Physiographic of Rajasthan

Physiographic Divisions

There are four physiographic divisions of Rajasthan

1. Western Sandy Plain
2. Aravalli Range & Hilly Region
3. Eastern Plain
4. South-East Rajasthan Plateau (Hadoti Plateau)

Western Sandy Plain

District:- Hanumangarh, Sriganganagar, Bikaner, Jaisalmer, Barmer, Jalore, Sirohi, Pali, Jodhpur, Nagaur, Churu, Sikar & Jhunjhunu
Area:- 1, 96,747 Sq. Km.
Length:- 640 Km.
Breadth:- 300 Km.
River:- Luni- It rises in the Aravallis South West of Ajmer & flows toward South West.Tributaries- Sukri & Jawai Reaches/Fall in the Rann of Kutch (Arabian Sea) only during rainy season.

It is a wide expanse of windblown sand, poorly watered & sterile Its eastern portion is known as Thar Desert which is perfectly dry & with desert plants.
Western Sandy Plain & Pakistan face each other across International boundary for about 1070 Km.
Western Sandy Plain further divided into two parts.

1. Sandy Arid Plain
2. Semi-Arid Plain/Bangur Region

Sandy Arid Plain:-

District – Jaisalmer, Barmer, Bikaner, Churu, Hanumangarh & Sriganganagar
Area - 61% of total area of W.S.P.
Population - 40%
Minimum Rainfall - 50 Cm
There are vast expanses of sand & rock outcrops mainly limestone are found in Jaisalmer, Barmer, Bikaner, Churu, Hanumangarh & Sriganganagar.
Sandy Arid Plain further Sub-divided into two parts.

1. Marusthali
2. Dune Free Tract

Marusthali :-

District - Bikaner, Barmer, Jaisalmer, Jodhpur, Nagaur, Churu.
Area - 120500 Sq. Km (Thar Desert)
Height of sand dunes – 6 m to 60 m
Length of sand dunes – 3 km to 5 km
Towards west this sandy arid Marushthali is known as Thar Desert.
Shifting sand dunes is locally terms as Dharians.
There are three types of dunes on the basis of shape size, wind direction.

1. Longitudinal Dunes:
2. Crescent Shaped Dunes:
3. Transverse Dunes:

Longitudinal Dunes:-
Run South West to North East
Parallel to the prevailing winds & mostly Sword-Shaped
Longer axis is parallel to the direction of wind

Crescent Shaped Dunes:-
Width of dunes - 100 m to 200 m
Height of dunes - 10 m to 20 m
Dunes have a gently sloping convex windward side & steep leeward side.
These dunes are mobile
These are found in isolation or occasionally side by side in lines.

Transverse Dunes:-
Dunes are formed across the wind direction.
Commonly found in eastern & northern parts of Marusthali.
Windward side is long & gently sloping, while leeward side is steep & abrupt.
These are U-shaped dunes.

Dune Free Tract :-

Districts - Bikaner, Jaisalmer, Phalodi & Pokhran
Area – 65 Sq. Km.
Limestone & Sandstone rocks exposes (to lay open) here belong to Jurassic & Eocene formations.
It is rocky but dune free tract.
Small hills are found within a circle of 64 Km of Jaisalmer town.
Dry beds & banks could easily be tapped for ground water.
Grid conglomerate, gneiss, schist & granite rocks are also exposed at places.

Semi-Arid Plain :-

District – Jaipur, Jodhpur, Nagaur, Pali, Jalore, Barmer
Area - 7500 Sq. Km
Rainfall – 20 cm
In it lies in the eastern part & drained by the Luni in its south-eastern portion.
Gullying has given rise to conglomerate landscape. Its eastern part is covered with superficial sand deposits.
Towards north lies the Shekhawati tract which is semi arid transitional plain characterized by inland drainage & stream with salt lakes like Sambhar, Didwana etc.
In the extreme north lies the Ghaggar Plain

There are four types of Semi-Arid Plain

1. Luni Basin:
2. Shekhawati Region:
3. Nagauri upland:
4. Ghaggar Plain:

Luni Basin:
District - Barmer, Jalore, Jodhpur, Nagaur
Area – 34866 .4 Sq. Km
Basin is drained by the Luni River & its tributaries Bandi, Sagi, etc.
Covers the area from its source to Tiwara (Barmer) where Sukari river meets it.
It is a seasonal river
Floods occur during the rains in Luni
Topography is marked by hills with steep slopes & extensive alluvial plains.
This area is locally known as Naid (Rel) & is one of best alluvial plains.

Shekhawati Region:
District - Churu, Sikar, Jhunjhunu & Nagaur
Live stock, Milk production & dairy are the occupation of this region
Aravalli hills runs through this region from south to north, cutting into almost two halves.
Topography of the Shekhawati tracts is characterized by an undulating sandy terrain traversed by longitudinal sand dunes.
There is only one seasonal river kantli
Here the sand dunes are of transverse type
The calcareous substratum is exposed of the tract from the sea level is 450m.

Nagauri upland:
District - Nagaur
Average Height of this region from sea level – 300 m to 500 m
Rainfall – 25 cm in west to 50 cm in east
This region is full of sand hills & low depressions.
The temp being High, the evaporation of the saline flood water results in the deposits of the salt & soda in these depressions.

Ghaggar Plain:
Districts - Hanumangarh & Sriganganagar
There is no stream or river except Ghaggar Nali which flows through the ancient bed of Ghaggar river which is now extinct & hence, this region is known as ‘Ghaggar Plain’.
This plain is a sandy plain interspersed with sand-dunes &small sand-hills.
A large part of it is (dreary &) full of sand dunes.
Northern part of this region is fully canalled & thus is made productive.
Sand ridge dunes are found on the bank of ancient rivers
Height of sand ridge dunes-6 m to 30 m.