Geology Hour Exam 2
Fluvial Processes contain 0.016% of the Earth's water.
The three major repositories are ocean, glaciers, groundwater.
Discharge is the amount of water going past a given point per unit.
The loads of sediment transport are bed, saltation, suspended, and dissolved.
Total load is referred to as stream capacity.
Capacity has functions of sediment availability and discharge.
Velocity is how fast the water is moving.
Velocity has functions of discharge and gradient.
A drainage basin is an area from which a stream collects water.
If a stream is in equilibrium it will concave up and be in a tectonically quiet area.
A stream in disequilibrium will have a portion that is convex up and will be in a tectonically active and topographically low area.
A flood plain is an area which a stream meanders.
Fast water is outside of the curve. Fast water causes erosion. Fast water is called a cut bank.
Slow water is inside the curve. Slow water causes deposition. Slow water is called a point bar.
An uplift is a young stream. Young streams have few meanders and are straight and immature.
The size of a channel is a function of normal stream flow.
Big inputs are infiltration, evaporation, and runoff.
Flood magnitude is controlled by the rate of runoff, amount of input, vegetation, and topography.
Upstream floods have a brief input over a limited area and cause brief localized flooding.
The main channel of a river is open during an upstream flood
Downstream floods have a sustained input. During a downstream flood the main channel of the river is full.
A 100 year flood plain is an area that will go underwater if a 100 year event occurs.
Human impacts of floods are urbanization and dams.
Flood prevention methods are levees, zoning/planning, channelization, and dams.
Pros of flood prevention are controlling floods and generating power. A con of flood prevention is habitat destruction.
A trailing margin has no active uplift. A trailing margin gets its sediment from further inland.
An active margin has an active uplift. The sediment in an active margin is from further inland and local sources.
Waves, tides, and eustatic sea level shape the coast.
Waves are predominant forces that produce rapid and substantial changes. There is an inversely proportional relationship between wave depth and height. Wave base is the depth below which no orbital motion occurs when a wave passes.
Tides focus where waves hit the coast. Tides are driven by the Moon. A tidal bulge is a bulge in the ocean caused by the moon's gravitational pull on Earth's waters.
Global sea levels vary. Global eustatic sea level varies depending on both sea floor spreading rates (tectonics) as well as global climate.
Wave refraction is when waves slow down as water depth decreases. Wave refraction happens on active margin coast that are not straight or in equilibrium. Wave refraction focuses wave energy on anything that sticks out along the coastline.
Longshore transport moves sediment laterally along the coast.
Groins are engineered structures built perpendicular to the shore.
Breakwaters are engineered structures built offshore parallel to the shoreline.
Riprap is a pile of walls.
Others ways to stabilize a beach are seawalls and beach replenishment.
Milankovitch theory is about natural climate change.
A part of the Milankovitch theory is the Earth's orbit which is in a 100,000 year cycle.
A part of the Milankovitch theory is the tilt axis of the Earth which is in a 41,000 year cycle. At the highest angle of tilt there is the most sunlight to the polar regions. When the tilt is upright there is less sunlight.
A part of the Milankovitch theory is precession which is in a 23,000 year cycle. Precession is the time of year when the Earth is closest to the Sun.
The Milankovitch theory discussed a 5-6 degree Celsius warming or cooling after each cycle.
Natural temperature and CO2 variability are also important parts of the Milankovitch theory.
The Greenhouse Effect is when CO2 acts like a blanket.
Some observations of climate change are global temperature rising, global atmosphere CO2 rising, ocean pH decreasing, ocean temperature rising, artic ice conditions, and global deforestation.
CO2 dissolves in the ocean.
Shift in ocean circulation can cause global scale changes.
Humboldt currents are formed in cold and upwells off of the coast of South America.
In El Nino conditions there is no Humboldt current.
Unsaturated zone, also called Vadose, of water has air and water in pore spaces.
Saturated zone, also called Phreatic, of water has only water in pore spaces. Water in saturated zones is not static; it flows slowly and moves to lower elevation in response to gravity.
Gaining streams receive water from groundwater. Losing streams lose water to groundwater.
An Aquifer is a volume of subsurface with sufficient porosity and permeability to be useful to humans,
There are two general types of aquifers confined and unconfined.
Unconfined aquifers are open to the surface and the recharge zone is directly above the aquifer.
Confined aquifers are not open to the surface and the recharge are is somewhere besides above the aquifer.
Aquiclude and aquitard are impermeable rock layers.
Artesian water is water that flows freely out of a pipe with no power.
Surface water is usable if evaporation is low, the water is good quality, and precipitation is high.
The biggest danger to a confined aquifer is a developing zone because it reduces the recharge area and causes the cone of depression to deflate.
Withdrawal that exceeds recharge means in many areas the water is non-renewable.
In areas where withdrawal is high, subsidence rates can be on order of a meter per year.
Consequences of withdrawal are WT decreasing, subsidence, saltwater intrusion, and loss of recharge.
Subsidence includes homes and loss of aquifer volume.
Saltwater intrusion is when saltwater resides under freshwater the freshwater lens depletes and the saltwater seeps upward.
Extending supply of water includes conservation, desalination, and transfer.
Transferring water means moving water from one drainage basin to another.