Chapter 3 Flashcards
What is a watershed?
A Catchment or drainage basin
- a land area that drains surface water to a common point or common body of water.
- watersheds are often the unit of management
- the issue with wetlands is urbanization
What is the hyporheic zone?
The zone beneath the river.
The saturated portions of streambeds that contain water that originates from a stream and returns to a channel
- mixing of shallow groundwater and surface water
What is a tributary?
smaller streams that combine to form larger streams, and ultimately rivers. They often look like branches of a tree
What are headwaters?
The beginning of a river, or it’s source
What is the confluence of a river?
the location at which the tributary joins the main river channel
What is the thalweg of a river?
The imaginary line that connects the deepest points of a river channel
What is the Strahler stream order?
- the uppermost channels of a drainage network are designated as first order streams, down to their first confluence.
Why do meandering rivers form?
The force of the water erodes and undercuts the river bank on the outside of the bend where water flow has most energy due to decreased friction.
Why do braided rivers form?
when excess geologic materials cannot be removed by the flow of a river and the channel simply moves to a location of less resistance.
What is an oxbow?
An oxbow wetland is a meander of a stream, river or creek, that has become separated from the flow of water. Oxbow wetlands store excess water that might otherwise lead to flooding, filter water to improve water quality and provide habitat to a variety of wildlife. Over time, some oxbows fill in with sediment due to erosion of soil in surrounding areas.
What are floodplains?
an area of land adjacent to a river. Floodplains stretch from the banks of a river channel to the base of the enclosing valley, and experience flooding during periods of high discharge.
What are deltas?
slow moving or stagnant water
What are alluvial fans?
at the base of mountains, fan out to form a lake of stagnant water as the flow of a river decreases in velocity
What are endorheic basins?
a region in which the river network is completely isolated from the world ocean: the water flowing in the rivers never reaches the sea.
How are tectonic lakes formed?
by the deformation and resulting lateral and vertical movements of the earth’s crust.
How are volcanic lakes formed?
a depression that fills with precipitation
How are glacial lakes formed?
Created by the actions of glaciers
How are fluvial lakes formed?
By rivers
How are solution lakes formed?
By a sinkhole
How are aeolian shoreline lakes formed?
by wind-blown sand
- a sand bar between the created lake and the larger body of water
How are organic lakes formed?
Created by the actions of plants and animals
- ex: beaver dams
How are anthropogenic meteorite lakes formed?
by human activity
What is the formula for measuring river discharge?
Q = AV
Q = discharge
A = cross-sectional area of a channel (width of channel * depth)
V = average water velocity
What is a rating curve?
- discharge can be determined directly from the river stage
- generated by making discharge measurements during various times of the year, usually monthly, and plotting these against the gage height. Once constructed, a rating curve eliminates the need for velocity and depth measurements unless the channel cross section changes.
What is flood frequency?
Understanding frequency and magnitude of floods based on historical records
- return period and exceedance probability
How do you calculate runoff ratio?
Runoff Ratio = R / P
- units of R and P need to be the same!
- stream discharge (m3) can always be expressed as runoff (mm) by dividing the watershed area and multiplying by 1000.
