Geography of Rajasthan: Climatic Characteristics. The climate of Rajasthan in northwestern India is generally arid or semi-arid and features fairly hot temperatures over the year with extreme temperatures in both summer and winter. The hottest months are May and June. The monsoon season is from July to September; however, rainfall remains moderate.
Rajasthan Action Plan on Climate Change (RAPCC) builds on the key areas as identified Under the CCAR by prioritizing urgent areas of action in a phased and time-bound manner And is in coherence with the Rajasthan State Environment Policy and Environment Mission While the RAPCC primarily focuses on risk reduction and adaptation measures, it also looks in to the co-benefits offered by specific strategies in the form of Mitigation.
Also, check: Rajasthan General Studies | General Knowledge of Rajasthan
Rajasthan Geography Climatic Characteristics
Task Force Constitution
The Rajasthan State Government established a ‘Climate Change and Clean Development Mechanism (CDM) Cell’ in the Rajasthan State Pollution Control Board (RSPCB) to act as a nodal agency for coordinating issues related to climate change in the State. The Cell was constituted in April 2010 and was involved in the drafting of the CCAR.
A Steering Committee has also been formed, headed by the Chief Secretary and Principal Secretaries of various key departments as members to monitor the implementation of various actions proposed under the Rajasthan Environment Mission. The State of Rajasthan has constituted a team to review the implementation of the Environment Mission.
The composition of the Environment Mission includes:-
Chairperson: Chief Minister
Convener: Principal Secretary, Environment
Members: Ministers of the under-mentioned departments, Chief Secretary, Principal
Secretaries and Secretaries in-charge of the under mentioned departments:
1. Environment
2. Forests
3. Mines and Petroleum
4. Industries
5. Water Resources
6. Command Area Development
7. Agriculture
8. Urban Governance
9. Transport
10. Energy, renewable energy
11. Science and Technology
12. Plan
13. Finance
14. Policy Planning
The Steering Committee is chaired by the Chief Secretary, headed by the Principal Secretary, Environment and members from each designated department mentioned above. The Steering Committee includes participation from the non-governmental bodies. Their role is to review the implementation of each of the mission.
For the implementation of the Environment Policy, Rajasthan Environment Mission and Climate Change Agenda task forces have been constituted for different sectors, viz.,
1. Industry
2. Water
3. Forestry and bio-diversity
4. Urban governance and sustainable habitat
5. Enhanced energy efficiency including solar energy
6. Strategic knowledge for climate change
The climate of Rajasthan state has varied contrasts. Different experts, each with their own focus parameters, have divided Rajasthan into different climatic regions.
However, three main approaches to climatic regions of Rajasthan are:
- Climatic Regions of Rajasthan based on Rainfall Intensity
- Koeppen’s Classification of climatic regions of Rajasthan
- Thornthwaite’s classification of climatic regions of Rajasthan
Also, check: RPSC RAS Prelims and Mains 2024 Preparation
1. Climatic Regions of Rajasthan based on Rainfall Intensity
The distribution of climatic regions of Rajasthan on the basis of rainfall and temperature variations includes following divisions:
Arid Region
a. 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.
b. Climate of the region is very severe and arid.
c. Rainfall less than 10 cm in extreme west parts of regions and rest areas record less than 20 cm rainfall.
d. The average temperature during summer is recorded more than 34degree C and during winters it ranges in between 12 DegC to 16DegC.
Semi-arid Region
i. The average temperature during winter season ranges between 10 Deg C and 17 Deg C and the summer season temperature range 32 Deg C to 36 Deg C.
ii. As the region has erratic as well as torrential rainfall it brings floods too each time.
iii. Rainfall ranges 20 to 40 cm.
iv. The winter season is very short and arid in the northern parts of this region.
v. This region comprises the western parts of Ganganagar, Hanumangarh, Jodhpur and Barmer districts.
Sub-humid Region
1. In the semi arid humid region, rainfall is meager and the amount of rainfall is limited to a few monsoon months only.
2. The rainfall is between 40 to 60 cm and the average temperature during summer season ranges from 28 Deg to 34 Deg C whereas it is recorded 12 Deg C in northern parts and 18 Deg C in the southern parts.
