Earth Science, Tarbuck Chap 9 Flashcards
What is Infiltration
Water soaks into the ground
What is Runoff
When rate of rainfall exceeds grounds capacity to absorb it, water flows into lakes, streams, etc.
What is transpiration
Water gets absorbed by plants which later release it back into the atmosphere
What is a Drainage bed/ Watershed
The area the stream drains
Where is the zone of sediment production usually found in a stream
headwater/ beginning of the stream
What are trunk streams
area where material produced in the zone of sediment is transported through.
When a river reaches the
ocean or another large body of water, it _________
Slows
Why is the sediment that reaches the ocean mostly fine
Coarse sediments are deposited at higher energy locations, i.e. higher upstream
What is dendritic drainage pattern
drainage pattern that has “Branch”-like pattern. Develops on mostly uniform surface material
What is Radial drainage pattern
Drainage pattern that has streams diverging from 1 central area. Usually develops on isolated volcanic cones or domes
What is rectangular drainage pattern
Drainage pattern that has streams exhibiting right-angle bends. Develops on bedrock crisscrossed with faults or joints.
What is Trellis Drainage Pattern
Drainage pattern where streams are nearly parallel. Usually develops on bedrock with crisscrossing resistant and less-resistant rock
What is Laminar Flow in a stream
slow flowing streams where water is flowing parallel to stream channel
What is turbulent flow in a stream
a type of stream flow that is more common than Laminar flow. These types of streams exhibit turbulent activity, such as whirlpools, eddies, etc.
Smooth River channels lead to _______ flow because
Uniform, as the water in contact with the channel experiences less friction
What is the discharge of a river
the volume of water
flowing past a certain point in a given unit of time
How is river discharge calculated
Stream’s cross sectional area multiplied by its velocity
What are intermittent streams
Streams that only flow during wet periods
What are ephemeral streams
Streams that only carry water occasionally in Arid climates
As a river moves from headwaters to the mouth, slope does what
Decreases
As a river moves from headwaters to the mouth, Discharge does what
increases
As a river moves from headwaters to the mouth, the channel gets finer or coarser
finer
3 ways a stream carries sediment
in solution(dissolved load), in suspension(suspended load), and bouncing along the bottom(bed load)
Relation of settling velocity, flow velocity, and suspended load
as long as flow
velocity exceeds settling velocity, sediment remains
suspended and is transported downstream
What type of sediment is usually carried as bed load
Coarser sediments that are too large to be carried through suspension
Sediment Capacity of a stream depends on what
Stream Discharge
Sediment competency of a stream depends on what
Velocity of the stream
General Term of Sediment deposited by rivers is
Alluvium
What are bedrock channels
Streams that cut into the bedrock, usually found upstream
What are Alluvial Channels
Stream channels composed of loosely unconsolidated sediment
What are the 2 common types of alluvial channels
Meandering channels and Braided channels
What is a meandering channel
Streams that transport much
of their load in suspension and move in sweeping bends
What is a Cut Bank
The outside of the meander, the zone of erosion in a meandering stream
What is a meander
The Sweeping Bends of Meandering Streams
Where is maximum velocity in a meandering stream
outside of the meander
How do Oxbow Lakes form
When a meandering stream reaches an area of more resistant bedrock, it causes the meander above to erode the material between the two meanders. This causes the river to form a narrow neck of land called a cutoff that leaves the abandoned bend as the oxbow lake
What are braided streams
Complex networks of converging and diverging channels that thread through numerous small islands. The streams load consists mostly of coarse material
What is a stream valley
consists of a channel and the surrounding terrain that directs water to the stream
What is the lower limit that determines how deeply a stream can erode
Base Level
Ultimate Base level of a stream is what
Sea Level
The Base level of a stream is
the level where a stream enters a ocean, lake, or another stream
What is Downcutting
process by hydraulic action that deepens the channel of a stream or valley by removing material from the stream’s bed or the valley’s floor
How are floodplains created
As the stream gradient decreases, a meandering stream develops and widens the valley as it erodes from one river bank to the next.
What is an Incised meander
Meandering channels that flow in steep, narrow valleys
How do Stream Terraces form
When the base level of a stream drops, it produces a new floodplain at a level below the old one
How does a delta form
Sediment-laden stream reaches a lake, sea, or ocean and flow slows down, leading to the stream dropping the sediment at the mouth. This causes distributaries to form as the stream seeks a shorter route to the base level
What are natural levees and how do they form
When streams have a floodplain, successive flooding leads to the water coming out of the channel and immediately dropping sediment in place, leading to a sloping levee.
