An aquifer storage account

A fictional annual water budget defines an aquifer area of 500 square kilometers and recharge depth of 45 millimeters over that area. Pumping removes 40 million cubic meters during the same year. For this exercise, other inflows and outflows are set to zero; these are assumptions, not claims about an actual aquifer. The team is asked to calculate the change in stored water and discuss a proposed prediction of groundwater-level decline. No storage coefficient, aquifer geometry beyond the area or spatial pumping distribution is given. The data support a volume account, but any conversion into a particular decline in meters requires information not supplied in the teaching model.