Uttar Pradesh State
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CLIMATE RESEARCH AND SERVICES INDIA METEOROLOGICAL DEPARTMENT MINISTRY OF EARTH SCIENCES PUNE Observed Rainfall Variability and Changes over Uttar Pradesh State Met Monograph No.: ESSO/IMD/HS/Rainfall Variability/27(2020)/51 Pulak Guhathakurta, Sudeep Kumar B L, Preetha Menon, Ashwini Kumar Prasad, S T Sable and S C Advani GOVERNMENT OF INDIA MINISTRY OF EARTH SCIENCES INDIA METEOROLOGICAL DEPARTMENT Met Monograph No.: ESSO/IMD/HS/Rainfall Variability/27(2020)/51 Observed Rainfall Variability and Changes Over Uttar Pradesh State Pulak Guhathakurta, Sudeep kumar B L, Preetha Menon, Ashwini Kumar Prasad, S.T. Sable and S C Advani INDIA METEOROLOGICAL DEPARTMENT PUNE - 411005 1 DOCUMENT AND DATA CONTROL SHEET 1 Document Title Observed Rainfall Variability and Changes Over Uttar Pradesh State 2 Issue No. ESSO/IMD/HS/Rainfall Variability/27(2020)/51 3 Issue Date January 2020 4 Security Unclassified Classification 5 Control Status Uncontrolled 6 Document Type Scientific Publication 7 No. of Pages 31 8 No. of Figures 42 9 No. of References 3 10 Distribution Unrestricted 11 Language English 12 Authors Pulak Guhathakurta, Sudeep kumar B L, Preetha Menon, Ashwini Kumar Prasad, S.T. Sable and S C Advani 13 Originating Climate Research Division/ Climate Application & User Division/ Group Interface Group/ Hydrometeorology 14 Reviewing and Director General of Meteorology, India Meteorological Approving Department, New Delhi 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 rent 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 Uttar Pradesh which is land locked state, situated between latitudes 23o87’ N and 30o40' N and longitudes 77.08°' E and 84.63° E,has Uttarakhand and Himachal Pradesh on the northwest, Haryana and Delhi on the west, Rajasthan on the southwest, Madhya Pradesh on the south, Chhattisgarh and Jharkhand on southeast, Bihar on the east and Nepal on its northeast. The Himalayas provide the northern, Yamuna-the Western, the Ganga-the southern and Gandaki-the eastern boundary of the state.On the basis of its physical features, the state can be divided into following broad regions: 1. Sub-mountainous region 2. The Ganga Plain region and 3. The Trans-Yamuna region Climate of Uttar Pradesh is predominantly Sub-tropical monsoon, mild and dry winter and hot summer. Many studies available on the observed trends and variability of rainfall and also extreme rainfall events over India, 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). Also, there are limited studies on district rainfall trends and variability of Uttar Pradesh state. 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 stations are computed and then monthly district rainfall series has been constructed by considering arithmetic average of all the station rainfall values within the district. Fig.1 gives the location of the districts of the state. The monthly rainfall series of the state has been computed by using area weighted rainfall values of all the districts within the state. The objective of the analysis is to: 1. Identify the spatial pattern of the mean rainfall 3 2. Understand district wise observed rainfall trend and variability in annual and SW monsoon season (June, July, august and September). Daily station rainfall data is utilized for identification of the mean spatial patterns and rainfall intensity trends. 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 Uttar Pradesh 3. State rainfall mean, 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 (34% of south west monsoon rainfall) in July month followed by August (31% of the south west monsoon rainfall). June and September receive 14% and 21% of south west monsoon rainfall, respectively. About 89% of annual rainfall receives during the southwest monsoon season only. The variability of monsoon and annual rainfall is 21% and 19%, respectively. 