User:Jcreer/SWB

The Soil-Water-Balance (SWB) model has been developed by USGS to allow estimates of potential recharge to be made quickly and easily.

Required Input

Four gridded datasets are required:

• Hydrologic soil group
• land-use/land cover
• Available soil-water capacity
• Surface-water flow direction

In addition to gridded land-surface data the model requires tabular daily climatological data (daily precip (inches), average air temperature [F], max air temp [F], min air temp [F]). Additional data may be required depending on model options: (1) daily average wind speed (m/s), (2) daily average relative humidity (%), (3) daily max relative humidity (%), (4) daily percentage of possible sunshine (%). Finally a lookup table must be supplied to assign curve numbers, interception values, rooting depths, and maximum daily recharge values.

Creating an SWB Simulation

To create an SWB simulation, do the following:

1. Right-click on the "Project" item the Project Explorer and select New Simulation | SWB.

Simulation Menu

Right-clicking on the simulation item in the Project Explorer will bring up the following menu command:

• Delete – Removes the simualation item.
• Duplicate Creates a copy for the simulation, including all parameters set in the model control.
• Rename – Allows changing the name of the simulation item.
• Model Control
• Model Check
• Export SWB
• Launch SWB
• Save, Export, and Launch SWB
• Properties

Model Control

The parameters for the SWB model run are set in the Model Control dialog.

Required Inputs

• Model Domain Definition
• Growing Season
• Climate Data
• Flow Direction
• Soil Group
• Land Use
• Available Soil-water Capacity
• Initial Soil Moisture
• Initial Snow Cover
• Runoff Calculation and Routing Method
• Evapotranspiration Method

External Links

• SWB website with USGS
• SWB User Manual