Section 2.3: Surface Water and Groundwater

Comprehensive flashcards covering surface water processes, river channel dynamics, erosion and deposition features, deltas, and subsurface groundwater characteristics.

How do surface water and groundwater differ in how they move after rain falls or ice melts?

Surface water moves across the surface of the Earth under the influence of gravity, whereas groundwater soaks into the ground under the influence of gravity.

What is the geological definition of a stream?

A stream is any channelized flow of water, regardless of its size, encompassing creeks, brooks, streams, and rivers.

What are the three ways streams transport material?

Streams transport material as a dissolved load, as a bed load, and as a suspended load.

What examples of dissolved solids carried in a stream's dissolved load are mentioned in the notes?

Salt, silica, and calcium.

What is the difference between a stream's bed load and its suspended load?

Bed load consists of sediments rolled along the bottom of a stream, while suspended load consists of fine sediment carried in suspension, which gives rivers a muddy appearance.

Where do the majority of rivers start and end?

The majority of rivers start in elevated areas called headlands and end at the sea or another body of water at their mouth.

What type of drainage pattern typically forms in river headlands?

A branching dendritic drainage pattern, which resembles the roots of a tree.

What are tributary streams?

Relatively small streams in headlands that join together and contribute water to a larger river.

How does water flow velocity and channel cross-section differ between a straight channel and a curved channel meander?

A straight channel has a symmetrical cross-section with highest flow velocity in the middle near the surface, while a curved channel meander has an asymmetrical cross-section with highest flow velocity moving to the outside of the curve.

What is alluvium?

Any sediment deposited by a stream.

How do cut banks and point bars develop along a meander?

A cut bank forms on the outside bank of a meander where steeper channel bottoms and fast-moving water cause erosion, while a point bar forms on the inside bank where slower water and less steep bottoms cause deposition.

What is a meander scar?

A crescentic feature produced by stream migration.

What is an abandoned meander?

A feature formed when a meander is bypassed by a stream's main course so that water no longer flows through it.

How is an oxbow lake formed from a meandering river?

An oxbow lake is formed when a meander is cut off, water velocity through it falls to zero, sediment drops out of suspension, and the ends become closed off from the river to form a free-standing body of water.

What is a floodplain?

A flat area adjacent to a stream created over time as the stream migrates laterally.

What real-world example demonstrates how topography can prevent floodplain formation?

The Colorado River flowing through the steep-sided rocky canyon of the Grand Canyon, maintaining its course without forming a floodplain.

What is a river's base level?

The lowest point that a river flows to, typically where it reaches the sea.

What is a delta and how does it form?

A delta is a large deposit of alluvium at the mouth of a river, formed when the river reaches its base level, fans out, and its flow velocity drops precipitously.

How do the shapes of the Nile River delta and the Mississippi River delta differ?

The Nile River delta has a distinctive triangle shape like the Greek letter delta ($\Delta$), whereas the Mississippi River delta is known as a birdfoot delta due to its odd shape.

What two primary factors dictate how well water moves through subsurface sediments and rocks?

Porosity and permeability.

What is an aquitard or aquiclude?

A material having very low porosity and/or permeability that prevents water from flowing through it.

How are the zone of saturation, groundwater, and the water table defined?

The zone of saturation is the subsurface area above an aquitard or aquiclude where all pore spaces are filled with water; groundwater is all the water within this zone; and the water table is the top boundary of the zone of saturation.

What rock example is provided in the lecture notes to illustrate subsurface porosity?

Porous Florida limestone.