sign in sign up
<<
Home , Ajmer, Alwar district, Banswara, Banswara district, Bundi, Dholpur

CLIMATE RESEARCH AND SERVICES METEOROLOGICAL DEPARTMENT MINISTRY OF EARTH SCIENCES

Observed Rainfall Variability and Changes over State

Met Monograph No.: ESSO/IMD/HS/Rainfall Variability/22(2020)/46

Pulak Guhathakurta, Divya Surendran, Preetha Menon, Ashwini Kumar Prasad, Neha Sangwan and S C Advani

GOVERNMENT OF INDIA MINISTRY OF EARTH SCIENCES INDIA METEOROLOGICAL DEPARTMENT

Met Monograph No.: ESSO/IMD/HS/Rainfall Variability/22(2020)/46

Observed Rainfall Variability and Changes Over Rajasthan State

Pulak Guhathakurta, Divya Surendran, Preetha Menon, Ashwini Kumar Prasad, Neha Sangwan and S C Advani

INDIA METEOROLOGICAL DEPARTMENT PUNE - 411005

1

DOCUMENT AND DATA CONTROL SHEET 1 Document Title Observed Rainfall Variability and Changes Over Rajasthan State 2 Issue No. ESSO/IMD/HS/Rainfall Variability/22(2020)/46 3 Issue Date 4 Security Unclassified Classification 5 Control Status Uncontrolled 6 Document Type Scientific Publication 7 No. of Pages 27 8 No. of Figures 42 9 No. of References 3 10 Distribution Unrestricted 11 Language English 12 Authors Pulak Guhathakurta, Divya Surendran, Preetha Menon, Ashwini Kumar Prasad, Neha Sangwan and S C Advani 13 Originating Climate Research Division/ Climate Application Division/ Group & User Interface Group/ Hydrometeorology 14 Reviewing and Director General of Meteorology, India Approving Meteorological Department, New Authority 15 End users Central and State Ministries of Water resources, agriculture and civic bodies, Science and Technology, Disaster Management Agencies, Planning Commission of India 16 Abstract India is in the tropical monsoon zone and receives plenty of rainfall as most of the annual rainfall during the monsoon season every year. However, the rainfall is having high temporal and spatial variability and due to the impact of climate changes there are significant changes in the mean rainfall pattern and their variability as well as in the intensity and frequencies of extreme rainfall events. The report brings the result of the analysis based on the recent 30 years of data (1989-2018) on the mean spatial rainfall pattern as well as mean spatial pattern of different rainfall events, trends and variability as well as extreme rainfall events during the monsoon months and annual for the state. 17 Key Words Rainfall trend, variability, extreme events, dry days

2

1. Introduction

The state of Rajasthan is located in the northwestern part of India. It is the largest state covering an area of 3,42,239 square kilometers, bounded by 23°30'North and 30°11'North latitude and 69°East and 78°East longitude. The state shares its west and northwestern boundary with which is about 1070 km. and part of on its south, rest of Madhya Pradesh and on its east and and on its north and northeast. This state has a type of rhomboid shape and stretches lengthwise 869 km from west to east and 826 km from north to south. The tropic of Cancer passes through its southern tip in the . This state is practically free from maritime to influence. Orographic features and absence of maritime influence affect the climate of the state to a large extent. The distinguishing feature of the state is the , the strong barrier which divides the plains of (lying between 24°37' and 27°42'North Latitudes and 70°05' and 75°22' East Longitude) from the high table land of (lying between 23°49' and 25°28'North Latitude and 73°01' and 74°49'East Longitude). The range which commences at the ‘Ridge’ at Delhi, comes into prominence near the town of , where it appears in a succession of parallel hills. The highest point, on which is perched the fort of Taragarh, rises immediately above the of Ajmer to a height of about 870 metres above sea level between 395 and 425 metres above the valley at its base. The 'Nagpahar' or serpent hill, 5 km west of Ajmer city, attains a slightly lower elevation. About 16 km from Ajmer, the hills disappear for a short distance but in the neighbourhood of form a compact double range which approach each other southward and finally meet near Todgarh, from where a succession of hills and valleys extends to the farthest extremity of the Merwara. Thence the range gradually becomes bolder and more precipitous, till it finally terminates in the southeast corner of the district near . The plateau on which the town of Ajmer stands, marks the highest point in plains of India and from the hills, which surround the land slopes away on every side range of hills between Ajmer and Nasirabad marks the dividing watershed of the Indian sub-continent. The entire portion of West Rajasthan formerly known as Marwar (lying 24o37'and 27°42' North Latitude and 70°05' and 70o22' East Longitude) is sterile, sandy inhospitable but improves gradually from a mere desert in the far west and north comparatively fertile and habitable lands in the northeast, east and southeast in neighbourhood of the Aravalli hills. The 'great desert', forming the whole of the West Rajasthan - Sind frontier, extends from the edge of the Rann of Kutch beyond northward and between it and what has been called the "little desert on the east is a zone of absolutely barren country, consisting of a rocky land cut off by limestone ridges, which to some extent protect it from the desert sands. These places are covered with sand hills, shaped generally in long straight ridges, which seldom meet but run in parallel lines. Some of these ridges may be 3 kilometres long.