3. 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.
4. This region has steppe type of vegetation.
Humid Region
1. This region receives winter rainfall associated with cyclones along with monsoon season rainfall which varies from 60 to 80 cm.
2. Deciduous trees dominate the region.
3. Humid region is found at the districts of Bharatpur, Dholpur, Sawai Madhopur, Bundi, Kota, Barmer and Rajsamand and the north-eastern parts of Udaipur.
Very Humid Region
Very Humid Region includes south-east Kota, Baran, and 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.
Also, check: Geography of Rajasthan For RPSC RAS Prelims
2. Koeppen’s Classification of climatic regions of Rajasthan
Koeppen’s classification for the World Climatic regions is totally based on the vegetation, as the effects of temperature and rainfall are directly evident and visible it. Here, the three categories are associated with Tropical climates, Dry (arid and semiarid) climates and Mild Temperate climates respectively.
The classification of Rajasthan according to Koeppen’s is as follows:
Aw or Tropical Humid Region:
- Winter season is arid and cool whereas summers experience scorching heat.
- Rainfall also mainly occurs in summer season.
- The temperature is more than 18 Deg. C in the coldest month records.
- The southern parts of Dungarpur district and Banswara come under the region.
- Arid tropical grasslands and Savanna like region are found along with deciduous trees of Monsoon type.
Bshw Climatic Region
- Vegetation is of steppe type, characterized with thorny bushes and grasses.
- Region comprises the districts of Barmer, Jalore, Jodhpur, Nagaur, Churu, Sikar, Jhunjhunu and Hanumangarh.
- This climatic region is semi-arid, where winters are dry and even in summers there is no sufficient amount of rainfall.
Bwhw Climatic Region
- The region has arid-hot desert climate with very scanty rainfall.
- On the contrary the process of evaporation is very active.
- North-western Jodhpur, Jaisalmer, western Bikaner and western parts of Ganganagar district are included in this category.
- Thus, these areas are known as desert region, limited to western parts of Thar Desert.
Cwg Climatic Region
- The south-eastern areas of Aravalli are the part of the region.
- Seasonal winds do not bring rains to this region during winters.
- Rains are limited to few monsoon months only.
IMD forecast method
The update forecast for the southwest monsoon season (June-September) rainfall over the Country as a whole is issued using following Parameter Ensemble Forecasting System.
- NE Pacific to NW Atlantic SST Anomaly Gradient (December + January)
- Southeast Equatorial Indian Ocean Sea Surface Temperature (February)
- East Asia Mean Sea Level Pressure (February + March)
- Central Pacific (Nino 3.4) Sea Surface Temperature Tendency (March to May –
- December to February)
- North Atlantic Mean Sea Level Pressure (May) and North Central Pacific 850 Zonal
- Wind gradient (May).
- The average rainfall in Rajasthan is 58-60cm (574mm).
- The eastern regions of the Rajasthan receives the total 100cm annual rainfall while the western most regions of the Rajasthan receives the total 10cm annual rainfall.
- The Rajasthan state receives the 90-91%% of total annual rainfall during the monsoon season, i.e. July to September by south-west monsoon.
- The July and August are the months which receives the 80% of total rainfall of the monsoon season.
- In the first second week of the September, the withdrawal of southwest monsoon begins from the north-west part of the state and by the mid-September, it withdraws from the entire state. In this time, the Rajasthan receives the little rainfall by this Retreating monsoon.
- During the winter season, al little amount of rainfall received by the shallow cyclonic depressions originating over the east Mediterranean Sea. This rainfall is also called ‘Mavat’.
