Exam 5 (Running Water, Groundwater) Flashcards
A summary of the circulation of Earth’s water supply
The Hydrologic Cycle
Processes involved in the hydrologic cycle (5)
Precipitation, Evaporation, Infiltration, Runoff, Transpiration
Land area that contributes water to the stream is the ____
Drainage basin (aka watershed)
The imaginary line separating one basin from another is called a ____.
Divide
____ is the overland transport of stormwater in a shallow concentrated flow.
Sheetflow
Term applying to a wide variety of processes that involve the downslope movement of rock, regolith, and/or soil under the force of gravity.
Mass wasting
Important “triggers” for mass wasting events
Role of water, oversteepening of slopes, removal of vegetation, earthquakes, and geologic time.
Maximum slope angle at which a material is stable.
Angle of Repose
Modest amounts of _____ increase adhesion; saturation decreases friction
Fluid
Fluid infiltrating soil and sediment may increase _____ _____ and promote movement.
Pore pressure
Principal factors controlling the velocity of water in a channel:
Gradient and channel characteristics (size, shape, roughness)
The volume of water moving past a given point in a certain amount of time.
Discarge
The maximum volume of load that a river can carry at a specific point in its course
Capacity
The measure of the maximum size of particles a stream can transport
Competence
Deposition of sediments is controlled mostly by a decrease in _____.
Velocity
Decrease in velocity also results in a decrease in _____ _____.
Stream competence
Where a high-gradient (slope) stream leaves a narrow valley.
Alluvial fan
Forms through the deposition of sediment when a stream enters an ocean or lake.
Delta
Valley characteristic of upland areas with higher gradient and significant downcutting?
V-Shaped valley
Valley characteristic of lowland areas with lower gradient and significant lateral erosion?
Wide valley.
______ ______ is what widens the valleys and causes meandering stream patterns
Lateral Erosian
How do meandering streams evolve?
Curves of the stream widen through repeated erosion/deposition
Features of a meandering stream:
Cut bank, point bar, oxbow lake.
Names for areas of deposition and erosion in a stream:
Deposition: Point bar
Erosion: Cut bank
Two ways that terraces can form:
Change in base level or change in climate. (Leads to change in discharge)
Water found in the pores of soil and sediment, plus narrow fractures in bedrock.
Groundwater
Largest reservoir of fresh water that is readily available to humans.
Groundwater.
Area above the water table, water cannot be pumped by wells.
Zone of aeration (AKA Vadose Zone)
The upper limit of the zone of saturation
Water table
Zone where all of the open spaces in sediment and rock are completely filled with water.
Zone of saturation (AKA Phreatic Zone)
Interaction between groundwater and streams where water is gained from the inflow of groundwater through the streambed.
Gaining Stream
Interaction between groundwater and stream where water is lost to the groundwater system by outflow through the streambed.
Losing stream
An accumulation of groundwater that is above the water table in the unsaturated zone.
Perched Water Table
A depression in the groundwater table or potentiometric surface that has the shape of an inverted cone and develops around a well from which water is being withdrawn.
Cone of depression
A situation in which groundwater under pressure rises above the level of the aquifier.
Artesian Well
Shape of water table is usually ____?
A subdued replica of the surface topography.
Percentage of total volume of rock or sediment that consists of pore spaces?
Porosity
The ability of a material to transmit a fluid
Permeability
Permeable rock that transmits groundwater freely (such as sands or gravels).
Aquifier
An impermeable layer that hinders or prevents water movement (such as clay).
Aquitard
The water table slope, determined by dividing the vertical difference between the recharge and discharge points by the length of flow between these points.
Hydraulic Gradient
The vertical difference between the recharge and discharge points.
Hydraulic head
Groundwater is replenished in ______ ______.
Recharge areas
Groundwater flows back to the surface in _____ _____.
Discharge areas
The deeper the groundwater gets, the ____ the quality of water.
Lower; deeper groundwaters have been in contact with bedrock longer and picked up more dissolved solids.
Natural outflows of groundwater that occur where the water table intersects Earth’s surface.
Springs
Intermittent hot springs that occur where underground chambers exist within hot igneous rock.
Geysers
Landscapes that have been shaped mainly by groundwater’s dissolving.
Karst Topography
Karst rock types
Soluble: Limestone
The collapse of a cavern over a large area.
Solution valley
Stream that disappears underground at a distinct sink point.
Sinking stream
Calcite deposited as dripping water evaporates.
Dripstone
How does an oxbow lake form?
When a curve in a meandering stream is bypassed.
How do stream terraces form?
Streams carve downward into their floodplains, leaving discontinuous remnants of older floodplain surfaces as step-like benches along the sides of the valley.
Primary factor responsible for determining whether erosion or deposition is occurring along any one segment of a typical stream system.
Stream gradient (slope)
What is most groundwater used for and briefly describe one viable alternative to current usage rates.
Wells; one alternative is harvested rainwater.
Why does the water table take the shape of a subdued replica of the surface topography?
Permeable soil depositions dictate the general shape of a piece of land.
