Catchment-Runoff
Catchment-Runoff Attributes
| Attribute | Description |
|---|---|
| Runoff Method | Lets you set what type of runoff method the currently highlighted element uses. The value chosen here affects the availability of other fields. You can select Unit Hydrograph , EPA-SWMM Runoff , User-Defined Hydrograph , None , or Modified Rational Method. |
| Characteristic Width | Characteristic width of the currently highlighted catchment. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Storage (Impervious Depression) | Depth of depression storage on impervious portion of the catchment. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Storage (Pervious Depression) | Depth of depression storage on the pervious portion of the catchment. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Manning’s n (Impervious) | Manning's N for overland flow over the impervious portion of the currently highlighted catchment. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Manning’s n (Pervious) | Manning's N for overland flow over the pervious portion of the currently highlighted catchment. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Percent Impervious | Percent of land area which is impervious. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Slope | Average slope, in percent, of the currently highlighted catchment. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Percent Impervious Zero Storage | Percent of the impervious area with no depression storage. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Subarea Routing | Lets you define the type of subarea routing at the currently highlighted element. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Percent Routed | Percent of runoff routed between subareas. This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff . |
| Runoff Hydrograph | Lets you define time vs. flow points for the currently highlighted element. Click the Ellipsis (…) button in this field to open the User Defined Hydrograph dialog box (see Specifying a Time of Concentration (Tc) Method for a Catchment). This attribute is available only when the Runoff Method attribute is set to User Defined Hydrograph . |
| Loss Method | Lets you define what type of loss method the currently highlighted element uses. You can select fLoss , Green and Ampt , SCS CN , or (Generic) Horton . The value chosen here affects the availability of other fields. |
| fLoss | Lets you define the initial infiltration rate at the time that infiltration begins for the currently highlighted element. This attribute is active only when the Loss Method attribute is set to fLoss . |
| Capillary Suction | Lets you define the capillary suction value for the soil type associated with the currently highlighted element. This attribute is active only when the Loss Method attribute is set to Green and Ampt . |
| Ks | The saturated hydraulic conductivity (the rate at which water travels through the soil when it is saturated) for the currently highlighted element. This attribute is active only when the Loss Method attribute is set to Green and Ampt . |
| Moisture Deficit | The value for moisture deficit, which is the saturated moisture content minus the original moisture content, for the currently highlighted element. This attribute is active only when the Loss Method attribute is set to Green and Ampt . |
| SCS CN | Lets you set a Cn value for the catchment. You can either type a value in the field or click the Ellipsis (…) button to open the Cn Area Collection dialog box (see Defining CN Area Collections for Catchments). This attribute is active only when the Loss Method attribute is set to SCS CN . |
| SCS CN (Composite) | The weighted CN value. This attribute is a calculated field and is active only when the Loss Method attribute is set to SCS CN . |
| Use Scaled Area? | If True, the area of the catchment will be calculated based on the area of the polygon. |
| fc | The equilibrium infiltration rate on the Horton infiltration curve reached once the soil becomes saturated. |
| fo | The initial or maximum infiltration rate on Horton infiltration curve. |
| Initial Abstraction | Lets you define the initial abstraction (Ia) for the currently highlighted element. The initial abstraction is a parameter that accounts for all losses prior to runoff and consists mainly of interception, infiltration, evaporation, and surface depression storage. This attribute is active only when the Loss Method attribute is set to (Generic) Horton . |
| K | Decay constant associated with the soil. |
| Recovery Constant | Dry weather regeneration rate constant for the Horton curve. This attribute is active only when the Loss Method attribute is set to (Generic) Horton . |
| Maximum Volume | ???? This attribute is available only when the Runoff Method attribute is set to EPA-SWMM Runoff and the Loss Method attribute is set to (Generic) Horton . |
| Unit Hydrograph Method | Lets you define the type of unit hydrograph method the currently highlighted element uses. The value chosen here affects the availability of other fields. You can select Generic Unit Hydrograph , SCS Unit Hydrograph , or RTK Unit Hydrograph . |
| RTK Set | Lets you assign an RTK table to the catchment. If there is no RTK table associated with your model, click the Ellipsis (…) button in this field to open the RTK Tables dialog box (Creating an RTK Table and Assigning it to a Catchment), where you can create new RTK tables. This field is available only when the Unit Hydrograph Method is set to RTK Unit Hydrograph . |
| RTK Table | Lets you assign an RTK table to the catchment. If there is no RTK table associated with your model, click the Ellipsis (…) button in this field to open the RTK Tables dialog box (Creating an RTK Table and Assigning it to a Catchment), where you can create new RTK tables. This field is available only when the Unit Hydrograph Method is set to RTK Unit Hydrograph . |
| Tc | The time of concentration for the currently highlighted element. It is available only when the Unit Hydrograph Method attribute is set to SCS Unit Hydrograph . |
| Tc (Composite) | The total summed Tc value derived from the individual Tc Methods in the Tc Data Collection. |
| Generic Unit Hydrograph | Lets you define time vs. flow points for the currently highlighted element. Click the Ellipsis (…) button in this field to open the Unit Hydrograph Data dialog box (Adding Generic Unit Hydrographs). This field is available only when the Unit Hydrograph Method is set to Generic Hydrograph . |
| Unit Hydrograph Data | Lets you define time vs. flow points for the currently highlighted element. Click the Ellipsis (…) button in this field to open the Unit Hydrograph Data dialog box (Adding Generic Unit Hydrographs). This field is only available when the Unit Hydrograph Method is set to Generic Hydrograph . |
| Shape Factor | Allows you to define the shape factor when using the Triangular SCS Unit Hydrograph Method. |
| Convolution Time Step | Lets you define the time step for the currently highlighted element. It is available only when the Unit Hydrograph Method is set to Generic Unit Hydrograph. |
| Tc Data Collection | Contains individual Tc components for calculating the total composite Tc for the current catchment. |
| Rational C | The Rational C coefficient of the catchment section. This field is available when the Runoff Method attribute is set to Modified Rational Method . |