river definitions Flashcards
base level
lowest point in the river profile
graded profile
model for a perfect concave profile which is energy efficient throughout its length
perennial river
river that flows all year round during normal rainfall
intermittent river
a river which can cease to flow over a long time period
ephemeral river
a river which only flows after periods of heavy rainfall or snowmelt and remains dry for the majority of the river regime
source zone
the rivers upper reaches, area from which water and sediment are derived. Most erosion occurs in this zone
transfer zone
zone through which eroded material is transported to be deposited in the third zone
deposition zone
the rivers lower reaches, where eroded sediment is deposited due to decreasing energy levels
long profile
section through the channel from its head to its mouth and is typically concave in shape because headwaters are steep and slope decreases progressively downstream
transportation
solution = flow of dissolved material suspension = flow of small particles in the water saltation = bouncing/ sliding movement of larger particles on the river bed traction = rolling of very large rocks/ boulders along the river bed
sinuosity
extent to which the river meanders and has a sinuous channel.
river becomes more sinous as lateral migration occurs
meander
feature of a sinuous river channel caused due to erosion becoming concentrated on the outside of the bend and deposition being concentrated in the inside causing the river channel to meander
lateral migration
refers to meanders moving across their floodplain
braided rivers
a river with numerous flows that split off and rejoin each other to give a braided appearance.
these flows are often separated by temporary islands of alluvium. found in regions with a steep gradient e.g. mountainous regions.
river delta
landform near the mouth of the river which is created as a result of sediment deposition. Delta often shaped like a triangle/ fan
