The Role Of Water In Systems And Processes And Arid Landscape Development

Question 1

What are the sources of water in hot desert environments?

Answer 1

1. Exogenous water is externally originate and flows through a desert. The Colorado River in the Majove is exogenous and it flows through.
2. Endoreic water end in the desert and provides a relatively constant water source. For example the Jordan River has been flowing into the Dead Sea for thousands of years
3. Ephemeral water is rare in deserts due to the lack of precipitation. It provides short bursts of energy that are high intensity that can cause sheet floods or flash flooding

Question 2

Using examples, explain why water in the desert is described as ‘episodic’ ?

Answer 2

The intense heating of the desert surface can lead to localised warming and rising of air and localised high pressure systems developing. With such intense heating and rising and cooling of the air, large releases of latent heat during condensation can fuel uplift, creating large but short lived thunder storms.

Question 3

What are sheet floods?

Answer 3

1. During intense torrential downpours, both the impermeability of some desert surfaces and the sheer speed and amount of rainfall can lead to sheet floods.
2. Initially the impact of the rain begins to dislodge and move loose material across the surface (known as sheet wash or sheet erosion)
3. As the volume of water increases, this overland flow intensifies and can rapidly develop into extensive but relatively shallow floods
4. This huge amount of overland flow can move large volumes of material as sheet erosion, thus creating erosional features but equally contributing to depositional features downstream.

Question 4

What are channel floods?

Answer 4

1. If the overland flow is funnelled into steep sided narrow valleys, common is some hot desert areas (known as wadis), channel flash flooding occurs.
2. These can move significant loads of sediment and can be very powerful due to the concentration of the water in such a narrow valley, creating a deep, fast flowing torrent of water with huge potential for erosion and transport of sediment, and thus significant depositional features when the flow recedes.

Question 5

Waidis

Answer 5

Dry river beds that form distinct channel in a lowland valley/ plain
- steep edges
- flat bottoms filled with sediment
- channels that split and rejoin = complex drainage basin due to high quantitates of sediment being transported

Question 6

Bajadas

Answer 6

Extensive alluvial dans emerging from upland areas.
Join to form a continuous layer of sediment that extents many km’s

Question 7

Pediments

Answer 7

Found where there is a distinct break in gradient in highland areas that meet lowland areas/ depressions

Question 8

Playas

Answer 8

Percolated water in a depression / hollow with no outflow. Water is shallow and salty

Question 9

Inselberges

Answer 9

Relic landforms that develop in rocks with no maters of variable rock strength / composition
May have formed in past climates as similar structures are found in NW England

Question 10

Badlands

Answer 10

Dry terrain
Sort sedimentary rock os extensively eroded in a dry climate usually by heavy sporadic rainfall that moulds a distinctive landscape over time
Each layer is a distinctive representation to a period of deposition millions of years ago