Geology 111 QUIZ 5
What energy is responsible for the movement of groundwater?
Gravity In response to gravity, water moves from areas where the water table is high to zones where the water table is lower.
What represents the largest reservoir of freshwater that is readily available to humans?
Groundwater
a form of storage that sustains streams during periods when rain does not fall:
Groundwater
The second largest volume of freshwater in the hydrosphere:
Groundwater with slightly more than 30 percent of the total
What is the principal source of drinking water of the U.S. population, and at what percent?
Groundwater Is the principal source of drinking water for about 50 percent of the U.S. population
What is groundwater, and how does it relate to the water table?
Groundwater is water that occupies the zone of saturation within the ground. The water table is the upper limit of the groundwater.
about 75 percent of our freshwater comes from surface sources.
Groundwater provides the remaining 25 percent
Water falling in Illinois would ultimately end up where?
Gulf of Mexico
Still water level of a wave
Half way between the crests and troughs which is the level the water would occupy if there were no waves
headward erosion
Headward erosion occurs when the surface flow converging at the head of a channel has enough power to cut the channel deeper (downcut). This lowering of the channel creates steeper headward slopes that erode more quickly. Thus, through headward erosion, a valley extends into previously undissected terrain
Wavelength
Horizontal distance between the crests or between the troughs of two adjacent waves
Bed load
Sediment moved along the bottom of a stream by moving water, or particles moved along the ground surface by wind.
The erosional power of a stream is related to its:
Slope and discharge
Which of the following sketches best represents the longitudinal profile of the slope of a streambed?
Slope decreases downstream.
Sediment deposition
Solid bits of weathered rock are eroded, then deposited by wind, water, ice, and gravity
Gaining streams
Streams that gain water from the inflow of groundwater through the streambed.
What has thr largest drainage basin in North America?
The Mississippi river, collecting and carrying 40 percent of the flow in the United States
How would a beach be affected if a wide berm were protected from erosion during winter months?
The wintertime beach would look similar to the summertime beach.
How are winter beaches different from summer beaches?
Winter waves are short and high, whereas summer waves are long and shallower.
Divide
a boundary, usually a hill or mountain, where water will flow in opposite directions on either side Eg. Appalachian Mountains
Cone of depression
a cone-shaped depression in the water table immediately surrounding a well Because the cone of depression increases the hydraulic gradient near the well, groundwater flows more rapidly toward the opening
Point bars
a crescent-shaped accumulation of sand and gravel deposited on the inside of a meander
When does a wave "break"?
a critical point is reached when the wave is too steep to support itself and the wave front collapses
What is a stream's longitudinal profile?
a cross-sectional view of a stream from the headwaters to its mouth
How long does it take berms to become narrow and rocky after summer has passed?
a few weeks
What is a meander scar?
a landscape feature formed after an oxbow lake dries up
What is an oxbow lake?
a meander that has been cut off from the original stream channel
Competence
a measure of the largest particle a stream can transport; a factor dependent on velocity
Tributary
a river that feeds into another river Eg. Big Horn River
Distributaries
a section of a stream that leaves the main flow
Cutoff
a short channel segment created when a river erodes through the narrow neck of land between meanders
Cross-sectional shape
a slice taken across the channel
Superposed stream
a stream whose geometry has been laid down on a rock structure and is not controlled by the structure, can erode its channel into and an existing structure
depositional floodplain
produced by major fluctuations in base level or climate conditions
What percentage is ground water used for rural domestic supplies?
provides about 96 percent of the water used for rural domestic supplies.
Steep bedrock channels often develop a sequence of steps and pools,
relatively flat segments (pools) where alluvium tends to accumulate, and steep segments (steps) where bedrock is exposed. The steep areas contain rapids or, occasionally, waterfalls.
Quarrying
removing loosened blocks from the bed of a channel during times of high flow rates
How can pieces of rock in contact with a stream bed move?
rolling, sliding, bouncing
Bars
small scale channel deposits composed of sand and gravel Such features, however, are only temporary, as the material will be picked up again and eventually carried to the ocean.
Sediment production
• Zone where most sediment is derived • Located in the headwater region of a river system • Sediment generated by - Bedrock broken into smaller pieces - Bank erosion - Scouring of the channel bed
Interface
Nowhere is the restless nature of the ocean more noticeable than along the shore—the dynamic interface among air, land, and sea. It is a common boundary where different parts of a system interact.
How does water get from the oceans onto land?
Ocean water evaporates to form gaseous water and moves into the atmosphere, where it condenses into liquid water and falls out of the atmosphere to land as rain.
How are oxbow lakes formed?
Oxbow lakes form when one meander erodes into another, cutting off water to part of the stream channel.
