Rivers and river valleys Flashcards
precipitation
Moisture falling from clouds as rain, snow, or hail.
Interception
Vegetation prevents water from reaching the ground
Surface Runoff
Water flowing over the surface of the land into rivers
Infiltration
Water absorbed into the soil from the ground.
Transpiration
Water lost through the leaves of plants.
Upper Course of a River
Near the source, the river flows over a steep gradient from the hill/mountains. This gives the river a lot of energy, so it will erode the riverbed vertically to form narrow valleys
Lower Course of a River
Near the river’s mouth, the river widens further and
becomes flatter. Material transported is deposited
River Discharge
River discharge is the volume of water that flows in a river.
Hydrographs that discharge at a certain point in a river changes over time in relation to rainfall
Peak discharge
the discharge in a period of time
. Lag time
the delay between peak rainfall and peak discharge
Rising limb
the increase in river discharge.
Falling limb
the decrease in river discharge to normal level
Geomorphic Processes Upper
– Features include V-Shaped valleys, rapids, and waterfalls.
High force Waterfall located close to Forest-in Teesdale drops 21m
and is made from harder Whinstone and softer limestone rocks.
Gradually a gorge has been formed.
geomorphic processes middle
– Features include meanders and ox-bow lakes. The
meander near Yarm encloses the town.
geomorphic processes lower
– Greater lateral erosion creates features such as floodplains & levees near Darlington. Mudflats at the river’s estuary.
Middle Course of a River
Here the gradient gets gentler, so the water has less energy and moves more slowly.
The river will begin to erode laterally making the river wider.
What are the characteristics of the upper course of a river?
Steep gradient Narrow v-shaped valley Narrow/shallow river Large angular sedimant load Mostly erosion taking place
What are the characteristics of the middle course of a river?
Shallower gradient Asymmetrical valley cross section Deeper river Smaller/rounded load Balance between erosion and transportation taking place
What are the characteristics of the lower course of a river?
Very low gradient U-shaped valley Wide/deep river Small suspended load Mostly deposition taking place
- when does deposition happen
when a rivers velocity decreases, and it no longer has the energy to transport its load, it deposits it.
- describe deposition
larger rocks transported mainly by traction are only carried short distances during periods of high flow. they are deposited in a rivers upper coarse.
smaller sediment is carried further downstream- mostly in suspension. it is deposited on a rivers bed and banks where velocity slows down due to friction
lots of deposition occurs at a rivers mouth where its velocity reduces because of the gentle gradient and also by interaction with tides
