(Feature image River Betwa in flood spate on Aug. 4, 2021. Source: Sharad Chandra, Director, CWC)
While India has received 874.6 mm rainfall which falls in normal[i] category in just concluded south west monsoon season, there have been at least 27 incidents of rivers crossing the Highest Flood Levels (HFLs) ever recorded in the past and attaining new HFLs in 5 river basins (some composite basins) in India, as recorded by the Central Water Commission (CWC) Flood Forecasting site[ii] during the monsoon.
The maximum 12 such instances have taken place in Ganga basin followed by 6 in west flowing rivers Tapi to Tadri basin, 5 in Godavari, 2 in West Flowing rivers Tadri to Kanyakumari basin and 1 each in Subernarekha and Tapi basin.
For past three years, SANDRP has been tracking the HFL breach incidents during monsoon season. The analysis of such HFL breaches in 2018[iii], 2019[iv] and 2020[v] can be seen on our website.
Ganga Basin
Out of 12 HFL breach incidents in Ganga basin 4 occurred in Bihar where Gandak at Sakra in Muzaffarpur, Burhi Gandak at Lalganj in Vaishali and Ganga river at Hathidah site in Patna and Bhagalpur have breached previous HFLs. All of these are level forecast (LF) sites. Sakra had crossed HFL in 2020 also but CWC has not upgraded the level.
In Uttarakhand, the Bhagirathi-I at Gangotri in Uttarakashi district and Pipalkoti site on Alaknanda in Chamoli district has topped previous HFL. Next is Amlav river at Kalsi in Dehradun district. Amlav is tributary of Yamuna river. All 3 are level monitoring (LM) sites and had attained the earlier HFLs in 2019.
Yamuna has also crossed HFL at Auraiya site in Uttar Pradesh. Rapti is another river in UP which breached previous HFL at Bansi site in Siddarath Nagar district. In Rajasthan an unnamed river at Barodiya and Parwati river at Khatoli have crossed previous HFLs. Both of the sites are in Kota district. Sind is only river in Madhya Pradesh that crossed previous HFL at Seondha site.
Of the total 12 HFL breach incidents, 4 took place in the month of July, 5 in August and 3 in September. These consist of 8 LF sites and 4 LM sites. For the LM sites, Warning Level (WL) and Danger Level (DL) are not given by CWC. So far CWC has updated the new HFL record for 4 sites.
| SN | Site | River | District State | WL | DL | Old HFL | Date | New HFL | Date/ Time | Rise |
| 1 | Gangotri | Bhagirathi-I | Uttarakashi Uttarakhand | 3054.1 m | 29.07.2019 | 3054.58 m | 27.07.2021 | 0.48 m | ||
| 2 | Pipalkoti | Alaknanda | Chamoli Uttarakhand | 1051.78 m | 19.08.2019 | 1051.86 m | 27.07.2021 05:00 hrs | 0.08 m | ||
| 3 | Kalsi | Amlav Yamuna | Dehradun Uttarakhand | 511.2 m | 18.08.2019 | 512.4 m | 11.07.2021 06:00 hrs | 1.2 m | ||
| 3A | Kalsi | Amlav Yamuna | Dehradun Uttarakhand | 511.2 m | 18.08.2019 | 511.47 m | 12.07.2021 12:00 hrs | 0.27 m | ||
| 4 | Auraiya | Yamuna | Auraiya Uttar Pradesh | 112 | 113 | 118.19 m | 25.08.1996 | 118.51 m | 06.08.2021 16:00 hrs | 0.32 m |
| 5 | Barodiya | NA | Kota Rajasthan | 322.46 m | 15.08.2019 | 322.75 m | 07.08.2021 06:00 hrs | 0.29 m | ||
| 6 | Khatoli | Parwati | Kota Rajasthan | 201 | 202 | 207.55 m | 23.08.1996 | 209.05 m | 04.08.2021 02:00 hrs | 1.5 m |
| 7 | Seondha | Sind | Datia Madhya Pradesh | 134.42 m | 135.42 m | 141.73 m | 24.07.1991 | 143.7 m | 04.08.2021 15:00 hrs | 1.97 m |
| 8 | Bansi | Rapti | Siddharth Nagar, UP | 83.9 m | 84.9 m | 85.88 m | 20.08.2017 | 85.95 m | 03.09.2021 08:00 hrs | 0.07 m |
| 9 | Sakra | Burhi Gandak | Muzaffarpur Bihar | 49.58 m | 50.58 m | 50.87 m | 15.08.2017 | 51.02 m | 12.07.21 01:00 hrs | 0.15 m |
| 50.87 m | 15.08.2017 | 51.40 m | 28.07.2020 | 0.53 m | ||||||
| 10 | Lalganj | Gandak | Vaishali Bihar | 49.5 m | 50.5 m | 51.75 m | 25.07.2020 | 51.83 m | 02.09.2021 | 0.08 m |
| 11 | Hathidah | Ganga | Patna Bihar | 40.76 m | 41.76 m | 43.17 m | 21.08.2016 | 43.52 m | 16.08.2021 11:00 hrs | 0.35 m |
