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