Eas 111 Exam 3- Streams And Rivers

Front 1

Drainage Basin

Back 1

extent of land where water from rain or snow melt drains downhill into a body of water,

-includes both the streams and rivers that convey the water as well as the land surfaces from which water drains into those channels,

-separated from adjacent basins by a drainage divide]

Front 2

Watershed

Back 2

-divide that separates one drainage area from another drainage area

Front 3

How are drainage basins and watersheds different?

Back 3

Drainage Basin- mapped to overall geography, raindrop to base level, better unit of analysis for understanding hydrology

Watershed- associated with individual river systems, most common unit of analysis for land managers

Front 4

Tributaries

Back 4

Smaller subsidiary channels
spread out discharge over time

Front 5

Dendritic style drainage basin

Back 5

Type of drainage patter that brances out and is tree-like, with smaller tributaries feeding into larger ones

Front 6

Radial drainages

Back 6

flow outward in all directions, like off a circular mountain

Front 7

In a figure of a stream profile, where is the stream gradient the steepest and the flattest?

Back 7

- tend to be steep near their origin, such as in hills and mountains
-becomes less steep (more gentle) down stream

Front 8

Base Level

Back 8

Sea level is ultimate base level

Base level can be the sea, lake, or closed basin

Front 9

High above base level erosion

Back 9

streams and rivers can have steeper gradients and erode sharply into terrain

Much Erosion

Front 10

Closer to base level erosion

Back 10

streams have lower gradient so less erosion

Front 11

Floodplain

Back 11

is flat or nearly flat land adjacent to a stream or river that experiences occasional or periodic flooding

Front 12

Stream Terraces

Back 12

Floodplains

These are old floodplains that remain relatively high above the present floodplain and indicate former courses of a stream.

Front 13

Floodplain

Meanders

Back 13

Flood plains are made by a meander eroding sideways as it goes downstream. Also when a river breaks its banks and floods it leaves behind layers of rock and mud. These gradually build up to create the floor of the flood plain.

Front 14

Levee:

Back 14

raised embankment, commonly on both sides of a river

Front 15

Natural Levees

Back 15

Keep water in the river during small floods

Trap flood waters if levee breached or overtopped during a flood

Front 16

How do river terraces form?

Back 16

Flow and erosion power of the stream increased

The landscape was being driven upwards by tectonics

Base level dropped

Front 17

How is discharge calculated?

Back 17

Discharge calculated by multiplying channel width X depth X velocity of water

cubic meters/sec
cubic feet/sec

Front 18

Where is discharge calculated?

Back 18

gauging station where cross section of the river has been measured

Front 19

Discharge

Back 19

Amount of water flowing through a channel over a given time

Front 20

How does discharge change with storm events?

Back 20

Vary in discharge, such as peak flow during spring snowmelt, or during a rainy season

Front 21

What is flood stage in terms of height and discharge?

Back 21

Stream discharge small and consistent before storm

Gradual increase in discharge during and after storm, with highest discharge at peak flood

Return to normal discharge after storm and flood pass

Front 22

Straight channel:

Back 22

fairly symmetric with highest velocity in center

Front 23

Inside of bend:

Back 23

channel shallower and velocity lower, so deposition forms a point bar

Front 24

Outside of bend:

Back 24

channel deeper and velocity faster, so erosion forms a cutbank

Front 25

Erosion of cutbank and deposition of point bar may be _______ so river maintains width

Back 25

balanced