Discrepancies in rainfall figures for Andhra Pradesh’s drought hit districts

On October 28, 2015, the government of Andhra Pradesh declared drought[1] in 196 mandals in seven of the thirteen districts of the state. Having seen the serious discrepancies (between IMD and state government) in the rainfall figures of districts in Maharashtra[2] and Madhya Pradesh[3] where the respective state governments declared drought earlier, we decided to check the same for these seven districts of AP too. The IMD figures[4] for the monsoon (June 1 to Sept 30) rainfall for these seven districts are given in terms of Normal Rainfall, Actual Rainfall and how much actual rainfall departure was there from Normal Rainfall. During 2015 monsoon, IMD figures  say that Coastal Andhra Pradesh (nine districts, three of which are declared drought affected now) received 642 mm rainfall, compared to normal rainfall of 581.1 mm, so a surplus of 10%. Rayalseema (comprising of four districts, all drought hit now) received 358.3 mm rainfall, 10% below the normal figure of 398.3 mm. In the previous year, both regions had 23% deficient rainfall, with actual rainfall of 448.7 mm in Coastal AP and 308.6 mm in Rayalseema.

The seven districts have total of 384 mandals, so a little over half the Mandals of these districts have been declared drought hit. 224 Mandals in these seven districts are declared to have deficient rainfall (deficit over 20%) and 14 have scanty rainfall (deficit over 60%). So out of these 238 mandals, most have been declared drought hit, possibly excluding the irrigated mandals. According to AP government, each of the 670 mandals in the state has a manual raingauge, in addition, the state has 1188 Automatic weather stations (AWS). The website gives district wise break up of these stations and also a map that provides location of these stations. No such information is available from IMD.

When we looked for the Andhra Pradesh government figures for the district wise rainfall, we were pleasantly surprised. Andhra Pradesh website, interestingly called CM Dash Board[5], not only provides district wise monsoon season (from June 1) rainfall for the whole monsoon season for each district, it also provides normal rainfall in these districts till that date. More interestingly, if you click on the district, you can get Mandal-wise rainfall figures, along with the normal rainfall, % departure, predominant crop and whether the irrigation status if the Mandal is in Command or not. This is indeed most remarkable and welcome. The website in fact provides much other useful information, though we could not locate the notification declaring drought in 196 mandals of seven districts. Andhra Pradesh received, as per state government figures, 519.7 mm rainfall in 2015 monsoon, which is 5.4% below normal state monsoon of 549.1 mm.

In the table below we have provided Actual, normal and % departure of rainfall figures for the seven districts that the state government has declared drought hit. The figures from IMD and AP government website are given separately.

DISTRICT-WISE RAINFALL: Comparison between IMD & Andhra Pradesh Govt. figures

(mm)

  IMD Andhra Pradesh Govt.
SN Districts Actual Normal % Dep Actual Normal % Dep
 

Coastal Andhra Pradesh

1 Nellore 349.8 352.4 -1 306.7 331.4 -7.4
2 Prakasam 384.9 382.5 1 342 388.3 -12
3 Srikakulam 750.8 745.7 1 638.9 705.7 -9.5
 

Rayaleseema

4 Anantapur 535.2 554.7 -4 319.6 338.4 -5.6
5 Chittoor 469.1 920.1 -49 338.7 439.4 -22.9
6 Cuddapah 385.2 653.7 -41 346.4 393.5 -12
7 Kurnool 832.5 796.6 5 321.3 455.1 -29.4

The figures in above table show a number of discrepancies in these rainfall figures:

  • If we go by IMD figures, only two districts of these seven districts have deficit above 20% and hence can be declared drought hit, these are Chittoor and Cuddapah. If we go by AP government figures, while Cuddapah, with 12% deficit, does not have the requisite 20% deficit, but Kurnool has the highest deficit among these seven districts at close to 30%. Strangely, by IMD figures, Kurnool had 5% surplus rainfall!
  • Comparison of actual rainfall figures for these seven districts show that in all seven districts, the rainfall as per state government is lower than the rainfall as per IMD figures. So here again we see a higher rainfall bias in IMD figures or lower rainfall bias in state figures.
  • More worryingly, there is no agreement between IMD and state government even what is normal rainfall in these districts. In case of six of these districts (except Prakasham, where IMD figue is slightly lower), the normal district rainfall as per IMD is higher than the state figures.
  • Shockingly, IMD figures for the normal rainfall in the four Rayalseema districts are MUCH higher than the state government figures. In case of Chittoor district, IMD figure of normal rainfall is more than DOUBLE the normal rainfall given by state government. In fact IMD says the normal monsoon figure for Rayalseema as a whole is 398.3 mm. in which case the district wise figures given for Normal monsoon rainfall are clearly wrong. IMD needs to explain a lot, it seems in case of Andhra Pradesh.
Andhra Pradesh Automatic Weather Stations Map

Andhra Pradesh Automatic Weather Stations Map

It is clear that there is a need to streamline and improve our monsoon rainfall reporting. This is especially important at a time when policies, drought assistance, insurance payment to farmers and water allocation decisions are heavily dependent on rainfall figures. If we cannot get our rainfall figures right, it raises a lot of questions about our capacity to monitor and understand the most important weather event of the year, on which lives of over 50% of the population directly depend! There is a vast difference not only in observed rainfall, but also supposed normal rainfall figures, as is clear in case of Andhra Pradesh figures  given here.

We hope IMD and Andhra Pradesh government will explain these discrepancies. We also hope friends in Media and civil society will raise necessary questions to make these agencies answerable.

Himanshu Thakkar (ht.sandrp@gmail.com), Bhim Singh Rawat

END NOTES:

[1] http://www.livemint.com/Politics/FPPW24ywpjbQmXHi9h8gvI/Andhra-Pradesh-declares-drought-in-196-mandals-across-seven.html

[2] https://sandrp.wordpress.com/2015/10/02/state-says-59-9-rainfall-imd-says-73-highlights-and-discrepancies-of-maharashtras-monsoon-2015/

[3] https://sandrp.wordpress.com/2015/10/28/imd-mp-govt-provide-shockingly-different-district-rainfall-figures-will-they-explain-please/

[4] http://www.imd.gov.in/section/hydro/dynamic/rfmaps/districtwise.htm

[5] http://www.core.ap.gov.in/CMDashBoard/UserInterface/Rainfall/RainfallMonthlyReport.aspx

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