Rivers And Streams Flashcards
Rivers and Streams:
Bodies of flowing water that play a crucial role in shaping the Earth’s surface through erosion and sediment transport.
Sediment:
Particles of rock and soil that are carried by water, wind, or ice and deposited elsewhere.
Water Cycle:
The continuous process by which water is circulated between the Earth’s surface, atmosphere, and bodies of water.
Groundwater:
Water that is found beneath the Earth’s surface in soil pore spaces and in the fractures of rock formations.
Meandering Streams:
Streams that follow a winding or sinuous course, characterized by loops and bends.
Floodplains:
Flat areas adjacent to rivers and streams that are prone to flooding.
Drainage Divides:
Boundaries that separate one watershed from another, determining the direction in which water flows.
Watersheds:
The area of land where all of the water that falls in it drains off into a common outlet, such as a river, lake, or ocean.
Oxbow Lakes:
U-shaped bodies of water that form when a meander of a river is cut off, creating a free-standing body of water.
Hydroelectricity:
Electricity generated by hydropower, the production of power through the use of the gravitational force of falling or flowing water.
Irrigation:
The artificial application of water to land or soil to assist in the production of crops.
Floodplains:
Low-lying areas adjacent to rivers and streams that are periodically flooded when water levels exceed the capacity of the channel
What are rivers and streams essential for creating?
Rivers and streams are essential for transporting sediments to create an ecosystem.
Why are rivers important to humans?
Rivers are crucial for human activities, including transportation, agriculture, and recreation.
What is the water table?
The water table is the level at which the ground is saturated with water and is the same as the stream channel.
Describe the flaws in streams.
Stream flaws can include fast-moving water, stream hydrographs, and drainage basins.
What is the purpose of drainage basins or watersheds?
Drainage basins or watersheds collect water and send it to a specific area, usually a larger water body.
How do streams change along their length?
Streams get older as they move closer to the mouth, while they are younger closer to the headwaters
What is the work of running water in streams?
Running water in streams erodes, breaks, and dissolves materials.
How do streams transport sediments?
Sediments are moved by the fastest water in streams.
What happens to sediments once the water reaches the sea?
Once the water reaches the sea, sediments settle and become stable.
What are meandering streams?
Meandering streams have a winding, sinuous channel with point bars and can form oxbow lakes when cut off from the main channel.
What causes raging water?
Raging water occurs when water overflows channels and floods adjacent land, often triggered by the ground’s inability to absorb water.
How are flood risks evaluated?
Flood risks are calculated as annual probabilities.
What are gaining and losing streams?
Gaining streams flow all year at or below the water table in humid or temperate climates with sufficient rainfall and low evaporation. Losing streams dry up part of the year, above the water table in dry climates with low rainfall and high evaporation.
What is a hydrograph?
A hydrograph is a plot of discharge versus time.
What causes river erosion?
River erosion is caused by the energy of flowing water from mass and gravity, with the greatest erosion during floods.
What are the three types of sediment load?
The three types of sediment load are dissolved load, suspended load, and bed load.
What is a delta?
A delta forms when a stream enters standing water, dividing into distributaries with slowing velocity and sediment deposition
What triggers floods?
Floods are triggered by conditions such as torrential rains, long periods of continuous rain, rapid snowmelt, and failure of dams or levees.
What is a flash flood?
Flash floods are rapid rises in water levels with little warning, often caused by intense rainfall or dam failures.
How can human activity increase flood hazards?
Land-use changes such as removal of natural vegetation, destruction of wetlands, and urbanization can increase flood hazards.
Overland flow
Precipitation moving down slope over the land surface
Stream discharge
Volume of water moving through the channel in given time
Groundwater baseflow
Groundwater discharges to the surface
Discharge (Q)
The amount of water flowing in a channel
Does watersheds exist at multiple scales
Yes
True or false: continental divides separate drainages that flow to different water bodies
True
True or false: a large watersheds doesn’t contain many smaller ones
False, large watersheds contain many smaller watersheds
The longitudinal profile describes:
The changes in a stream channel’s elevation from its mouth to its headwaters
Near the headwaters
Steep and straight
Near the mouth
Flat and curved
Stream gradient
Changes in elevation per distance flowed
River erosion
The energy of flowing water is from mass and gravity
Erosion is greatest during a flood because energy is
Higher which causes to erode more and transport more
How do streams erode
1- scouring: water licks up and moves sediments
2-breaking and lifting: rapidly moving water:
Breaks chunks of rocks off the channel and lifts rocks and sediments of the channels bottom
3- abrasion: the “sandblasting” of rock particles in fast-moving water
4-Dissolution: running water can dissolve soluble minerals
Sediment load
Materials moved by running water
Dissolved load
Ions from chemical weathering
Suspended load:
Fine particles (silt and clay) in the water
Bed load
Larger particles roll, slide, and bounce along the bottom
Bed load move by a process called
Saltation
Meanders form where
1- the stream gradient is low
2- the substrate is soft and easily eroded
3-the stream exists within a broad floodplain
Base level
1-Lowest level to which a stream can cut downward
2- sea level is the ultimate base level
3-lakes, reservoirs and resistant rock bodies can create temporary base levels
As streams approach their base level
1-streams gradient decreases
2-meanders get wider
3-streams carved out a wider flood plain
4-oxbow developed during times of flooding
Does a delta plain form when the distribution continues to provide sediment
Yes
When does flood occur
1-When flow exceeds channel capacity
2- water overflow the channel onto adjacent land
3-fast-moving water from channel flows onto floodplain, slows down and drops sediments
What triggers floods
1-torrential rain rapidly dumping large volumes of water
2-long period of continuous rain;ground is saturated
3-rapid snowmelt across a large drainage basin
4-failure of dam or levee
Dam failure
Catastrophic amounts of water released from impoundment in a very short period of time
Downstream floods
Where a river in the lower part of a drainage basin leaves its channel flowing out onto its floodplain
Is flood control expensive
Yes
What levees and flood walls prevent
They prevent overflow to floodplains
What does installation artificial levee prevents sediment from reaching?
They prevent them from reaching the flood plains, which causes the entire delta region to sink
Recurrence interval
The average number of tears between floods of a particular sizes
Can human activity lead flooding
Yes, land use changes can Increase the hazards associated with floods.
As well the removal of natural vegetation and destruction of wetlands. Construction activity and urbanization are all ways to create flooding
How to reduce floods
1-dams
2-artificial levees
3-channelization
4-retention basins
5-erosion controls
6-wetlands restoration
7-floodplain management
8-education
