- Although rainfall is scanty in desert areas but thunderstorm & cloudburst do occur which leads to torrential downpour of rain, producing devastating effects
- A single rainstorm may bring several inches of rain within a few hours, drowning people who camp there & flooding mud baked houses into oasis;
- Also leads to formation of gullies & ravines (badland topography)
- As deserts have little vegetation to protect the surface soil, large quantity of rock waste are transported in sudden raging torrents known as flash floods.
- There is so much material in flash flood that the flow becomes liquid mud.
- When the masses of debris are deposited at the foot of the hill or at the mouth of the valley, an alluvial cone or fan or dry delta is formed, over which temporary stream discharges through several channels, depositing more material.
- Alluvial deposits are subjected to rapid evaporation by the hot sun & downward percolation of water into porous ground, & soon dry up leaving mounds of debris.
- Also known as Playas, Salina or Salars
- Formed in arid or semi-arid areas by intermittent streams flowing into depressions
- Contain high percentage of salts due to high evaporation & lower precipitation
Bajada & Pediment
The floor of desert depression is made up of two features viz. Bajada & Pediment.
- Bajda → Depositional feature made up of alluvial material lay down by intermittent streams.
- Pediment → An erosional plain formed at the base of the surrounding mountain scarps (steep slope)