| 12 | Bhagalpur | Ganga | Bhagalpur Bihar | 32.68 m | 33.68 m | 34.72 m | 26.08.2016 | 34.86 m | 18.08.2021 07:00 hrs | 0.14 m |
More details on HFL breach in Ganga basin
| SN | Sites |
| 1 | The HFL at Gangotri site at Bhagirathi-I is breached after 2 years. CWC has upgraded new HFL. |
| 2 | The HFL at Pipalkoti level monitoring site on Alaknanda river is breached after 2 years. CWC has upgraded new HFL. |
| 3 | The Amlav river breached old HFL at Kalsi level monitoring site due to sudden flood spell briefly staying over old HFL for 3 hrs. The river again breached the old HFL reaching 511.47 m at 12:00 hrs on July 12, 2021. HFL is breached after 2 years. CWC has upgraded the HFL. |
| 4 | Flood level flew over old HFL for 22 hrs at Auraiya level forecast site on Yamuna from 04:00 hrs on August 06 to 02:00 hrs on August 07, 2021. HFL is breached after 25 years. CWC has upgraded the new HFL. |
| 5 | River name is not mentioned for Barodiya level forecast site which is part of Chambal sub-basin. Flood level remained above old HFL for 12 hrs from 21:00 hrs on August 6 to 09:00 hrs on August 07. The HFL is breached after 2 years. |
| 6 | The flood level remained above old HFL for 17 hrs from 19:00 hrs on August 3 to 12:00 hrs on August 04, 2021. HFL is breached after 25 years. |
| 7 | The flood level remained above old HFL for 26 hrs at Seondha level forecast site on Sind river from 08:00 hrs on August 4 to 7:00 hrs on August 05, 2021. HFL is breached after 30 years. |
| 8 | The flood level remained above old HFL for 55 hrs at Bansi level forecast site on Rapti river from 07:00 hrs on Sept. 2 to 14:00 hrs on Sept. 4, 2021. HFL is breached after 4 years. |
| 9 | In 2020, Sakra level forecast site on Burhi Gandak was upgraded into level forecasting site from level monitoring. The Old HFL was breached at 01:00 hrs on July 10, 2021. The flood level remained over old HFL probably till July 14, 2021. The HFL is breached after 4 years. Despite flowing in extreme flood situation, CWC did not mention it in its Daily Flood Summary reports of July 12 and 13. HFL was breached at this site on 28 July 2020 also then attaining new HFL of 51.40 however the CWC has not updated the HFL attained even last year. |
| 10 | Flood level remained above old HFL for 22 hrs at Lalganj level forecast site on Gandak river from 10:00 hrs on Sept. 2 to 08:00 hrs on Sept. 3, 2021. HFL is breached after one year. |
| 11 | Flood water remained above old HFL for 142 hrs at Hathidah level forecast site on Ganga river from 03:00 hrs on August 13 to 01:00 August 19, 2021. HFL is breached after 5 years. |
| 12 | Flood level remained above old HFL 86 hrs at Bhagalpur level forecast site on Ganga from 04:00 hrs on August 16 to 18:00 hrs on August 19. HFL is breached after 5 years. Daily Flood Summary report of August 16, 17, 18, 2021. |
Subernarekha Basin
The Mathani road bridge LF site on Jalka river in Baleshwar district of Odisha has also crossed HFL last year on August 27, 2020 but CWC has not updated the HFL record for the site so far.
| SN | Site | River | District State | WL | DL | Old HFL | Date | New HFL | Date/ Time | Rise |
| 1 | Mathani Road Bridge | Jalka | Baleshwar Odisha | 5.5 m | 5.5 m | 7.05 m | 27.08.2020 04:00 hrs | 7.31 m | 22.09.2021 10:00 hrs | 0.26m |
The flood level remained over old HFL for 10 hrs at Mathani RB level forecast site on Jalka river from 07:00 hrs to 17:00 hrs on Sept. 22, 2021. The HFL is breached after one year. Last year HFL 6.8 m (date not known) was breached by 0.25 m at 04:00 hrs on Augt. 27, 2020 when flood level stayed over HFL for 48 hrs.
Godavari Basin
In Godavari basin HFL has been breached at 5 locations. All of these are LM sites. Of which 3 are in Maharashtra namely Shivna at Lasur in Aurangabad, Wardha at Kapsi and Wardha at Dhanora in Chandrapur district and 2 are in Telangana including Penganga at Tharnam in Adilabad and Maner at Somanpally site in Karim Nagar. The HFL record has not been updated by CWC for 3 locations.