3

Many studies are available on the observed trends and variability of rainfall and also extreme rainfall events, but all the studies are based on past 100 years or more data and also the recent years are not included (Guhathakurta et al, 2015; Guhathakurta et al, 2011; Guhathakurta & Rajeevan, 2008 etc). In the present report all the analysis of observed rainfall patterns, trends and variability have been done based on recent past 30 years (1989-2018) that will help to have idea of the recent changes for climate change adaptation and management by the state authorities.

2. Data and Methodology

Daily Rainfall data from 1989 to 2018 is considered for analysis of trend variability and mean rainfall patterns. From the daily rainfall data monthly rainfall series of each station are computed and then monthly district rainfall series has been constructed by considering arithmetic average of all the station rainfall values within the district. The monthly rainfall series of the state has been computed by using area weighted rainfall values of all the within the state. The analysis has been done in two parts. For identification of the spatial pattern mean rainfall and variability and observed trends we have used district rainfall series and results have been brought out for four southwest monsoon months viz. June, July, August, September, for the southwest monsoon season and also for annual. Fig.1 gives the location of the districts of the state. For identification of mean pattern and trends of intensities of various rainfall events we used the station daily rainfall data. From mean and standard deviation (SD), the coefficient of variation (CV) is calculated as follows:

Standard Deviation Coeffcient of variation (CV) = × 100 Mean

Fig. 1 Location of the districts of Rajasthan 4

3. State rainfall mean and variability and trend Table 1 shows the mean rainfall (mm) and coefficient of variation of the state for the monsoon months, southwest monsoon season and annual during the period 1989-2018. It can be seen that the state gets highest rainfall (38%) of south west monsoon rainfall in July month while the August month get 35% of the south west monsoon rainfall. June and September receive 12% and 15% of south west monsoon rainfall. Also more than 91% of annual rainfall receives during the southwest monsoon season only. The variability of monsoon or annual rainfall is also very less (24-25%).

June July August September JJAS Annual Mean 51.5 156.1 144.7 61.9 414.2 454.9 CV 53.5 38.5 47.3 60.8 25.5 24.0

Table 1 Mean rainfall (mm) and coefficient of variation of the state for the monsoon months, southwest monsoon season and annual

Fig. 2 and 3 show the time series of rainfall in mm for the months of June, July, August, September and southwest monsoon season, annual respectively. The trend lines are also displayed for each of the series. Neither monthly rainfall nor seasonal or annual rainfall shows any significant increasing/decreasing trend. All the monsoon months as well as southwest monsoon and annual rainfall shows increasing trend ( nonsignificant). During the last 30 years highest rainfall of June (128.9 mm) received in 1996, July (262.4 mm) received in the year 2015 while highest rainfall of 278.1mm in August received in the year 2016 and of 138mm in September received in the year 2011. The highest annual rainfall of 618.4 mm and highest southwest monsoon rainfall of 573.7 mm received in the year 2013 and 1994 respectively.

5

Fig. 2 Time series of rainfall in mm for the months of June, July, August, September and trends

Fig. 3 Time series of rainfall in mm for the southwest monsoon season and annual trends

6

4. District rainfall mean, variability and trend 4.1 Mean and coefficient of variation Table 2 gives the rainfall statistics for the districts of Rajasthan for the four monsoon months, southwest monsoon season and annual while Fig. 4 to 5shows the spatial pattern of these statistics. It can be seen that south-eastern districts viz. Pratapgarh, Banswara, , Baran and Sirohi receive highest rainfall over other districts during all the months and season. Rainfall receives over these districts are around 85-100 mm in June, 280-335mm in July, 265-320mm in August, 120-140mm in September, 720- 880mm in SW monsoon and 780-920mm in annual. Lowest rainfall receives during the SW monsoon season(169.9mm) as well as annual (208.5m) is over district of northern Rajasthan.

