Gaining vs. losing streams Source: U.S.G.S.

Effects of pumping on GW - surface water interaction Source: U.S.G.S.

Schematic showing basic elements of an unconfined aquifer system Source: U.S.G.S.

Example of a perched water table and its relationship to the regional unconfined aquifer system

Layered aquifer system(s), showing confined aquifer beneath an unconfined aquifer. Note the artesian conditions in the valley.

Aquifer in fractured volcanic rocks (Kona, HI) Source: U.S.G.S. National Groundwater Atlas

Regional aquifers in the Mid-Atlantic U.S. Fractured limestone and metamorphic rock Unconsolidated sediments & sedimentary rock Source: U.S.G.S. National Groundwater Atlas

Locations of major sandstone aquifers in the U.S. Source: U.S.G.S.

Example showing porosity (note that for illustration purposes, the sand grains are shown to be unrealistically far apart) Types of porosity

Example showing porosity in a thin section of sandstone

Hydrostatic Head: An Example... Which way does the groundwater flow? 10 m 3 m 0 m

What is the head at each point? 10 m B Pressure head = 7 m Elevation Head = 3 m Total Head = 10 m 3 m A C 0 m

What is the head at each point? 10 m B Pressure head = ?? m Elevation Head = ?? m Total Head = ?? m 3 m A C 0 m

What is the head at each point? 10 m B Pressure head = 0 m Elevation Head = 10 m Total Head = 10 m 3 m A C 0 m