Chapter 5 - Running Water and Groundwater

Gullies

Rills meet to form gullies.

Aquifer

"Water Bearer" Aqui- = Water, fer = Bearer or Carrier. Rock or rock material has both good porosity and good permeability. Example: Sandstone

Aquiclude

"Water Blocker" Aqui- = Water clude = Blocked (e. g., The blood vessel was occluded by a blood clot...). Rock or rock material has neither good porosity nor good permeability. Example: Granite

Aquitard

"Water Hinderer" Aqui- = Water, tard = Late or Hindered. Rock or rock material has either poor porosity or poor permeability. Example: Shale

Stalactite

"c" = ceiling and "t" = top. Stalactites are speleothems or limestone structures that hang down from the ceiling at the top of a cave!

Stalagmite

"g" = ground and "m" = mound. Stalagmites are speleothems or limestone structures that form mounds on the ground (or floor) of a cave!

Factors affecting flow velocity

(The ability of stream to erode and transport material directly related to its flow velocity.) Stream gradient; Stream discharge; Channel shape, size, and roughness

Stream capacity vs. Stream competence

1. Capacity - the maximum particle load that a stream can transport, volume of water affects this 2. Competence - the maximum particle size that a stream can transport, dependent upon velocity

Types of stream flow

1. Laminar: slow moving, particles move in straight lines downstream, stream bed is well sorted with all particles as the same size 2. Turbulent Flow: rapid movements, stream bed is poorly sorted with different sized particles

Stream erosion

1. gravel sized particles, hydraulic action or plucking, traction downstream 2. sand sized particles, abrasion, saltation or leapfrogging

Bajada (Extra Credit)

A broad slope of debris spread along the lower slopes of mountains by descending streams. A bajada is often formed by the coalescing of several alluvial fans.

Column

A stalactite and a stalagmite that have fused together to form one complete limestone structure!

Channel size, shape, and roughness

Affect the amount of friction. Large channels = efficient flows, smooth channel = uniform flow, irregular channel = creates turbulence, slows the stream

Ultimate base level

All rivers and streams erode toward sea level, which is also known as the "ultimate base level."

Temporary base level

Any base level, other than sea level, below which a land area temporarily cannot be reduced by erosion. Also known as local base level.

Types of sediment loads

Bed load (gravel and sand), Suspended load (silts and clay), Dissolved load (travels as anions and cations within an aqueous solution)

Drainage Divide

Boundaries between basins are called divides.

Formation of Cut banks and Point bars

By eroding its outer bank and depositing material on the inside of the bend, a stream is able to shift its channel.

Precipitation

Cloud formation results in precipitation (rain, snow, sleet, or hail that falls to the ground or into the ocean).

Development of an erosional floodplain

Continuous side-to-side erosion by shifting meanders gradually produces a broad, flat valley floor. Alluvium deposited during floods covers the valley floor.

Earth's water is distributed 3 ways. How?

Cryosphere; 1.76% - Global Oceans; 96.5% - Lakes, Streams, Groundwater, and Atmosphere; 2.74%

Trellis Pattern

Develops in areas of alternating weak and resistant bedrock

Rectangular Pattern

Develops on highly jointed bedrock

Radial Pattern

Develops on isolated volcanic cones or domes

Dendritic Pattern

Develops on relatively uniform surface materials

Alluvial Channels

Dominated by streamflow through alluvium previously deposited by the stream.

Zones of a river

Each of the three zones is based on the dominant process that is operating in that part of the river system.

Hydrologic Cycle

Evaporation, condensation, precipitation, infiltration or transpiration and respiration or sublimation, and surface runoff

Cryosphere

Glaciers and ice sheets

Tributaries

Gullies meet to form tributaries (river or stream flowing into a larger river or lake).

Zone of Sediment Production

Head of Stream, Drainage basin/Watershed, Contributaries, Alluvial fan

Infiltration

If precipitation falls to the ground, a portion of the water soaks into the ground.

Once precipitation has fallen on land, what paths might it take?

Infiltration or Runoff, then evaporation, then precipitation

5 factors that affect Surface Runoff vs. Infiltration

Intensity and duration, amount of soil moisture, surface material, land slope, vegetation extent and type

River systems

Involve a network of stream channels and entire drainage basin. Sediment is being eroded, transported, and deposited along the stream

Sinkhole (Sinks)

Karst topographic structure that forms when the roof of a cave or cavern falls in or fails.

Karst Topography

Many areas of the world have landscapes that, to a large extent, have been shaped by the dissolving power of groundwater. (develops in limestone regions and exhibits irregular terrain punctuated with many depressions called sinkholes)

Discharge

Measure most often used to compare sizes of streams. The volume of water flowing past a certain point in given unit of time. Determined by multiplying a stream's cross-sectional area by its velocity. Discharge is not constant. Q=Local Stream Velocity x Stream Area. Stream area= Stream width x Stream Depth.

Zone of Sediment Deposition

Mouth of stream: Delta (Distributaries), Base level (ocean)

Braided Stream

Multiple channels separated by migrating gravel bars.

Drainage patterns

Networks of streams form a variety of patterns.

Formation of Oxbow Lakes

Oxbow lakes occupy abandoned meanders.

Rills

Sheet flow is unconfined and eventually develops threads of current that form tiny channels called rills.