Interestingly in Maharashtra, all 3 sites witnessed HFL breaching incident twice in this monsoon season. Shivna river at Lasur site breached the HFL twice in September month on September 8 and 28. Similarly, Wardha river crossed HFL twice at Dhanora site first on July 23 then on September 8. The Wardha river also breached previous HFL at Kapsi, first on September 8 and then next day on September 9.
| SN | Site | River | District State | WL | DL | Old HFL | Date | New HFL | Date/ Time | Rise |
| 1 | Lasur | Shivna | Aurangabad Maharashtra | 511.6 m | 11.08.1998 | 512.6 m | 08.09.2021 08:00 hrs | 1.0 m | ||
| 1A | 513.5 m | 28.09.21 18:00 hrs | 1.9 m | |||||||
| 2 | Kapsi | Wardha | Wardha Maharashra | 204.91 m | 30.08.2020 | 205.71 m | 08.09.2021 13:00 hrs | 0.8 m | ||
| 2A | 205.96 m | 09.09.2021 23 hrs | 1.05 m | |||||||
| 3 | Dhanora | Wardha | Chandrapur Maharashtra | 171.44 m | 30.07.2020 | 174.09 m | 23.07.2021 14:00 hrs | 2.65 m | ||
| 3A | 174.53 m | 08.09.2021 14 hrs | 3.09 m | |||||||
| 4 | Tharnam | Penganga | Adilabad Telangana | 215.28 m | 15.08.2020 | 215.59 m | 23.07.2021 06:00 hrs | 0.31 m | ||
| 5 | Somanpally | Maner | Karim Nagar Telangana | 127.344 m | 24.07.1989 | 127.65 m | 08.09.2021 02:00 hrs | 0.306 m |
More details on HFL breach in Godavari basin
| SN | Site |
| 1 | The Lasur level monitoring site on Shivna river breached HFL twice first on Sept. 8, 2021 when flood level remained above old HFL for 7 hrs from 06:00 hrs to 13:00 hrs. Then on Sept. 28, 2021 when the water level stayed over old HFL for 10:00 hrs from 16:00 hrs on Sept. 28 to 2:00 hrs on Sept. 29, 2021. The HFL is breached after 23 years. CWC has upgraded new HFL. |
| 2 | The old HFL has been breached twice at Kapsi slevel monitoring site on Wardha river. First on Sept. 8 flood level flew over old HFL for 6 hrs from 11:00 hrs to 17:00 hrs. Then on Sept. 9, the flood level stayed over old HFL for 12 hrs from 17:00 hrs Sept. 9 to 05:00 hrs on Sept. 10, 2021. HFL is breached after one year. Strangely, CWC hydrograph now shows HFL to be 212.31 m attained on 12.07.1994 after the passage of HFL events. |
| 3 | The HFL was breached at 00:00 hrs on July 23, 2021 at Dhanora level monitoring site on Wardha river. The flood level remained above old HFL for 35 hrs till 13:00 hrs on July 24. HFL was breached again at this site on Sept. 8-9, 2021 and the water level flew over old HFL for 21 hrs from 04:00 on Sept 8 to 01:00 hrs on Sept. 9. Strangely, CWC hydrograph now shows HFL to be 186.52 m attained on 14.08.1998, after the passage of above flood events. |
| 4 | Old HFL is breached at 05:00 hrs on July 23 at Tharnam level monitoring site on Penganga river and flood level remained above old HFL for 6 hrs till 11:00 hrs on July 23. HFL is breached after 1 year. CWC has not upgraded new HFL as on Oct. 2, 2021. Strangely, CWC hydrograph now shows HFL to be 223.6 m attained on 12.09.1998. |
| 5 | At Somanpally level monitoring site on Maner river, the flood level remained over old HFL for 7 hrs from 21:00 hrs on Sept. 7 to 04:00 hrs on Sept. 8, 2021. HFL is breached after 32 years. CWC has upgraded new HFL. |
Tapi Basin
The date of previous HFL breach for Kholwad LM site on Tapi river in Surat district is not mentioned by CWC.
| SN | Site | River | District State | WL | DL | Old HFL | Date | New HFL | Date/ Time | Rise |
| 1 | Kholwad | Tapi | Surat Gujarat | 11.5 m | NA | 11.92 m | 29.09.2021 11:00 hrs | 0.42 m |
The flood level remained over old HFL at Kholdwad on Tapi river for 21 hrs from 08:00 hrs on Sept. 29 to 05:00 hrs on Sept. 30, 2021.