Aquifers
Permeable rock strata or sediment that transmit groundwater freely larger particles, such as sand or gravel, have larger pore spaces. Therefore, the water moves with relative ease. Sands and gravels are common examples.
What would you do to both grow a large beach and protect a harbor mouth?
Place two jetties on either side of the harbor mouth, and build a breakwater upcurrent from the harbor mouth.
Contrast porosity and permeability.
Porosity is the percentage of the total volume of rock or sediment that consists of pore spaces, whereas permeability is the ability of a rock or sediment to transmit fluid.
Where does coastal erosion happen?
Predominantly, and most severely across the east coast Moderately across the west coast
Flood prediction formula:
Recurrence Interval = RI = N +1 / M N = # of years of records M = rank of discharge
When the surface material is impermeable or when it becomes saturated, what is the dominant process?
Runoff. Runoff is also high where slopes are steep and in cities where large areas are covered with impermeable buildings, roads, and parking lots.
Which of the following are part of the bed load? CHOOSE ALL THAT APPLY
Sand, gravel
Ultimate base level
Sea level; the lowest level to which stream erosion could lower the land.
Troughs
The low points on a wave
Bankfull
The maximum discharge that a river channel is capable of carrying without flooding.
Permeability
The measure a material's ability to transmit a water or fluid Porosity alone cannot measure a material's capacity to yield groundwater. The pores must be connected to allow water flow, and they must be large enough to allow flow. the ability of a clay deposit to store water may be great, due to high porosity, but its pore spaces are so small that water is unable to move through it. Thus, we say the clay is impermeable.
Is the most efficient channel one with the lease or most wetted perimeter for its cross-sectional area?
The most efficient channel is one with the least wetted perimeter for its cross-sectional area, therefor less frictional drag.
circular orbital motion
The motion of water particles caused by a wave as the wave is transmitted through water. The water itself doesn't travel this distance, but the wave form does. As the wave travels, the water passes the energy along by moving in a circle.
What would happen to the oceans if surface runoff and groundwater flow did NOT occur?
The oceans would become smaller.
What do drainage patterns depend on?
The pattern that develops depends primarily on the kind of rock present and/or the structural pattern of joints, faults, and folds.
Mouth (of a river)
The point downstream where a river empties into another stream or water body--a river, a lake, or the ocean.
Dissolved load
The portion of a stream's load that is carried in solution. When water percolates through the ground, it acquires soluble soil compounds. Then it seeps through cracks and pores in bedrock, dissolving additional mineral matter. Eventually much of this mineral-rich water finds its way into streams.
Discharge
The size of a stream channel is largely determined by the amount of water supplied from the drainage basin. This measure most often used to compare the size of streams, which is the volume of water flowing past a certain point in a given unit of time.
Gradient
The slope of a stream generally expressed as the vertical drop over a fixed distance.
hydraulic gradient
The slope of the water table. It is determined by finding the height difference between two points on the water table and dividing by the horizontal distance between the two points.
Settling velocity
The speed at which a particle falls through a still fluid. The size, shape, and specific gravity of particles influence settling velocity. The larger the particle, the more rapidly it settles toward the streambed.
What is the primary energy source that drives the hydrologic cycle and most other cycles on Earth?
The sun
What powers the hydrologic cycle?
The sun
Capacity
The total amount of sediment that a stream is able to transport is the maximum load of solid particles a stream can transport per unit time.
Water table
The upper level of the saturated zone of groundwater below the water table, the water pressure is great enough to allow water to enter wells, thus permitting groundwater to be withdrawn for use.
Porosity
The volume of open spaces in rock or soil The quantity of groundwater that can be stored depends on this.
What is the Earth's overall "water balance"?
The volume that passes through each part of the cycle annually. The amount of water vapor in the air at any one time is just a tiny fraction of Earth's total water supply. But the absolute quantities that are cycled through the atmosphere over a 1-year period are immense—some 380,000 cubic kilometers (91,000 cubic miles)—enough to cover Earth's entire surface to a depth of about 1 meter (39 inches).
How does the water table change around a pumping water well?
The water table elevation decreases.
How would the water table be affected if Earth were made up of uniform, permeable material?
The water table would not exist.
What is an important factor influencing stream turbulence?
The water's flow velocity, and frictional resistance. As the velocity of a stream increases, the flow becomes more turbulent. Flow velocities can vary significantly from place to place along a stream channel, as well as over time, in response to variations in the amount and intensity of precipitation.
In which direction does the longshore current move?
parallel to shore
to ensure a continuous supply of water, a well must:
penetrate below the water table
Factors that influence flow velocities and, therefore, control a stream's potential to do "work" include:
(1) channel slope, or gradient, (2) channel cross-sectional shape, (3) channel size and roughness, and (4) discharge, or the amount of water flowing in the channel.
