Chapter 16: Groundwater in Developing Industrial Region Reading Quizzes

consequences of rapid groundwater withdrawal

- A cone of depression forms. - Pore collapse occurs. - Wells go dry.

Which of the following statements accurately describe what is happening in the subsurface?

- The size of the cone of depression is primarily a function of pumping rate. - Well A will run dry before Well B. EXPLANATION: The size and shape of the cone of depression are controlled by the properties of the aquifer, the rate at which water is being pumped out of the ground, and the depth of the well. If water continues to be pumped from Well B, the water table overall could drop low enough so that Well A would run dry. If water was being injected into Well B, we might actually see a rise in the water table in its vicinity.

Groundwater

- accounts for 95% of the liquid freshwater on Earth, but having enough accessible _________ can be a problem. - typically moves slowly within the ground through porous rock layers like sandstone.

Darcy's law

- an equation used by hydrologists. - developed experimentally to characterize groundwater flow velocity. - states that discharge equals the hydraulic conductivity coefficient times the hydraulic gradient times the area involved. FALSE: is a method to determine the degree of saturation of water at any specified depth.

Water combines with carbon dioxide

- as a natural process, which produces a corrosive component to groundwater. - creating slightly acidic groundwater that dissolves limestone and forms caves. - as it filters through organic-rich soil on its way down to the water table. FALSE: forms carboxylic acid.

water table

- boundary between the saturated and unsaturated zones - may be defined by the surface of a permanent stream, lake, or marsh. - becomes a downward-pointing cone-shaped surface around the bottom of a well. - mimics the topography of the land it underlies. FALSE: lies within a few meters of the surface in arid areas.

thermophilic bacteria and archaea

- bright colors around the edge of the pool are a result of which of this - bright colors are generated in association with the metabolic processes of heat-loving organisms

Water underground

- can completely fill pores in the saturated zone - partially fills pores in the unsaturated zone. - can adhere temporarily to sediment particles and eventually evaporate back into the atmosphere or be absorbed by plant roots (soil moisture).

hot springs

- can dissolve more mineral matter than can cold water springs. - may occur in geothermal regions where current (or recent) volcanism occurs. - may precipitate mounds and terraces of travertine (limestone) as waters cool. FALSE: contain water that is at least boiling temperature (100°C or 212°F).

water table

- defined as top of zone of saturation -

Rate of groundwater flow

- depends on the permeability of the material it flows through and on the hydraulic gradient. - flow rate is 0.5-500 meters, not miles, per year, which is much slower than flow rate of surface water - rate can be measured.

Karst landscapes

- develop after caves collapse - caves are usually formed by water and left empty by a decrease in water level.

soda straws

- develop into stalactites, which hang from cave ceilings - begin as delicate, hollow structures

Stalagmites

- dripstone, not flowstone, which precipitate as sheets of material across broad surfaces - composed of limestone precipitated out of cave water.

area of rolling hills, groundwater moves.....

- from regions under hills to regions under valleys. - along a curved path. - from where the water table is at high elevation to where the water table is at low elevation. FALSE: sometimes parallel to the slope of the water table and sometimes straight down, but never upward.

What is a spelunker NOT likely to encounter?

- geysers because its a surface feature in geothermal areas - limestone columns, speleothems, and flowstones denote structures found in caves, which these explore

Sulfuric acid cave formation

- occurs where limestone overlies strata rich in hydrocarbons like oil. - occurs because microbes convert sulfur in the oil into hydrogen sulfide gas, which oxidizes in the limestone to sulfuric acid. - produces gypsum and CO2 gas as a by-product of the chemical reaction. FALSE: responsible for roughly 50% of all caves.

capillary fringe.

- thin layer - can seep up from the water table due to electrostatic attraction of water molecules to mineral surfaces and form a thin layer

electrostatic attraction

- water moves upward in capillary fringe due to this process - occurs between its molecules and mineral surfaces

groundwater removal steps

1. groundwater rapidly removed from a system 2. level of water table drops 3. pore collapse takes place 4. subsidence occurs over broad region Level of the water table can be lowered. This results in pore collapse because the pore spaces that were once filled with water become filled with air, which is more readily compressible. When this happens over a broad region, subsidence, or the sinking of the ground surface overall, occurs.

factors depending on permeability of a rock

1. number 2. size 3. straightness of available conduits

probable causes for decrease in level of water table

1. urbanization 2. drought 3. well usage

porosity decreases when....

