Chapter 6 - Running Water and Groundwater

Cut bank

Outside of the meander where erosion, velocity, and turbulence are greatest

Hard water

Water that has certain dissolved ions in it - predominately calcium and iron ions. Forms scum with soap instead of suds. Clogs pipes, but is not a health risk

stalactites

dripstone icicle-like stone pendants that hang from the ceiling of a cavern. Forms when water repeatedly seeps through cracks in the cavern ceiling and leaves dissolved carbon dioxide and calcite behind until it becomes cone shaped.

stalagmites

formations that develop on the floor of a cavern and reach up toward the ceiling. Larger and more rounded than on their upper ends than stalactites due to water with calcite splashing on the cavern floor

Maximum velocity of a straight stream

near the center of the channel just below the surface

Aquifers

permeable rock layers or sediments that transmit groundwater freely. Source of well water

Velocity

the distance that water travels in a period of time

Infiltration

the movement of surface water into rock or soil through cracks and pore spaces

water table

the upper limit of the zone of saturation. Borders the zone of aeration

discharge

the volume of water in a stream flowing past a certain point in a given unit of time.

Types of base level

ultimate base level and temporary base level

Groundwater

water that is in the zone of saturation.

Downcutting

when a stream erodes the bottom of its channel resulting in a deepening of the channel. (Can form steep, narrow valleys)

Sources of groundwater pollution

Sewage, waste from factories, oil/gas on roads from cars and drilling, fertilizers and pesticides from farms and gardens

Velocity effects

The ability of a stream to erode and transport

Bed Load

The part of a stream's load of solid material that is made up of sediment too large to be carried in suspension. Moves along the bottom of the stream channel. Only moves when the force of the water is great enough to move it. Causes erosion via grinding.

stream piracy

The process by which one stream captures the headwaters of another stream (Maumee River, captures St. Joseph River and St. Marys River before making it to Lake Erie)

Maximum velocity of a curved stream

Towards the outer bank just below the surface

Narrow Valley

V-shaped valley that shows that the stream's primary work has been downcutting toward base level. Rapids and waterfalls are common where the stream profile drops rapidly. (Yellowstone River)

Distributaries

When a main channel divides into several smaller channels (Often due to deltas/sediment blocking the original channel). These shifting channels act in the opposite way of tributaries. Carries water away from the main channel

Transpiration

When plants absorb water and release it into the atmosphere

Runoff

When the rate of rainfall exceeds Earth's ability to absorb it, the excess water flows over the surface into lakes and streams

discharge increases

While gradient decreases between a stream's headwaters and mouth,________. This is because more and more tributaries enter the main channel as it moves downstream.

cone of depression

a cone-shaped depression in the water table immediately surrounding a well due to drawdown. When wells are used for irrigation or industry, a very wide and steeps one of these can result

soda straw

a hallow limestone tube formed by calcite

well

a hole bored into the zone of saturation

permeability

a material's ability to transmit a fluid

Cavern

a naturally formed underground chamber formed from erosion caused by groundwater with calcium bicarbonate in solution. Forms at or below the water table in the zone of saturation. Is a form of karst topography

Natural levee

a ridge made up mostly of coarse sediments that parallels some streams. Forms when a stream repeatedly overflows its banks and leaves sediment behind

cutoff

a shorter channel segment created when a meander overtakes another due to resistance in the floodplain.

Hot spring

a spring that is 6 degrees to 9 degrees Celsius warmer than the annul air temperature where the spring occurs. Forms when the groundwater becomes heated by cooling igneous rock

tributary

a stream that empties into another stream. Carries water to the main channel

divide

an imaginary line that separates the drainage of two streams. Ranges in scale from a ridge separating two small gullies on a hillside to a continental _______.

Meander Scar

an oxbow lake that doesn't have any water

Human flood control strategies

artifical levees, flood control dams, and placing limits on floodplain development

Distribution of Earth's Water

97.2% Oceans, 2.15% Glaciers, 0.62% Groundwater, 0.03 % Others

Meander

A bend in a stream. When a stream is in a broad, flat-bottomed valley that is near its base level, it often develops many of these bends

spring

A flow of groundwater that emerges naturally at the ground surface. Forms when an aquitard blocks downward movement of groundwater and forces it to move laterally

oxbow lake

A meander that has been cut off from the stream due to hitting a resistant segment in a floodplain. After deposits of sediment fully cut off the meander it forms

delta

Accumulation of sediment formed where a stream enters a lake or ocean. Formed when a stream enters the relatively slow-moving water of an ocean or a lake, its velocity drops. As a result, the stream deposits sediment and forms it. May form a triangle.

Worlds to 3 largest rivers ranked by discharge

Amazon River, Congo River, Yangtze River,

Precipitation

Any form of water that falls from clouds and reaches Earth's surface.

Dissolved load

Enters streams through groundwater. Dissolving rock also contributes this. Expressed as parts of dissolved minerals minerals per million parts of water (parts per million or ppm)

Clay's interaction with groundwater

Has high porosity, but water cannot move as it is impermeable due to its pore spaces being too small (aquitard)

Sand's interaction with groundwater

Has larger pore spaces due to larger particles, making it easier for water to move through (permeable). It is an aquifer

aquitards

Impermeable layers that prevent water movement

What three ways do Streams transport sediment

In solution (dissolved load), in suspension (suspended load), and bouncing or rolling along the bottom (bed load)

Temporary base level

Includes lakes, resistant layers of rock and main streams that act as a base level for their tributaries

Limiting floodplain development

Leaving floodplains in their natural state is much easier than trying to prevent them from flooding when there are buildings on them