Streams transport their load of sediment in three ways:
(1) in solution (dissolved load), (2) in suspension (suspended load), and (3) by sliding, skipping, or rolling along the bottom (bed load).
Which of the choices below correctly describes four types of drainage patterns?
(1) rectangular pattern, which develops on highly jointed bedrock; (2) trellis pattern, which develops in areas of alternating weak resistant bedrock; (3) dendritic pattern, which develops on relatively uniform surface materials; (4) radial pattern, which develops on isolated volcanic cones or domes
The amount of water that runs off compared to the amount that infiltrates depends on several factors:
(1) the intensity and duration of rainfall, (2) the amount of water already in the soil, (3) the nature of the surface material, (4) the slope of the land, and (5) the extent and type of vegetation.
The height, length, and period that are eventually achieved by a wave depend on three factors:
(1) the wind speed, (2) the length of time the wind has blown, and (3) the fetch, or the distance the wind has traveled across open water.
How do a gaining stream and a losing stream differ? Select all that apply.
- A gaining stream exists when the elevation of the water table is higher than the surface of the stream. In contrast, a losing stream exists when the elevation of the water table is lower than the surface of the stream. - A gaining stream gains an influx of groundwater through the streambed, whereas a losing stream loses water to the groundwater through the streambed.
A friend is considering purchasing a vacation home on a barrier island. Given what you've learned about the impact of waves on coastal landforms, what information and advice could you offer your friend?
- A home on a barrier island is likely to take the full brunt of storm waves, making it a risky proposition. Your friend should think twice before purchasing. - Barrier islands tend to experience significant erosion and deposition of sand. Mitigating these effects is extremely difficult and costly. Your friend would be wise to reconsider.
In which ways do sinkholes form? Select all that apply.
- A roof of an already formed cavern collapses under its own weight. - Limestone is dissolved by rainwater, the bedrock surface lowers, and groundwater that is flowing in the passages below washes away the soil.
A stream's ability to carry solid particles is described using two criteria:
- Capacity - Competence
How did the features in the ocean form?
- Continental Shelves •Continental Slopes •Continental Rises •Abyssal Plains •Seamounts
As the stream's forward motion is slowed, sediments are deposited by the dying current, producing three types of beds:
- Foreset beds are composed of coarse particles that drop almost immediately upon entering the water to form layers that slope downcurrent from the delta front. - Topset beds horizontal beds deposited during floods - Bottomset beds The finer silts and clays settle away from the mouth in nearly horizontal layers
What are the primary ways that we use groundwater?
- More groundwater is used for irrigation than for all other uses combined. - Public and domestic uses include water for indoor and outdoor household purposes as well as water used for commercial purposes. - Common indoor uses include drinking, cooking, bathing, washing clothes and dishes, and flushing toilets. - Major outdoor uses are watering lawns and gardens. - Water for domestic use may come from a public supply or may be self-supplied. - Another category, aquaculture, involves water used for fish hatcheries, fish farms, and shellfish farms - Many mining operations require significant quantities of water, as do industrial processes such as petroleum refining and the manufacture of chemicals, plastics, paper, steel, and concrete.
Several factors contribute to the irregular surface of the water table:
- One important influence is the fact that groundwater moves very slowly and at varying rates under different conditions. Because of this, water tends to "pile up" beneath high areas between stream valleys. - Other causes for the uneven water table are variations in precipitation and differences in the permeability of surface and subsurface materials from place to place.
The nature of subsurface materials strongly influences the rate of groundwater movement and the amount of groundwater that can be stored. Two factors are especially important:
- Porosity - Permeability
How are rivers measured?
- River discharge - River stage
During a visit to the beach, you get in a small rubber raft and paddle out beyond the surf zone. You become tired, so you stop and take a rest. Describe the movement of your raft beyond the surf zone.
- The raft's net movement is not toward the shore compared to the surf zone. - The raft moves in a circle, and it returns to essentially the same place.
Which is characteristic of waves "feeling bottom"? Choose all that apply.
- The wave front breaks. - The wave is in water depth equal to half the wavelength. - The wave will slow down.
What is lag time?
- Time of heavy discharge - Time of peak discharge
Powell identified two types of base level:
- Ultimate base level. the level of the sea to be a grand base level - Local (or temporary) base levels. for local and temporary purposes, other base levels of erosion.
Knowing the water table level is important in predicting the productivity of:
- Wells - Explaining the changes in the flow of springs and streams - Accounting for fluctuations in the levels of lakes
Which of the following would produce a LOWER water table? CHOOSE ALL THAT APPLY.
- a decrease in the amount of recharge to groundwater - an increase in the amount of discharge to surface water
Which of the following structures are types of coastal stabilization structures?
- groins - breakwaters - jetties
What features are caused by excessive groundwater withdrawal? Choose all that apply.
