Vocab
Bed load
A stream’s load of solid material made up of sediment too large to be carried
Divide
separation of one stream from another
Competence and capacity
The stream’s ability to carry a load is determined by two factors. The streams competence and its capacity.
Competence increases with the velocity.
The capacity is the maximum amount the stream could carry.
Deposition
Situations reverse whenever a stream slows down.
Deposition occurs when streamflow drops under critical settling velocity of specific particle size.
The sediment in the category begins to settle out.
The process called sorting is when stream transport separate solid particles that are different sizes.
Floods and flood control
Heavy precipitation caused the chaotic overflows in the upper mississippi river in the summer of 1993.
Humans messing with the stream system can better or worsen the cause of flood.
Floods are the most common natural disaster. Flash floods happen in little to know warning.
A dam is a structure that can contain a flood to a certain size.
Capacity
A stream’s maximum load to be carried
Floods
floods are source of water that overflows
Dissolved load
Streams are entered by dissolved load that travel through groundwater. Some may enter by the dissolved rocks near the stream.
The geologic setting and climate also alters the capacity of material the stream can hold.
The dissolved load can be expressed ppm meaning parts per million.
Deltas
Accumulation of sediment formed where a stream enters a lake or ocean.
A stream’s gradient lessens and the water slows down as a result of accumulation movement in a stream slowing down
The river changes direction as it seeks for a easier route to base level
Flood control dam
Store floodwater and then let out slowly
Many dams have other non-flood related functions, such as providing water for irrigation and for hydroelectric power generation
The volume of the stored water will gradually diminished
Alluvium
Sorted material deposited by stream
Natural Levee
landform that reflects some streams
Suspended load
Streams transport larger particles during a flood when water velocity increases.
Visible cloud of sediment suspended in water of portions of a stream’s load.
The amount of material a stream can carry in suspension increases dramatically during floods
Natural Levees
Landform that reflects some streams.
Formed when a stream overflows its bank.
Its velocity decreases and leave coarse sediment deposits in lines that border the channel.
Uneven distribution of material produces gentle slopes of natural levees
Artificial Levees
Another name for artificial level are earthen mound and they are usually built on banks of rivers.
The stream cannot deposit material outside of its channel because it is built upwards.
And when its built upwards it minimizes the amount of water it takes to fill up.
Delta
Accumulation of sediment formed where a stream enters a lake or ocean
Floodplain
During a flood the river overflows its bank
Bed load
Larger coarser particles move along the bottom of stream channels.
Solid material made up of sediment too large to be carried.
Moves only when a force of water has been great enough to move larger particles .
The grinding act of the bed load is very important from eroding the stream channel.
Narrow valleys
V-shaped valley shows that a stream’s primary work and had been downcutted towards base level.
Rapids and waterfall have been the most prominent features of a narrow valley
Both rapids and waterfall occur when the stream primary drops rapidly
Variations in the erosion of underlying bedrock causes rapid drops
Limiting Development
Instead of building structures engineers and scientists advocate floodplain sound management.
Which often mean preserving floodplains in their natural state.
Lowering the development makes floodplains absorb the floodwater with minimal damage.
Drainage Basin
land area that contributes water to streams
Erosion
Channels lifting loose particles by abrasion, dissolving soluble material
Force of water running water rapidly erodes streambeds and banks.
The stronger the current, the more erosional power streams have the more effectively the water will pick up particles
Pebbles caught in swirling stream currents can act like cutting tools and bore circular “potholes”
Wide valleys
Downward erosion becomes less dominant when stream’s cut closer to the base level.
The floodplain is made by the side to side cutting of a stream.
Meanders are movements of streams that flow on floodplains.
Erosion occurs outside the meanders.
Drainage basins
Land area that contributes water to a stream
A line divider separates a drainage basin of one stream from another
Divide range splits continents into enormous streams
The Mississippi river has the largest drainage basin in North America