The Hidden Reservoirs: Groundwater Aquifers Quiz

If the movement of water is being described as downward into the earth, then there must be a force pulling it toward the center of the planet. If gravity is the universal force that attracts objects with mass toward each other, then gravity is the specific force pulling water through the pores of soil and rock.

If a geological formation is being evaluated for its ability to both hold water and allow it to move, then it must have high porosity and permeability. If an "aquifer" is defined as a body of rock or sediment that yields a usable quantity of water, then this is the correct term for the storage and transmission layer.

If we distinguish between the zone where pores contain both air and water and the zone where all pores are filled with water, then there must be a dividing line between them. If the "water table" is the top of the saturated zone, then it represents the level below which the ground is fully saturated.

If porosity is the measure of empty space (holes) in a material, then many small holes indicate high porosity. If permeability is the ability for fluids to flow through those holes, and the holes are not connected, then the fluid cannot flow, resulting in low permeability.

If groundwater exists within the earth, it must occupy the space available. If most subsurface material consists of soil, sand, and rock with tiny pores rather than vast empty caverns, then the water is stored in these microscopic spaces. Therefore, the idea of vast underground "rivers" is generally a misconception.

If an aquifer is "unconfined," it is open to the surface and atmospheric pressure. If it is "confined," it is sandwiched between layers that prevent water from easily moving in or out vertically. Therefore, an aquifer trapped between impermeable layers is a confined aquifer.

If the water table is maintained by "recharge" from precipitation, then a lack of rain means no new water is being added. If gravity and human extraction continue to pull water away while no new water arrives, then the volume of stored water decreases, causing the water table level to fall.

If permeability depends on the ability of water to move through a material, then the spaces must be large enough for water molecules to pass. If clay consists of extremely fine particles that pack tightly together, then the pathways for water are restricted. Thus, clay prevents flow and is impermeable.

If water rises without a pump, there must be pressure pushing it upward. If pressure builds up when water is trapped between two impermeable layers at a higher elevation than the well head, then this setup requires a confined aquifer. Therefore, artesian wells only occur in confined systems.

If water falls on the land surface as rain or snow, it must enter the soil to become groundwater. If "infiltration" is the term for the downward entry of water into the soil or rock surface, then this is the specific process that feeds aquifers.

If water is removed from a single point (the well) faster than it can flow back in from the surrounding area, then the water level at that point will drop locally. If this creates a V-shaped or funnel-shaped dip in the water table around the well, then this feature is known as a cone of depression.

If we define "saturated" as "filled to capacity with water," then this must occur deeper where gravity pulls the water. If the "unsaturated" zone contains both air and water, it must be the layer closer to the surface. Since the water table is the dividing line, the saturated zone lies beneath it.

If groundwater requires specific rock properties like porosity and permeability to exist, then the type of rock present is critical. If geological processes (like sedimentation or volcanic activity) determine which rocks are in a specific location, then those processes directly control where water can be stored.

If water has mass, it is subject to gravity. If gravity pulls all objects toward a lower potential energy state, then it will pull groundwater from areas of higher elevation (recharge zones) to areas of lower elevation (discharge zones like springs or oceans).

If an aquifer loses water to wells or springs, it must be replenished to remain sustainable. If replenishment occurs when surface water infiltrates the soil and reaches the saturated zone, then the geographic area where this happens is called the recharge zone.

If permeability is the measure of flow, then a material that stops flow must have the opposite property. If the prefix "im-" means "not," then "impermeable" is the correct technical term for a substance that acts as a barrier to water.

If a high-yielding aquifer requires both storage space (porosity) and easy flow (permeability), then the material must have large, connected gaps. If loose gravel and sand have significantly larger spaces between particles than clay or solid rock, then they provide the best environment for water movement.

If an unconfined aquifer is open to the surface, any liquid on the surface can infiltrate the soil. If there is no "aquiclude" or impermeable barrier between the surface and the water table, then the chemicals will follow the path of the water down into the storage zone, causing contamination.

If groundwater must travel through tiny, twisting pores in rock and soil, it encounters a massive amount of friction. If friction slows down the movement of fluids, then the water will move very slowly (often only inches or feet per day). Therefore, it does not flow like an open surface river.

If the water table intersects the land surface (perhaps on a hillside), the water will naturally flow out of the ground. If a "spring" is defined as a place where water wells up from an underground source to the surface, then this is the correct term for a natural discharge point.