River valley Flashcards
what is the rivers course
the path of a river as it flows downhill
what are the 3 courses of a river
-upper
-middle
-lower
what do rivers form as they flow downhill
channels and valleys
what does the long profile of a river tell you
how the gradient changes over different courses
what does the cross profile of a river show you
what a cross section of the river would look like
describe the upper course of a river
-steep
-v shaped valley
-steep sides
- narrow,shallow channel
describe the middle course of a river
-medium gradient
-gently, sloping valley sides
-wider deeper channel
describe the lower course of a river
-gentle gradient
-very wide
-very flat valley
-very wide deep channel
name the 2 types of erosion
lateral
vertical
what changes the cross profile of a river
vertical and lateral erosion
what’s vertical erosion
-deepens river valleys and makes the channels **v-shaped **
-dominant in upper course of river
-high turbulence causes rough rocks to be **scraped along river bed **causing intense downward erosion
what’s lateral erosion
-widens river valley and channel during formation of meanders
-dominant in middle and lower courses
what are 4processes of a river
-hydraulic action
-abrasion
-attrition
-solution
what’s hydraulic action
the force the water breaks rock particles away from the river channel
what’s hydraulic action
the force the water breaks rock particles away from the river channel
what’s abrasion
eroded rocks picked up by the river scrape and rub against the channel causing it to wear away
what’s attrition
eroded rocks picked up by the river smash into each other and break into smaller fragments. their edges become rounded as they rub together
what’s solution
river water dissolved some type of rock
what are the 4 processes of transportation
traction
saltation
suspension
solution
transportation is the
movement of eroded material
what does the transport of material depend on
the velocity of the water and size of particles
what is traction
large particles like boulders are pushed along the river bed by the force of water
what’s suspension
small particles like silt and call are carried along the water
what’s saltation
pebble sized materials are bounced along the river bed by the force of water
what’s solution
soluble materials dissolve in the water and are carried along
what’s deposition
when a river drops the eroded material it’s transporting
where are waterfalls and gorges found
upper course of the river
explain how a waterfall is formed
-river flows over area of hard rock and then soft rock
-the soft rock is eroded more then hard rock creating a step in the river
-as water goes over step it erodes more and more of softer rock
-steep drop
where do waterfalls form
they form where a river flows over an area of hard rock followed by soft rock
what are soft engineering methods to reduce the effect of flooding
-flood warning
-preparation
-flood plain
-zoning