JUNE JULY AUGUST SEPTEMBER MONSOON ANNUAL DISTRICT MEAN CV MEAN CV MEAN CV MEAN CV MEAN CV MEAN CV AJMER 48.3 74 158.8 44 165.5 55 64.4 82 437.0 31 472.4 30 71.6 110 172.4 51 191.7 59 98.4 77 534.1 39 602.0 36 BANSWARA 90.8 65 320.0 41 296.2 65 142.3 63 849.2 36 879.9 34 BARMER 31.9 97 111.6 88 102.3 102 46.1 110 291.8 54 315.5 50 BHARATPUR 62.1 94 179.7 47 185.8 53 97.9 68 525.5 31 577.5 27 59.6 64 221.4 40 215.4 61 72.1 66 568.5 29 597.2 28 41.6 83 87.7 59 68.4 65 31.5 95 229.3 35 286.3 32 69.0 73 226.5 49 229.6 46 83.5 66 608.6 23 638.3 22 67.6 67 270.7 37 264.1 63 93.9 63 696.3 29 725.2 28 CHURU 54.2 70 118.1 50 93.8 64 45.8 84 312.0 38 378.0 35 80.8 69 265.7 44 234.6 68 111.5 75 692.6 37 717.9 56 GANGANAGAR 29.7 90 57.7 71 46.4 92 36.1 118 169.9 54 208.5 49 60.5 77 168.3 40 171.5 63 72.8 67 473.1 31 524.3 28 28.2 106 65.0 83 62.0 87 26.9 127 182.1 43 210.9 39 38.1 91 190.5 88 125.0 94 67.5 118 421.1 56 446.6 53 JHALAWAR 99.7 83 312.4 46 298.9 49 120.1 63 831.1 28 879.5 28 68.3 92 136.9 52 132.7 61 59.3 80 397.3 37 470.9 32 36.4 92 107.8 59 98.6 62 42.2 109 285.0 35 312.4 35 KOTAH 77.6 96 239.2 53 241.4 52 80.7 67 638.9 36 673.7 35 NAGOUR 52.5 103 125.5 45 121.0 181 44.2 70 343.1 78 384.4 72 PALI 40.4 81 184.3 70 163.9 78 57.4 101 446.1 51 464.5 51 61.6 87 207.3 52 222.4 58 81.8 78 573.1 36 614.1 33 62.9 89 143.1 49 133.3 73 50.3 85 389.6 39 447.0 36 SIROHI 54.3 80 333.6 92 221.4 88 112.2 122 721.6 62 746.4 61 TONK 45.1 433 183.8 226 197.7 125 64.2 510 490.8 106 525.4 115 63.2 61 240.1 48 198.9 67 99.0 74 601.1 36 624.9 34 57.0 108 186.7 47 209.8 51 102.4 68 555.9 32 611.1 30 BARAN 99.7 119 307.8 48 287.8 50 108.7 71 804.0 34 847.0 32 61.3 85 201.0 49 206.4 68 96.2 218 564.9 65 609.6 77 RAJASMAND 57.6 56 203.4 47 188.5 53 82.5 79 532.0 28 566.8 27 46.9 71 82.7 61 60.6 80 41.3 93 231.6 33 286.1 116 64.2 316 173.9 135 204.3 126 77.9 265 520.3 70 565.8 67 PRATAPGARH 95.7 73 331.8 38 318.9 60 133.7 54 880.2 30 918.8 28 Table2. Rainfall statistics for the districts of Rajasthan for the four monsoon months, southwest monsoon season and annual

7

Fig.4 Mean rainfall pattern over districts of Rajasthan

8

Fig.5 Coefficient of Variation (%) over districts of Rajasthan

9

4.2 Trend in district rainfall

Fig.6 shows the trends in district rainfall for (a) June, (b) July (c) August (d) September (e) JJAS and (f) annual. It can be seen that June rainfall has shown a significant increasing trend over and insignificant increasing trend in most of the districts except for Barmer, Sikar, Banswara, Prathapgarh which showed a non-significant decreasing trend. For the July month only significant trend has been noticed in (significant decreasing trend). No districts of entire Rajasthan have shown any significant trend in August rainfall while September rainfall of of northern Rajasthan has shown a significant increasing trend. None of the districts of entire Rajasthan state showed any significant trend in the southwest monsoon season rainfall as well as in the annual rainfall.

a b

c d

10

e f Fig.6 Trends in district rainfall for (a) June, (b) July (c) August (d) September (e) JJAS and (f) annual

5. Analysis of Average frequencies for rainfall events of different intensities

5.1 Average frequency of Rainy days The average frequency of rainy days is calculated for Rajasthan for June, July, August, September, June to September and Annual. Figure 7 shows that in the month of June the maximum number of rainy days lies in the range of 4 to 6 days especially over south eastern part of Rajasthan (Banswara, Dungarpur, Udaipur, Pratapgarh, Chittorgarh, Kota, Bundi, Swai Madhpur, Jhalawar, Baran and Kota) and in some parts of western and north-western Rajasthan (Barmer, Jaisalmer and Bikaner districts). While minimum number of rainy days lies in the range of 2-3 days especially in some parts of Jodhpur, Nagour, Jaisalmer, Sri Ganganagar, Hanumangarh, Barmer and Ajmer districts. For the remaining districts, the number of rainy days lies in the range of 3-4 days.

Figure 8 shows that in the month of July the maximum number of rainy days lies in the range of 9 to 12 days especially over south eastern parts of Rajasthan (Banswara, Dungarpur, Pratapgarh, Chittorgarh, Bundi, Swai Madhpur, Sirohi, Karauli ,Dausa, Jhalawar, Baran and Kota ). While minimum number of rainy days lies in the range of 5 to 7 days especially in northern districts Sri Ganganagar and Hanumangargh and some parts of Jaisalmer, Barmer and Jodhpur districts. Whereas in remaining districts, the number of rainy days lies in the range of 7 to 9 days.

