The Groundwater Flow Editor is invoked when the Groundwater property of a subcatchment is being edited. It is used to link a subcatchment to both an aquifer and to a node of the drainage system that exchanges groundwater with the aquifer. It also specifies coefficients that determine the rate of groundwater flow between the aquifer and the node. These coefficients (A1, A2, B1, B2, and A3) appear in the following equation that computes groundwater flow as a function of groundwater and surface water heads:

Qgw = A1(Hgw - E)B1 - A2(Hsw - E)B2 + A3(HgwHsw)

where

Qgw = Groundwater flow (cms per hectare or cfs per acre).
Hgw = Elevation of groundwater table (m or ft).
Hsw = Elevation of surface water at receiving node (m or ft).
E = Threshold groundwater table elevation or elevation of node invert (m or ft).

Option

 

Description

Aquifer Name

Name of aquifer object that supplies groundwater. Leave this field as None if you want the subcatchment not to generate any groundwater flow.

Receiving Node

Name of node that receives groundwater from the aquifer.

Surface Elevation

Elevation of ground surface for the subcatchment that sits above the aquifer (m or ft).

Groundwater Flow Coefficient

Value of A1 in the groundwater flow formula.

Groundwater Flow Exponent

Value of B1 in the groundwater flow formula.

Surface Water Flow Coefficient

Value of A2 in the groundwater flow formula.

Surface Water Flow Exponent

Value of B2 in the groundwater flow formula.

Interaction Coefficient

Value of A3 in the groundwater flow formula.

Fixed Surface Water Depth

Fixed depth of surface water at receiving node (m or ft). Set to zero if surface water depth will vary as computed by flow routing.

The values of the flow coefficients must be in units that are consistent with the groundwater flow units, which can either be cms/ha for metric units or cfs/acre for US units.

If groundwater flow is simply proportional to the difference in groundwater and surface water heads, then:

See Also SWMM Runoff