rivers and floods

Question 1

What is the representation of water stored?

Answer 1

oceans 97% of volumes
3% in fresh water
2/3 in ice
1/3 in ground
0.03% in lakes, streams, vegetations and atmosphere

Question 2

what is the hydrological cycle?

Answer 2

water is constantly on the move
It is evaporated from the oceans, lakes, streams, the surface of the land, and plants (transpiration) by solar energy. It is moved through the atmosphere by winds and condenses to form clouds of water droplets or ice crystals.

Question 3

What is the region drained by a single river variously is called a

Answer 3

drainage basin, watershed, river basin or catchment

Question 4

What is gradient?

Answer 4

slope of the land it flows over

-determined by calculating the vertical drop in elevation of the channel over some horizontal distance

-meters per kilometer or feet per mile. If a river falls 1 meter per km, the slope is 1/1000 or 0.001 (0.1 percent).

Question 5

what is the downstream elevation in river’s elevation?

Answer 5

The longitudinal profile

Question 6

When do floods normally occur in the USA?

Answer 6

Spring

Question 7

When does a river usually have steeper-sides and deeper valley?

Answer 7

At high elevation near headwaters
- base level is where wide floodplain is present

Question 8

What happens at higher elevations?

Answer 8

the steeper river gradient increases flow velocity, which, in turn, increases erosional down-cutting by the river.

Question 9

What does dissolve load consist of?

Answer 9

dissolved load consists of atoms or molecules, called ions, which are carried in chemical solution

Question 10

Mandering pattern

Answer 10

• single-thread channel similar to the curves of a moving snake
  -migrate back and forth floodplains

Question 11

Braid pattern

Answer 11

multithread channel where there are two or more channels that unite and divide as the river flows downstream

Question 12

What is a floodplain?

Answer 12

major river landform that develop over a period of years to decades and much longer

Question 13

What is most floodplain related to?

Answer 13

amount and distribution of precipitation in the drainage basin, the rate at which the precipitation infiltrates (soaks) into the earth, and how quickly surface runoff from that precipitation reaches the river.

Question 14

How are floods characterized?

Answer 14

here they occur in a drainage basin
-zones 1, 2, and 3

Question 15

What is a flashflood

Answer 15

• most common in areas with steep topography or little vegetation, and following breaks of dams, dykes, and ice jams
• typically occur in the upper part of a drainage basin
• in zone 1

Question 16

what is downstream floods of ZONE 2 associated with

Answer 16

inundation of the floodplain.

Zone 2 floods may cover a wide area and are usually produced by storms of long duration that saturate the soil and produce increased runoff.

Question 17

Zone 3 association

Answer 17

particularly dangerous due to the uncertain and changing flow paths of both the river itself and ocean currents, waves and tides.

Question 18

what is river discharge

Answer 18

int along its course is the amount of water passing through the channel cross-section at that point during a specified interval of time. River discharge is usually measured in cubic meters per second.

Question 19

Why is knowledge about rivers important?

Answer 19

Understanding river behavior is essential for understanding the evolution of landscapes, environmental planning, and territorial planning.

Question 20

What is river discharge?

Answer 20

River discharge is the amount of water passing through a channel cross-section at a point during a specified interval of time, usually measured in cubic meters per second.

Question 21

What are some physical factors that affect river discharge?

Answer 21

Lithology and soil type, size and shape of the drainage basin, precipitation, and vegetation.

Question 22

What are some human factors that affect river discharge?

Answer 22

mpermeable man-made surfaces, deforestation, and river management.