- land subsidence - a cone of depression
How does ocean water circulate?
- moon's greatest gravitation attraction - largest tidal bulge - north pole - smaller tidal bulge
What are some problems with rivers?
- overuse (eg. colorado river) - Avulsion - River channel is abruptly abandoned in favor of a new channel
Types of rivers:
- permanent - ephemeral
What factors determine the height, length, and period of a wave? Select all that apply.
- the speed of the wind - the length of time that the wind has blown - the distance that the wind has traveled across open water
Why are coastal stabilization structures built along coastlines?
- to protect coastal property from wave erosion - to stop beach sand erosion
Drawdown
-The difference in height between the bottom of a cone of depression and the original height of the water table. -Whenever water is withdrawn from a well, the water table around the well is lowered. -decreases with increasing distance from the well -when wells are heavily pumped for irrigation or for industrial purposes, drawdown can be great enough to create a very wide and steep cone of depression. -This may substantially lower the water table in an area and cause nearby shallow wells to become dry.
Zone of erosion (locations)
-mountains -headwaters -steep gradient -big boulders on the bed -small volume of water -small channel size
Zone of deposition (locations)
-mouth -large volume of water -large channel size -gentle slope
The change in slope observed on most stream profiles is usually accompanied by...
...an increase in discharge and channel size and a reduction in sediment particle size
The largest volume of freshwater in the hydrosphere occurs as:
Glacial ice
The type and amount of material carried in suspension are controlled by two factors:
1. Flow velocity 2. Settling velocity
The interaction between the groundwater system and streams is a basic link in the hydrologic cycle. This interaction can take place in one of three ways:
1. Streams may gain water from the inflow of groundwater through the streambed Such streams are called gaining streams 2. For this to occur, the elevation of the water table must be higher than the level of the surface of the stream. Streams may lose water to the groundwater system by outflow through the streambed. The term losing stream is applied to this situation. When this happens, the elevation of the water table must be lower than the surface of the stream. 3. The third possibility is a combination of the first two: A stream gains in some sections and loses in others.
Take another look at the image (in Part B) showing a portion of the New Jersey shoreline. Examine the pier-like structures that extend from the beach out to sea, and apply what you've learned about wave erosion and shore stabilization to complete the following sentences.
1. The pier-like structures are installed perpendicular to the shore. 2. The purpose of the pier-like structures is to maintain or widen the beach and prevent erosion. 3. The pier-like structures trap sand that is moving parallel to the shore. 4. Beaches downcurrent from a groin tend to erode because of beach drift. 5. The photo of the New Jersey shore is an example of a groin field.
For an artesian system to exist, two conditions usually are met:
1. Water is confined to an aquifer that is inclined so that one end can receive water, 2. aquitards, both above and below the aquifer, must be present to prevent the water from escaping.
The River System can be divided into three zones:
1. Zones of sediment production (where erosion dominates) 2. Sediment transport 3. Sediment deposition
Minnesota caves:
1.Mystery Cave 2.Niagara Cave
What percentage of Earth's total freshwater supply is groundwater?
30.1 percent
When ice is excluded and just liquid water is considered?
96 percent of all freshwater is groundwater.
Bedrock channels
A channel in which a stream is cutting into solid rock. Such channels typically form in the headwaters or river systems where gradients are high. The energetic flow tends to transport coarse particles that actively abrade the bedrock channel. Potholes are often visible evidence of the erosional forces at work.
longitudinal profile
A cross section of a stream channel along its descending course from the head to the mouth.
Oxbow lake
A curved lake that is created when a stream cuts off a meander.
Potholes
A depression formed in a stream channel by the abrasive action of the water's sediment load.
Rectangular pattern
A drainage pattern characterized by numerous right angle bends that develops on jointed or fractured bedrock (in squares)
Hydraulic conductivity
A factor relating to ground-water flow; it is a coefficient that takes into account the permeability of the aquifer and the viscosity of the fluid.
stream terraces
A flat, benchlike structure produced by a stream, which was left elevated as the stream cut downward.
Perched water table
A localized zone of saturation above the main water table, created by an impermeable layer (aquiclude). forms where an aquitard is situated above the main water table.
Discharge areas
A location, such as a spring or a stream, where groundwater flows back to the surface. Discharge also occurs at springs, lakes, or wetlands, and in coastal areas, as groundwater seeps into bays or the ocean.
Water gap
A pass through a ridge or mountain in which a stream flows.
What happens to precipitation once it has fallen on land?
A portion of the water soaks into the ground (called infiltration), slowly moving downward, then moving laterally, and finally seeping into lakes, streams, or directly into the ocean.
capillary fringe
A relatively narrow zone at the base of the zone of aeration. Here water rises from the water table in tiny, threadlike openings between grains of soil or sediment. Here groundwater is held by surface tension in tiny passages between grains of soil or sediment.
