hydrologic cycle
evaporation, transpiration, precipitation, infiltration, runoff
evaporation
process of water turning from liquid to vapor-hydro, atmos
transpiration
water vapor to atmosphere by plants through pores in leaves, plants absorb water from ground through roots
precipitation
water, falls to the ground, from atmos to hydro
infiltration
surface water draining into the ground crack and pores spaces in the regolith
runoff
water flowing over land rather than infiltrating the ground
running water
the most important erosional agent affecting earths land surface
infiltration capacity
controlled by intensity and duration of precipitation, soil saturation level, soil texture, slope of the land, vegetation type/extent
sheet flow
water draining in shallow unconfined sheets across the ground
rivers and streams
water flowing in a channel
-key effects on landscape formation
-erosion of channels in the land
-transport of sediments provided by weathering/mass wasting
-depositation of sediment in a variety of landforms
stream flow types
laminar/ turbulent flow
stream flow velocity
variation in stream flow is primarily due to differences in velocity
factors: gradient of channel, channel morphology, discharge
stream flow discharge
volume of water flowing past a certain point in a given unit of time: measured in meters of cubed per second
discharge equation
channel width
channel depth
velocity
drainage basin
land area where runoff drains downhill into a waterway, also called a watershed
drainage networks
interconnected system of tributaries, creeks, stream, rivers, etc.
divide
each drainage basin is separated topographically from adjacent basins by a ridge, hill, or topographic high line
continental divide
mountainous line that forms the border between two major watersheds on the NA continent.
base level
lowest point to which a stream can erode
ultimate base level
local base level
sea level
level of a lke, resistant rock layer, any other base level that stands above sea level
changing base level
changing condition cause readjustment of stream flow,
RULES: raising the base level= deposition
lowering base level=erosion
stream erosion
streams cause erosion by lifting loosely consolidated particles
abrasion-physical weathering
dissolution-chemical weathering
evidence of erosion
potholes, gorges: rapid down cutting by a stream (steep sided cuts)
sediment transport
transported material is called the streams load
types of load
dissolved load-solution
suspended load-suspension
bed load- moved along channel bottom
capacity/competenece
maximum load
largest particle a stream can transport
determined by velocity
sediment deposition
when streamflow velocity decreases, competence is reduced and sediments are deposited
alluvium
sediments deposited by streams;generally well sorted, as the largest particles drop out first
channel deposits
sediment accumulation within a channel
types: bars: sand/gravel deposit in channel
braided stream: stream consisting of numerous intertwining channels.
floodplain deposits
natural levee: elevated landform composed of alluvium: parallel and confines stream
backswamp: poorly drained area on floodplain
vazoo tributary: tributary flowing parallel to main stream because of natural levee
alluvial dan
a fan shaped deposit of sediment formed on land when stream slop is abruptly reduced
deltas
a fan shaped deposit of sediment formed where a stream enters a lake or ocean and slows
stream valleys
most common landforms on earths surface.. generalized types-narrow and wide valleys
narrow valleys
V shaped with rapid downcutting toward base leve: typical features include rapids
wide valleys
valley formed when stream is near base level. downward erosion is less dominant
floodplains, meanders
meander
looplike bend in the course of a stream
cutbank
pointbar
cutoff
oxbow lake
incised meanders
meanders in steep narrow valleys cause by a drop in base level or uplift of region
terraces
remnants of an old flood plain indicating that a river has adjusted to a relative drop in a base level by down cutting
drainage patterns
vary in response to underlying rock types and structure.
dendritic
radial
rectangular
trellis
stream piracy
diversion of the drainage of one stream resulting from the headward erosion of another
water gaps
notch in landscape where a river cuts through a ridge that lies in its path
methods of formation (water gaps)
antecedent stream-existed before ridge
superposed stream- let down upon an existing structure
floods and types
most common and destructive hazard
regional flood
flash flood
ice jam flood
dam failure
flood control approaches
engineer efforts-dams, channelization, levees
non structural approaches- floodplain management