Aquifer — StormNET Help

⚠ StormNET vs SwaNET vs IGW-NET groundwater — three different models
All three MAGNET4WATER platforms have a "groundwater" component, but they solve fundamentally different problems:

StormNET (this page): SWMM-style 2-zone aquifer storage per subcatchment (unsaturated + saturated zones). Used to compute groundwater contribution to/from the stormwater drainage system at the subcatchment scale.
SwaNET: SWAT-style single-aquifer baseflow per HRU (linear-reservoir recession). Used for watershed-scale baseflow contribution to streams.
IGW-NET: Full 3D MODFLOW groundwater simulator (multi-layer heads, flow paths, pumping, transport). Used for detailed groundwater modeling.

Neither StormNET's nor SwaNET's groundwater component is a substitute for IGW-NET. Use the platform that matches your scale and physics.

Aquifers are sub-surface groundwater zones used to model the vertical movement of water infiltrating from the subcatchments that lie above them. They also permit the infiltration of groundwater into the drainage system, or exfiltration of surface water from the drainage system, depending on the hydraulic gradient that exists. Aquifers are only required in models that need to explicitly account for the exchange of groundwater with the drainage system or to establish baseflow and recession curves in natural channels and non-urban systems.

The parameters of an aquifer object can be shared by several subcatchments but there is no exchange of groundwater between subcatchments. A drainage system node can exchange groundwater with more than one subcatchment.

Aquifers are represented using two zones - an un-saturated zone and a saturated zone. Their behavior is characterized using such parameters as soil porosity, hydraulic conductivity, evapotranspiration depth, bottom elevation, and loss rate to deep groundwater. In addition, the initial water table elevation and initial moisture content of the unsaturated zone must be supplied.

Aquifers are connected to subcatchments and to drainage system nodes as defined in a subcatchment's Groundwater Flow property. This property also contains parameters that govern the rate of groundwater flow between the aquifer's saturated zone and the drainage system node.

The Aquifer Editor is invoked whenever a new Aquifer object is created or an exisitng Aquifer object is selected for editing. It contains the following data fields:

Field	Description
Name	User-assigned aquifer name
Porosity	Volume of voids / total soil volume (volumetric fraction).
Wilting Point	Soil moisture content at which plants cannot survive (volumetric fraction).
Field Capacity	Soil moisture content after all free water has drained off (volumetric fraction).
Conductivity	Soil's saturated hydraulic conductivity (in/hr or mm/hr).
Conductivity Slope	Average slope of log(conductivity) versus soil moisture deficit (i.e., porosity minus moisture content) curve (unitless).
Tension Slope	Average slope of soil tension versus soil moisture content curve (inches or mm).
Upper Evaporation Fraction	Fraction of total evaporation available for evapotranspiration in the upper unsaturated zone.
Lower Evaporation Depth	Maximum depth below the surface at which evapotranspiration from the lower saturated zone can still occur (ft or m).
Lower Groundwater Loss Rate	Rate of percolation to deep groundwater when the water table reaches the ground surface (in/hr or mm/hr).
Bottom Elevation	Elevation of the bottom of the aquifer (ft or m).
Water Table Elevation	Elevation of the water table in the aquifer at the start of the simulation (ft or m).
Unsaturated Zone Moisture	Moisture content of the unsaturated upper zone of the aquifer at the start of the simulation (volumetric fraction) (cannot exceed soil porosity).
Upper Evaporation Pattern	The name of a monthly time pattern used to adjust the Upper Evaporation Fraction for different months of the year. Leave blank if not applicable.