Rivers flashcards

Pregunta	Respuesta
processes of erosion	hydraulic action: force of water breaks rock particles away corrasion: rocks scrape against river channel wearing it away attrition: rocks smash into each other corrosion: water dissolves some rock e.g chalk/limestone
processes of transportation: the movement of eroded material	traction: large particles pushed along river bed by water saltation: pebble-sized particles bounce along riverbed suspension: small particles (silt) carried along by water solution: soluble materials dissolve in water
course of the river	upper - steep - narrow/shallow middle - medium - wider/deep lower - gentle - very wide/deep
features of a drainage basin	tributary: smaller river joins main river source: where river starts in upland area e.g mountains confluence: point where two rivers join mouth: river flows into sea or lake
causes of flooding	prolonged rainfall heavy rainfall snowmelt
flood managements	dams and reservoirs channel straightening man-made levees flood warnings preparation flood plain zoning
the hydrological cycle	shows how water moves around
infiltration	water soaks into the soil
percolation	water moves vertically down through soil and rock
throughflow	water in the soil flows downhill
groundwater flow	water in rock flows downhill
surface runoff	water flows overground
channel flow	the flow of water in a river
channel storage	water is held in a river
groundwater storage	water is stored underground in soil and rock
interception storage	water lands on things like leaves and doesn't hit the ground
surface storage	water is held in things like lakes, reservoirs and puddles
permeable rocks	rocks that absorb water: chalk
impermeable rocks	rocks that don't absorb water: granite
drainage basin	the area of land drained by a river
drainage basins are separated by a boundary called a watershed - ridges of high land	Image: download__12_ (image/jpg)
a drainage basin	Image: images__5_ (image/jpg)
tributary	smaller river that joins a main river
source	where the river starts, usually in an upland area
confluence	the point where two rivers join
mouth	where a river flows into the sea or a lake
weathering in a drainage basin	the breakdown of rocks where they are (material doesn't get taken away)
mechanical weathering	the breakdown of rock without changing its chemical composition - freeze-thaw
chemical weathering	the breakdown of rock by changing its chemical composition - carbonation weathering
biological weathering	the breakdown of rocks by living - plant roots grow into cracks on the surface, pushing them apart
hydraulic action	the force of water breaks rock particles away from the river channel
corrasion	eroded rocks scrape against river channel wearing it away
attrition	rocks smash into each other breaking them into smaller fragments
corrosion	water dissolves some rock e.g chalk/limestone
traction	large particles are pushed along the river bed by the force of the water
saltation	pebble-sized particles are bounced along the river bed by the force of the water
suspension	small particles like silt and clay are carried along by the water
solution	soluble materials dissolve in the water and are carried along
deposition	when a river drops eroded material - happens when a river loses velocity (slows down)
waterfalls and gorges are found in the upper course of a river	Image: download__13_ (image/jpg)
interlocking spurs	Image: images__6_ (image/jpg)
meanders: large bends in a river	Image: download__14_ (image/jpg)
ox-bow lakes: formed from meanders	Image: g514_b.gif (image/gif)
flood plain	the wide valley floor on either side of a river which occasionally gets flooded
levees: natural embankments along the edges of a river channel	Image: natural_levees (image/jpg)
deltas: low lying areas where a river meets the sea or a lake	rivers slow down when they meet the sea/lake and deposit material - it builds up, the channel is blocked and splits up into smaller rivers: distributaries
types of delta	Image: deltargb250 (image/jpg)
river discharge	the volume of water that flows in a river per second - measured in cumecs
storm hydrograph	Image: download__15_ (image/jpg)
peak discharge	the highest discharge in the period of time
lag time	the delay between peak rainfall and peak discharge
rising limb	the increase in river discharge as rainwater flows into the river
falling limb	the decrease in river discharge as the river returns to its normal level
factors that increase discharge and make the hydrograph steeper	high rainfall intense rainfall impermeable rock previously wet conditions - saturated soil steep slopes less vegetation
factors that decrease discharge and make the hydrograph gentler	low rainfall light rainfall permeable rock previously dry conditions gentle slopes more vegetation
urban areas have drainage systems and are covered with impermeable materials increasing discharge so hydrographs are steep	rural areas have more vegetation and reservoirs decreasing discharge so hydrographs are gentle
human causes of flooding	deforestation - more water reaches river channel urbanisation - buildings are impermeable increasing surface runoff
hard engineering to reduce flooding	dams and reservoirs channel straightening man-made levees
soft engineering to reduce flooding	flood warnings preparation flood plain zoning
hard engineering	man made structures built to control the flow of rivers and reduce flooding
soft engineering	schemes set up using knowledge of a river and its processes to reduce the effects of flooding
flood in MEDC: River Eden, Carlisle, 8.1.2005 heavy rainfall	3 deaths 3000 homeless 4 schools flooded some roads were damaged
flood in LEDC: River Ganges, India, July 2007 heavy rainfall	2000 deaths 25 million homeless 44 schools destroyed 10,000km road destroyed

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