Surface Water

Question 1

What is the hydrologic cycle?

Answer 1

The hydrologic cycle is a summary of the continuous circulation of Earth’s water
supply

Question 2

where do streams originate? What are the characteristics of this location?

Answer 2

Head waters: stream source
Gradient is steep
Discharge is low
Competence is high

Question 3

Where do streams terminate? What are the characteristics of this location?

Answer 3

Near the streams Base level:
Gradient is nearly flat.
◼ Discharge is high.
◼ Competence is low
(sediments are fine).
◼ Channels curve and twist

Question 4

What is a drainage basin/watershed?

Answer 4

the whole land area that
collects/drains water to a specific stream

Question 5

What is a drainage divide?

Answer 5

imaginary line separating one
basin from another.

Question 6

What are the 4 types of drainage patterns?

Answer 6

Dendric, Radial, Rectangular and Trellis

Question 7

What is an ephemeral stream?

Answer 7

Flow only during a storm and a short period afterwards. Typically in dryer climates

Question 8

What are braided streams?

Answer 8

Network of interweaving channels
Forms when there is low discharge
(insufficient flow) and a lot of sediment, so the
streams capacity is exceeded

Question 9

What are meandering streams?

Answer 9

very curved, high sinuosity: ‘snakes’ around
Forms when there is a low surface gradient
(gentle slope

Question 10

what is a point bar?

Answer 10

inside curve of a meander
characterized by slower moving water and
deposition where piles of sediment are
visible.

Question 11

what is a cutbank?

Answer 11

outside curve of a meander
characterized by fastest moving water and
erosion along the bank. The fast water
CUTS into the bank

Question 12

What is the difference between stream capacity and stream competence?

Answer 12

Capacity
* The maximum load a stream can transport
Competence
* Indicates the maximum particle (clast) size a stream can transport

Question 13

What is the thalweg?

Answer 13

the deep part of a channel where most flow occurs.
It acts like a vortex of the highest velocity of water!

Question 14

What is stream discharge?

Answer 14

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

Question 15

what is stream velocity?

Answer 15

depends on the stream gradient, shape and roughness;
* Speed

Question 16

What is base level? And where can base level erode down to?

Answer 16

The lowest level to which a stream can erode its channel, the
elevation at a stream’s mouth.

Question 17

What is the definition of a stream gradient? And where is the stream gradient typically highest, the source or the
mouth?

Answer 17

Stream Gradient (slope): vertical elevation drop over a given horizontal distance
* this determines velocity and discharge! The source

Question 18

What is downcutting?

Answer 18

vertical erosion process that deepens the channel of a
stream or valley by removing material
from the stream’s bed or valley’s floor

Question 19

What is headward erosion?

Answer 19

A stream with vigorous headward erosion and steeper
gradient intercepts a stream with a gentler gradient

Question 20

What is lateral erosion?

Answer 20

The wearing away of the sides of the river (cut bank) making it wider

Question 21

What are oxbow lakes?

Answer 21

Meanders will become more sinuous
through time until two meanders
merge, forming a cutoff and oxbow
lake.

Question 22

What is the biggest con of constructing a dam?

Answer 22

River no longer carries
sediment downstream
to replenish nutrients
on floodplain so
downstream is
STARVING for
sediment making it
erode much more
quickly