Climate and Soils of Rajasthan: Rainfall, Loo and Mawath
Climate and soils of Rajasthan for state exams: rainfall belts, loo and mawath, climatic regions, sandy, alluvial, black and saline soils, erosion and MCQs.
By GK24 Editorial Team· Published · 3 min read
Rajasthan is the driest large state of India, and its climate is the reason every other chapter of its geography reads the way it does: the thin rivers, the salt lakes, the bajra fields and the moving sand dunes all follow from rainfall that falls away as you travel west. The Aravalli range runs from the south-west to the north-east, almost parallel to the path of the Arabian Sea branch of the south-west monsoon, so it cannot stand in the way of those winds and lift their moisture; the rain sails past and the west of the state stays a desert while the south-east, reached by the Bay of Bengal branch, is green. Examiners ask the wettest and driest places, the local names of the winds and the rains, and the district that goes with each soil.
The climate of Rajasthan
The state has a hot, dry, continental climate with a short monsoon. About nine tenths of the year's rain falls between June and September. The average for the state is roughly 525 to 575 millimetres, but the figure means little by itself: parts of Jaisalmer get under 200 millimetres while Mount Abu in Sirohi, the state's only hill station, gets well over 1,000. The Tropic of Cancer passes through the southern part of Banswara district, so almost the whole state lies in the subtropical belt.
Summer is fierce. Churu, Phalodi, Bikaner and Barmer are among the hottest places in the country in May and June, and the same western districts also fall very cold in January because dry sandy ground loses heat as fast as it gains it; that daily and seasonal swing is the mark of a continental desert climate. The two local names examiners want are loo, the hot dry west wind of summer that often comes with the dust storms called andhi, and mawath, the light winter rain brought by western disturbances from the Mediterranean, which is a blessing for the standing rabi crops of wheat, gram and mustard.
| Climatic region | Rainfall | Districts |
|---|---|---|
| Arid, hot desert | Under 300 mm | Jaisalmer, Barmer, Bikaner, Churu, Sri Ganganagar |
| Semi-arid, steppe | 300 to 500 mm | Jodhpur, Nagaur, Pali, Jhunjhunu, Sikar |
| Sub-humid | 500 to 700 mm | Jaipur, Ajmer, Alwar, Bhilwara, Tonk |
| Humid and very humid | Above 700 mm | Jhalawar, Banswara, Pratapgarh, Mount Abu area of Sirohi |
Soils of Rajasthan
Soil in Rajasthan changes with the parent rock and the rainfall, so the map of soils runs in the same belts as the map of rain. The sandy desert soil of the west covers the largest area of the state. It is more than nine tenths sand, poor in nitrogen and organic matter but often rich in lime and phosphate, and it grows bajra, moth, guar and groundnut when the rain comes.
| Soil | Where it is found | Crops |
|---|---|---|
| Sandy or desert soil | Jaisalmer, Barmer, Bikaner, Churu, Jodhpur, Nagaur | Bajra, moth, guar |
| Alluvial soil | Eastern plains: Jaipur, Alwar, Bharatpur, Dholpur, Dausa, Tonk | Wheat, mustard, gram |
| Red and yellow, red loam | Ajmer, Bhilwara, Udaipur, Rajsamand, Chittorgarh | Maize, pulses, jowar |
| Medium black soil | Hadoti: Kota, Bundi, Baran, Jhalawar | Soybean, cotton, wheat |
| Mixed red and black | Banswara, Dungarpur, Pratapgarh, Chittorgarh | Maize, rice, pulses |
| Saline soil | Pachpadra, Didwana, Sambhar basin, parts of Jalore | Barley, salt-tolerant crops |
What spoils the soil, and what is done about it
- Wind erosion and the movement of sand dunes in the western districts, checked by shelter belts and by planting along the Indira Gandhi canal.
- Gully erosion, the ravines locally called bihad, along the Chambal in Dholpur, Karauli and Sawai Madhopur.