Figure 9 shows that in the month of August the maximum number of rainy days lies in the range of 9 to 12 days especially over south eastern parts of Rajasthan (Banswara, Dungarpur, Udaipur, Pratapgarh, Chittorgarh, Bhilwara, Bundi, Swai Madhpur, Tonk, Jaipur, Alwar, Sirohi, Pali, Rajasmand, Bhilwara, Karauli ,Dausa, Jhalawar, Baran and Kota). While minimum number of rainy days lies in the range of 4 to

11

6 days especially in northern districts Sri Ganganagar and Hanumangargh and some parts of Jaisalmer, Barmer, Jodhpur, Churu and Bikaner districts. While in remaining districts, the number of rainy days lies in the range of 6 to 9 days.

Figure 10 shows that in the month of September the maximum number of rainy days lies in the range of 5 to 7 days especially over the south eastern districts (Banswara, Dungarpur, Pratapgarh, Chittorgarh, Rajasmand, Bhilwara, Swai Madhopur, Dausa, Karaul, Dholpur and Bharatpur), south western districts (Barmer ,Shirohi and Jalore) and the western district(Jaisalmer and Barmer) of Rajasthan. While minimum number of rainy days lies in the range of 2 to 4 days especially in over Sri Ganganagar, Hanumangargh, Bikaner, Churu, Jhunjhunu, Sikar Ajmer and Rajasam and districts. Whereas in remaining districts, the number of rainy days lies in the range of 4 to 5 days.

Figure 11 shows that during June to September the maximum number of rainy days lies in the range of 26 to 34 days especially over Sirohi, Udaipur, Banswara, Pratapgargh, Chittorgarh, Rajamand, Bhilwara, Bundi, Kota, Baran and Jhalawar districts. While minimum number of rainy days lies in the range of 15 to 19 days especially in some parts of Sri Ganganagar, Hanumangargh, Bikaner, Sikar , Jaisalmer, Barmer, and Jhodhpur districts. While in remaining districts, the number of rainy days lies in the range of 19 to 26 days.

Figure 12 shows that during the entire year the maximum number of rainy days lies in the range of 30-38 days especially in some parts of Jaisalmer, Sirohi, Udaipur, Banswara, Pratapgargh, Chittorgarh, Rajamand, Bhilwara Pali, Tonk, Bundi, Kota, Swai Madhpur, Baran, Jhalawar, Karauli, Dholpur, Bharatpur and Alwar districts. While minimum number of rainy days lies in the range of 19-27 days especially in some parts of Sri Ganganagar, Hanumangargh, Bikaner, Jaisalmer and Jodhpur districts. Whereas in remaining districts, the number of rainy days lies in the range of 27 to 30 days.

12

Fig. 7 Average frequency of rainy days: June Fig. 8 Average frequency of rainy days: July

Fig.9 Average frequency of rainy days: August Fig. 10 Average frequency of rainy days: September

Fig. 11 Average frequency of rainy days: JJAS Fig. 12 Average frequency of rainy days: Annual

13

5.2 Average frequency of Heavy rainfall days

The average frequency of Heavy rainfall days is calculated for Rajasthan for June, July, August, September, June to September and Annual. Figure 13 shows that in the month of June the maximum number of heavy rainfall days lies in the range of 0.2 to 1 days especially in some parts of Bikaner, Jodhpur, Barmer, Jalore, Sirohi, Udaipur, Dungarpur, Banswara, Pratapgarh, Bundi, Kota, Baran and Jhalawar districts. While minimum number of Heavy rainfall days lies in the range of 0.01 to 0.17 days especially in some parts of Sri Ganganagar, Hanumangargh, Churu, Jhunjhunu, Sikar, Jaipur, Ajmer, Pali, Rajasmand and Bhilwara districts. Whereas in remaining districts, the number of Heavy rainfall days lies in the range of 0.17 to 0.22 days.

Figure 14 shows that in the month of July the maximum number of heavy rainfall days lies in the range of 0.7 to 1 days especially in some parts of Barmer, Jalore, Sirohi, Pali Udaipur, Dungarpur, Banswara, Pratapgarg, Chittorgarh, Bundi, Kota, Baran and Jhalawar districts. While minimum number of Heavy rainfall days lies in the range of 0.1 to 0.6 days especially over north and Northeastern districts (Sri Ganganagar, Hanumangarh, Churu, Jhunjhunu, Sikar, Ajmer, and ) and some parts of Jaisalmer and Barmer districts. Whereas in remaining districts, the number of Heavy rainfall days lies in the range of 0.6 to 0.7 days.

Figure 15 shows that in the month of August the maximum number of heavy rainfall days lies in the range of 0.6 to 1 days especially in some parts of Sirohi, Udaipur, Dungarpur, Banswara, Pratapgarh, Chittorgargh, Kota, Baran and Jhalawar districts. While minimum number of Heavy rainfall days lies in the range of 0.1 to 0.5 days especially in some parts of Sri Ganganagar, Hanumangarh, Bikaner, Churu, Nagaur, Sikar, Jhunjhunu, Jhodhpur, Barmer and Jaisalmer districts. Whereas in remaining districts, the number of Heavy rainfall days lies in the range of 0.5 to 0.6 days.

