD transfer rate |
| Nitrification | kn | day⁻¹ | 0.20 | NH₄ → NO₃ oxidation rate |
| Denitrification | ki | day⁻¹ | 0.00 | NO₃ → N₂ reduction rate |
| Org N hydrolysis | khn | day⁻¹ | 0.02 | Organic N → NH₄ transfer rate |
| Org P hydrolysis | khp | day⁻¹ | 0.01 | Organic P → Inorg P transfer rate |
| Pathogen die-off | kb | day⁻¹ | 1.00 | Pathogen first-order decay rate |
| ISS settling | vss | m/d | 0.00 | ISS settling velocity |
| SOD | SOD | g O₂/m²/d | 0.00 | Sediment oxygen demand |
| O₂:N ratio | ron | mg O₂/mg N | 4.57 | Stoichiometric oxygen:nitrogen ratio |