- Salinity and alkalinity in the closed basins of Sambhar, Didwana and Pachpadra, where the water has no outlet and salts collect.
- Waterlogging, called sem, in the canal command of Sri Ganganagar and Hanumangarh, where too much irrigation raises the water table.
- The Central Arid Zone Research Institute at Jodhpur, set up in 1959, is the national centre for research on desert soils and dry farming.
Exam Point of View
State exams ask three things from this chapter: an extreme, a local word and a soil to district match. Keep Jaisalmer with the least rain and Mount Abu with the most; keep loo, andhi, mawath and sem apart, because they are set as a matching question; and keep each soil with its region, sandy with Marwar, alluvial with the eastern plains, red and yellow with the Aravalli belt, medium black with Hadoti and saline with Sambhar, Didwana and Pachpadra. Reason-based questions ask why the Aravalli does not stop the Arabian Sea branch, and the answer is that the range lies parallel to the wind.
Important Facts
| Lowest rainfall | Jaisalmer, under 200 mm in parts of the district |
|---|---|
| Highest rainfall | Mount Abu, Sirohi district, well above 1,000 mm |
| State average rainfall | About 525 to 575 mm, nine tenths of it from June to September |
| Loo | Hot dry west wind of May and June, with dust storms called andhi |
| Mawath | Winter rain from western disturbances, a blessing for rabi crops |
| Tropic of Cancer | Passes through southern Banswara, the southernmost district |
| Largest soil group | Sandy or desert soil of the western districts |
| Most fertile soil | Alluvial soil of Jaipur, Alwar, Bharatpur and Dholpur |
| Medium black soil | Hadoti: Kota, Bundi, Baran, Jhalawar, formed from basalt |
| Saline soils | Sambhar basin, Didwana, Pachpadra, parts of Jalore |
| Gully erosion | Chambal ravines of Dholpur, Karauli and Sawai Madhopur, called bihad |
| Waterlogging | Called sem, in the canal command of Sri Ganganagar and Hanumangarh |
| Arid zone research | Central Arid Zone Research Institute, Jodhpur, set up in 1959 |
Practice MCQs on this topic
Which district of Rajasthan receives the lowest average annual rainfall?
- A.Churu
- B.Jaisalmer
- C.Bikaner
- D.Nagaur
Show answer
It lies in the extreme west of the state, farthest from both branches of the south-west monsoon, and parts of the district record under 200 millimetres a year, which is why the sand dunes there are the largest and the most mobile in Rajasthan.
Read the full explanation →The light winter rainfall caused by western disturbances in Rajasthan is locally known as
- A.Loo
- B.Andhi
- C.Mawath
- D.Sem
Show answer
These are the showers of December to February, brought by western disturbances that travel from the Mediterranean across Iran and Pakistan into north-western India, and they are valued because they water the standing rabi crops of wheat, gram, barley and mustard without any cost to the farmer.
Read the full explanation →The Tropic of Cancer passes through which district of Rajasthan?
- A.Banswara
- B.Jhalawar
- C.Dungarpur
- D.Udaipur
Show answer
The Tropic of Cancer crosses the southern part of Banswara, the southernmost district of Rajasthan, so the whole of the state except that small corner lies north of the tropic, in the subtropical belt.
Read the full explanation →Medium black soil in Rajasthan is found mainly in which region?
- A.Shekhawati
- B.Hadoti
- C.Marwar
- D.Mewat
Show answer
The soil there is formed from the weathering of the basalt of the Deccan trap, so it is clayey, holds moisture well and cracks in summer, and it carries the state's soybean, cotton and wheat.
Read the full explanation →Which soil covers the largest area of Rajasthan?
- A.Alluvial soil
- B.Red and yellow soil
- C.Sandy or desert soil
- D.Medium black soil
Show answer
The Thar desert and the arid plains west of the Aravalli take up the greater part of Rajasthan, and their soil is overwhelmingly sand, low in nitrogen and organic matter, porous so that water sinks away quickly, but often well supplied with lime and phosphate.