Figure 16 shows that during September the maximum number of heavy rainfall days lies in the range of 0.2 to 1 days especially in some parts of Alwar, Dholpur, Bharatpur, Baran, Jhalwar, Pratapgarh, Banswara, Dungarpur, Udaipur, Sirohi, Jalore, Barmer, Jaiselmer, Pali and Bikaner districts. While minimum number of Heavy rainfall days lies in the range of 0.1 to 0.21 days especially in some parts of Sri Ganganagar, Hanumangarh, Churu, Bikaner, Jhunjhunu, Jaipur, Sikar, Nagaur, Ajmer, Pali, Jodhpur and Bilwara districts. Whereas in remaining districts, the number of Heavy rainfall days lies in the range of 0.21 to 0.26 days.

14

Figure 17 shows that during June to September the maximum number of heavy rainfall days lies in the range of 1.8 to 3 days especially in some parts of Jaisalmer, Barmer, Jalore, Sirohi, Udaipur, Dhungarpur, Banswara, Pratapgarh, Chittorgarh, Kota, Baran and Jhalawar districts. While minimum number of Heavy rainfall days lies in the range of 0.7 to 1 days especially in some parts of Sri Ganganagar, Hanumangarh, Bikaner, Churu, Nagaur, Sikar and Jhunjhunu districts. Whereas in remaining districts, the number of Heavy rainfall days lies in the range of 1 to 1.86 days.

Figure 18 shows that during the entire year the maximum number of heavy rainfall days lies in the range of 1.9 to 3 days especially in some parts of Jaisalmer, Barmer, Jalore, Sirohi, Pali, Udaipur, Dhungarpur, Banswara, Pratapgarh, Chittorgarh, Kota, Baran and Jhalawar districts. While minimum number of Heavy rainfall days lies in the range of 0.8 to 1.2 days especially in some parts of Sri Ganganagar, Hanumangarh, Bikaner, Churu, Nagur, Jodhpur, Jaisalmer, Barmer, Sikar and Jhunujhunu districts. Whereas in remaining districts, the number of Heavy rainfall days lies in the range of 1.2 to 1.9 days.

Fig. 13 Average frequency of heavy rainfall days: June Fig. 14 Average frequency of rainy days: July

15

Fig. 15 Average frequency of rainy days: August Fig. 16 Average frequency of rainy days: September

Fig. 17 Average frequency of rainy days: JJAS Fig. 18 Average frequency of rainy days: Annual

5.3 Average frequency of Dry days

The average frequency of dry days is calculated for Rajasthan for June, July, August, September, June to September and Annual. Figure 19 shows that in the month of June the maximum number of dry days lies in the range of 26 to 27 days especially in most parts of Sri Ganganagar, Hanumangarh and Ajmer districts and some parts of Jaisalmer, Barmer, Jodhpur, Bikaner, Churu and Nagaurdistricts. While minimum number of dry days lies in the range of 23-24 days especially in most parts of south eastern districts (Banswara, Pratapgargh, Chittorgargh, Bilwara,Bundi , Kota, Jhalawar and Baran) of Rajasthan. For the remaining districts, the number of dry days lies in the range of 24 to 26 days.

16

Figure 20 shows that in the month of July the maximum number of dry days lies in the range of 22 to 25 days especially in most parts of northern districts (Sri Ganganagar, Hanumangarh, eastern part of Bikaner, Churu and Jhunjhunu and some parts of Jaisalmer, Barmer and Jodhpur districts . While minimum number of dry days lies in the range of 16-19 days especially in most parts of south eastern districts(Udaipur, Sirohi, Dungarpur, Banswara, Pratapgargh, Chittorgargh, Bilwara, Bundi, Kota, Jhalawar, Baran, Tonk, Swai Madhopur, Dousa, Karouli, and Dholpur) districts of Rajasthan. In the remaining districts, the number of dry days lies in the range of 19 to 21 days.

Figure 21 shows that in the month of August the maximum number of dry days lies in the range of 22 to 25 days especially in most parts of northern districts Sri Ganganagar, Hanumangarh, Churu, Jhnujhnuand some parts of Jaisalmer, Barmer and Bikaner districts. While minimum number of dry days lies in the range of 16 to 20 days especially in most parts of south eastern districts (Udaipur, Sirohi, Dungarpur, Banswara, Pratapgarh, Chittorgarh, Bilwara, Bundi, Kota, Jhalawar, Baren, Bundi, Tonk, Swai Madhopur, Dousa, Karouli, and Dholpur) districts of Rajasthan . Whereas in remaining districts, the number of dry days lies in the range of 19 to 22 days.

Figure 22 shows that in the month of September the maximum number of dry days lies in the range of 25 to 27 days especially in most parts of northeren districts (Sri Ganganagar, Hanumangarh, Bikaner, Churu, Sikar, Jhunjhunu and Ajmer and some parts of Jaisalmer, Barmer and Jodhpur districts. While minimum number of dry days lies in the range of 22 to 24 days especially in most parts of Udaipur,Pratapgarh, Dungarpur, Chittorgarh, Baran, Kota and Jhalawar districts. Whereas in remaining districts, the number of dry days lies in the range of 24 to 25 days.

