EGS Frank Week 3 Catchments Flashcards
Definition
Catchment Area:
1. Def 1
2. Def 2
- Areas that store & channel surface water and direct it from higher to lower lying areas (towards coast)
- Areas collecting water, especially rainfall over a natural drainage area
How are catchments generally defined?
3 points
- By Topography
- But human interventions, e.g. pumping water between them, = making the system more complex.
- They naturally channel water, but human modifications also play a role
Distribution of Earth’s Water P1/6
Total Global Water:
(1)
(2)
(3)
(4)
Name; not %
- Oceans
- Saline Lakes
- Saline Groundwater
- Fresh water
Distribution of Earth’s Water P2/6
Total Fresh Water:
(1)
(2)
(3)
Name; not %
- Glaciers & Icecaps
- Groundwater
- Surface water & Other Freshwater
Distribution of Earth’s Water P3/6
Surface Water & Other Freshwater:
(1)
(2)
(3)
(4)
(5)
(6)
(7)
Name; not %
- Ice & Snow
- Lakes
- Soil Moisture
- Swamps & Marshes
- Rivers
- Biological Water
- Atmos. Water
Distribution of Earth’s Water P4/6
Total Global Water:
1. Oceans -
2. Saline Lakes -
3. Saline Groundwater -
4. Fresh Water -
- 96.5% - Oceans
- 0.07% - Saline Lakes
- 0.93% - Saline Groundwater
- 2.5% - Fresh Water
Distribution of Earth’s Water P5/6
Total Fresh Water:
1. Glaciers & Ice Caps -
2. Groundwater -
3. Surface & Other Freshwater-
- 68.6% - Glaciers & Ice Caps
- 30.1% - Groundwater
- 1.3% - Surface & other freshwater
Distribution of Earth’s Water P6/6
Surface Water & Other Freshwater:
1. Ice & Snow -
2. Lakes -
3. Soil Moisture -
4. Swamps & Marshes -
5. Rivers -
6. Biological Water
7. Atmosphere Water -
- 73.1% - Ice & Snow
- 20.1% - Lakes
- 3.52% - Soil Moisture
- 2.53% - Swamps & Marshes
- 0.46% - Rivers
- 0.22% - Biological water
- 0.22% - Atmos. Water
What is the outline of any catchment?
2 points
- Often bowl-shaped (formed by mountains & valleys)
- Drainage Basin/Catchment Basin def
Full Definition
Drainage Basin/Catchment Basin definition
An extent/area of land where all surface water from:
* rain
* melting snow
* or ice
Converges to a single point @ a lower elevation, usually the basin’s exit, where the waters join another body of water, such as a:
* river
* lake
* reservoir
* estuary
* wetland
* sea, or ocean
1/2 of definition
Drainage Basin/Catchment Basin definition P1:
An….
An extent/area of land where all surface water from:
* rain
* melting snow
* or ice
2/2 of definition
Drainage Basin/Catchment Basin definition P2:
Converges…. @ a …..
Converges to a single point @ a lower elevation, usually the basin’s exit, where the waters join another body of water, such as a:
* river
* lake
* reservoir
* estuary
* wetland
* sea, or ocean
Amazon River Catchment:
- Amazon River @ () = ()% of Worlds Freshwater
- River Gradient =
- @ (), Amazon R is () deep & () wide
- Amazon Discharge per year =
- Amount of water in Amazon actually causes a () in the (): causes it to () with the () & () with the ().
- Amazon River @ Manaus = 15% of Worlds Freshwater
- River Gradient = 2-3 cm/km
- @ Manaus, Amazon R is 90m deep & 15km wide
- Amazon Discharge per year = 6,300 km^3 /year
- Amount of water in Amazon actually causes a global deformation in the land (geoid): causes it to sink with the rainy season & rise with the dry season
Lake Chad:
- Location:
- In the 1960s =
- In 2004 =
- () over the last few decades
- W. Lake Chad, you can see () in terms of (), but also () in () with a ()
- Location: in the Sahel
- In the 1960s = 26,000 km^2
- In 2004 = 1,500 km^2
- Pronounced shrinking over the last few decades
- W. Lake Chad, you can see seasonality in terms of precipitation, but also long term trends in precipitation with a decline
Aral Sea:
- 1960 =
- 2004 =
- Decline largely attributed to () of rivers/cathgments e.g. ()
- Become a prolific ()
- 1960 = 65,000 km^2
- 2004 = 17,000 km^2
- Decline largely attributed to extensive modification of rivers/catchments e.g. large agri. activity
- Become a prolific dust source
Arid Catchments:
- Popular for (), but prone to (), which is an issue bc () establish themselves in ().
