Environmental Geology - Chapter 6: Streams and Flooding
Factors Governing Flooding
- Excessive rainfall - Snowmelt off in mountains - Severe storms - Hazardous blockage of stream channel - Trees - Rock avalanches
An ____ ____ is a fan-shaped deposit pf sediment formed where a stream flows from a mountain into a dry plain or desert, or flows into a more slowly flowing, large stream.
Alluvial Fan
Stream ____ is a measure of the total load of material a stream can carry.
Capacity
Meanders
Curves in a stream (or river)
A ____ is a fan-shaped deposit of sediment formed at a stream's mouth.
Delta
Stream ____ is the amount of water flowing past a given point in a specified length of time.
Discharge
A ____ ____ is constructed by plotting stream stage or discharge as a function of recurrence interval or annual probability of occurrence.
Flood-frequency Curve
A ____ is the area surrounding a stream channel into which the stream spills over during floods.
Floodplain
A ____ is constructed by plotting stream stage or discharge as a function of time.
Hydrograph
The ____ ____ includes all the processes by which water in the hydrosphere circulates.
Hydrologic Cycle
The ____ includes all the water at and near the earth's surface.
Hydrosphere
____ are raised banks along a stream channel that help to contain high discharge to to prevent flooding.
Levees
The ____ River is the highest-discharge stream in the United States.
Mississippi
A hundred year old flood is a flood with a ____ ____ of one hundred years.
Recurrence Interval
Point Bar
Sediment deposited on the insides of meanders
The ____ of a stream is the elevation of the stream's water surface at any point along the stream's course.
Stage
A ____ is any body of flowing water confined within a channel.
Stream
Cut Bank
The outside and downstream side of the meander. Faster water flows
Load
The total quantity of material that a stream transports by all methods (traction, saltation, suspended, and dissolved)
____ is the most important agent in sculpting the earth's surface.
Water
Compared to upstream floods, downstream floods...
are often a result of prolonged heavy rains over broad areas
In the development of stream meanders, channel erosion is greatest...
at the outside of curves on the downstream side
The lowest elevation to which a stream can erode its channel is called its...
base level
Most human activities tend to...
decrease the recurrence intervals of high-discharge intervals
The size of a stream may be described by its...
discharge
The geographic region from which a stream draws water is called it's...
drainage basin
On a hydrograph, an upstream flood appears as a...
high, sharp peak
All of the following processes add water to the atmosphere except...
infiltration
Meander cutoffs are called...
oxbows
The process of sediment transport in which particles more in short hops or jumps is called...
saltation
A disadvantage of both channelization and levees as methods of reducing flood hazards is...
the increased risk of downstream flooding
The largest single reservoir in the hydrologic cycle is...
the oceans
In temperate climates, as stream gradient decreases from source to mouth...
total discharge increases
Most of the water in the hydrosphere...
was outgassed from the earth's interior early in its history