TOP FIVE STATIONS RECEIVED HIGHEST RAINFALL DURING MONSOON
S.No. District Rainfall Station Normal Rainfall (mm) Actual Rainfall (mm)
1 Sirohi Mount Abu 868.6 3280.2
2 Sirohi Reodar 868.6 1618.0
3 Pratapgarh Pratapgarh 845.8 1572.0
4 Jalore Raniwara 394.2 1443.0
5 Sirohi Sirohi 868.6 1343.4
During the south-west monsoon period extending from June to September the state receives about 90% of the total rainfall. The cold weather period (January and February) receive the Remaining portion of rainfall which occurs in association with the local convective activity. There is a wide variation in the mean annual rainfall over Rajasthan as the extreme western parts of Jaisalmer district receive rainfall less than 100mm in contrast to more than 900mm in the eastern parts of Jhalawar and Banswara.
The lowest recorded annual rainfall in the past 100 years i.e. between 1900 and 2010 was 24 mm in the western Rajasthan and whereas it was never below 120 mm in the eastern Rajasthan.
The principal rainy season when the Rajasthan state receives 91% of its annual rainfall is during the South-West monsoon. The total normal annual rainfall in the state varies from 1000 cm over the South-Eastern parts to 14 cm over the extreme North-Western parts. The rest share of rainfall comes during the cold weather season about 2%, the summer season about 3% and during the post-monsoon season about 4% of the annual total rainfall respectively.
LEAST-10 STATIONS RECEIVED LOWEST RAINFALL DURING MONSOON
S.No. District Rainfall Station Normal Rainfall (mm) Actual Rainfall (mm)
1 Ganganagar Sri Bijainagar 201.4 48.0
2 Ganganagar Raisinghnagar 201.4 64.3
3 Ganganagar Suratgarh 201.4 90.0
4 Ganganagar Anupgarh 201.4 91.0
5 Jodhpur Bap 274.5 103.0
6 Hanumangarh Nohar 252.5 107.0
7 Jaisalmer Sam 158.4 114.0
8 Ganganagar Gharsana 201.4 135.0
9 Jaisalmer Ramgarh 158.4 138.0
10 Ganganagar Sadulsahar 201.4 139.0
The onset of the southwest monsoon over the eastern parts of the state is witnessed almost by the last week of June which extends over the entire state by the first week of July. Amounting individually to about 34% of the annual rainfall each, July and August are generally the rainiest months.
Around 1st September the withdrawal of the southwest monsoon begins from the northern western parts of the state and by 15th September it withdraws from the entire state. During cold weather season a small amount of rainfall i.e. 1cm and 0.7 cm in East and West Rajasthan is received. This respectively is of great significance for agriculture and if occurs in association with western disturbances which move from west to east across the northern parts of the country.
During the south-west monsoon period extending from June to September the state receives about 90% of the total rainfall. The cold weather period (January and February) receive the Remaining portion of rainfall which occurs in association with the local convective activity.
The Rajasthan State Water Policy 2010
- The growing imbalance between demand and supply of water
- Low operational efficiency of water resource development projects
- Inequity in access to water
- High cost of service, low cost recovery and low level of expenditure
- Lack of ownership among stakeholders
- Depleting groundwater resources and deteriorating quality of water
- Uncertainty in availability of water
The policy has evolved out of the earlier policy documents and intends to function from the new perspective of Integrated Water Resources Management, which is holistic and includes a bottom up Approach.
The new policy document addresses issues related to:
- Water supply and development
- Water conservation
- Water quality
- Environmental management
- Water pricing
- Integrated Water Resource Management
- Irrigation
- Water resources infrastructure
- Legal enablement
- Capacity building
- Research
- Monitoring and evaluation of water policy and action plans
Distribution of Rainfall in Rajasthan
There is a wide variation in the mean annual rainfall over Rajasthan as the extreme western parts of Jaisalmer district receive rainfall less than 100mm in contrast to more than 900mm in the eastern parts of Jhalawar and Banswara.
The districts of East Rajasthan receive more rainfall than those of West Rajasthan. The mean annual rainfall in the East and West Rajasthan is about 64.9 cm and 32.7 cm respectively.
There is a huge variation in the mean annual rainfall over the entire Rajasthan state. The extreme western parts of Jaisalmer districts receives the rainfall less than 10cm wherein the south-eastern parts of Rajasthan receives the rainfall more than 100 cm, which is 10 time more of earlier.