What are yazoo tributaries
Tributary stream that cannot enter a stream because levees block the way
What are alluvial fans and how do they form
high-gradient stream leaves a narrow valley in mountainous terrain and comes out suddenly onto a broad, flat plain or valley
floor causing the stream to drop the sediment at the opening, leading to a fan shaped sediment.
Groundwater usually occurs where
tiny pore spaces in grains of soil and sediment
Geologically, groundwater is important as an ________
agent
Erosional
Groundwater slowly dissolves what type of rock
Soluble Rocks, like limestone
A large amount of precipitation soaks into the ground and
moves slowly to stream channels
Connection of Groundwater to Streams
Stores water that sustains streams during dry periods
Upper Limit of Zone of Saturation
Water Table
What is the Zone of Saturation
area where all the open spaces in sediment and rock are completely filled with water
What is the Unsaturated Zone
area above the water table where the soil, sediment, and rock are not saturated
What does porosity of material tell us
The quantity of groundwater that can be stored
What is porosity of material
The percentage of the total volume of sediment or rock that consists of pore spaces
Why is porosity often low in igneous and metamorphic rocks
Rock grains are tightly pack together
What is permeability of a material
its ability to transfer fluids
tell me about clay’s porosity and permeability
Clay has high porosity, leading it to be able to store a lot of water but due to Clay also having low permeability, as it contains fine grains, water stored in clay cannot usually move
Fine grained rocks typically have what Porosity and Permeability
High Porosity, Low Permeability
coarse grained rocks typically have what Porosity and Permeability
High Porosity, High Permeability
What are Aquitards
Impermeable layers that hinder or prevent water movement
What are aquifers
Permeable rock strata or sediments that transmit groundwater freely
Where does groundwater move
Areas where water tables are high to Areas where water tables are low(High to low pressure)
What is the energy that makes Groundwater move
Gravity
GroundWater usually gravitates toward
Stream Channel, Lakes, etc.
Most common way of removing groundwater
Drilling Wells
What is the Drawdown Effect
Water table is lowered around the well as water is pumped out
To ensure a continuous flow of water, what must wells do
Be drilled below the water table
What is the Cone of Depression
Conical Depression formed by wells taking groundwater.
What is an artesian system
Situation where groundwater rises in a well above the level initially encountered
What are the two conditions needed for an artesian system to exist
- Water must be confined to an aquifer that is inclined so that one end is exposed at the surface, allowing for it to receive water
- Aquifer must be confined by aquitards on the top and bottom
What is the pressure surface in an artesian system
hypothetical level to which water would rise in wells tapping the confined aquifer, due to the hydraulic pressure within the aquifer.
As you move farther away from the recharge location in a pressure system, what happens
Pressure increases and Friction increases
What is a spring
Whenever water table intersects ground surface
What is geothermal Gradient
How much temperature increases with decreasing elevation
How does water in hot springs get heated
Water that circulates at deep depths is heated
What are geysers
intermittent fountains in which columns of hot water and steam are ejected with great force
Why does Pumping of Groundwater sometimes lead to surface subsidence
As water is withdrawn, water pressure is transferred to the sediment and they are forced to be compacted tighter, leading to ground subsidence.
What type of Aquifers can cleanse contaminated groundwater rather quickly
Aquifers that are not too permeable
How are caverns formed
Groundwater dissolves limestone, leading to large limestone caverns to form
How is travertine formed
As limestone is dissolved into the groundwater, calcium carbonate is dissolved in it. When the calcium carbonate precipitates, travertine is the product.
Travertine most often forms what type of structure
Dripstone
How do Stalactites form
after a river downcuts into a valley, in turn lowering the water table, and the cave is in the unsaturated zone, water enriched with calcium carbonate seeps into cracks of the overhead rock, eventually dripping onto the top of the cavern. As groundwater comes in contact with air, the dissolved carbon dioxide associated with the formation of carbonic acid escapes. This causes precipitation of the calcite and forms a ring of travertine around the water drop.
At the beginning of stalactite formation, what shape does it take on,
Soda Straw shape, Inside is hollow and stalactite has tube-like shape.
How do Stalagmites form
As water drops down from the stalactite, it drops on the ground and more calcite forms into a larger mass of travertine.
What is Karst Topography
Landscape Heavily affected by Groundwater dissolution
Which regions generally do not exhibit karst topography
arid and semiarid locations
2 ways sinkholes can form
1.Gradual Dissolution of limestone layer, leads to gentle slopes and shallow sinkholes
- Sudden collapse of Limestone Cavern Ceiling as it collapses on its own weight. Leads to steep slopes and deep sinkholes
Relation of Stream number to Karst Topography
There are very little streams in areas of karst topography
