For the InstructorThese student materials complement the Water Science and Society Instructor Materials. If you would like your students to have access to the student materials, we suggest you either point them at the Student Version which omits the framing pages with information designed for faculty (and this box). Or you can download these pages in several formats that you can include in your course website or local Learning Managment System. Learn more about using, modifying, and sharing InTeGrate teaching materials.
Atlantic Coastal Plain Aquifer System
The Atlantic Coastal Plain aquifer system extends North-South along much of the Eastern portions of New Jersey, Delaware, Pennsylvania, Virginia, and North Carolina (Figure 19). It consists of a sequence of layered sedimentary aquifers (sands and gravels) separated by series of aquitards, all deposited starting around 100 million years ago and continuing today. The layers slope, or dip, to the East and extend offshore for tens of km beneath the continental shelf (Figure 21).
Source: USGS Water Atlas
Recharge occurs by both natural and managed infiltration on land across much of the coastal plain; groundwater flow in the subsurface is mainly to the East along the sediment layers. One interesting consequence of this flow pattern is that there may be a sizable freshwater resource offshore that could be accessed by drilling in relatively shallow water on the continental shelf. During the last ice age, when conditions were substantially wetter than today and a nearly mile-thick ice sheet covered the northern extent of the aquifer system, recharge was probably even larger - and thus may have forced fresh water several tens of km offshore, where that "fossil" water may remain today!
The Atlantic Coastal Plain system is an important water source for domestic/municipal supply and industry in population centers throughout coastal North Carolina, Maryland, Virginia, Delaware, and New Jersey. However, concentrated, localized pumping has led to a reversal of flow direction (toward the wells instead of Eastward) in some of the aquifer units throughout the region. In addition to overarching concerns about the sustainability of withdrawals that exceed recharge rates, the flow reversal has led to local salt-water intrusion, whereby saline ocean water infiltrates the aquifer and in some cases renders it non-potable.