Hot springs
A spring in which the water is 6-9°C (10-15°F) warmer than the mean annual air temperature of its locality
Alluvial channels
A stream channel in which the bed and banks are composed largely of unconsolidated sediment (alluvium) that was previously deposited in the valley. Because the banks and beds of alluvial channels are composed of unconsolidated sediment (alluvium), they can undergo significant changes in shape as material is continually being eroded, transported, and redeposited.
Graded stream
A stream that has the correct channel characteristics to maintain exactly the velocity required to transport the material supplied to it. On average, a graded system is neither eroding nor depositing material but simply transporting it.
Losing stream
A stream that loses water to the groundwater system by outflow through the streambed. Losing streams can be connected to the groundwater system by a continuous saturated zone, or they can be disconnected from the groundwater system by an unsaturated zone.
Radial pattern
A system of streams running in all directions away from a central elevated structure, such as a volcano, or mountain.
Artesian well
A well in which water rises because of pressure within the aquifer and is applied to any situation in which groundwater under pressure rises above the level of the aquifer. in some wells, water rises without being pumped, sometimes overflowing at the surface.
Meanders
A winding, looping curve in the course of a river on soft, flat flood plain These streams flow in relatively deep, smooth channels and primarily transport mud (silt and clay), sand, and occasionally fine gravel. The lower Mississippi River exhibits this type of channel.
Zone of soil moisture
A zone in which water is held as a film on the surface of soil particles and may be used by plants or withdrawn by evaporation. The uppermost subdivision of the unsaturated zone. It is crisscrossed by roots, voids left by decayed roots, and animal and worm burrows that enhance the infiltration of rainwater into the soil.
What is the bulk of the earth's wanter content of the hydrosphere?
About 96.5 percent, is stored in the global ocean. Ice sheets and glaciers account for an additional 1.76 percent, leaving just slightly more than 2 percent to be divided among lakes, streams, groundwater, and the atmosphere
How much of Earth's surface water exists in the oceans?
Almost all of Earth's surface water exists in the oceans.
What is the difference between an aquifer and an aquitard?
An aquifer is a rather permeable rock, whereas an aquitard is an impermeable rock.
Confined aquifer
An aquifer that has impermeable layers (aquitards) both above and below. When such a layer is tapped, the pressure created by the weight of the water above forces the water to rise. If there were no friction, the water in the well would rise to the level of the water at the top of the aquifer. However, friction reduces the height of the pressure surface. The greater the distance from the recharge area (where water enters the inclined aquifer), the greater the friction and the less the rise of water.
Non flowing artesian well
An artesian well in which water does not rise to the surface because the pressure surface is below ground level. because at this location, the pressure surface is below ground level.
Flowing artesian well
An artesian well in which water flows freely at Earth's surface because the pressure surface is above ground level. When the pressure surface is above the ground and a well is drilled into the aquifer
Darcy's Law
An equation which states that groundwater discharge depends on the hydraulic gradient, hydraulic conductivity, and cross-sectional area of an aquifer.
What is the single most important agent that's sculpting Earth's land surface?
An immense volume of moving water, which causes enormous erosion.
Where must all rain fall eventually go to complete the hydrologic cycle?
Back to the ocean, from where it originally came
What banks tend to be relatively resistant to erosion?
Banks that consist of coarse gravels or cohesive clay and silt particles
In general, what do beaches look like at the end of winter?
Beaches tend to have a narrow berm and a prominent longshore bar.
In general, what do beaches look like at the end of summer?
Beaches tend to have a wide berm and no longshore bar.
What is the difference between capacity and competence?
Capacity is the maximum load of solid particles a stream can transport per unit of time, whereas competence is a measure of a stream's ability to transport particles based on size rather than quantity.
How does groundwater create caverns?
Caverns are created when acidic groundwater dissolves and carries away limestone.
What types channels are generally more easily eroded?
Channels composed of unconsolidated materials are more easily eroded than channels cut into bedrock
Where did the oceans come from?
Co2 H2o NH3
In the long term, what do beach drift and longshore current do?
Move sediment parallel to the shoreline
A stream valley
Consists of a channel and the surrounding terrain that directs water to the stream. It includes the valley floor, which is the lower, flatter area that is partially or totally occupied by the stream channel, and the sloping valley walls that rise above the valley floor on both sides.
A storms rotation is due to something called the
Coriolis affect, to cause water at or above earth's survice to circle spinning around it's axis
How does ocean water circulate?
Density driven Wind driven
Where do deposition and erosion of material occur along a meander?
Deposition occurs on the inside of the meander, whereas erosion occurs on the outside.
Wetted perimeter
Determines, to a large extent, the amount of flow in contact with the banks and bed of the channel.The total distance in a linear cross-section of a stream that is in contact with water.
