Chapter 16 - Running Water (streams)

How does a stream erode its channel?

1) Hydraulic action - flowing water pries rocks loose. 2) Solution - flowing water may gradually dissolve some rock types or cements. 3) Abrasion - flowing water causes the stream channel bedrock to erode from impact with the sediment load (ex. potholes).

Proportion of fresh water

1. Groundwater = 30.1% 2. Glaciers = 68.6% 3. Surface water = 1.3%

Alluvial Fans

A fan-shaped deposit of sediment formed when a stream's slope is abruptly reduced

Natural Levees

Deposits formed along both sides of a stream channel; from flooding.

Competence

Indicates the maximum particle size a stream can transport

Bed Load

Materials are large enough to sink to the bottom

Dissolved Load

Materials dissolved in water

Point Bar

deposit of sediment build up by a river on the inside bend of a meander

Delta

depositional features created by streams that have longer life spans

Incised Meander

meandering channels that flow in steep, narrow bedrock valleys -formed on floodplain that's base level changed over time and stream began downcutting

Bars

small scale channel deposits when flow is sluggish, the stream deposits coarsest materials as elongate structures called bars

Meander

streams that transport much of their load in suspension generally move in sweeping bends

Cut Bank

the area of active erosion on the outside of a meander

Drainage Basin

the land area that contributes water to a stream

Discharge

the quantity of water in a stream that passes a given point in a period of time

Gradient

the slope of a stream channel, expressed as the vertical drop of a stream over a specified distance

Runoff

when precipitation falls on land it flows over the surface

Infiltration

when precipitation falls on land it is soaked into the ground

Drainage Divide

An imaginary line that separates the drainage of two streams, often found along a ridge

Transpiration

Water that is soaked into the ground is absorbed by plants, which later releases it into the atmosphere

Floodplain

A low plain adjacent to a river that is formed chiefly of river sediment and is subject to flooding

Oxbow Lake

A meander that has been cut off from the river

Braided Streams

A type of an Alluvial Channel. Interwoven appearance of streams said to look braided

Evapotranspiration

The evaporation of water from soil plus the transpiration of water from plants.

Hydrologic Cycle

The unending circulation of Earth's water supply. The cycle is powered by energy from the Sun and is characterized by continuous exchanges of water among the oceans, the atmosphere, and the continents

Suspended Load

Too small to sink so the materials stay floating

Cutoff

a short channel segment created when a river erodes through the narrow neck of land between meanders