Environmental Geology 150 Lecture Exam Two

Glaciers hold 2.5%

Start of the river, higher elevation, steep slope, faster water, carry large sediment.

End of the river, lower elevation, shallow slope, water is slower, carry smaller sediment.

water flows year around, ground water is the primary source of water (baseflow), supported by runoff.

water only flows after precipitation, runoff is the primary source of water, no baseflow, common in arid regions.

flows during part of the year when sufficient ground water/precipitation supports flow, classified by channel pattern.

streams are a network of entwined channels that split and reunite around gravel bars and islands, common near glaciers; supplies coarse sediment, meltwater floods.

stream has many meanders (curves), forms in areas with gentle slope and soft substitute, meanders constantly evolve; NOT STATIONARY

Deposit of sediment on the inside of a meander. There is low water velocity.

The outside bank of a meander where erosion occurs. There is high water velocity.

A cut off meander that has been filled with water.

Erodes the sides (banks); causes channel to become wider; occurs in the middle and lower stages of river.

vertical erosion into the bed; causes channel to become deeper; occurs at upper stages of river.

erosion at the head of the stream; lengthens the channel in a direction opposite to flow direction.

The bedload is the large particle (sand and gravel) that bounceoll along river bed.

The suspended load is small grains (silt and clay) that float in the river.

The dissolved load is ions dissolved in water from chemical weathering (K^*, Ca^2+, HCO3^-)

Point Bar: inside of the meander where water slows down.
Floodplain (fertile soil): flat land on either side of stream, river overflows channel, spreads out, velocity decreases.
Delta: fan-shaped deposit formed at mouth of river when running water enters standing water (velocity decreased).
Alluvial Fan: fan-shaped deposit formed when a mountain stream empties out onto a flat plain (slope decrease, velocity decrease).

measures the suspended solids (clay, silt, plant material). The higher the turbidity the more stuff that is in the water. Turbidity also affects light penetration depth and therefore plant growth depth.

Total Dissolved Solid (TDS): all ions dissolved in the water. Estimated by the electrical conductivity. If there are no ions it means that there will be no electric current. A high conductivity means a high TDS reading. TDS also deals with hardness; only dissolved Ca^2+ and Mg^2+.

Flooding is a function of the amount of water/precipitation. Ex: heavy rainfall, fast melt of heavy snow, dam or levee breaking (rate of infiltration; decreased infiltration equals flood), vegetation (decreased vegetation, decreased infiltration), topography (steep slope, decreased infiltration), or permeability of soil (low permeability, low infiltration).

Seasonal floods take hours-days to develop and last days-weeks. They occur when sustained rains fully saturate the soil. They flood large areas and migrate for downstream. They cause property damage.

Flash floods occur fast and end fast. They occur from intense rainfalls, and are commonly in arid climates and canyons. These cause greater loss of life.

The percent of open, empty space (pores) in rocks and sediment. This is were groundwater resides not in underground lake or rivers. Empty space could be between grains (primary) that is affected by packing, sorting, rounding, and cementation. Empty space could also be in fractures (secondary).

Permeability is the ability to transmit fluid (does the water flow?). Permeability depends on interconnectedness of pores. Porosity does NOT equal permeability. Pores can be filled with water, oil, gas, or air; not clay or sediment.

the boundary between the saturated and unsaturated zones. It is not flat, and is usually a subdued version of surface topography. The depth varies; in humid regions it is near the surface, in arid regions it is far underground, and it moves up and down with the seasons.

It represents the potential height to which water will rise if it could flow freely.

The region below the water table where pore space is filled with water.

Zone above the zone of saturation in which the earth's pores are mostly filled with air.

a geological unit that is saturated (below the water table), porous (can hold water), and is permeable (allows useable quantities of water to flow through it).

An aquitard is a geological unit that does NOT transmit water easily. AKA low permeability.

A confined aquifer is trapped beneath an aquitard.

An aquifer is open to Earth's surface.

When water rises above water table and ground surface.

When water can rise above the water table.

The potential energy of water. In an unconfined aquifer the hydraulic head is the water table. In a confined aquifer the hydraulic head is the potentiometric surface.

Gravity causes water to flow down slope, hydraulic head (elevation and pressure).

Velocity depends on permeability of rock and sediment and slope of hydraulic head (aka slope of water table OR potentiometric surface): hydraulic gradient.

Q (discharge) = K (permeability) x A (area of flow) x change in height / change is distance between two points.

Environmental: management of land, water, wildlife, etc.
Economic: taxation and incentives for businesses.
Social: education, promoting peace (wars waste resources).

Drawdown is the lowering of the water table. The effects are lower surface water levels, affects wildlife and tourism, wells can dry up, it can form a cone of depression from pumping in an unconfined aquifer, and it can locally change the direction of groundwater flow.

Saltwater intrusion is the movement of saline water into freshwater aquifers along coasts. As fresh water is over pumped, salt water rushes in to take its place.

Nitrate, microbes, and bacteria.

PFAs

Shallow water table depth and little topsoil and high permeability.

Karst topography is characterized by caves, sinkholes, and disappearing streams. There are two main rocks associated with karst topography and those are limestone and dolostone because they can be dissolved by acidic groundwater.

Urbanization increases flooding severity and frequency. This is represented on a storm hydrograph by the visual representation of the change in river discharge in response to a rainfall event.

Over-enrichment of water by nutrients. This sets off a chain reaction.

Crest: high point of the wave.
Trough: low point of the wave.
Wave height: vertical distance between crest and trough.
Wave length: horizontal distance between two crests.

Energy moves with the wave, but the water itself does not advance; instead the water is moving in circular orbits. The orbits decrease in size with depth, motion is gone when depth = 1/2 the wave length = wave base.

When the wave base hits the ground, orbits flatten to ovals and waves slow down. The wave length decreases, wave height increases. A breaker (surf) are waves that have become so steep that they "break". Waves no longer have orbital motion; instead waves move back and forth. Swash: water moves toward the short. Backwash: water moves toward the ocean.

Weak current that runs parallel to the coast. This causes a net transport of water and sediment along the shore.

The gravitational pull of the moon.

Surface currents are influenced by wind and Earth's rotation.

Deep water currents are caused by differences in water density (temp and salinity).

Coastal erosion is based on headlands, and deposition is based on embayment's.

Emergent: coast exposed by decrease sea level or uplift in land. Terraces are seen in emergent areas, flat surface; exposed erosional surface; indicate past sea levels.

Submergent: flooded by increased sea level. Fjords; deep glacially carved valley filled with water, estuary; "flooded" river channel in which seawater and freshwater interact. Both fjords and estuary's are seen in submergent areas.

Erosional: waves wash away sediment faster than it can be supplied. Waves cut a platform, sea arch, sea stack, or cliffs.

Depositional have beaches, spits; shore-parallel sediment deposits connected to the mainland at one end, lagoons; and partially enclosed coastal water bodies by spits, reefs, or barrier islands.

Active: develop along active plate boundaries. They are more likely to have cliffs, rocky shorelines.
Passive: transition from continent to oceanic crust. These are typically flatter and wider beaches.