Which of the following statements about drainage basins is FALSE?
Drainage basins only contain one river.
How big can a drainage divide get?
Drainage divides range in scale from a small ridge separating two gullies on a hillside to a continental divide that splits an entire continent into enormous watersheds.
What is drawdown, and how does it relate to the cone of depression?
Drawdown is the term describing the process in which the water table around a well is lowered because of water discharge. This depression in the water table is conical and is called a cone of depression.
Why does groundwater discharge to Earth's surface?
Earth's surface is irregular, and permeability decreases with depth within Earth.
Flood Mitigation:Structural Solutions
Engineering approach -Channel modification -Dams -Retention Ponds -Levees, Dikes, and -Floodwalls -Floodways
Turbulent flow
Erratic movement of water often characterized by swirling, whirlpool-like eddies. Most streamflow is of this type. Even streams that appear smooth on the surface often exhibit turbulent flow near the bottom and sides of the channel, where flow resistance is greatest. Turbulence contributes to a stream's ability to erode its channel because it acts to lift sediment from the streambed.
Transpiration
Evaporation of water from the leaves of a plant
Whitecaps
Eventually a critical point is reached where waves grow so tall that they topple over, forming ocean breakers
How geysers work
Geysers occur where extensive underground chambers exist within hot igneous rocks As relatively cool groundwater enters the chambers, it is heated by the surrounding rock. At the bottom of the chambers, the water is under great pressure because of the weight of the overlying water. The heating causes the water to expand, with the result that some is forced out at the surface. This loss of water reduces the pressure on the remaining water in the chamber, A portion of the water deep within the chamber quickly turns to steam, and the geyser erupts.
Aquitards
Impermeable layers that hinder or prevent water movement Clay is a good example
Slot canyons
In some arid regions, where weathering is slow and rock is particularly resistant, narrow valleys having nearly vertical walls are also found. Such features are called slot canyons
Laminar flow
In very slowly flowing streams, water moves in nearly straight-line paths parallel to the stream channel
Dendritic pattern
Is the most common drainage pattern. A stream system that resembles the pattern of a branching tree.
How do natural levees form?
Levees form as the result of the repeated flooding of a river within a floodplain. Each time the floodwaters recede, the suspended load that had been carried by the water is deposited, building up levees along the banks of the river.
Which of the following statements is true?
Low gradient is associated with deposition.
How much of the Mn population depends on groundwater?
More than 70% of Minnesotans depend on groundwater for drinking water
Unsaturated zone
The area above the water table where openings in soil, sediment, and rock are not saturated but filled mainly with air. Also called the vadose zone. The pore spaces in this zone contain both air and water. Although a considerable amount of water can be present in the unsaturated zone, this water cannot be pumped by wells because it clings too tightly to rock and soil particles.
Floodplain
The area subject to flooding during a given number of years according to historical trends. The continuous lateral erosion caused by shifting meanders gradually produces a broad, flat valley floor covered with alluvium, that creates a floodplain
What would happen to atmospheric water if Earth were mostly covered with land?
The atmosphere would contain less water.
How might building a dam on a river that flows to the sea affect a coastal beach?
The beach becomes narrower and the cliffs behind it are subjected to a higher rate of erosion.
Head or headwaters
The beginning or source area for a stream. Also called headwaters.
hydrologic cycle (water cycle)
The cycle through which water in the hydrosphere moves; includes such processes as evaporation, condensation, precipitation, and surface and groundwater runoff and infiltration
Water can also be pushed upward, apparently against the force of gravity, and enter through the bottom of the channel, what causes this?
The deeper you go into the zone of saturation, the greater is the water pressure. Water at any given height is under greater pressure beneath a hill than beneath a stream channel, and the water tends to migrate toward points of lower pressure.
Sorting
The degree of similarity in particle size in sediment or sedimentary rock.
Fetch
The distance that the wind has traveled across open water
Evapotranspiration
The evaporation of water from soil plus the transpiration of water from plants. Because both evaporation and transpiration involve the transfer of water from the surface directly to the atmosphere.
Abrasions
The grinding and scraping of a rock surface by the friction and impact of rock particles carried by water, wind, and ice by scraping, rubbing, and bumping, abrasion erodes a bedrock channel and simultaneously smooths and rounds the abrading particles. That is why smooth, rounded cobbles and pebbles are found in streams.
What does the hydrologic cycle describe?
The hydrologic cycle describes how liquid and gaseous water move between the ocean, atmosphere, and land.
In the diagram above, two wells are drilled to the same depth. Why was one well successful but the other not?
The left well is unsuccessful because it reaches into the unsaturated zone, whereas the well on the right is successful because it reaches into water on a perched aquifer on top of an aquitard.
