upper,middle,lower pg Flashcards
describe middle course valley characteristics and channel
widen bottom, with gently sloping valley sides
channel
wider and deeper with meanders
describe lower valley characteristics and channel
very wide with no obvious valley sides with flood plains and levees
channel
at its widest and deepest gentle gradient with some meanders
def vertical and lateral erosion
vertical
erosion happening downwards direction
lateral
erosion happening sideways direction
vertical erosion in rivers
river bed eroded downwards with abrasion. usually occurs in upper course where lots potential energy and large boulders that erode the bed if traction occurs channel gets deeper than wide
lateral erosion in rivers
banks or river eroded by abrasion as sediment carried in suspension in middle to lower course of river. river channel wider than deep
what is bradshore model
model which describes how rivers characteristics vary between upper middle lower.
cross profile of river valley and river channel in upper middle lower
upper
cross section is verical
channel is sideways 1.5m
middle
cross section lateral erosion
channel sideways 5m
lower
cross section sideways 2km across floodplain
channel sideways 20m
width upper middle lower
upper
narrow 1.5m
middle
wide 5m
lower
wider 20m
upper middle lower depth
upper
shallow
middle
deep
lower
deeper
upper middle lower relief
upper
steep
middle
gentle
lower
gentler
upper middle lower velocity
upper
slow
middle
fast
lower
faster
upper middle lower sediment size
upper large
middle medium
lower small
upper middle lower sediment angularity
upper
most angular
middle
round
lower
rounded
upper middle lower landforms found
upper: v shaped valley, interlocking spurs, waterfalls, gorges
middle: meanders, ox bow lakes
lower: flood plains, levees, estuaries, deltas, meanders
how to calculate discharge and def
width x depth x velocity = discharge (volume of water passing a point every sec)
