O-Level Geography Chapter 1 Topography of Pakistan Deserts

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Deserts

A desert is a place that receives very low amount of precipitation (less than 250mm). It is an area that can support almost no vegetation. Deserts can be cold as well as hot (have a high rate of evapotranspiration). Pakistan has 3 main deserts; the Thal, Tharparkar and the Kharan desert, all of which are hot deserts.

• Thal is found in Punjab between Jhelum and Indus Rivers.
• Tharparkar is divided into 3 parts; Cholistan is found in Southern Punjab, Nara in Eastern Sindh and Thar in the South East of Sindh.
• Kharan is found in Western Balochistan.
• Cholistan :

Topography:

There are strips of soil found between sand dunes along with the sandy plains. Sand dunes shift grain by

grain due to the pattern of the blowing wind. Sand dunes sometimes reach a height of 150m, and are both longitudinal and latitudinal in direction. All of the sand dunes are crescent shaped. When the wind blows away the top cover of sand away, bare and weathered rocks are exposed onto the surface.

Desertification:

Desertification occurs due to continuous land abuse. It is caused by both natural and manmade factors. Among the natural forces are continuous wind and water erosion (which erode the fertile topsoil so only few plants can then grow) along with long-term changes in rainfall patterns due to climate change (such as a drought). Human factors include overgrazing by animals, strip mining, the excessive usage of groundwater supplies and deforestation (mainly shrubs and wild grass).

Pide-mont plains:

Pied-mont plains are found in the foot hills of Sulaiman kirthar mountains towards river Indus.few the pied-mont plains are also found in the Hills of mountaineers north. The pied-mont plains were formed by the deposition of rivers flowing down the Mountain .The river flow only where and when rainfall taxes place. they come down the Mountain slopes at great speed on reaching the foot hills the gradient decreases and the river loses its speed. This diop in speed cause the river to deposit a substance part of it loads within the river channel. The river is spht in a number of channels known as the braided channel. The sediment deposited with the river channel makes a heap known as alluvial fans. Alluvial fans are the dominant feature of pied-mont plains beyond the alluvial fans the land has a gentler slope and is covered with sand, silt and clay and lined with meandering line. Agriculture is possible in this region but it depends upon rainfall. This type of agriculture is known as rainfed of Baravi agriculture.