Lok Sabha Question No. 3270 (UNSTARRED), answered on 2023-08-09
Subject: Forecasting of Landslides
Ministry: EARTH SCIENCES
Asked by: Abhishek Banerjee

## GOVERNMENT OF INDIA

## MINISTRY OF EARTH SCIENCES LOKSABHA

## UNSTARRED QUESTION NO. 3270

## TO BE ANSWERED ON WEDNESDAY, 9 TH  AUGUST, 2023

## FORECASTING OF LANDSLIDES

## 3270.   SHRI ABHISHEK BANERJEE:

Will the Minister of EARTH SCIENCES be pleased to state:

- (a) the number of landslides that has occurred in the past five years, year-wise;
- (b) the major reasons for the same;
- (c) the monitoring system in place for the same; and
- (d) the number of these landslides that were forecasted?

## ANSWER

## THE MINISTER OF EARTH SCIENCES (SHRI KIREN RIJIJU)

- (a) The  Geological  Survey  of  India  (GSI)  under  the  administrative  control  of  Ministry  of Mines collects data and keep records of major landslides that occurred in different States/ UT, which have impacted lives and/ or infrastructure. The onsite field investigations are mainly  carried  out  in  response  to  the  requests  received  from  the  concerned  State Governments.  The  study  involves  various  geoparametric  attributes  of  each  landslide, including studying its impacts, future vulnerability etc. All the above data are also used for  updating  GSI's  existing  national  landslide  inventory.  The  details  of  Post  disaster landslide studies carried out by GSI in last 5 years is given in Annexure-I.

GSI  has  also  carried  out  the  National  Landslide  Susceptibility  Mapping  (NLSM) Programme since 2014-15 and prepared 1: 50,000 scale landslide susceptibility mapping of the total area of 4.3 lakh sq. km. in different landslide prone States/ UTs (AnnexureII).  During  NLSM,  GSI  also  collected  historical  information  on  major  landslides polygons using both remote sensing (RS) and field-based source data, out of which,many landslides  have  already  been  field  validated  by  GSI.  This  huge  historical  national landslide inventory is continuously being updated with the new landslide data collected year-wise as part of Post-disaster studies.

- (b) From the post disaster investigations of the landslides, it is revealed that major trigger of landslides is due to unprecedented high rainfall. The other important geo-factors such as terrain character, slope  forming  material, geomorphology,  land-use  /land-cover  in different terrain etc. are the preparatory factors for initiation of landslides.  The anthropogenic causes such as unprotected slope cuts, blocking of drainages etc. has also been reported in many of the slides.
- (c) No site-specific landslide monitoring project has been taken up by GSI.
- (d) GSI as part of the LANDSLIP project (www.landslip.org) has developed an experimental regional  Landslide  Early  Warning  System  (LEWS)  based  on  rainfall  thresholds  pilot study  areas  viz.  Darjeeling  district  of  West  Bengal  and  the  Nilgiris  district  of  Tamil Nadu. Since 2020 monsoon, GSI started issuing daily landslide forecast bulletins during monsoon  to  the  district  administrations  in  these  two  pilot  areas.  Now  GSI  is  in  the process of extending the similar endeavour in multiple landslide-prone states in India. In this  connection,  GSI  has  already  extended  the  Landslide  Early  Warning  System  in Kalimpong  district,  West  Bengal  and  Rudraprayag  district,  Uttarakhand  and  started issuing daily landslide forecast bulletins during monsoon to the district administrations. (Kalimpong - from  July 2021;  Rudraprayag from August  2022). The feedback on 883 landslide information have been received during the last two monsoon seasons from these districts for evaluation of the forecast model.

GSI  has  also  initiated  R  &  D  activities  for  developing  regional  landslide  Forecasting systems (LEWS).

Annexure-I Year-wise details of  post disaster major landslide studies carried out by GSI

| Year    |   Post disaster landslide studies completed | State                                                                                                                                                                                                   |
|---------|---------------------------------------------|---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| 2017-18 |                                          70 | Arunanchal Pradesh, Assam, Meghalaya, Mizoram, Tripura, Manipur, Nagaland, Sikkim, Himachal Pradesh, Uttarakhand, Maharashtra                                                                           |
| 2018-19 |                                        2210 | Arunanchal Pradesh, Assam, Meghalaya, Mizoram, Tripura, Manipur, Nagaland, Sikkim, Himachal Pradesh, Jammu & Kashmir (UT),Ladakh (UT), Uttarakhand , Karnataka, Tamil Nadu, Kerala, Maharashtra         |
| 2019-20 |                                         386 | Arunanchal Pradesh, Assam, Meghalaya, Mizoram, Nagaland, Sikkim, Himachal Pradesh, Jammu & Kashmir (UT), Ladakh (UT), Uttarakhand , Karnataka, Tamil Nadu, Kerala, Maharashtra, West Bengal             |
| 2020-21 |                                         845 | Arunanchal Pradesh, Assam, Meghalaya, Manipur, Nagaland, Sikkim, Himachal Pradesh, Jammu & Kashmir (UT), Ladakh (UT), Uttarakhand , Karnataka, Tamil Nadu, Kerala, Maharashtra, West Bengal             |
| 2021-22 |                                         156 | Arunanchal Pradesh, Assam, Meghalaya, Mizoram, Manipur, Nagaland, Sikkim, Himachal Pradesh, Jammu & Kashmir (UT),Ladakh (UT), Uttarakhand , Karnataka, Kerala, Andhra Pradesh, Maharashtra, West Bengal |
| Total   |                                        3667 |                                                                                                                                                                                                         |

Annexure-II Status National Landslide Susceptibility Mapping (NLSM) Programme

| State/ UT           |   Target area completed so far (km 2 ) |   Landslide polygons mapped (Nos.) |   Landslides field validated (Nos.) |
|---------------------|----------------------------------------|------------------------------------|-------------------------------------|
| Assam               |                                  24144 |                                527 |                                 598 |
| Meghalaya           |                                  22601 |                               1525 |                                 791 |
| Mizoram             |                                  21864 |                               4221 |                                2003 |
| Tripura             |                                   1367 |                                 57 |                                  56 |
| Manipur             |                                  23250 |                               2405 |                                1548 |
| Nagaland            |                                  17294 |                               2742 |                                1554 |
| Sikkim              |                                   4979 |                               3379 |                                 651 |
| Himachal Pradesh    |                                  42108 |                              17127 |                                6420 |
| Jammu &Kashmir (UT) |                                  28890 |                               7465 |                                2174 |
| Ladakh (UT)         |                                  40065 |                                838 |                                 166 |
| Uttarakhand         |                                  39009 |                              14782 |                                4927 |
| Karnataka           |                                  31323 |                               1248 |                                1278 |
| Goa                 |                                   3546 |                                 76 |                                  76 |
| Tamil Nadu          |                                  10549 |                                782 |                                 863 |
| Kerala              |                                  19301 |                               1396 |                                3016 |
| Andhra Pradesh      |                                   1124 |                                 29 |                                  29 |
| Maharashtra         |                                  29191 |                               1134 |                                1152 |
| West Bengal         |                                   2980 |                               1554 |                                1529 |
| Arunanchal Pradesh  |                                  71228 |                              25172 |                                 907 |
| Total               |                                 434813 |                              86459 |                               29738 |

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