Regional Imbalance in rainfall - APPSC G1 mains - Paper 3- Section 3- Unit 3

Rainfall

 

The rainfall in Andhra Pradesh is influenced by both South-West and North-East monsoons.  Of the normal annual rainfall of 940 mm,  624 mm (66%) is contributed by South-West Monsoon (June-September) followed by 224 mm (24%) during the North-East Monsoon (October-December) and 10% during the Winter and Summer months.

Region wise Rainfall (in mm) During South West Monsoon -2010

Sl. No.	Region	01.06.2010 – 30.09.2010			Status
		Normal	Actual	Dev (%)
1	Coastal Andhra	620	868	(+)40	Excess
2	Rayalaseema	407	529	(+)30	Excess
3	Telangana	715	892	(+)25	Excess
State		624	808	(+)29	Excess

 

 The normal annual rainfall of the State is 940 m.m. Major portion (66%) of rainfall is contributed by South-West Monsoon (June-Sept) followed by (24%) North-East Monsoon (Oct-Dec). The rest 10% of the rainfall is received during the winter and summer months.

The Normal rainfall distribution in the three regions of the State differs with the season and Monsoon. The influence of South-West Monsoon is predominant in Telangana region (716m.m) followed by Coastal Andhra (620 m.m) and Rayalaseema (407 m.m), whereas the North-East Monsoon provides high amount of rainfall in Coastal Andhra area (324 m.m) followed by Rayalaseema (238 m.m) and Telangana (129 m.m). There are no significant differences in Normal distribution of rainfall during winter and hot weather periods among three regions

 

 

 

S.No YEAR South-West Monsoon North-East Monsoon including Winter and Hot Weather period Total Rainfall (in mm)     Normal Actual % dev Normal Actual % dev Normal Actual % dev 1 1966-67 600 643 7 290 305 5 891 947 6 2 1976-77 602 673 -12 293 352 20 895 1025 15 3 1986-87 602 597 -1 294 271 -8 896 868 -3 4 1996-97 634 737 16 291 373 28 925 1109 20 5 2005-06 624 690 11 316 457 45 940 1147 22 6 2006-07 624 627 0.5 316 231 -27 940 858 -9 7 2007-08 624 747 +20 316 333 +5 940 1080 +15 8 2008-09(*) 624 666 +7 274 149 -45 898 815 -9 (*) (from 1.6.08 to 1.4.09)

 

According to data provided by the Indian Metrological Department (IMD) to the State, traditionally drought-prone part of Rayalaseema has recorded 52 per cent excess rain (236.6 mm as against normal of 155.5 mm) and Coastal Andhra region received 48 per cent excess rain (375.2 mm as against the normal rainfall of 253.9 mm). The Telangana region, including the twin cities of Hyderabad and Secunderabad, has received about 10 per cent excess rain (361.9 mm as against 327.8 mm).

Studies made by Hydrological Project Circle, Hyderabad, Guntur Division have found that quantum of summer monsoon rainfall in the district has been steadily increasing in the last decade which could lead to severe imbalances in the rainfall distribution resulting in extremities like flash floods or severe drought conditions.

There will be no change in the average quantum of rainfall in the country. But, significant changes in rainfall recorded region-wise are likely. For instance, if June received good rains, July might see a dull monsoon and if August sees a good monsoon, September might go dry.

The farmers should be educated on these aspects in advance so that they could change their sowing pattern accordingly.

The most significant changes could be intensity and rise in frequency of tropical cyclones, rise in frequency of low pressure depressions intensifying and turning into cyclones and a rise in maximum temperature across the country. The data revealed that summer temperatures in the country over the past 100 years had showed an increase between 0.6 degree and one degree Celsius.

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