Figure 23 shows that during June to September the maximum number of dry days lies in the range of 91 to 101 days especially in most parts of Sri Ganganagar and Hanumangarh and some parts of Barmer, Jailsalmer, Jodhpur, Bikaner, Churu, Nagaur, Ajmer, Sikar and Jhunujhunudistricts. While minimum number of dry days lies in the range of 76 to 82 days especially in Udaipur, Pratapgarh, Dungarpur, Chittorgarh, Baran, Kota, Bundi, Bilwara, Tonk, Swai Madhopur, Karauli and Jhalawar districts. While in remaining districts, the number of dry days lies in the range of 86 to 91 days.

Figure 24 shows that in the month of during the entire year the maximum number of dry days lies in the range of 315 to 332 days especially in most parts of Sri Ganganagar and Ajmer districts and some parts of Hanumangarh, Jaisalmer, Barmer, Jodhpur,Bikaner, Churu, Naguar and Sikar. While minimum number of dry days lies in the range of 292 to 308 days especially in some parts of Udaipur, Bundi, Kota, Baren,

17

Jhalawar and Tonk districts. Whereas in remaining districts, the number of dry days lies in the range of 308 to 315 days.

Fig. 19 Average frequency of dry days: June Fig. 20 Average frequency of dry days: July

Fig. 21 Average frequency of dry days: August Fig. 22 Average frequency of dry days: September

18

Fig. 23 Average frequency of dry days: JJAS Fig. 24 Average frequency of dry days: Annual

6 Trends in the frequencies of different rainfall events

6.1Trend in frequency of Rainy days

The Trend in frequency of rainy days is calculated for the rain gauge stations of Rajasthan for June, July, August, September, June to September and Annual. Figure 25 shows that in the month of June there is a significant increase in Rainy days in some stations of Jodhpur, Dungarpur, Sikar, Hanumangarh, Bundi, Bharatpur, Dholpur and Alwar districts. Whereas there is a significant decrease in Rainy days in some stations of Sirohi, Dungarpur, Jaipur and Alwar districts. While remaining districts did not show any significant change.

Figure 26 shows that in the month of July there is a significant increase in Rainy days in stations in Jhalawar, Kota, Baran, Udaipur, Ajmer, Bundi and Rajasamand districts. Whereas there is a significant decrease in Rainy daysin stations in Jaipur, Alwar, Dausa and Bilwara districts. While remaining districts did not show any significant change.

Figure 27 shows that in the month of August there is a significant increase in Rainy days in stations in Udaipur, Barmer, Jodhpur, Bikaner, Sri Ganganagar, Ajmer, Tonk and Bundi districts. Whereas there is a significant decrease in Rainy days in stations in Jaipur and Alwar districts. While remaining districts did not show any significant change.

19

Figure 28 shows that in the month of September there is a significant increase in Rainy daysin stations in Udaipur, Sri Ganganagar, Hanumangarh and Ajmer districts. Whereas there is a significant decrease in Rainy days in one station of . While remaining districts did not show any significant change.

Figure 29 shows that in the month of June to September there is a significant increase in Rainy days in stations in Sri Ganganagar, Bikaner, Jodhpur, Udaipur, Chittorgarh, Ajmer, Bundi, Jhalawar and Baran districts. Whereas there is a significant decrease in Rainy days in stations Banswara, Bilwara and Jaipur districts. While remaining districts did not show any significant change.

Figure 30 shows that during the entire year there is a significant increase in Rainy days in many stations in Sri Ganganagar, Ajmer, Chittorgarh and Bundi districts and some stations of Bikaner, Jodhpur, Rajasmand and Udaipur districts. Whereas there is a significant decrease in Rainy days in some stations of Banswara, Bhilwara, Jaipur and Baran districts. While remaining districts did not show any significant change.

Fig. 25 Trend in frequency of rainy days: June Fig. 26Trend in frequency of rainy days: July

20

Fig. 27 Trend in frequency of rainy days: August Fig. 28 Trend in frequency of rainy days: September

Fig. 29 Trend in frequency of rainy days: JJAS Fig. 30 Trend in frequency of rainy days: Annual

6.2 Trend in frequency of Heavy rainfall days

The Trend in frequency of Heavy days is calculated for Rajasthan for June, July, August, September, June to September and Annual. Figure 31 shows that in the month of June there is a significant increase in Heavy rainfall days in some stations od Sirohi, Ajmer, Bilwara and Chittorgarh districts. Whereas there is a significant decrease in Heavy days in one station of . While remaining districts did not show any significant change.

Figure 32 shows that in the month of July there is a significant increase in Heavy rainfall days in Sirohi, Udaipur, Dungarpur, Chittorgarh, Jhalawar, Bhartpur, Karauli and Dholpur districts and decrease in Heavy rainfall days in Banswara, Jalore, Jodhpur, Bikaner, Ajmer, Bhilwara, Jaipur, Alwar and Hanumangarh 21 districts. While remaining districts did not show any significant change.