Flood stage
The level at which stream discharge begins to spill out of the channel into the surrounding area.
Rills
Tiny grooves in soil made by flowing water
Saltation
Transportation of sediment through a series of leaps or bounces
How does the use of water by humans affect the water table?
Use of water by humans increases discharge, resulting in lowered water tables.
What are some problems with rivers?
Water Quality / Pollution
zone of saturation (phreatic zone)
Water that is not held as soil moisture percolates downward until it reaches a zone where all the open spaces in sediment and rock are completely filled with water into the _____ Water in the zone of saturation is called groundwater.
Which of the following statements about wave period is most accurate?
Wave period is the inverse of wave frequency.
While you are playing Frisbee in the surf zone with another person, your friend watches while sitting on the beach nearby. After a while, you look up at the beach and realize you are no longer directly in front of your friend, who remained stationary on the beach all the while—you are still in the surf zone, but 30 to 40 yards from where you started. What is the correct reason for this movement?
Waves were coming at the shore at an angle. The longshore current moved downstream to that angle and pushed you in that direction.
How are wave period and wavelength related?
Waves with shorter periods have shorter wavelengths.
What is the most common method for removing groundwater?
Wells: a hole bored into the zone of saturation. Wells serve as small reservoirs into which groundwater migrates and from which it can be pumped to the surface.
When are waves said to be "fully developed"?
When the maximum fetch and duration are reached for a given wind velocity The reason that waves can grow no further is that they are losing as much energy through the breaking of whitecaps as they are receiving from the wind.
Runoff
When the rate of rainfall exceeds the ground's ability to absorb it, the surplus water flows over the surface into lakes and streams.
Groundwater flow system
a three-dimensional body of Earth material saturated with moving groundwater. - It shows groundwater moving along flow paths from recharge areas, where groundwater is being replenished - to discharge areas along streams, where groundwater is flowing back to the surface. - Transpiration by plants whose roots extend to near the water table represents another form of groundwater discharge.
Each day in the United States we use about:
about 306 billion gallons of freshwater.
Deltas
an accumulation of sediment formed where a stream enters a lake or ocean
Watershed
an area in which all water falling in it flows out through one location Eg. Missouri River Basin
Drainage basin or watershed
an area of land that contributes water to a particular stream or river, a basic unit of landscape
Recharge areas
an area where groundwater is replenished
Divide
an imaginary line that separates the drainage of two streams; often found along a ridge
Geysers
are intermittent hot springs or fountains in which columns of water are ejected with great force at various intervals, often rising 30 to 60 meters (100 to 200 feet) into the air. After the jet of water ceases, a column of steam rushes out, usually with a thunderous roar.
Where is most of Earth's freshwater found?
as ice at Earth's surface
Which way would sediment move if NO beach drift existed?
at an angle to shore
What are the three types of loads carried by streams?
bed load, suspended load, dissolved load
How do jetties protect harbor entrances?
by inhibiting the deposition of sand in the harbor mouth
Complete this analogy: Bouncing is to sand as suspension is to_____________.
clay
Gullies
deep ditches formed after heavy rainfall
streams create depositional features that have longer life spans:
deltas, natural levees, and alluvial fans.
Why are oceans salty?
dissolved minerals are carried by rivers and streams erosion from the land
What is the dominant fluvial process in a clear, sediment-poor stream moving down a steep slope?
downcutting
What are stream measurements useful for?
essential components of river models used to make flood forecasts and issue warnings. data are also used in making decisions related to water supply allocations, operation of wastewater treatment plants, design of highway bridges, and recreation activities.
What is the largest freshwater reservoir in the hydrosphere?
glaciers
Hydraulic gradient formula
h1-h2/d where h1 is the elevation of one point on the water table, h2 is the elevation of a second point, and d is the horizontal distance between the two points
River stage
height of water in the river
Complete this analogy: Sliding is to gravel as dissolution is to_____________.
ions
What is the majority of groundwater used for in the United States?
irrigation
River
is a general term for streams that carry substantial amounts of water and have numerous tributaries.
Trellis pattern
is a rectangular drainage pattern in which tributary streams are nearly parallel to one another and have the appearance of a garden trellis
water content of the hydrosphere
is an estimated 1.36 billion cubic kilometers (326 million cubic miles)
Shoreline
is the line that marks the contact between land and sea. Each day, as tides rise and fall, the position of the shoreline migrates.
Hillslope erosion
is the main source of fine particles (clays and fine sand) carried in stream channels.
What is meant by a nonstructural approach to flood control?
limiting certain activities or land uses and implementing appropriate zoning regulations in high-risk flood areas
Two common types of alluvial channels are:
meandering channels and braided channels.
incised meanders
meandering channels that flow in steep, narrow, valleys. It forms either when an area is uplifted or when the base area drops
What type of stream is associated with the formation of an oxbow lake?
meandering stream
Voids
most often are spaces between sedimentary particles but also common are joints, faults, cavities formed by the dissolving of soluble rock such as limestone, and vesicles (voids left by gases escaping from lava).