- Floodwater can bring () and ().
- Popular for agri. & other activities but prone to flooding, which is an issue bc. many societies establish themselves in floodplains
- Floodwater can bring new nutrients & sediments and recharges groundwater.
Major Transboundary River Basins:
- The major Transboundary River Basins of () present a variety of () & () to the () & () who share them.
-
River Basins of Southern Africa:
(1)
(2)
(3)
(4)
- The major transboundary basins of Africa present a variety of challenges & opportunities to the people & countries who share them.
- River Basins of Southern Africa:
- Orange River Basin
- Cunene River Basin
- Limpopo River Basin
- Okovango River Basin
Human Activities that modify catchments:
(1)
(2)
(3)
(4)
(5)
(6)
(briefly list)
- Urbanization
- Agriculture
- Deforestation
- Dam Construction
- Pollution
- Groundwater extraction
Human Activities that modify catchments P1/6
(1) Urbanization:
Urban development -> increase in (), such as (a, b & C) -> reduced () & increased (), which can result in more frequent & severe (), () & () of water bodies.
Urban development -> increase in impervious surfaces, such as roads, buildings & parking lots -> reduced inflitration & increased surface runoff, which can result in more frequent & severe flooding, erosion & pollution of water bodies
Human Activities that modify catchments P2/6
(2) Agriculture:
Conversion of land for agri:
(1)
(2)
(3)
which then impacts () & ().
Conversion of land for agri:
1. alters nat. veg cover
2. increases soil erosion
3. intro. pollutants (fertilizers & pesticides) into water bodies
which then impacts water quality & ecosystems.
Human Activities that modify catchments P3/6
(3) Deforestation:
Clearing forests within catchments disrupts (), leading to:
(1)
(2)
(3)
Clearing forests within catchments disrupts natural hydrological cycles, leading to:
1. changes in water flow patterns
2. increased sedimentation of rivers & streams
3. and loss of habitat for wildlife
Human Activities that modify catchments P4/6
(4) Dam Construction:
Dams & reservoirs built for (), (), or () can:
(1)
(2)
(3)
Dams & reservoirs built for water supply, hydropower generation, or flood control can:
- Alter the natural flow of rivers
- Fragment habitats
- Affect downstream ecosystems & communities.
Human Activities that modify catchments P5/6
(5) Pollution:
(1)
(2)
(3)
introduce pollutants such as:
(1)
(2)
(3)
into catchment water bodies, posing a risk to () & ().
- Industrial activities,
- Improper waste disposal &
-
Urban Runoff
introduce pollutants such as:
(1) Heavy metals,
(2) Nutrients &
(3) Pathogens
into catchment water bodies, posing a risk to human & ecosystem health.
Human Activities that modify catchments P6/6
(6) Groundwater Extraction:
- Groundwater has () & thus influences the (), etc.
- If it’s drained/not allowed to replenish then -> () -> ()
- Moreover, draining/not allowing it to replenish -> increase in () which affects the ().
- Groundwater has signif. weight & thus influences the stability of the ground, etc.
- If it’s drained/not allowed to replenish then ground could become unstable -> sinking ground.
- Moreover, draining/not allowing it to replenish -> increase in salinity which affects the water quality.
General
- The state of the catchment determines the () & () of water.
- Well-Managed Catchment:
(1)
(2) - Badly Managed Catchment:
(1)
- The state of the catchment determines the quality & quantity of water.
- Well-Managed Catchment:
(1) protection of veg. & thus
(2) protection of soil (reg. agri activity & sustainable development) - Badly Managed Catchment:
(1) deforestation -> soil degradation, pollution
