Surface Water Flashcards
What is the hydrologic cycle?
The hydrologic cycle is a summary of the continuous circulation of Earth’s water
supply
where do streams originate? What are the characteristics of this location?
Head waters: stream source
Gradient is steep
Discharge is low
Competence is high
Where do streams terminate? What are the characteristics of this location?
Near the streams Base level:
Gradient is nearly flat.
◼ Discharge is high.
◼ Competence is low
(sediments are fine).
◼ Channels curve and twist
What is a drainage basin/watershed?
the whole land area that
collects/drains water to a specific stream
What is a drainage divide?
imaginary line separating one
basin from another.
What are the 4 types of drainage patterns?
Dendric, Radial, Rectangular and Trellis
What is an ephemeral stream?
Flow only during a storm and a short period afterwards. Typically in dryer climates
What are braided streams?
Network of interweaving channels
Forms when there is low discharge
(insufficient flow) and a lot of sediment, so the
streams capacity is exceeded
What are meandering streams?
very curved, high sinuosity: ‘snakes’ around
Forms when there is a low surface gradient
(gentle slope
what is a point bar?
inside curve of a meander
characterized by slower moving water and
deposition where piles of sediment are
visible.
what is a cutbank?
outside curve of a meander
characterized by fastest moving water and
erosion along the bank. The fast water
CUTS into the bank
What is the difference between stream capacity and stream competence?
Capacity
* The maximum load a stream can transport
Competence
* Indicates the maximum particle (clast) size a stream can transport
What is the thalweg?
the deep part of a channel where most flow occurs.
It acts like a vortex of the highest velocity of water!
What is stream discharge?
The volume of water passing a certain point per unit time
* How much water a stream is transporting
* Varies due to season, weather, and other factors
what is stream velocity?
depends on the stream gradient, shape and roughness;
* Speed
What is base level? And where can base level erode down to?
The lowest level to which a stream can erode its channel, the
elevation at a stream’s mouth.
What is the definition of a stream gradient? And where is the stream gradient typically highest, the source or the
mouth?
Stream Gradient (slope): vertical elevation drop over a given horizontal distance
* this determines velocity and discharge! The source
What is downcutting?
vertical erosion process that deepens the channel of a
stream or valley by removing material
from the stream’s bed or valley’s floor
What is headward erosion?
A stream with vigorous headward erosion and steeper
gradient intercepts a stream with a gentler gradient
What is lateral erosion?
The wearing away of the sides of the river (cut bank) making it wider
What are oxbow lakes?
Meanders will become more sinuous
through time until two meanders
merge, forming a cutoff and oxbow
lake.
What is the biggest con of constructing a dam?
River no longer carries
sediment downstream
to replenish nutrients
on floodplain so
downstream is
STARVING for
sediment making it
erode much more
quickly
