Lok Sabha Question No. 2857 (UNSTARRED), answered on 2021-03-12
Subject: Technology for Forecasting of Floods
Ministry: EARTH SCIENCES
Asked by: Vijay Baghel, Arun Sao

## GOVERNMENT OF INDIA LOK SABHA

## MINISTRY OF EARTH SCIENCES UNSTARRED QUESTION NO. 2857

## TO BE ANSWERED ON FRIDAY, MARCH 12, 2021

## TECHNOLOGY FOR FORECASTING OF FLOODS

## 2857.   SHRI VIJAY BAGHEL: SHRI ARUN SAO:

## Will the Minister of EARTH SCIENCES be pleased to state:

- (a)     the details of technology being used by Indian Meteorological Department regarding prevention and forecasting of floods in the country;
- (b)      the comparative study of technology being used in the country at par with international standards;
- (c)    whether the Government proposes to prevent and check the devastation caused by floods on large scale with the help of present forecasting technology;
- (d)       if so, the details thereof; and
- (e)       the details of proposals received by the Government in this regard during the last three years?

## ANSWER MINISTER FOR MINISTRY OF SCIENCE AND TECHNOLOGY AND MINISTRY OF EARTH SCIENCES (DR. HARSH VARDHAN)

- (a) Forecasting  and  prevention  of  floods  are  the  responsibilities  of  the  Central  Water Commission  (CWC),  Ministry  of  Water  Resources.  However,  India  Meteorological Department (IMD) supports flood warning services of Central Water Commission (CWC) by providing observed and predicted rainfall. In order to meet specific requirements of flood  warnings  by  CWC,  India  Meteorological  Department  (IMD)  operates  Flood Meteorological  Offices  (FMOs)  at  13  locations  viz.,  Agra,  Ahmedabad,  Asansol, Bhubaneshwar, Guwahati, Hyderabad, Jalpaiguri, Lucknow, New Delhi, Patna, Srinagar, Bengaluru and Chennai. Apart from this, IMD also supports Damodar Valley Corporation (DVC) by providing Quantitative Precipitation Forecast (QPF) for Damodar river basin areas for their flood forecasting activities. Flood Meteorological Offices (FMO) provide meteorological support to the CWC for issuing flood warnings well in advance in respect of 153 river basins.

CWC  issues  flood  forecasts  as  a  non-structural  measure  of  flood  management,  to concerned  State  Governments  depending  on  the  requisition  from  them  at  identified locations. CWC also issues inflow forecasts to identified reservoirs for proper reservoir regulation. Flood forecast formulation methodology used by CWC includes:

Conventional statistical correlation methodology: It includes gauge to gauge correlation between base station (upstream of forecasting station) and forecasting station. This method provides advance warning time from 6 to 24 hrs depending upon the terrain.  IMD provides 3 day Quantitative Precipitation Forecast (QPF) in ranges of 0, 0.1-10mm, 11-25 mm, 2637mm, 38-50 mm, 51-75 mm, 76-100 mm and >100 mm for various  river sub-basins to the concerned Divisional Flood Control Room of CWC  through their Flood Meteorological Offices spread all over the country.

Rainfall-Runoff mathematical modeling technology: It includes mathematical modeling of river basin based on rainfall runoff methodology. Input taken is rainfall provided by IMD through its Automatic Weather Station (AWS) & Automatic Rain Gauge  (ARG) stations and CWC telemetry stations.  The three days advance forecast is generated using various available rainfall data products as a major input into the system like IMD Gridded Rainfall  product  and  other  global  rainfall  products  such  as  GSMaP  (Global  Satellite Mapping  of  Precipitation),  GPM  (Global  Precipitation  Measurement)  and  the  IMD forecasted  rainfall  data  (WRF-  Weather  Research  and  Forecast,  GFS-  Global  Forecast System). Numerical Weather Prediction (NWP) model products viz. Weather Research and Forecast  (WRF) model which is given for 3 days and Global Forecasting System (GFS) model product which is given for 10 days are seamlessly shared by IMD for use in mathematical models by CWC. Mathematical model has been used for formulation of advisories and these advisories are shared with stake holders using dedicated website.

Besides this, CWC is also providing inundation forecast in the same platform using 2dimensional models for main Brahmaputra and is also shared with beneficiaries through the same website.

Modernization of dissemination of flood forecasts: Dissemination of flood forecasts have been modernised by having a dedicated website. The flood information is also shared via various social media platforms of CWC Flood Forecast dissemination system. Daily Flood Situation Report cum Advisories are also shared with all stake holders as well as general  public.  CWC  has  signed  an  MOU  with  M/s  Google  Inc  for  using  their  vast repository of high resolution Digital Elevation Models and the power of dissemination to send alerts regarding inundation through Google Platform using the flood forecasts issued by CWC.