What are the five steps of stream formation?

Sheet flow, rills, gullies, tributaries, streams

When do streams deposit sediments?

Streams deposit sediment when velocity slows and competence is reduced. This results in sorting, the process by which like-size particles are deposited together.

Transportation of Sediment

Streams transport their load of sediment in three ways. The dissolved and suspended loads are carried in the general flow. The bed load includes coarse sand, gravel, and boulders that move by rolling, sliding, and saltation.

Formation of a simple delta

Structure and growth of a simple delta that forms in relatively quiet waters.

Sheet flow

Surface runoff initially flows in broad, thin sheets.

Base level

The base level of a river or stream is the lowest point to which it can flow, often referred to as the 'mouth of the river'.

Sublimation

The change in state from a solid directly to a gas without passing through the liquid state. (Ice to water vapor)

Drainage basin/watershed structure

The land area that contributes water to a river system. (The area drained by a stream and its tributaries.)

Distributaries

The main channel divided into several smaller ones.

Permeability

The permeability of a material indicates its ability to transmit a fluid through interconnected pore spaces. Key factor affecting the movement of groundwater.

Potholes

The rotational motion of swirling pebbles acts like a drill. (Swirling eddies can act like "drills" and bore circular potholes into the channel floor)

Alluvial fans

Typically develop where a high-gradient stream leaves a narrow valley in mountainous terrain and comes out suddenly onto a broad, flat plain or valley floor. (Fan-shaped deposits of alluvium that form where steep mountain fronts dorp down into adjacent valleys.)

Zone of Sediment Transport

Valley floor: Meanders (Cut banks and Point bars)

Transpiration

Water is absorbed by plants, which then release it into the atmosphere.

Condensation

Water vapor (gas) changes to liquid and results in cloud formations.

Floodplain

When a river overflows its banks during flood stage, it overwhelms the floodplain.

Surface Runoff

When rainfall exceeds Earth's ability to absorb it, the surplus flows over the surface into lakes and streams.

Alluvium

a deposit of clay, silt, sand, and gravel left by flowing streams in a river valley or delta, typically producing fertile soil

Ephemeral streams

arid climates, many streams carry water only occasionally, after heavy rainstorm

Meanders

change shape through erosion at the cut bank and deposition of sediment on point pars.

Longitudinal profile of a stream

cross-sectional view of a stream from source area (head or headwaters) to the mouth (point downstream where it empties into other water body). Usually the gradient and roughness of the stream channel decrease going downstream, whereas the size of the channel, stream discharge, and flow velocity increase in the downstream direction.

Intermittent streams

exhibit flow only during wet periods

Caverns

form at the zone of saturation, but later dropping of the water table may leave them open and dry

Delta

forms where a sediment-charged stream enters the relatively still waters of a lake, an inland sea, or the ocean.

Hot springs

groundwater that circulates deep below the surface, it may become heated and emerge at the surface as a hot spring

What triggers floods?

heavy rains and/or snowmelt

What is the source of heat for most hot springs and geysers?

hot igneous rock

Velocity

important factor influencing stream turbulence. Velocity increases - flow becomes more turbulent.

Stream valley

includes: the channel, adjacent floodplain, and the relatively steep valley walls.

Size of stream channel

largely determined by amount of water supplied from drainage basin

Sediment production

most of the sediment is derived. Much of the Sediment is carried by streams begins as bedrock, brakes down by weathering, then transported downslope by mass wasting & overland flow. Bank erosion also contributes significant amount of sediment.

Geysers

occur when groundwater is heated in underground chambers and expands, with some water quickly changing to steam and causing the geyser to erupt

Springs

occur when the water table intersects the land surface and a natural flow of groundwater results

Wells

openings bored into the zone of saturation, withdraw groundwater and may create roughly conical depressions in the water table known as cones of depression

Variables affecting discharge

rainfall and snowfall

Growndwater

represents the largest reservoir of freshwater that is readily available to humans, NOT a renewable resource, occupies the pore spaces in sediment and rock in a zone beneath the surface called the zone of saturation

Natural levees

result from sediment deposited along the margins of a stream channel by many flooding events.

Dripstone

rock deposited by dripping of water containing dissolved calcium carbonate inside caverns. (stalactites, stalagmites, and columns)

Sediment transport

sediment acquired by a stream is transported through the channel network along sections (trunk streams). In balance: amount of sediment eroded from banks = amount deposited elsewhere in channel. Trunk streams are not a source of sediment, nor do they accumulate or store it

Artesian wells

tap into inclined aquifers bounded above and below by aquitards.

What is the unending circulation of water is called?

the hydrologic cycle

Point bars

the inside of a meander

Water table

the level below which the ground is saturated with water

Infiltration capacity

the limit for ground to soak in water

Cut bank

the outer edge of the meander

Porosity

the percentage of the total volume of rock or sediment that consists of pore spaces (cannot measure a material's capacity to yield ground water alone) (quantity of water that can be stored in the open spaces in rock or sediment)

Sediment deposition

when a river reaches the ocean or other large body of water, it slows (energy to transport greatly reduced). Most sediment accumulate at mouth of river to form delta or moved far offshore by ocean currents. Coarse sediments tend to be deposited upstream - fine sediments (clay, silt, fine sand) reach the ocean