4 June July August September JJAS Annual Mean 96.1 238.6 219.0 142.9 696.7 784.1 CV 60.9 29.5 34.5 49.8 20.8 18.7 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. The southwest monsoon season rainfall and the annual rainfall show significant decreasing trends. In the monthly rainfall of southwest monsoon, it is observed that September month has a significant decreasing trend, whereas other months do not have any significant trend. Although, an insignificant decreasing trend is observed in June and August months and an insignificant increasing trend is observed in July month. In the last 30 years, the highest rainfall of June, July, August and September received 251.8 mm (Year 2013), 1424.8 mm (Year 1990), 401.9 mm (Year 1991) and 344 mm (Year 2003) respectively and the lowest rainfall of June, July, August and September received in the year 2012 (13.6 mm), 2002 (72.6 mm), 1997 (41.8 mm) and 2015 (23.9 mm), respectively. Highest southwest monsoon rainfall of 987.6 mm and annual rainfall of 1074.5 mm received in the year 2003 and the lowest southwest monsoon rainfall of 417.8 mm and annual rainfall of 484.1 mm received in 1997. Fig. 2 Time series of rainfall in mm for the months of June, July, August, September and their trends 5 Fig. 3 Time series of rainfall in mm for the southwest monsoon season and annual and their trends. 4. District rainfall mean, variability and trend 4.1 Mean and coefficient of variation Table 2 gives the rainfall statistics for the districts of Uttar Pradesh for the four monsoon months, southwest monsoon season and annual, and Fig. 4-5 show the spatial pattern of these statistics. It can be seen that Gorakhpur receives the highest rainfall over other districts during all the southwest monsoon months and the season. Rainfall received over Gorakhpur is 192.7 mm in June, 367.2 mm in July, 337.4 mm in August and 220.2 mm in September, 1117.5 mm in southwest monsoon and 1245.3 mm in annual. Gorakhpur and Bahraich received maximum amount of rainfall in annual time scale (1089-1245 mm). In general, districts over the northeast of Uttar Pradesh (except Khushi Nagar and Ballia) received high amount of rainfall and districts over southwest of Uttar Pradesh received less amount of rainfall. The districts with fewer amounts of rainfall during the southwest monsoon season (421-560 mm) and annual (464-620 mm) are: Baghpat, Bulandshahar, Aligarh, Mathura, Mahamaya Nagar, Etah, Ayodhya, Agra, Etawah, Kannauj, Auraiya, Kanpur Dehat, Kanpur, Mahoba, Rae Bareli, Kaushambi and Khushi Nagar. Districts with minimum amount of rainfall in June, July, August, September, southwest monsoon season and annual are Mathura (37.1 mm), Auraiya (148.1mm), Rae Bareli (121.0 mm), Mahoba (74.0 mm), Rae Bareli (420.8 mm and 463.8 mm), respectively. The districts exhibiting maximum and minimum variability of mean rainfall are Chandauli and Kheri Lakhimpur for June, Kannauj and Bahraich for July, Chandauli and Kheri Lakhimpur for August and Shravasti and Bahraich for September. Khushi Nagar and Bahraich show the maximum and 6 minimum variability of rainfall during the southwest monsoon and Kaushambi and Bahraich show the maximum and minimum variability of rainfall during annual time scales respectively. JUNE JULY AUGUST SEPTEMBER MONSOON ANNUAL DISTRICT MEAN CV MEAN CV MEAN CV MEAN CV MEAN CV MEAN CV AGRA 48.8 115 171.7 138 169.1 58 101.3 81 490.8 68 548.5 80 ALIGARH 51.6 382 198.6 53 188.1 61 108.5 82 546.8 62 623.5 73 ALLAHABAD 93.7 96 243.8 44 223.2 40 158.7 64 719.4 32 800.1 63 AMBEDKAR NGR 125.5 183 254.4 138 224.2 148 175.7 138 779.7 93 873.5 94 AURAIYA 51.2 86 148.1 152 147.2 60 102.5 99 449.0 69 493.7 97 AZAMGARH 103.4 207 259.6