Bhubaneswar: Future tense for Odisha? Looks very likely. The trend of annual rainfall over a period of 30-years (1989-2018) in Odisha reveals big. Annual dry days in Odisha hovered at around 250-280 days; annual rainy days at only around 43-70 days.
The IMD in its recent study on rainfall variability in Odisha documents a declining trend in the annual rainfall over the last three-decades in the State. On the contrary, there is a significant increase in dry days in all the districts of Odisha, except Angul.
However, the respite for the state is rainfall trend during the monsoon period of June - September didn't post any declining trend. At the same time, the point to note is it hasn't increased either during the last 3-decades. (See the image below).
The rainfall trend analysis by IMD drops big hints for the powers that be in the State. It will come handy for the Odisha government in drawing up its contingency plans for the management of both - water and floods.
Regarding rainfall during monsoon season, IMD study finds an increasing trend during the months of July and September, whereas a falling trend recorded in months of June and August.
IMD says the 30-years monsoon rainfall data reveals that during the whole southwest monsoon season, only one district, Koraput, has shown a significant increasing trend. In contrast, the annual rainfall pattern shows a significant decreasing trend in Dhenkanal district.
IMD study shows during August, a significant declining rainfall trend was noticed in Dhenkanal along with the districts like Jajpur and Nayagarh. The study, however, found a significant increasing rainfall trend in September rainfall in districts like Boudh and Malkangiri.
"During the last 30 years, highest rainfall for June, July, August and September was recorded in the years 2008, 2009, 2006 and 2007 respectively (344.1mm, 587.2mm, 626.3mm and 400.1mm respectively)," reveals the study and added that when Odisha received its highest annual rainfall of 1905.2 mm in 1990, the highest southwest monsoon rainfall of 1528.1 mm received in the year 1994.
In estimating number of rainy days in the State, study says while the maximum number of rainy days are in the range of 10 to 11 days in June, it's 15-16 days in July, 15-17 days in August and 11-12 days in September.
However, the rider here is the maximum number of rainy days in each month is limited to only parts of some districts.
For instance, maximum rainy days in June recorded in parts of Mayurbhanj, Balasore, Keonjhar, Kandhamal, Koraput and Nabarangpur districts; whereas in July the maximum number of rainy days was recorded in some parts of Mayurbhanj , Sundargarh, Jharsuguda, Sambalpur, Deogarh, Sonapur, Kalahandi, Kandhamal, Koraput , Nabarangpur and Malkangiri districts.
Similarly, in the month of August the maximum number of rainy days was witnessed in some parts of Mayurbhanj , Sundargarh, Jharsuguda, Sambalpur, Deogarh, Kalahandi, Kandhamal, Koraput, Nabarangpur and Malkangiri.
In the month of September, maximum number of rainy days observed in some parts of Mayurbhanj, Keonjhar, Balasore, Cuttack, Khurda, Kandhamal, Gajapati, Koraput, Nabarangpur and Malkangiri districts.
If the whole of monsoon month is taken into account, during June to September the maximum number of rainy days lies in the range of 50 to 52 days in some parts of Mayurbhanj, Balasore, Keonjhar, Sundargarh, Deogarh, Kandhamal, Kalahandi, Nabarangpur, Koraput and Malkangiri districts.
And the minimum number of rainy days was recorded in the range of 41 to 43 days in some parts of Ganjam, Gajapati, Koraput, Nabarangpur, Nuapada and Malkangiri districts.
A look at the annual rainfall also shows Mayurbhanj tops the State with rainfall recorded in the range of 66-70 days; whereas minimum number of rainy days (52 to 56 days) was observed in some parts of Sundargarh, Bargarh, Sonepur, Boudh, Bolangir, Nuapada, Kalahandi, Nabarangpur, Malkangiri and Ganjam.
The big takeaway here is Mayurbhanj receives good rainfall during the whole of monsoon season; whereas a poor rainfall is recorded in districts like Ganjam and Gajapati. And for rest of the districts, the rainfall is maximum is some parts and minimum in other parts.
The average frequency of heavy rainfall days during the monsoon season in Odisha is estimated in the range of 4-5 days in some parts of Kendrapada, Jajpur, Angul, Sambalpur, Bargarh, Sonepur, Bolangir, Kandhamal, Kalahandi, Koraput and Nabarangpur districts.
The minimum number of heavy rainfall days lies in the range of 1 to 2 days especially in some parts of Ganjam, Gajapati, Rayagada, Koraput and Malkangiri districts, finds the study.
Regarding dry days in Odisha, the study finds during the entire year the maximum number of dry days was observed in the range of 273 to 280 days in some parts of Jajpur, Kendrapada, Cuttack, Khurda, Nayagarh, Jagatsingpur, Puri, Ganjam, Bargarh, Bolangir, Nuapada and Kalahandi districts.
"When minimum number of dry days lies in the range of 247 to 254 days especially in some parts of Mayurbhanj, Gajapati, Koraput and Malkangiri districts, the number of dry days in the remaining district lies in the range of 254 to 273 days," the study highlighted.