running water (16) Flashcards
What are the four spheres of the earth?
Hydrosphere
Atmosphere
Geosphere
Biosphere
Hydrologic cycle
The unending circulation of Earth’s water supply. The cycle is powered by energy from the Sun and is characterized by continuous exchange of water among the oceans, the atmosphere, and the continents
What is the distribution of total global water?
Oceans (96.5%)
Freshwater (2.5%)
Saline lakes and groundwater (1%)
What is the freshwater distribution?
Glaciers and ice sheets (68.6%)
Groundwater (30.1%)
Surface water and other freshwater (1.3%)
What is the surface water distribution?
Snow and ice (73.1%)
Lakes (20.1%)
Soil moisture (3.52%)
Swamps (2.53%)
Evaporation
The process by which liquid water changes into water vapor (gas)
Infiltration
The movement of surface water into rock or soil through cracks and pore spaces
Runoff
Water that flows over land rather than infiltrating into the ground
Transpiration
The release of water vapor to the atmosphere by plants
Evapotranspiration
The combined effect of evaporation and transpiration
Water balance
The volume that passes through each part of the cycle annually
What is the absolute quantity that is cycled through the atmosphere over a 1-year period?
380,000 cubic kilometers
Explain the idea that the hydrologic cycle is balanced.
Annual precipitation worldwide must equal the quantity of water evaporated
What is the most important force sculpting the Earth?
Water
What factors determine the amount of runoff?
The intensity and duration of rainfall The amount of water already in the soil The nature of the surface material The slope of the land The extent and type of vegetation
Why is runoff high in urban areas?
Many features are impermeable (buildings, roads, parking lots, etc.)
Sheet flow
Initial runoff flows in broad, thin sheets across slopes
Rills
Threads of current that form tiny channels
Gullies
Rills joined to form streams, and eventually, rivers
Stream
A general term to denote the flow of water within any natural channel. Thus, a small creek and a large river are both streams
River
A general term for a stream that carries a substantial amount of water and has numerous tributaries
What are the two sources that support streamflow in humid regions?
Overland flow that sporadically enters the stream and groundwater that enters the channel
How do streams lose water in arid regions?
The water table may be below the level of the stream channel. The stream loses water to the groundwater system by outflow percolating through the streambed
Drainage basin/watershed
The land area that contributes to a stream
Divide
An imaginary line that separates the drainage of two streams, often found along a ride
What river has the larges drainage basin in North America?
Mississippi River; 40% of the flow of the United States
What is the main source of fine particles (clays and fine sand) carried in stream channels?
Hillslope erosion
Headward erosion
The extension upslope of the head of a valley due to erosion
What causes downcutting?
Headward erosion
Three zones of a river system
Zones of sediment production (erosion)
Zone of sediment transport
Zone of sediment deposition
Zone of sediment production
Where most of the sediment is derived
Located in the headwaters
Zone of sediment transport
Trunk systems are how sediment travels
Zone of sediment deposition
Fine sediments and dissolved ions are typically the sediment that actually reaches the ocean
Dendritic pattern
A stream system that resembles the pattern of a branching tree
Radial pattern
A system of streams running in all directions, away from a central elevated structure, such as a volcano
Rectangular pattern
A drainage pattern characterized by numerous right angle bends that develops on jointed or fractured bedrock
Trellis pattern
A system of streams in which nearly parallel tributaries occupy valleys cut in folded strata
When does a dendritic pattern develop?
When the surface material is essentially uniform in its resistance to erosion (pattern is determined chiefly by the direction of slope of the land)