Suspended Load

Most streams carry the the largest part of their load in this. The visible cloud of sediment is the most obvious portion of a streams load. Carries sand, silt, clay, and others(If it is a flood). Amount carried increases during floods

Point bars

Much of the debris the stream removes at the cut bank moves down stream where it is deposited in zones of decreased velocity on the inside of meanders

Flood control dam

store floodwater and then let it out slowly. Traps sediment and leads to deltas and floodplains downstream eroding due to receiving no sediment

zone of aeration

the area above the water table where the soil, sediment, and rock are not saturated. Wells cannot pump water from this zone

Balance in the water cycle

the average annual precipitation over Earth equals the amount of water that evaporates and transpires

stream channel

the course the water in a stream follows

Geyser cycle

the cycle in which groundwater is turned to steam, erupts out of the ground, and the water is replaced

drainage basin (watershed)

the land area that contributes water to a stream (Mississippi River is the largest one of these in the USA)

Base level

the lowest point to which a stream can erode its channel. The level at which the mouth of a stream enters the ocean, a lake, or another stream

Capacity

the maximum load a stream can carry. Is directly related to a stream's discharge. It increases as the volume of the water in the stream increases. A large river with high velocity also has high ________.

porosity

the percentage of the total volume of rock or sediment that consists of pore spaces.

Flow and Storage of groundwater depends on

the porosity and permeability of the subsurface material

gradient

the slope of steepness of a stream channel, varies throughout the stream (steeper=more energy)

alluvium

the sorted material deposited by a stream. Many different depositional features are made of it. Some occur within stream channels. Some occur on the valley floor next to the channel. Others occur at the mouth of a stream

mudpot

thick, bubbling mineral springs that form when hot acidic groundwater mixes with minerals from adjacent rock

How does groundwater move?

by twisting and turning through interconnected small openings

dripstone

cave deposits, composed of travertine. Deposition of this is not possible until the caverns are in the zone of aeration.

artesain well

when groundwater rises up own its own under pressure in a well, sometimes overflowing the surface. Needs a tilted aquifer partially exposed at the surface, and an aquitard above and below the aquitard to form

Sorting

when stream transport separates solid particles of various sizes, large to small. Explains why particles of similar sizes are deposited together

Deposition

when streamflow drops below the critical settling velocity of a certain particle size. The sediment begins to settle out

flood

when the discharge of a stream becomes so great that it exceeds the capacity of its channel and overflows its banks. Most common and most destructive of all natural geologic hazards. Most caused by rapid spring snow melt, or storms that bring heavy rain over a large region. (Mississippi River Valley Summer of 1933)

drawdown

when the water table around a well drops whenever a substantial amount of water is withdrawn from the well. Decreases with an increase of distance from the well

Stream valley

consists of the channel and surrounding terrain that directly contributes water to a stream. Range in size from narrow, steep-sided valleys to those that are wide and flat.

How construction affects discharge

covers soil that soaked up water, less water soaks into soil, runoff increases, increases flood frequency and magnitude. Dry season flow of streams is also reduced.

stream profile

cross-sectional view of stream from its source (headwaters) to its mouth. Typically shows a decreasing gradient from its headwaters to its mouth

evaporation

when water turns to water vapor due to heat

Factors that affects amount of water that ends up underground

depends on steepness of slopes, the nature of surface materials, the intensity of rainfall, and the type and amount of vegetation.

sinkhole

depression produced in a region where groundwater has removed soluble rock. Forms either without physical disturbance to the rock and the depressions are fairly shallow and have gentle slopes, or are formed suddenly when the roof of a cavern collapses and forms a steep-sided, steep depression

Continental divide

divide that splits continents into enormous drainage basins

Artificial levees

earthen mounds built by humans on the banks of a river. Increase the volume if water a channel can hold. Prevents sediments from depositing on the sides of the stream, making them settle on the bottom instead, raising the water level and increasing the chance of a flood. It will need a periodical height increase to prevent flooding

What powers the water cycle?

energy from the sun and gravity

Flood plain (wide valley)

flat valley floor through which a river flows. During a flood the river overflows its banks and floods the plains. Streams that flow on it move in meanders

Factors that determine stream velocity

gradient, shape, size, roughness of channel, discharge

Pore spaces smaller=

groundwater moves more slowly or not at all

Contamination and overuse threaten what?

groundwater supplies in some areas

Karst areas typically:

have irregular terrain, with many sinkholes

Geyser

intermittent hot spring or fountain in which a column of water shoots up with great force at various intervals. Form where extensive underground chambers with groundwater exist within hot igneous rocks

karst topography

landscapes that have been shaped largely by the dissolving power of groundwater. Occur in many areas that are underlain by limestone.

Three ways that streams erode their channel

lifting loose particles, abrasion and grinding, and by dissolving soluble material

travertine

limestone formed by calcium carbonate

Competence

measures the largest particles a stream can transport. Increases with velocity. Increase four times when velocity doubles (c=v^2). Can move larger objects during floods

zone of saturation

much of the water in soil seeps downwards until it reaches this. It is the area where water fills all of the pore spaces in sediment and rock. Water can be pumped from here with a well

Belt of soil moisture

near surface zone where water is held in place by molecular attraction as a film on soil particles. Roots, voids left behind by decayed roots, and animal and worm burrows criss-cross this zone

pore spaces

openings in bedrock, sediment, and soil. These openings are similar to those of a sponge

ultimate base level

sea level. It's the lowest level that stream erosion can lower the land.

What affects stream friction

shape, size, and roughness of the channel. (boulders in stream=slower, smooth channel=faster)

Water Cycle

The unending circulation of Earth's water supply through the oceans, the atmosphere, geosphere, and biosphere

Critical settling velocity

The velocity at which a stream must move to keep a particle in it from settling.