Ch. 5 (Kaitlin) Flashcards
Understand how the hydrologic cycle works
A huge system of the movement of water powered by the Sun’s energy.
PRIMARY MOVEMENTS
- EVAPORATION
- liquid water changes to water vapor - PRECIPITATION
- after precipitation has fallen on land, inflitration (water soaking into the ground and seeping into lakes and other bodies of water) occurs. - RUNOFF
- surplus water that can’t be absorbed will flow over the surface and into bodies of water. Transpiration is the process of plants absorbing water and releasing it back into the atmosphere.
evapotranspiration is the combined processes of evaporation and transpiration.
Understand gradient, velocity, and discharge
Gradient-the slope of a stream channel expressed as the vertical drop of a stream over a specified distance.
Settling Velocity-the speed at which a particle falls through a still fluid. The larger the particle, the more rapidly is settles.
Discharge-the volume of water flowing past a certain point in a given time. the measure most often used to compare the size of streams.
Understand base level, and how base level affects sedimentation and erosion
Base level is the lowest elevation to which a stream can erode its channel.
Sea level -the ultimate and lowest base level.
Temporary/Local base levels -lakes, resistant layers of rock, main streams.
When a stream enters a lake, its velocity slows and it’s ability to erode below its base level ceases.
When a damn is built along a stream, the reservoir that forms causes the base level to RAISE, and the gradient is REDUCED upstream, lowering both velocity and the ability to transport sediment.
If a stream has no energy to TRANSPORT sediment, it will DEPOSIT sediment.
Understand these stream transport concepts: competence, capacity, and bed/suspended/dissolved load
COMPETENCE- a measure of a stream’s ability to transport particles based on SIZE rather than quantity.
FASTER STREAM EQUALS GREATER COMPETENCE.
CAPACITY- the maximum load of solid particles a stream can transport per unit of time. THE GREATER THE DISTANCE, THE GREATER THE CAPACITY.
STREAMS TRANSPORT THEIR LOAD IN 3 WAYS:
- DISSOLVED LOAD -mineral rich solution brought to the stream by groundwater. Velocity has no affect on the carrying ability of dissolved loads.
- SUSPENDED LOAD -fine sediment carried within the body of flowing water. Largest portion. Muddy appearance.
- BED LOAD -larger sediment carried by a stream along the bottom of its channel. Particles in bed load move by rolling, sliding, and saltation.
Understand the difference between meandering and braided streams
MEANDERING STREAMS - streams that transport much of their load in suspension move in SWEEPING BENDS called meanders. Flow in deep, smooth channels and transport mud.
BRAIDED STREAMS -complex network of converging/diverging channels that thread their way through islands or gravel bars. INTERWOVEN APPEARANCE.
Understand what a drainage basin is, and name the four different drainage basin types.
DRAINAGE BASIN - the land area that contributes water to a river system.
drainage basins are separated by a DIVIDE (imaginary line).
FOUR TYPES:
- DENDRITIC
- RADIAL
- TRELLIS
- RECTANGULAR
Understand the natural and anthropogenic (human-made) factors that cause flooding.
A flood occurs when the flow of a stream exceeds the capacity of its channel and will overflow.
NATURAL FLOOD CAUSES:
- rapid melting of snow
- major storms
- topography
- rainfall duration and intensity
- surface conditions
- steep slopes of mountainous areas
HUMAN INTERFERENCE THAT CAUSES FLOODING:
- dam failure
- artificial levee failure
- impervious surfaces like parking lots and roofs.
Understand engineering efforts used to control flooding, such as dams, levees, floodplain management, etc.
FLOOD CONTROL DAMS- built to store floodwater and let it out slowly. dams trap sediment and is NOT A PERMANENT SOLUTION.
ARTIFICIAL LEVEES- earthen mounds built on river banks to increase the volume of water the channel can hold. MOST COMMON. NOT MADE FOR EXTREME FLOODING.
CHANNELIZATION - altering a channel to stop the flow of water to prevent it reaching flood height.
FLOODPLAIN MANAGEMENT - a nonstructural approach that includes identifying high risk areas and using zoning regulations.
Understand the difference between the unsaturated zone, the saturated zone, and the water table
ZONE OF SATURATION - a zone where all open spaces in sediment and rock are completely FILLED WITH WATER.
WATER TABLE- the upper limit of the zone of saturation.
UNSATURATED ZONE -the area above the water table where openings in soil, sediment, and rock are not saturated but FILLED WITH AIR.
Understand the difference between aquifers and aquitards.
AQUIFER- rock or soil through which groundwater EASILY MOVES.
AQUITARD- impermeable beds that PREVENT MOVEMENT of groundwater.
Understand the difference between porosity and permeability.
POROSITY - the volume of open spaces in rock or soil.
PERMEABILITY -a measure of a material’s ability to transmit water.
EXAMPLE:
Clay can hold a lot of water and therefore has high porosity, but the pore spaces are so small that water can’t move through it, therefore it is impermeable.
CONE OF DEPRESSION
a cone shaped depression in the water table immediately surrounding a well.
CONTAMINATION
the pollution of groundwater that affects our water supply.
usually from sewage, highway salt, fertilizers, pesticides, industrial leaks, landfills, holding ponds.
HOT SPRING
a spring in which the water is 6-9 degrees Celsius (10-15 F) warmer than the mean annual air temperature of its locality.
KARST TOPOGRAPHY
a topography consisting of numerous depressions called sinkholes.
