Flashcards in Module 6 Deck (89)
Rivers and lakes make up how much of the earth total water supply?
True or false. water is distributed evenly throughout the world.
Floodplains provide which benefits?
-Zones of filtration
-Habitat for plants and animals
Based on the concept of balance, an increase in water discharge and decrease in sediment discharge lead to ....
= an increase in the erosive power of the stream or river.
Wolves affect the rivers in Yellowstone National Park by predating on deer who eat the vegetation needed to stabilize banks. true or false.
without the wolves, there was an overpopulation of deer which was leading to a degradation of the parks ecosystem due to overgrazing.
True or false. flooding and channel migration are unnatural processes; the only way to manage them is through hard engineering practices.
What are some other management practices other than hard engineering?
implementing fluvial corridors and eco-engineering decision scaling (EEDS).
What is the current trend in river management that most reflects an ecosystem approach?
Leaving more room around rivers for flood water and channel erosion, using an ecosystem approach and adaptive governance.
What are the potential problems with hard-engineering structures such as levees?
-Disconnecting rivers from their floodplain
-Encouraging floodplain development by providing a false sense of security
-Increasing flow velocity during floods
Oxbow lakes are created by:
Floodplains are flooded when the river channel exceeds its bankfull discharge. This happens on average :
Between 1.5 and 2 years
true or false? Meandering rivers occur when the sediment is small in size and supply, and slope is gentle. They are considered stable channels.
true or false? Clean fresh water is a readily available resource around the world.
What human modifications were made on the Mississippi River since the early 20th century:
-Straightening the channel by removing meander loops
Stream orders 1 and 2 represent:
Small, headwater channels, often with steep slopes and gravel particles on the bed.
What are fluvial systems?
systems of rivers, lakes, streams and wetlands through which the fresh water flows on this planet
What is the hydraulic cycle?
water flows through the different sheered of the planet (hydrosphere, lists-here, biosphere, and atmosphere).
explain the hydraulic cycle (10)
1. water from the ocean will evaporate.
2. then condense into clouds.
3. which can fall as rain over land
4. where it will flow at different speeds over land and into lakes, streams, or rivers.
5. which will flow into ocean.
6. this rain can also be infiltrated into the ground
7. where It will flow at much slower rate as groundwater
8. evaporated water can also condense
9. and fall as snow
which can accumulate into glaciers in cold climates or high altitudes
10. and eventually melt and runoff into rivers and lakes like rain
in the hydraulic cycle, water can take on which 3 states?
1. liquid (water found in oceans, rivers and lakes)
2. solid (ice and snow)
3. gaseous (water vapour formed by evapotranspiration and sublimation and which falls as precipitation
What are fluvial systems?
they have clear boundaries( watersheds) and a hierarchy in rivers and streams.
what happens within a watershed?
both water and sediments are transferred from upstream to downstream reaches.
What are the 3 zones that a watershed can be divided into?
1. headwaters (or erosion zone)
2. transfer zone
3. depositional zone
what happens in zone 1- headwaters?
mountain headwater streams flow swiftly down steep slopes and cup a deep v-shaped valley.
-rapids and waterfalls are common here.
what happens in zone 2- transfer zone?
low-elevation streams merge and flow down gentled slopes. the valley broadens and the river begins to meander.
what happens in zone 3- depositional zone?
at an even lower elevation a river wanders and meanders slowly across a nearly flat valley.
-then it may divide into many separate channels as it flows across a delta built up of river-borne sediments and into the sea.
what are the 9 systems of a fluvial system?
4. riparian wetlands
explain system 1 (source) from a fluvial system
the source of river water, the hydrologic cycle
explain system 2 (tributary) from a fluvial system
break off from main channel (the source)
explain system 3 (confluence) from a fluvial system
where tributaries join main channel.