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Streams and Floods (Hydrologic cycle
Definition: the movement of water…
Streams and Floods
Hydrologic cycle
- Definition: the movement of water between the ocean (hydrosphere), air (atmosphere), and land (lithosphere)
Distribution of water: from most to least-> Oceans, ice caps and glaciers, groundwater, rivers and lakes, soil water, atmosphere
Processes: (driven by sun)
- evaporation, precipitation, infiltration, evapotranspiration, runoff
-
Water residence times-> bigger body of water, longer residence time
Aquifer-> is a geologic unit that can store and transmit water
Unconfined aquifer-> is an aquifer that has the ground surface as an upper bound; interacts with surface water and streams
Confined aquifer-> is an aquifer that has a confining unit as an upper and lower bound
Water table-> is the zone between saturated and unsaturated soil
Municipal water table-> water from pump station, into water storage tank, then to water user
Water storage in an aquifer is controlled by the porosity, infiltration and runoff
- depends on void space, soil type, thickness, original water content, precipitation characteristics
- infiltration-> aggregated soil
- runoff-> soil crusts after aggregates break down
Stream Systems
- A stream is a body of water that carries rock particles and dissolved ions, flowing downslope along a clearly defined path, called a channel
- carry most water from land to the sea (part of the water cycle)
- carry dissolved ions (product of chemical weathering) into the oceans
- major part of erosional process
- carry alot of sediment (main agent of erosion)
- major source of water and transportation
Stream system components:
- Valley, channels and floodplains
-channels and floodplains are located in the valley
-valleys-> sloping area around the stream
-channels-> bottom of valley, where the water flows
-floodplains-> flat area in valley level with tope of channel. (part that can be flooded)
-
Base level and graded streams:
- Base level-> level below which a stream cannot erode
-Increase in base lvl-> longitudinal profile adjusts by increasing deposition
-Decrease in base lvl-> longitudinal profile adjusts by increasing transport and increasing erosion
- Graded stream-> equilibrium state where channel geometry and hydraulic parameter enable the stream to transport its load with neither deposition nor erosion
-
Stream deposits: due to the decrease in velocity
- floodplain
- levee
- terrace
- alluvial fan (steep mountain stream enters a flat valley)
- delta (a stream that enters a standing body of water)