Read the full explanation →The Central Arid Zone Research Institute, the national centre for research on desert soils and dry farming, is located at
- A.Bikaner
- B.Jodhpur
- C.Jaipur
- D.Udaipur
Show answer
The Central Arid Zone Research Institute was set up at Jodhpur in 1959 and works on sand dune stabilisation, shelter belts, dry farming, desert pasture and the spread of the desert, which is why it is the institute named in questions on the Thar.
Read the full explanation →Gully erosion, which has created the ravines locally called bihad, is a serious soil problem along which river of Rajasthan?
- A.Luni
- B.Banas
- C.Chambal
- D.Mahi
Show answer
Where the Chambal runs through the soft alluvium of Dholpur, Karauli and Sawai Madhopur, the monsoon run-off cuts deep channels that widen year after year into the badlands called bihad, taking farmland out of use and giving the area its old reputation as a hiding place for outlaws.
Read the full explanation →Saline soil in Rajasthan is most typically found around which of the following?
- A.Pachpadra and Didwana
- B.Kota and Bundi
- C.Alwar and Bharatpur
- D.Banswara and Dungarpur
Show answer
These, with the Sambhar basin, are the inland basins of Rajasthan: the streams that reach them have no outlet to the sea, so the water evaporates and leaves its salts behind, and the same salt is worked commercially at Sambhar, Didwana and Pachpadra.
Read the full explanation →Which of the following places in Rajasthan receives the highest average annual rainfall?
- A.Jaipur
- B.Mount Abu
- C.Kota
- D.Jodhpur
Show answer
It is the highest part of the Aravalli range and the only hill station of Rajasthan, so the monsoon winds are forced to rise over it and it receives well over a thousand millimetres a year, far more than anywhere else in the state.
Read the full explanation →Why does the Aravalli range fail to bring good rainfall to western Rajasthan from the Arabian Sea branch of the monsoon?
- A.It is too low to obstruct any winds
- B.It lies almost parallel to the path of those winds
- C.It lies to the east of the desert
- D.It is covered with dense forest
Show answer
The Aravalli runs from the south-west to the north-east, which is the same direction in which the Arabian Sea branch travels, so the winds slide along the range instead of being forced up over it; without that lifting there is little cooling and little rain, and the moisture is carried…
Read the full explanation →Frequently Asked Questions
Why is western Rajasthan a desert?
Because the Aravalli range lies almost parallel to the path of the Arabian Sea branch of the south-west monsoon, so those winds are not forced to rise and shed their moisture; they slide along the range and carry the rain away to the north.
What is mawath?
Mawath is the light winter rainfall of December to February brought to Rajasthan by western disturbances travelling from the Mediterranean. It waters the standing rabi crops of wheat, gram, barley and mustard and is considered golden rain by farmers.
Which soil covers the largest part of Rajasthan?
Sandy or desert soil, found in Jaisalmer, Barmer, Bikaner, Churu, Jodhpur and Nagaur. It is mostly sand, poor in nitrogen and organic matter, and grows bajra, moth and guar when the rain is good.
Where is medium black soil found in Rajasthan?
In the Hadoti region of the south-east, that is Kota, Bundi, Baran and Jhalawar. It is formed from the basalt of the Deccan trap, holds moisture well and grows soybean, cotton and wheat.
Which district of Rajasthan is the hottest in summer?
Churu, Phalodi, Bikaner and Barmer in the arid west record the highest summer temperatures in the state, and the same western districts also become very cold in January because sandy ground loses heat quickly.
Sources
- India: Physical Environment (Class XI), chapters on Climate and Soils — NCERT
- Agro-climatic zones and soils of Rajasthan — Department of Agriculture, Government of Rajasthan
- Research on arid soils, sand dune stabilisation and dry farming — Central Arid Zone Research Institute, Jodhpur
- Climatological normals for Rajasthan — India Meteorological Department, Ministry of Earth Sciences
