Lok Sabha Question No. 1179 (UNSTARRED), answered on 2022-02-09
Subject: Incidents of Heavy Rains
Ministry: EARTH SCIENCES
Asked by: Shashi Tharoor

## GOVERNMENT OF INDIA MINISTRY OF EARTH SCIENCES LOKSABHA

## UNSTARRED QUESTION NO. 1179 TO BE ANSWERED ON 9 TH FEBRUARY, 2022

## INCIDENCE OF HEAVY RAINS

## 1179. DR. SHASHI THAROOR:

Will the Minister of EARTH SCIENCES be pleased to state:

- (a) whether the Ministry has noted an increase in heavy downpour of rains in Kerala in the past five years and if so, the details thereof;
- (b) whether the Ministry has conducted any study on the incidence of heavy rains in Kerala over the next ten years;
- (c) if so, the details thereof, if not, the reasons therefor;
- (d) whether the Ministry has conducted a study on the water holding capacity of soil in the different regions of Kerala, if so, the details thereof;
- (e) whether the Ministry has implemented procedures for improving the water holding capacity of soil in Kerala to reduce the incidence of landslides; and
- (t) if so, the extend of success achieved in this regard?

## ANSWER

## THE MINISTER OF STATE (INDEPENDENT CHARGE) FOR MINISTRY OF SCIENCE AND TECHNOLOGY AND EARTH SCIENCES (DR. JITENDRA SINGH)

- (a) Yes sir. India Meteorological Department (IMD) has noted an increase in heavy downpour of rains in Kerala in the past five years. During this period, the highest number of heavy rainfall incidences was observed in the year 2018. The details of heavy (64.5 mm - 115.5 mm I day), very heavy (115.6 to 204.4 mm I day) and extremely heavy rainfall ( more than 204.4 mm I day) incidents observed over Kerala since 2015 are given in Annexure I.

The Annual Maximum Probable frequency of Heavy, Very Heavy and Extremely Heavy Rainfall events over various districts of Kerala for the decade 2001 to 2010 and for the decade 2011 to 2020 are given in Figure l(a) and Figure 1(b) respectively. From these figures, it is clear that there is an increase in heavy rainfall events in recent decades over Kerala.

IMD's report on "Climate Hazard & Vulnerability Atlas of India" prepared for the thirteen most hazardous meteorological events in the country, which cause extensive damages including economic, human, and animal losses is available at https:llimdpune.gov.inlhazardatlas/abouthazard.html.

,

- (b)-(c) As per the recently published MoES report "An Assessment of Climate Change over the Indian Region", global as well as regional models project an increase in seasonal mean rainfall over India. Frequency of extreme precipitation events may increase all over India, and more prominently so over the central and southern parts, in near future, as a response to enhanced warming.
- (d) Ministry of Earth Sciences (MoES) did not conduct a study on the water holding capacity of soils of Kerala. However, Government of Kerala had published various information on Kerala soils and is available at http://www.keralasoils.gov.in/index.php/20 16-04-27-09-26-39/soils-of-kerala#red-soils
- (e) MoES did not recommend procedures for improving the water holding capacity of soil in Kerala. The Kerala landslides mainly fall under the type "debris flow", which occurs due to intense rainfall causing loose soil, boulders and rock pieces to slide along steep slopes. Therefore, the safe and quick passage of surface water through drainage channels without any blockage is preferred rather than increasing the water holding capacity of soil strata of the slopes. The enhanced water retention in slopes increases the weight of overburden, which promotes occurrence of landslides.
- (t) Does not arise.

## "Cf)l

~1d!ACt)-1 dI faCt)I 1. ri2015 ~ 3{if (fCf)" ~ 11~ ~, iI§"ff ~ (tlfl ~ ~ qqf <1ft vc;rr3il Fc\qt(OII