- (b) Flood  Forecasting  by  CWC  uses  all  the  latest  technology  including  remote-sensing, Geographical  Information  System  (GIS),  Internet,  Artificial  Intelligence  and  Machine Learning in development/ running/ formulation and calibration of Mathematical models and for providing Inundation Alerts which are closely at par with international standards.
- (c)-(d) Yes Sir. At the end of flood season CWC prepares an Appraisal of flood forecasting activity in which the accuracy/performance of the forecasts are compiled.  In conventional

methodology of forecast, a level forecast is deemed to be accurate if the forecasted level is  within  +/-  0.15  m  from  the  actual  river  water  level  attained  at  the  forecasted  time. Similarly, for inflow forecast, if the forecasted inflow is within +/- 20% from the actual inflow into the reservoir.  Statement showing the accuracy of the system for the period 2000-2020 is given in Annexure-I.

- (e)   Ministry of Earth Sciences has not received any proposals in this regard.

*****

## FLOOD FORECASTING PERFORMANCE FROM 2000 TO 2020 (as provided by Central Water Commission)

| Year    | No.of Level Forecasts issued   | No.of Level Forecasts issued             | No.of Level Forecasts issued   | No.of Inflow Forecasts issued   | No.of Inflow Forecasts issued                 | No.of Inflow Forecasts issued   | Total No.of Forecasts issued   | Total No.of Forecasts issued                             | Total No.of Forecasts issued   |
|---------|--------------------------------|------------------------------------------|--------------------------------|---------------------------------|-----------------------------------------------|---------------------------------|--------------------------------|----------------------------------------------------------|--------------------------------|
| Year    | Total                          | Within +/-15 cm of deviation from actual | Accuracy (%)                   | Total                           | Within +/- 20% cumec of deviation from actual | Accuracy (%)                    | Total                          | Within +/-15 cm or +/-20% cumec of deviation from actual | Accuracy (%)                   |
| 2000    | 5622                           | 5504                                     | 97.90                          | 821                             | 747                                           | 90.99                           | 6443                           | 6251                                                     | 97.02                          |
| 2001    | 4606                           | 4533                                     | 98.42                          | 857                             | 809                                           | 94.40                           | 5463                           | 5342                                                     | 97.79                          |
| 2002    | 3618                           | 3549                                     | 98.09                          | 623                             | 602                                           | 96.63                           | 4241                           | 4151                                                     | 97.88                          |
| 2003    | 5989                           | 5789                                     | 96.66                          | 611                             | 586                                           | 95.91                           | 6600                           | 6375                                                     | 96.59                          |
| 2004    | 4184                           | 4042                                     | 96.61                          | 705                             | 654                                           | 92.77                           | 4889                           | 4696                                                     | 96.05                          |
| 2005    | 4323                           | 4162                                     | 96.28                          | 1295                            | 1261                                          | 97.37                           | 5618                           | 5423                                                     | 96.53                          |
| 2006    | 5070                           | 4827                                     | 95.21                          | 1593                            | 1550                                          | 97.30                           | 6663                           | 6377                                                     | 95.71                          |
| 2007    | 6516                           | 6339                                     | 97.28                          | 1707                            | 1651                                          | 96.72                           | 8223                           | 7990                                                     | 97.17                          |
| 2008    | 5670                           | 5551                                     | 97.90                          | 1021                            | 1003                                          | 98.24                           | 6691                           | 6554                                                     | 97.95                          |
| 2009    | 3343                           | 3298                                     | 98.65                          | 667                             | 629                                           | 94.30                           | 4010                           | 3927                                                     | 97.93                          |
| 2010    | 6491                           | 6390                                     | 98.44                          | 1028                            | 988                                           | 96.11                           | 7519                           | 7378                                                     | 98.12                          |
| 2011    | 4848                           | 4795                                     | 98.91                          | 1143                            | 1109                                          | 97.03                           | 5991                           | 5904                                                     | 98.55                          |
| 2012    | 4200                           | 4136                                     | 98.47                          | 831                             | 803                                           | 96.63                           | 5031                           | 4939                                                     | 98.17                          |
| 2013    | 5741                           | 5471                                     | 95.30                          | 1319                            | 1289                                          | 97.73                           | 7060                           | 6760                                                     | 95.75                          |
| 2014    | 3884                           | 3804                                     | 97.94                          | 888                             | 863                                           | 97.18                           | 4772                           | 4667                                                     | 97.80                          |
| 2015    | 3500                           | 3429                                     | 97.97                          | 572                             | 562                                           | 98.25                           | 4072                           | 3991                                                     | 98.01                          |
| 2016    | 4969                           | 4891                                     | 98.43                          | 1270                            | 1057                                          | 83.23                           | 6239                           | 5948                                                     | 95.34                          |
| 2017    | 5085                           | 4975                                     | 97.84                          | 1212                            | 926                                           | 76.40                           | 6297                           | 5901                                                     | 93.71                          |
| 2018    | 4969                           | 4871                                     | 98.03                          | 1882                            | 1624                                          | 86.29                           | 6851                           | 6495                                                     | 94.80                          |
| 2019    | 6004                           | 5773                                     | 96.15                          | 3750                            | 2678                                          | 71.41                           | 9754                           | 8451                                                     | 86.64                          |
| 2020    | 8243                           | 8133                                     | 98.67                          | 3478                            | 3065                                          | 88.13                           | 11721                          | 11198                                                    | 95.54                          |
| Average | 5089                           | 4965                                     | 97.56                          | 1299                            | 1165                                          | 89.68                           | 6388                           | 6129                                                     | 95.95                          |

## Annexure I