Hi,
I am using MODFLOW5 within Groundwater Vistas. I inserted pumping shapefile and well data into it with negative sign (as pumping is going out from the system). But after simulation it shows as positive value and counts as input value in water balance. May be I am doing/counting something in a wrong way.
Could you please share your experience/expertise regarding this issue?
Thank you.
Rahena
In MODFLOW 5 and Groundwater Vistas, when you are simulating groundwater flow in a model, "pumping data" is typically counted as a positive value because it represents the removal or extraction of groundwater from the system. Groundwater pumping is often a significant factor in groundwater modeling because it reflects the withdrawal of water from the aquifer for various purposes such as municipal water supply, industrial use, or agricultural irrigation.
Here's why pumping data is counted as positive:
In MODFLOW, which is a widely used groundwater flow simulation software, the concept of "pumping data counted as positive" refers to the convention used for specifying the flow rates of wells or sources in the model. This convention is not unique to Groundwater Vistas but is a standard convention followed in MODFLOW-based modeling software, including MODFLOW-2005 (MODFLOW5).
In MODFLOW, the convention is as follows:
- Pumping or extraction wells: When you specify the flow rate for a pumping well, you should enter a positive value if water is being pumped out of the aquifer. This follows the standard convention of considering water extraction as a positive flow out of the aquifer.
- Injection or recharge wells: Conversely, if you are specifying an injection well or a well that is recharging water into the aquifer (such as an artificial recharge well), you should enter a negative value for the flow rate. This indicates that water is being added to the aquifer.
This convention simplifies the input process for the user and ensures that flow rates are correctly represented in the groundwater flow simulation. It also aligns with common hydrogeological practice where extraction is considered a positive flow and injection is considered a negative flow.
Keep in mind that this convention is used for specifying flow rates in MODFLOW input files, including those created or edited using software like Groundwater Vistas, which is a graphical user interface (GUI) for MODFLOW. When you input data into Groundwater Vistas or similar software, it typically follows this standard convention to ensure consistency with the underlying MODFLOW model.