1. with increasing crystallization of sediments into sedimentary rock. 2. with the cementing of sediments by minerals from groundwater. 3. when grains don't fit together during deposition.

Which of the following statements is FALSE? (A)

A. Over the span of 10 to 1,000 years, groundwater behaves as a renewable resource. (XX) B. Withdrawal of groundwater faster than natural recharge occurs has caused extreme land subsidence in the San Joaquin Valley, California. C. Overuse of groundwater in the Everglades of Florida has caused parts of the swamp to dry up. D. A sinkhole developed at Winter Park, Florida, due to dissolution of limestone bedrock.

karst landscapes

Features that are created when water dissolves surface and subsurface limestone, like sinkholes, troughs, caverns, natural bridges, and towers, are collectively called this

geyser

Groundwater in underground, constricted fractures is heated past its normal boiling temperature by surrounding hot rocks. The superhot liquid expands in volume; this reduces its confining pressure, and it flashes into steam. This is an explanation of which geologic feature?

springs

Interconnected fractures that open onto a hillside and an impermeable rock layer intersecting a hillside are both likely of this location

bioremediation

The technique that injects oxygen and nutrients into a contaminated aquifer to foster the growth of bacteria that can break down contaminant molecules

potentiometric surface.

Water in a water tower sits at a higher level than the water in the city's pipes, creating pressure that forces water into the plumbing of surrounding homes. This pressure is created because water in the network of pipes in the community will rise to an imaginary plane (the dashed line in this figure), called the....

perched water table

can occur anywhere that an impermeable lens of rock stops the downward percolation of groundwater

unconfined aquifer

can reach Earth's surface, so it lies above any aquitards

precipitation

chief source of groundwater

hot springs and mud pots

don't have constricted fractures where water expands in volume significantly and escapes as steam.

aquicludes

don't transmit water at all.

aquitards

don't transmit water easily

lowering of water tables

growing problem in California FALSE: A. Pumping on a well can produce a local slope to the water table, but cannot affect the direction of groundwater flow. B. ​Mining groundwater simply means pumping it out of wells. C. In coastal areas saltwater can enter an aquifer, float on the freshwater there, and be drawn up in wells.

What kinds of properties allow this volcanic rock to float on water?

high porosity, low permeability

Pumping on the large irrigation well

improved the quality of the home's water supply well.

aquitard

inhibits the flow of water so that water in a confined aquifer cannot reach Earth's surface

geothermal landscapes

involve geysers, hot springs, and mud pots

Potentiometric surfaces

levels to which artesian waters have the potential to rise

unsaturated zone

lies above the water table. In the unsaturated zone, pore spaces are filled with both air and water

saturated zone

lies below the water table, all of the pore spaces are filled (or saturated) with water

Groundwater contaminants

like methane, arsenic, and salt may occur naturally here FALSE B. dissipate quickly into the groundwater reservoir and often do not pose a problem. C. are all eventually removed by rock and sediment acting as natural filters. D. are always toxic materials like arsenic, mercury, and lead.

porosity

measure of how much water rock can hold

permeability

measure of how well water can travel through that rock

artesian spring

not geothermal feature

Primary porosity

porosity developed during both sediment deposition and rock formation

Interconnected fractures

provide conduits for groundwater to reach the surface and can produce springs.

secondary porosity

refers to new pore spaces formed in existing rock by jointing, faulting, and dissolution

subsidence

sinking of the ground surface overall

hydraulic gradient

slope of the water table

This image shows contaminated groundwater spilling from a collapsed seam in a coal mine. What source causes this distinctive type of pollution?

sulfide minerals

geysers

surface feature in geothermal areas

Aquifers

transmit water easily

artesian well

well in which the water rises on its own to a level above its aquifer