3. Soils of Rajasthan; Climate, Monsoon and Rainfall; Geography of Rajasthan, Civil Services Exam | RAS RPSC Prelims Preparation - Notes, Study Material & Tests - RPSC RAS (Rajasthan) PDF Download

Soils of Rajasthan and its Problems 

The soils of Rajasthan are complex, and highly variable, reflecting a variety of differing parent materials, physiographic land features, range of distribution of rainfall and its effects, etc.  However, broadly, the soils can be put in five major groups, based on the basic fabric of soils i.e. soil texture which governs its many other properties.  They are, (1) sandy soils or light soils, (2) sandy loam or light medium soils, (3) loam or medium soils, (4) clay loam to clay or heavy soils and (5) skeletal soils or shallow rocky and hilly soils.

Soil Problems in Rajasthan:-

Major problems are as follows:-

1. Salinity and Alkalinity
2. Wind Erosion
3. Shifting sand dunes
4. Ravine lands
5. Water logging
6. Low soil moisture
7. Soil conservation

Rajasthan: Climate of Rajasthan, Monsoon and Rainfall

The climate of Rajasthan state has varied contrasts and the presence of Aravallis is the greatest influencing factor. The state can broadly be divided into Arid, Semi-Arid and Sub-Humid Regions, on the basis of rainfall intensities.

The Western Rajasthan i.e. in the arid region consist of the districts of Hanumangarh, Jaisalmer, Barmer, Ganganagar, Churu, Jhunjhunu, Sikar, Nagaur, Jodhpur, Pali and Jalore covering an area of nearly 1,43,842 sq.km. The region is characterized by low and highly variable rainfall years creating inhospitable living condition to both human and livestock population.

 An area of 9,290 sq km in extreme western parts of the state has true desert conditions. With an improvement in rainfall pattern from the west towards the east Rajasthan semi-arid conditions are created in an area of about 66,830 sq km in the districts of Alwar, Jaipur, Bharatpur, Ajmer, Tonk, Sawai Madhopur, Bhilwara, Bundi, Kota, Chittorgarh, Udaipur, Sirohi, Dungarpur and parts of Jhalawar and Banswara. The distribution of climatic regions of Rajasthan on the basis of rainfall and temperature variations is divided into the following categories: -

(1) Arid Region: The Arid region includes Jaisalmer district, northern parts of Barmer, western of the Phalodi Tehsil of Jodhpur, western parts of Bikaner and southern parts of Ganganagar district. Climate of the region is very severe and arid. Rainfall less than 10 cm in extreme west parts of regions and rest areas record less than 20 cm rainfall. The average temperature during summer is recorded more than 34o C and during winters it ranges in between 12oC to 16oC

(2) Semi-arid Region: The average temperature during winter season ranges between 10o C and 17o C and the summer season temperature range 32o C to 36o C. As the region has erratic as well as torrential rainfall it brings floods too each time. Rainfall ranges 20 to 40 cm. This region comprises the western parts of Ganganagar, Hanumangarh, Jodhpur and Barmer districts. The winter season is very short and arid in the northern parts of this region.

(3) Sub-humid Region: In the semi-arid humid region, rainfall is meagre and the amount of rainfall is limited to a few monsoon months only. The rainfall is between 40 to 60 cm and the average temperature during summer season ranges from 28o to 34o C whereas it is recorded 12o C in northern parts and 18o C in the southern parts. Alwar, Jaipur, Dausa and Ajmer, eastern parts of Jhunjhunu, Sikar, Pali and Jalore districts, north-western parts of Tonk, Bhilwara and Sirohi districts are included in this category. This region has steppe type of vegetation.

(4) Humid Region: this region receives winter rainfall associated with cyclones along with monsoon season rainfall which varies from 60 to 80 cm. Deciduous trees dominate the region. Humid region is found at the districts of Bharatpur, Dholpur, Sawai Madhopur, Bundi, Kota, Barmer and Rajsamand and the north-eastern parts of Udaipur.

(5) Very Humid Region: Very Humid Region includes south-east Kota, Baran, Jhalawar, Banswara, south-west Udaipur and adjacent areas of Mt. Abu. Here, the summers are very hot and winters are cold and dry. Rainfall received is between 80 cm to 150 cm, which is mostly during the rainy season. Monsoon savanna type of vegetation is present in the region.

Rainfall in large parts of the State is not only inadequate but also varies sharply from year to year and place to place. The average rainfall of Rajasthan is 564.89 mm (1960 to 2009) compared to the all-India average of 1,100mm and a significant variation is seen across different regions.

The South-west monsoon brings the maximum rainfall in the state. In certain areas south-east and intermediate rainfalls also contribute towards the total rainfall. Pre-monsoon showers start towards the end of June and post-monsoon showers may continue till the first week of October.

At many of the places highest rainfall is received in July and August. The period of monsoon is shortest, ranging around 2 to 2.5 months. Its onset is late and withdrawal early as compared to other States and one or two dry spells is a common phenomenon. 90 percent of the total rainfall is received during monsoon season (July-September).

In the western Rajasthan, the average annual rainfall during 1980 to 2009 ranges from less than 171.12 mm in north-western part of Jaisalmer (lowest in the state) to 400 mm in Sikar, Jhunjhunu region and along the western periphery of the Aravalli range. In the eastern region, the rainfall ranges from around 400 mm in Ajmer to 762.19 mm in Jhalawar. In plains, Banswara (795.25 mm) and Jhalawar (762.19 mm) districts receive the maximum annual rain.

The highest rainfall is received in the southwest region of the State. The annual spatially averaged rainfall is highly variable and it is most erratic in the western region with frequent dry spells, punctuated occasionally by heavy downpour in some years associated with the passing low pressure systems over the region.

The number of rainy days during the south west monsoon period from June end to mid-September over Rajasthan varies from 10 in Jaisalmer to 40 in Jhalawar and to 48 in Mount Abu. The quantum of rain and number of rainfall days during the rest of the year in different parts of Rajasthan range from 2.1 cm at Jaisalmer to 7.2 cm at Jaipur, distributed over 2.5 to 6 rainy days.

During the rainfall deficit year of 2002, the state received just 220.4 mm rainfall up to September, against the normal of 518.6 mm in the overall monsoon .The maximum average rainfall of 726 mm was recorded in 1996 and minimum 291.6 mm was recorded in 1987, prior to 2002.

Rajasthan is heavily dependent on rainfall as it is the major source of water resource in the arid / semi-arid state. All the rivers of Rajasthan are rain-fed, the only exception being river Chambal.

The major land use is rain-fed cropping, the Eastern Rajasthan that falls in the semi-arid 500–1000mm annual rainfall zone and is intensively cultivated. Thus, any fluctuation of rainfall in the climate sensitive state of Rajasthan can pose a multitude of socio-economic problems.