Geology & Groundwater Hydrology Flashcards

What term describes the pressure surface to which water in a confined aquifer will rise in a tightly cased well?

Answer: Piezometric surface

The piezometric (potentiometric) surface represents the hydraulic head in a confined aquifer and is the level to which water rises under artesian pressure.

Which sedimentary rock type is MOST commonly associated with karst aquifer systems?

Answer: Limestone

Limestone is soluble in slightly acidic groundwater, creating caves, sinkholes, and conduit flow networks characteristic of karst systems.

Darcy's Law states that groundwater flow rate is proportional to which property?

Answer: Hydraulic gradient and hydraulic conductivity

Darcy's Law (Q = K·i·A) shows that flow is directly proportional to both hydraulic conductivity (K) and hydraulic gradient (i).

A formation that transmits water but yields it slowly, often acting as a leaky boundary, is called a(n):

Answer: Aquitard

An aquitard restricts but does not completely prevent groundwater flow, and can contribute water to adjacent aquifers through leakage.

What is the primary mechanism by which an artesian well flows at the surface without pumping?

Answer: Hydrostatic pressure in a confined aquifer exceeds the land surface elevation

A flowing artesian well occurs when the potentiometric surface of a confined aquifer lies above the ground surface at the well location.

During a pumping test, the cone of depression expands outward until it reaches:

Answer: A recharge boundary or equilibrium

The cone of depression expands until inflow from recharge or hydraulic boundaries equals the pumping rate, achieving steady-state conditions.

Which rock characteristic makes fractured crystalline bedrock a viable but unpredictable water source?

Answer: Secondary porosity from fractures and joints

Crystalline rocks like granite have very low primary porosity but can yield significant water through secondary porosity created by fractures, faults, and joints.