Figure 33 shows that in the month of August there is a significant increase in Heavy rainfall days in Udaipur, Dungarpur, Pratapgarh, Baran, Bundi, Ajmer, Hanumangarh, Churu and Sikar districts. Whereas there is a significant decrease in Heavy rainfall days only in one station of . While remaining districts did not show any significant change.

Figure 34 shows that in the month of September there is a significant increase in Heavy rainfall days in Udaipur, Bhilwara, Chittorgarh, Sri Ganganagar, Hanumangarh, Bharatpur and SwaiMadhopur districts. Whereas there is a significant decrease in Heavy rainfall days in Jaipur, Tonk, Karauli and SwaiMadhopur districts. While remaining districts did not show any significant change.

Figure 35 shows that during June to September there is a significant increase in Heavy rainfall days in Udaipur, Pali, Chittorgarh, Dungarpur, Pratapgarh, Jhalawar, Kota, Baran, Ajmer and Sikar districts. Whereas there is a significant decrease in Heavy rainfall days in Alwar, Jaipur, Karauli, Nagaur, Ajmer and Dungarpur districts. While remaining districts did not show any significant change.

Figure 36 shows that during the entire year there is a significant increase in Heavy rainfall days in Udaipur, Dungpur, Chittorgarh, Pratapgarh, Ajmer, Karauli, Sikar and Jhalawar districts. Whereas there is a significant decrease in Heavy rainfall days in Alwar, Jaipur, Karauli, Ajmer, Nagaur, Bhilwara and Kota districts. While remaining districts did not show any significant change.

Fig.31 Trend in frequency of heavy rainfall days: Fig. 32 Trend in frequency of heavy rainfall days: June June

22

Fig. 33 Trend in frequency of heavy rainfall days: Fig. 34 Trend in frequency of heavy rainfall days: August September

Fig. 35 Trend in frequency of heavy rainfall days: Fig. 36 Trend in frequency of heavy rainfall days: JJAS Annual

6.3 Trend in frequency of Dry days

The Trend in frequency of dry days is calculated for Rajasthan for June, July, August, September, June to September and Annual. Figure 37 shows that in the month of June there is a significant increase in dry days in Banswara, Dungarpur, Udaipur, Bundi and Jaipur districts. Whereas there is a significant decrease in dry days in Sri Ganganagar, Hanumangarh, Churu, Jhunjhunu, Ajmer, Jaipur, Chittorgarh, Bharatpur, Dholpur and Jhalawar districts. While remaining districts did not show any significant change.

Figure 38 shows that in the month of July there is a significant increase in dry days in Jaipur, Banswara, Udaipur and Jaipur districts. Whereas there is a significant decrease in dry days in some stations of Jodhpur, Ajmer, Chittorgarh, Jhalawar, Baran and Dholpur districts. While remaining districts did not show any

23 significant change. Figure 39 shows that in the month of August there is a significant increase in dry days in Bundi, Jaipur and Alwar districts. Whereas there is a significant decrease in dry days in Sri Ganganagar, Hanumangarh, Ajmer, Udaipur and Bhanswara districts. While remaining districts did not show any significant change.

Figure 40 shows that in the month of September there is a significant increase in dry days in few stations Udaipur, Bundi, Jaipur and Kota districts. Whereas there is a significant decrease in dry days in many station of Sri Ganganagar, Hanumangarh and one station of Ajmer districts. While remaining districts did not show any significant change.

Figure 41 shows that in the month of June to September there is a significant increase in dry days in some stations of Udaipur,Jaipur and Kota districts. Whereas there is a significant decrease in dry days in many stations of Sri Ganganagar, Hanumangarh, Bhilwara, Rajasmand , Jodhpur and Ajmer districts. While remaining districts did not show any significant change.

Figure 42 shows that during the entire year there is a significant increase in dry days in Jaipur, Udaipur and Jhalawar districts. Whereas there is a significant decrease in dry days in Bikaner, Sri Ganganagar, Ajmer, Sikar, Bhartpur, Dholpur, Karauli and Bundi districts. While remaining districts did not show any significant change.

Fig. 37 Trend in frequency of dry days: June Fig. 38Trend in frequency of dry days: July

24

Fig. 39 Trend in frequency of dry days: August Fig. 40 Trend in frequency of dry days: September

Fig. 41 Trend in frequency of dry days: JJAS Fig. 42 Trend in frequency of dry days: Annual 7. Conclusions

In the present study we have investigated the rainfall pattern and it its variability and also changes based on recent 30 years data. In the analysis we have considered monsoon months, the monsoon season and annual scale. The spatial scale has been considered from state to district for study of rainfall total and stations are being considered for seeing intensities of rainfall. The analysis brought many significant features of rainfall pattern and can be used for water agricultural managements. Some of the important results can be summarized as: Rajasthan gets maximum rainfall in July (38% of SW monsoon rainfall) followed by August (35 % of SW monsoon rainfall). 92% of annual rainfall receives during southwest monsoon rainfall (June –September).

