General Slots
Area
Type: Scalar
Units: Area
Description: The horizontal area of the aquifer.
Information: This value must be non zero.
I/O: Required Input
Links: Not Linkable
Head
Type: Series
Units: Length
Description: This represents the hydraulic or piezometric head, which is a specific measurement of liquid pressure.
Information: This value is presented at the computational timestep.
I/O: Typically Output, but a specified value (input/rules) is required for initialization as follows. If the run start date falls on the first date of a computational timestep, a value must be provided for the Head at the run initial date. If not, Head Previous must be specified as described below.
Links: Typically not linked.
Head Previous
Type: Series
Units: Length
Description: This slot holds the value of the Head from the previous computational timestep duplicated over the run timesteps, during the computational timestep.
Information: This slot holds values at the run timestep.
I/O: Typically computed, but if the run start date falls after the first date of a computational timestep, a value must be provided for the Head Previous on the start timestep.
Links: Linkable to one or more adjacent objects Head Previous L/R/U/D/A/B
Specified Inflow
Type: Series with Periodic Input
Units: Flow
Description: Inflows to the aquifer typically from other sources that are not modeled. This slot provides a place to specify any inflows that aren’t classified as other inflows, such as recharge.
Information: This value can be positive (into the object) or negative (out of the object). Specified Inflows that are negative can cause the storage to become negative.
I/O: Input as a periodic or series data. Specify a single value if you have a constant value. If no value is specified, it is assumed the value is zero, but that is not shown on the slot.
Links: Not Linkable
Storage
Type: Series
Units: Volume
Description: The volume of water in the aquifer.
Information: This value is computed by the mass balance computation.
I/O: Typically output, but the value on the last timestep of the previous computational timestep must be specified.
Links: Not linkable.
Storativity
Type: Scalar
Units: No Units
Description: The storativity or storage coefficient is the volume of water released/gained from storage per unit decline/increase in hydraulic head in the aquifer, per unit area of the aquifer. Storativity is a unit less quantity, and ranges between 0 and the effective porosity of the aquifer.
Information: This value must be non zero.
I/O: Required Input
Links: Not Linkable
User Methods
User method categories are as follows.
• Pumping
Revised: 11/11/2019