| \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   | \lrihm~~ (64.5 f~r4ht 115.5 ~ WIClIQ")   |
|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|------------------------------------------|
| CI1f                                     | ~                                        | ~                                        | lffif                                    | ~                                        | lit                                      | 'GFI                                     | ~                                        | ~                                        | ~(lRH                                    | "IctCGI,(                                | ~                                        | ~~RH                                     | cnf\tcf;                                 |
| 2015                                     |                                          |                                          | 5                                        | 29                                       | 23                                       | 116                                      | 61                                       | 9                                        | 35                                       | 44                                       | 30                                       | 8                                        | 360                                      |
| 2016                                     |                                          | 5                                        | 2                                        |                                          | 34                                       | 108                                      | 44                                       | 4                                        |                                          | 22                                       | 6                                        |                                          | 225                                      |
| 2017                                     |                                          |                                          | 6                                        | 1                                        | 27                                       | 114                                      | 21                                       | 48                                       | 98                                       | 16                                       | 20                                       | 9                                        | 360                                      |
| 2018                                     |                                          |                                          | 3                                        | 5                                        | 35                                       | 147                                      | 198                                      | 144                                      | 8                                        | 53                                       | 13                                       | 1                                        | 607                                      |
| 2019                                     |                                          |                                          |                                          | 3                                        | 3                                        | 40                                       | 123                                      | 184                                      | 57                                       | 101                                      | 14                                       | 3                                        | 528                                      |
| 2020                                     | 2                                        |                                          | 1                                        | 9                                        | 27                                       | 71                                       | 75                                       | 132                                      | 124                                      | 32                                       | 10                                       | 1                                        | 484                                      |
| 2021                                     | 11                                       | 1                                        | 2                                        | 8                                        | 130                                      | 52                                       | 107                                      | 50                                       | 35                                       | 112                                      | 62                                       | 4                                        | 574                                      |

| ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   | ~ rcr ~ ( 115.6 ~ 204.4~ ~ftt~~ )   |
|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|-------------------------------------|
| ri                                  | ~                                   | ~                                   | lffif                               | •                                   | 1lf                                 | 'GFI                                | ~                                   | ~                                   | ~(lRH                               | ~- ""~ .. ~                         | ~~RI~ ~                             | ~                                   | ~                                   |                                     |
| 2015                                |                                     |                                     | 7                                   | 3                                   | 19                                  | 6                                   |                                     | 2                                   | 2                                   | 4                                   |                                     |                                     |                                     |                                     |
| 2016                                |                                     |                                     |                                     | 7                                   | 16                                  |                                     |                                     |                                     |                                     |                                     |                                     |                                     | 43 23                               |                                     |
| 2017                                |                                     | 1                                   |                                     | 2                                   | 8                                   | 2                                   | 3                                   | 14                                  | 4                                   | 2                                   | 2                                   | 38                                  | 38                                  |                                     |
| 2018                                |                                     | 1                                   |                                     | 7                                   | 35                                  | 34                                  | 74                                  | 1                                   | 7                                   | 4                                   |                                     | 163                                 | 163                                 |                                     |
| 2019                                | 1                                   |                                     |                                     |                                     | 6                                   | 22                                  | 71                                  | 2                                   | 15                                  |                                     |                                     | 117                                 | 117                                 |                                     |
| 2020                                |                                     |                                     | 3                                   | 3                                   | 16                                  | 20                                  | 40                                  | 26                                  | 1                                   |                                     | 1                                   | 110                                 | 110                                 |                                     |
| 2021                                | 2                                   |                                     | 1                                   | 51                                  | 5                                   | 9                                   | 4                                   | 4                                   | 24                                  | 14                                  | 1                                   | 115                                 | 115                                 |                                     |

!

| ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   | ~~crqf~~( >204.4 ~~ftt~~)   |
|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|-----------------------------|
| ri                          | ~                           | ~                           | lffif                       | lit                         | \'iff                       | ~ ~                         | ~(lRI~                      | ~                           | ~ ~~RI~                     | ~                           |                             |                             |                             |
| 2015                        |                             |                             |                             |                             | 1                           |                             |                             |                             |                             | 1                           |                             |                             |                             |
| 2016                        |                             |                             |                             |                             | 1                           |                             |                             |                             |                             | 1                           |                             |                             |                             |
| 2017                        |                             |                             |                             |                             |                             |                             | 1                           |                             | 1                           | 2                           |                             |                             |                             |
| 2018                        |                             |                             |                             | 3                           | 3                           | 25                          |                             |                             | 1                           | 32                          |                             |                             |                             |
| 2019                        |                             |                             |                             |                             | 4                           | 29                          |                             |                             |                             | 33                          |                             |                             |                             |
| 2020                        |                             |                             |                             | 1                           | 1                           | 5                           | 1                           |                             |                             | 8                           |                             |                             |                             |
| 2021                        | 1                           |                             |                             | 5                           |                             |                             | 5                           |                             |                             | 11                          |                             |                             |                             |

...

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I

Fig.I. Annual Maximum Probable frequency of Heavy, Very Heavy and Extremely I Heavy Rainfall events (Rainfall >= 64.5 mm/day) over various district of Kerala for the (a) decade 2001 to 2010 and (b) for the decade 2011 to 2020.

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