25

There is a significant increasing trend observed over Sawai Madhpur district in month of June and over Sri Ganganagar district in the month of September. Hanumangarh district of northern Rajasthan showed a significant decreasing trend in rainfall for the month of July. Remaining districts showed no significant trends in monthly rainfall. During the SW monsoon season, districts in south-eastern Rajasthan receive maximum rainfalls (580-860mm) while the north-western parts of the state receive lowest rainfall (170-312mm). Sri Ganganagar is the district which receives lowest rainfall of 169.9mm. During the year maximum rainfall receives over the districts in south-eastern Rajasthan (625- 920mm) while the north-western parts receive lowest annual rainfall of 200-350mm. None of the districts showed any significant trend in the SW monsoon rainfall as well as in the annual rainfall. South-eastern Rajasthan receive on an average 26 to 34rainy days (daily rainfall >=2.5mm) out of 122 days of SW monsoon season while northern Rajasthan gets 15 to 19 rainy days and central parts of Rajasthan get around 20-25 rainy days. For heavy to extremely heavy rainfall (daily rainfall >=6.5mm) districts of South-eastern Rajasthan and some parts of west Rajasthan get 1.8 to 3 days during the SW monsoon season, northern and central parts of the state get around 0.7 to 1.5 heavy to extremely heavy rainfall days. Number of dry days is maximum over the northern parts of the state (91 to 101 dry days out of 122 days) during the SW monsoon season while on an average 315 to 332 dry days in 365 days have been observed in many parts of western, northern and central districts of Rajasthan. During the period June to September there is a significant increase in Rainy days in stations in Sri Ganganagar, Bikaner, Jodhpur, Udaipur, Chittorgarh, Ajmer, Bundi, Jhalawar and Baran districts. Whereas there is a significant decrease in Rainy days in stations Banswara, Bilwara and Jaipur districts. While remaining districts did not show any significant change. During the entire year there is a significant increase in Rainy days in many stations of Sri Ganganagar, Ajmer, Chittorgarh and Bundi districts and some stations of Bikaner, Jodhpur, Rajasmand and Udaipur districts. Whereas there is a significant decrease in Rainy days in some stations of Banswara, Bhilwara, Jaipur and Baran districts. During June to September there is a significant increase in Heavy rainfall days in Udaipur, Pali, Chittorgarh, Dungarpur, Pratapgarh, Jhalawar, Kota, Baran, Ajmer and Sikar districts. Whereas there is a significant decrease in Heavy rainfall days in Alwar, Jaipur, Karauli, Nagaur, Ajmer and Dungarpur districts. While remaining districts did not show any significant change.

26

During the entire year there is a significant increase in Heavy rainfall days in Udaipur, Dungpur, Chittorgarh, Pratapgarh, Ajmer, Karauli, Sikar and Jhalawar districts. Whereas there is a significant decrease in Heavy rainfall days in Alwar, Jaipur, Karauli, Ajmer, Nagaur, Bhilwara and Kota districts. While remaining districts did not show any significant change. During June to September there is a significant increase in dry days in some stations of Udaipur, Jaipur and Kota districts. Whereas there is a significant decrease in dry days in many stations of Sri Ganganagar, Hanumangarh, Bhilwara, Rajasmandu, Jodhpur and Ajmer districts. While remaining districts did not show any significant change. During the entire year there is a significant increase in dry days in Jaipur, Udaipur and Jhalawar districts. Whereas there is a significant decrease in dry days in Bikaner, Sri Ganganagar, Ajmer, Sikar, Bhartpur, Dholpur, Karauli and Bundi districts.

Acknowledgement:

The authors acknowledge Secretary, MOES, DGM, India Meteorological Department and Head, Climate Research and Services for guidance, suggestions and encouragement to carry out the works. Acknowledge also to Hydrology section and National Data Centre for making availability of the data.

References:

1. Guhathakurta P, Rajeevan M, Sikka D R and Tyagi A, 2015 “Observed changes in southwest monsoon rainfall over India during 1901–2011”, Int. J. Climatol, 35, 1881-1898. 2. Guhathakurta P, Sreejith O P and Menon P A, 2011 “Impact of climate changes on extreme rainfall events and flood risk in India”, J. Earth System Science. 120, No. 3, 359-373. 3. Guhathakurta P and Rajeevan M, 2008 “Trends in rainfall pattern over India”, International J. of Climatology, 28: 1453–1469

27

The report brings out observed rainfall variability and trends over the state as an impact of climate change based on recent 30 years of data ( 1981 - 2018 )

Rainfall pattern of monsoon months, south west monsoon season and annual of the state and it’s districts as well as extreme rainfall event of different intensity of stations are analysed.

Observed Rainfall Variability and Changes over Andhra Pradesh State

PREPARED AND DESIGNED AT HYDROMETEOROLOGY SECTION CLIMATE APPLICATION AND USER INTERFACE GROUP CLIMATE RESEARCH AND SERVICES, PUNE