Agroclimatic charecterization of parbhani district
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Date
2018-08-23
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Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani
Abstract
The research work was conducted on “AgroclimaticCharecterizationof Parbhani District” during (2017-18). The historical weather data (1987-2016)collected from Department of Agricultural Meteorology, VNMKV, Parbhani. The rainfall data analysed statistically and different statistical parameters like mean, median, standard deviation, coefficient of variation, coefficient of skewness and kurtosis. Onset, withdrawal of rainy season and length of growing period also determined. Mann-Kendall seasonal decadal and monthly decadaltrend analysis and sen’s slope of rainfall estimated (1987–2016).Initial and conditional probabilities of dry and wet spell for monsoon and post-monsoonrainy season for 20 mm, 40 mm, 60 mm, 80 mm and 100 mm for the 22nd to 48thSMWwere determined, to obtain specific information needed for crop planning and for carrying out agricultural operations. The weekly potential evapotranspiration values were estimated by the Penman-Monteith method and water balance components were determined by Thornthwaite’s book-keeping technique.
Average annual rainfall is 949.8 mm with a standard deviation 284.6 mm and coefficient of variation 30 percent. Maximum and minimum rainfall is found to be 1711 mm (1990) and 569.7 mm (2014) respectively. Seasonal mean rainfall for the period June to September is 793.6 mm with standard deviation 285.2 mm. Maximum and minimum seasonal rainfall is found to be 1533.1 mm (1988) and 398.1 mm (2014) respectively.Early onset of rainy season is at 20th week and maximum delay is up to 30th week with mean of 25th week. Early withdrawal of rainy season is at 31stweek, late withdrawal of rainy season in 49th weekwith a mean value of 43rd week.The average growing length period of the study area is 34week of year, minimum length of growing season was found to be 30week of the year (1991 and 1992) and maximum length was found 40 week of (1997).Spatial and temporal distribution of rainfall at Gangakhed and Pathri, Kendall’s tau values for two decades 1981-1990 and 1991-2000 shows rising trend and one decade 2001-2010 shows falling trend. The Sen’s slope estimator revealed that, among three decades 1981-1990, 1991-2000 decade shows rising trend another decade 2001-2010 showed falling trend. At Pathri Kendall’s tau and Sen’s slope estimator values of all decades show rising trend,
The probability of occurrence of wet week preceded by another wet week is higher from 23rd to 39th SMW because in this area rainfall occurred only in monsoon season and in post-monsoon season the probability of occurrence of dry week preceded by another dry week is higher because in these weeks there is less rainfall or no rainfall recorded.Incomplete gamma probability distribution for weekly total rainfall at Parbhani shows there was 90% probability of getting an assured rainfall of at least 641.6 mm and 50% probability of getting 961.2 mm. However, the analysis indicates that at 75% and 25% probability level the rainfall values were 782.1 mm and 1165.9 mm respectively.Probability of two consecutive dry and wet weeks for monsoon season and post-monsoon season (22ndto 48thSMW) also obtained.Probability of 20 mm rainfall P(2D) is lowest 0.0 in 35th SMW of monsoon. In other weeks it remains high in post- monsoon. P(2W) is high enough in 24th, 27th, 30th, 32th, 36thand 37th SMW of monsoon.
The total average rainfall of 30 years in the study area is 988.3 mm while the surplus water in the system amount is 183.5 mm. The surplus water 183.5 mm. Estimation of water balance shows that, only 27th to 38th SMW except 37thare water surplus while the rest of the weeks are water deficit week. The potential evapotranspiration exceeds rainfall in the weeks 37th to 52ndexcept 38thand 1st to 26th which makes them water deficit weeks. 6th to 23rd weeks are the weeks of maximum water deficit while the excess water adds to the system. In 24th to 44th SMW have more than 0.75 Moisture Availability Index (MAI) which are excellent for crop growth and 45th to 49th SMW are good for crop growth. While crops are under moderate stress in 1st, 2nd, 23rd and 50th to 52ndSMW and in 3rd to 22ndSMW crops under severe stress.
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