Final Geo Lab Study Guide

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Streams and Flooding (Pg. 195-230)
Chapter 8
Base Flow
Stream flow coming from groundwater seepage into a stream
Base Level
The lowest level to which a stream can erode its bed, commonly sea level
Oxbow Lake
Formed when a meander loop is isolated from the main channel by erosion of the narrow neck of land between the upstream and downstream segments of the meander loop
Cut-Bank (erosion)
Is the OUTSIDE bank of a stream, which is continually undergoing erosion.
Point Bar (deposition)
Is a depositional that accumulates on the INSIDE bend of streams.
Steam Gradient
Measure of the vertical distance that a stream channel falls over a given horizontal distance (SLOPE)
-Expressed in ft/mile or m/km
(Elevation change)/
(Horizontal surface)
Stream Discharge
Volume of water passing a fixed reference point per unit time
Ex: cubic feet per second
5x3x3=45
If a cork thrown into a river travels 15ft in 5 seconds and the river has a width of 5ft and an average depth of 3ft, what is the rivers discharge?
Velocity=Distance/Time
Width X Depth X Velocity = Discharge
Rule of V's
Water flows away from the V's
V-water is moving north
^-water is moving south
Recurrence Interval
Is the average time interval between floods of a particular
=(N+1)/M
N=number of years
M=rank of each flood event
EXAMPLE: Records of a river have been kept for 49 years, what is the recurrence interval for the largest magnitude flood?
RI=(49+1)/1=50
for the 2nd ranked flood?
RI=(49+1)/2=25
Annual Probability of Recurrence
=(1/RI)x100
EXAMPLE:
What is the annual probability of the 100 year flood in percent?
=(1/100)x100=1%
Of a 400 year flood in percent?
=(1/400)x100=.25%
Of a 500 year flood in percent?
=(1/500)x100=.1%
Hydrograph
Is a plot of stream discharge versus time
-Show changes in stream discharge over time
Rising Limb
Is steeper then the recession limb
Recession Limb
Is less steep then the rising limb
Downstream Flood
Floods that affect large stream systems and large drainage basins
-Longer lag time
Upstream Flood
Small, localized floods (sudden, locally intense rains and events such as dam failure)
-Referred to as flash flooding
-Short lag time
Groundwater (Pg. 231-248)
Chapter 9
Porosity
The percentage of void space in rock sediment, determines the volume of water in the zone of saturation
-Expresses as percent
Permeability
Is the ability of rock or soil to allow water to flow through it
-Expresses as a rate - 2in/day
Permeability, Hydraulic Gradient
The rate or velocity of which groundwater flows is determined by the ____________ and the ___________ __________.
Hydraulic Gradient
The slope at which groundwater flows
Unsaturated Zone (Zone of Aeration)
Zone near the surface, and the pore spaces are mostly filled with air
Water Table
The line between the water-saturated soil and the soil that is not saturated with water (beneath the Earth's surface)
Saturated Zone (Zone of Saturation)
Below the water table and pore spaces are filled with water
Hydraulic Head
Is the height of a column of water above sea level
-Groundwater flows in the direction of decreasing hydraulic head
Confined Aquifer
An aquifer that is overlain by a confining bed, which has significantly lower hydraulic conductivity than the aquifer.
-Also called an Artesian Aquifer
Unconfined Aquifer
An aquifer in which there are no confining beds between the zone of saturation and the ground surface.
-There is a water table
-Also called a Water Table Aquifer
Darcy's Law
V=(K/P)/(H/L)
V=Velocity
K=Hydraulic Conductivity
P=Porosity
H=Head
L=Length
Soluble Rocks like Carbonate rocks like limestone and dolomite
In what rock types does Karst Topography primarily develop?
Sinkholes, Caves, Residual Hills
Name three surface or underground features or landforms that are associated with Karst Topography?
Windward Side
The side of a dune that faces the wind and is less steep than the other side
Leeward Side
The side of a dune that faces away from the wind direction and is more generally more steep than the other side
Slip Face
The steeper cliff on the leeward side of a dune and has an angle around 30 degrees
Parabolic Dune
Type of dune that are characterized by horns that point UPWIND.
Barchan
Type of dune that are characterized by horns that face DOWNWIND.
Transverse Dune
Type of dune that has a linear ridge that is PERPENDICULAR to the wind direction.
Longitudinal Dune
Type of dune that has a linear form that is PARALLEL to the wind direction
Longshore Current
A water current that moves parallel to a shoreline due to waves approaching the shoreline at an angle and subsequently bending parallel to the shoreline as they enter shallow water.
Direction
When a longshore current passes a point and enters deeper water, it slows and some of its load is deposited forming a spit which is a ridge extending from the point in the direction of longshore drift. This is how you determine longshore current ___________ from the orientation of a spit.
Spit, Baymouth Bar
A ____ is an emergent ridge of sand and when it extends completely across the mouth of a bay, it is called a _________ ___.
Headlands
A steep face irregular area, usually rocky and protrudes oceanward along a shoreline
Sea Stacks
Pillar-like, isolated mass of rock near a steep shoreline which has been detached from a sea cliff by wave erosion.
Baymouth Bar
Deposit of sand that completely crosses the mouth of a bay
Tombolo
Sand ridges connecting islands to the shore
Lagoon
A shallow stretch of seawater partly or completely separated from the Ocean by a spit, baymouth bar, barrier island, or reef.
Tidal Inlet
A narrow inlet between barrier islands that allows seawater to flow back and forth between the open ocean and the lagoons or sounds.
Barrier Island
Low, narrow ridge of sand that parallels the shoreline and is separated from the main land my a lagoon and/or tidal flat
Estuary
Inlet to the sea formed by flooding of a river mouth due to a rise in sea level or subsidence of the land
Erosional Shores
Typically have well-developed cliffs and are in areas where tectonic uplift of the coast occurs
-Features:
headlands
wave-cut cliffs
sea stacks
Depositional Shores
The shore is gradually subsiding with sand deposits and offshore barrier islands common
-Features:
Spit
Baymouth Bar
Tombolo
Barrier Island
Lagoon
Beach
Marine Terrace
Terraces that are the result of continuing uplift coupled with sea level fluctuations.
Primary Shorelines
Shorelines formed by erosional or depositional processes or tectonic processes
Influenced by land phenomenon
Secondary Shorelines
Shorelines formed by erosion or deposition due to waves, tides, or currents
Influenced by ocean phenomenon