The southern and south-eastern districts, Jhalawar and Banswara, receive the maximum rainfall in the state, which is about 120 cm.
The southern and south-eastern districts Kota, Baran, Jhalawar, Baswara, Pratapgarh and Udaipur and Mount Abu region of the Rajasthan receive the rainfall more than 100 cm.
The districts of Eastern plains i.e. Bharatpur, Dholpur, Kota, Bundi, Sawai Madhopur, North-west Udaipur, South-east Tonk and Chittorgarh receive the 60-80 cm rainfall.
The districts of Aravalli Range i.e. Alwar, Japur, Ajmer, Pali, Jalore, Eastern parts of Nagaur and Jhunjhunu and north-west part of Tonk, Bhilwara and Sirohi receive the 40-60 cm rainfall.
The districts, Shri Ganganagar, Hanumangarh, Churu, Southern Barmer, Eastern parts of Bikaner and Jodhpur and western parts of Pali, Jalore, Sikar, Nagaur and Jhunjhunu receive the 20-40 cm rainfall.
The districts or western Rajasthan, Thar Desert, i.e. Jaisalmer, Hanumangarh, Eastern Barmer, Southern Shri Ganganagar and Western Bikaner and Jodhpur receive the rainfall less than 20cm.
The maximum rainfall in the state is received in the Southern or South- Eastern districts of the state. On the west of Aravalli hills Pali and Jalore districts receive maximum amount of rain of 50 cm and 43 cm in West Rajasthan.
In the North or North-Western districts Jaisalmer district receives the lowest rainfall. Bikaner, Ganganagar, Jaisalmer receive annual rainfall of 26cm, 24cm and 17cm respectively. The adjoining areas of these districts constitute the driest zone of the state.
The lowest recorded annual rainfall in the past 100 years i.e. between 1900 and 2010 was 24 mm in the western Rajasthan and whereas it was never below 120 mm in the eastern Rajasthan.
Humidity in Rajasthan
The relative humidity in the arid region of western Rajasthan is also very high. However, due to unfavorable circulation of the atmosphere, low precipitation occurs in this region as compared to semi-arid and sub-humid regions of the Rajasthan.
During the monsoon months, July to September the relative humidity is generally high in the state of Rajasthan. The humidity is about 45%-47% in June, which rises to a little less than 70% during August in West Rajasthan and to about 76%-77% in East Rajasthan. The Graph depicts the humidity regime in the state from 1980 to 2009. The average annual humidity percentage during these 30 years was 55.4 %. The trend line in the figure shows a gradual decrease in humidity percentage in the state from 1980 to 2009.
The annual average of relative humidity of Rajasthan was 61% in 1980. Now, the annual average of relative humidity of Rajasthan was 49% in 2010. There is a gradual decline in the annual average of relative humidity of Rajasthan over the last 30 years.
The variation in the relative humidity is low during the monsoon in the East Rajasthan. However, in the western Rajasthan, the variation is much higher. The relative humidity drops to 22-27% in the afternoon due to high temperature. This makes this region a dry and arid region.
The main reason in this decline is the deforestation and other activities.
The diurnal variation in relative humidity is least during monsoon in the East Rajasthan; on the contrary it is higher in West Rajasthan. In the summer afternoons the relative humidity is least, i.e. about 20 to 30% in most of the state which makes the summer very dry and hot. In the winters (December-January and February) the diurnal variation is highest.
Factors affecting the climate of Rajasthan
1. Temperature
2. Rainfall
3. Thunder Storms
4. Wind
5. Humidity
6. Dust Storms
Weather Seasons of Rajasthan
The geographical diversity of the state causes varied weather conditions even during same season. However, Rajasthan has four distinct weather seasons:
1. The Hot weather season (March to Mid-June)
2. The Season of general Rains or Rainy Season (June to September)
3. The Season of Retreating Monsoon (October – November)
4. The Cold Season (December to February)