GEO Chapter 14 Exam 3

Precipitation

(rain, snow, hail) brings water to land surface Groundwater springs also bring water to the land surface

Define Channel

- a trough dug into the ground surface by flowing water

Characteristics of Ephemeral Streams

-Do not flow all year -Bed/floor of channel is above the water table -Dry climates -Low rainfall -High evaporation -Flows mostly during rare flash floods

Characteristics of Permanent streams?

-Water flows all year -Bed/floor of channel is at or below the water table -Humid or temperate climates -Sufficient rainfall -Low evaporation -Discharge varies seasonally

What is the formation of a Stream Formation?

1. Precipitation (Rain) Occurs 2. Sheetwash flows downhill 3. Flowing water digs tiny channels called rills 4. Rills downcut; develop into streamflow

Define Longitudinal profile

A cross-section image showing the variation in elevation along the length of a river

Define Alluvial fan ..

A gently sloping apron of sediment dropped by an ephemeral stream at the base of a mountain in arid or semi-arid regions

Braided stream

A sediment-choked stream consisting of entwined sub-channels

Define Meander

A snake-like curve along a stream's course

Which river has the most discharge Mississippi river or the amazon river?

Amazon river =200,000 m3/s

What is larger solid particles (sand, pebbles, or cobbles) that bounce or roll along stream floor called?

Bed load

The elongated depression or trough through which water flows is the steam ___________.

Channel

______________ of a stream refers to the maximum particle size it carries while the ___________ of a stream refers to the total quantity of sediment it can carry.

Competence; capacity

The sediment load consists of three components:

Dissolved, Suspended, & Bed Load

All water flows through a stream/river at the same speed (flow velocity) True or False?

False. Not All water flows through at the same speed.

__________pulls surface water downhill into a stream channel, which is a trough in the surrounding substrate.

Gravity

Surface water concerns are..

Levee failures, flooding , river pollution

Small volume, slow-moving, clear water is not

Not efficient at erosion

The ________ load typically consists of solid clasts (silt or clay size) that swirl in the water without settling to the floor of the channel.

Suspended

Define Floodplain

The flat land on either side of a stream that becomes covered with water during a flood

True or False ? The geology (rock type) of land surface is the major control over the type drainage network that develops.

True

Large volume, fast-moving, turbulent, sediment-laden water

Very efficient at erosion

A lot of erosion can occur during

a flood! (more energy)

Define Turbulent Flow

a flow regime characterized by chaotic property changes

A Stream is__________

a ribbon of water that flows in a channel

(Sediment deposition) Delta

a wedge of sediment formed at a river mouth when the running water of the stream enters standing water, the current slows, the stream loses competence, and sediment settles out

Define Point bar

a wedge-shaped deposit of sediment on the inside bank of a meander

Define Drainage network (basin)

an array of interconnecting streams that together drain an area

A Flood is...

an event during which the volume of water in a stream becomes so great that it covers areas outside the stream's normal channel

Define Discharge

area of the stream times average stream velocity

The lowest elevation that a stream channel's surface can reach at a particular location is referred to as the ___________ of the stream.

base level

Natural systems have what?

complex water flow patterns.

The five types of drainage networks are ______________.

dendritic, radial, rectangular, trellis, parallel

The volume of water passing through a cross section of the stream in a given time is the ________________.

discharge

__________a highland or ridge that separates one watershed from another . _______ separates drainage that flows into one ocean from drainage that flows into another ocean

drainage divide ,continental divide

What do streams do?

erode, transport, and deposit sediment

Meandering steams typically occur where the stream's gradient is very ________.

gentle (low angle)

What occurs in the center of a straight channel__________? What slows it down?

maximum velocity, friction

Define Laminar Flow

occurs when a fluid flows in parallel layers, with no disruption between the layers

A _________ is where water slows along the inner edge of a stream meander and sediment is deposited.

point - bar

Define Breaking and lifting

running water can break clasts of solid rock off the channel floor or walls, or may lift clasts off the channel floor

Define Abrasion

running water containing sand to gravel size particles that act like sandpaper and grinds away at the channel floor or walls

Define Dissolution

running water dissolves soluble minerals as it passes and carries the minerals away in solution

Define Scouring

running water removes loose fragments of sediment

Ultimate base level is ...

sea level (sea level can move up and down)

Define Fluvial deposits (alluvium)

sediment deposited in a stream channel, along a stream bank, or on a floodplain

Fast moving water promotes ____________, while slow moving water promotes __________.

sediment erosion; sediment deposition

Geologists refer to the total volume of sediment carried by a stream as its

sediment load

Define Suspended load

small solid particles (silt or clay size) that swirl along in the water without settling to the floor of the channel

Water table

the boundary, approximately parallel to the Earth's surface, that separates substrate in which groundwater fills the pores from substrate in which air fills the pore

Define Headward erosion

the process by which a stream channel lengthens up its slope as the flow of water increases

Define Stream gradient

the slope of a stream's channel in the downstream direction

Efficiency of erosion is a function of ______, ________, _________ content of water.

velocity, volume, and sediment

Define Dissolved load

water seeping through rock surrounding stream channel dissolves certain minerals and transports these ions down the stream