Which stream environment has the highest competence?
near the headwater region of a glacial braided stream in summer
Which of the following methods of flood control is the cheapest and most effective?
nonstructural floodplain management
How much of the earth's water is groundwater?
only about six-tenths of 1 percent is located underground.
When observing waves, always remember:
that you are watching energy travel through a medium (water) Wind-generated waves provide most of the energy that shapes and modifies shorelines. Where the land and sea meet, waves that may have traveled unimpeded for hundreds or thousands of kilometers suddenly encounter a barrier that will not allow them to advance farther and must absorb their energy.
Which ocean is Earth's largest?
the Pacific Ocean
Cut bank
the area of active erosion on the outside of a meander
When a stream's gradient is steep,
the channel is well above base level, and the dominant erosional process is downcutting
Wave base
the depth, approximately equal in distance to half a wavelength in a body of water, beneath which there is no wave movement
What is the wavelength?
the distance between consecutive wave crests or troughs
What is the wave height?
the distance between the highest and lowest part of the wave
Suspended load
the fine sediment carried within the body of flowing water the muddy appearance created by suspended sediment is the most obvious portion of a stream's load Usually only very fine sand, silt, and clay particles are carried this way, but during flood stage, larger particles can also be transported in suspension
What is suspended load?
the fine-grained particles that travel in the water column above the stream bed
What is the crest of a wave?
the highest part of the wave
Base level
the level below which a stream cannot erode Essentially, it is the level at which the mouth of a stream enters the ocean, a lake, or a trunk stream.
Local (temporary) base level
the level of a lake, resistant rock layer, or any other base level that stands above sea level
Downcutting
the lowering of a streambed toward base level as turbulent water lifts unconsolidated material or when bedrock channels are lowered by means of quarrying, abrasion, and corrosion
What is the trough of a wave?
the lowest part of the wave
Sediment transport
the movement of eroded materials from one place to another by water, wind, and/or glaciers.
Sheet flow
the movement of water in broad sheets across the land
What serves as the ultimate base level for streams?
the ocean
Why do some artesian wells not flow at Earth's surface?
the pressure surface is below ground level
Trunk Stream
the primary river flowing out of a drainage basin Eg. Mississippi River
Corrosion
the process by which soluble rock is gradually dissolved by flowing water
What is the cone of depression?
the shape that the water table takes on near a pumping well
Pore space depends on:
the size and shape of the grains, how they are packed together, the degree of sorting, and, in sedimentary rocks, the amount of cementing material. For example, clay may have a porosity as high as 50 percent, whereas some gravels may have only 20 percent voids.
Wave period
the time interval between the passage of successive crests at a stationary point
What is the wave period?
the time it takes for one wavelength of a wave to pass a particular point
What is the water table?
the top of the saturated zone beneath Earth's surface
How is the Earth's hydrologic cycle balanced?
the total amount of water vapor in the atmosphere remains about the same, the average annual precipitation worldwide must be equal to the quantity of water evaporated. However, for all the continents taken together, precipitation exceeds evaporation. Conversely, over the oceans, evaporation exceeds precipitation.
What is evapotranspiration?
the transfer of water directly from the land's surface into the atmosphere
Wave height
the vertical distance from the crest of a wave to the trough
Groundwater
the water that is beneath Earth's surface Where these subsurface pore spaces are saturated with water, that stored water
Crests
tops of a wave
Zone of transportation (locations)
trunk stream -meander -moderate volume -moderate channel size
Braided channel
type of alluvial channel consisting of a broad network of diverging and converging channels; forms where the stream's load includes abundant coarse material and the discharge is highly variable form where a large portion of a stream's load consists of coarse sediment (sand and gravel) and the stream has a highly variable discharge. Because the bank material is readily erodible, braided channels are wide and shallow. One setting in which braided streams form is at the end of glaciers, where there is a large seasonal variation in discharge.
Alluvium
unconsolidated sediment deposited by a stream
Which processes result in the widening of the floodplain of a meandering stream?
undercutting and lateral erosion
How is discharge measured?
usually measured in cubic meters per second or cubic feet per second, is determined by multiplying a stream's cross-sectional area by its velocity.
What is the longshore current?
water forced by waves to move along the shore
Stream
water that flows in a channel, regardless of size.
erosional floodplain
when a river erodes laterally and creates a floodplain
When will a cone of depression stop enlarging?
when the amount of water flowing toward the well equals the amount of water being pumped out of the well
When might a well, Well A, go dry?
when the cone of depression of a second well intersects the deepest part of Well A