West flowing rivers basin from Tapi to Tadri
In a single day on July 23, 2021, HFL breaching was witnessed at 6 sites including 2 LF sites and 4 LM sites in West flowing rivers Tapi to Tadri basin of which 4 sites are in Maharashtra and 2 in Goa.
| SN | Site | River | District State | WL | DL | Old HFL | Date | New HFL | Date/ Time | Rise |
| 1 | Belne Bridge | Gad | Sindudurg Maharashtra | 19.3 m | 06.08.2019 | 20.01 | 23.07.2021 09:00 hrs | 0.71 m | ||
| 2 | Niivali | Bav | Ratnagiri Maharashtra | 9.4 m | 11 m | 12.465 m | 05.08.2019 | 15.155 m | 23.07.2021 05:00 hrs | 2.69 m |
| 3 | Mahad | Savitri | Raigad Maharashtra | 10 m | 11 m | 11.93 m | 25.07.2005 | 13.46 m | 23.07.2021 03:00 hrs | 2.03 m |
| 4 | Muradpur | Vashisti | Ratnagiri Maharashtra | 8.22 m | 04.08.2019 | 9.63 m | 23.07.21 05:00 hrs | 1.41 m | ||
| 5 | Collem | Khadepar | South Goa Goa | 72.89 m | 21.07.1982 | 73.5 m | 23.07.2021 06:00 hrs | 0.61 m | ||
| 6 | Ganjem | Madai | North Goa Goa | 12.52 m | 29.07.1982 | 14.5 m | 23.07.21 06:00 hrs | 1.98 m |
More details on HFL breach in West flowing rivers basin from Tapi to Tadri
| SN | Site |
| 1 | At Belne bridge level monitoring site on Gad river, the old HFL is breached twice first on July 22 then on July 23 at 06:00 hrs. Level remained above old HFL for about 5 hrs till 11:00 hrs on July 23. HFL is breached after 2 years. |
| 2 | At Niivali level forecast site on Bav river, the old HFL is breached at 07:00 hrs on July 22. Level remained above old HFL for about 28 hrs till 11:00 hrs on July 23. HFL is breached after 2 years. |
| 3 | At Mahad level forecast site on Savitri river the old HFL is breached at 18:00 hrs on July 22. Level remained above old HFL for about 14 hrs till 08:00 on July 23. HFL is breached after 16 years. |
| 4 | Old HFL is breached at 09:00 hrs on July 22 at Muradpur level monitoring site on Vashisti river. Level remained above old HFL for about 25 hrs till 10:00 hrs on July 23. HFL is breached after 2 years. CWC has not upgraded new HFL as on Oct. 3, 2021. |
| 5 | At Collem level monitoring site Khadepar river breached old HFL at 02:00 hrs on July 23 and remained over old HFL for 5 hrs till 07:00 hrs on July 23. HFL is breached after 39 years. |
| 6 | The water level was above old HFL for 6 hrs at Ganjem level monitoring site on Madai river from between 04:00 hrs – 10:00 hrs on July 23. HFL is breached after 39 years. |
West flowing rivers from Tadri to Kanyakumari
The Kodaiyar river breached the HFL at Thiruvarambhu LF site in Tamil Nadu on May 26 which is pre monsoon month.
| SN | Site | River | District State | WL | DL | Old HFL | Date | New HFL | Date/ Time | Rise |
| 1 | Thiruvarambu | Kodaiyar | Kanyakumari Tamil Nadu | 11 m | 12 m | 14.58 m | 15.08.2018 | 14.68 m | 26.05.2021 14:00 hrs | 0.10 m |
| 2 | Santeguli | Aghanashini | Uttara Kannada Karnataka | 14 m | 17 m | 19.66 m | 18.08.2008 | 20.2 m | 23.07.21 11:00 hrs | 0.54 m |
At Thiruvarambu level forecast site on Kanyakumari, the water level remained above old HFL for 2 hrs from 13:00 rs to 15:00 hrs on May 26. HFL is breached after 3 years. CWC has upgraded new HFL.
The Aghanashini river breached old HFL at Santeguli level forecast site at 10:00 hrs on July 23 and remained above old HFL for 05 hrs till 15:00 hrs. HFL is breached after 13 years. CWC has upgraded new HFL.
River Basin Wise Summary
The HFL breach incidents have taken place at 27 sites consisting of 14 level monitoring and 13 level forecast sites mainly in 5 river basin during 4 month long south west monsoon season 2021. Maximum HFL breach incidents 12 have taken place in Ganga basin following by 6 in West Flowing Tapi to Tadri basin and 5 in Godavari basin.
| SN | Basin | States | Level Monitoring | Level Forecasting | Total |
| 1 | Ganga | Uttarakhand | 03 | 00 | 03 |
| Uttar Pradesh | 00 | 02 | 02 | ||
| Rajasthan | 01 | 01 | 02 | ||
| Madhya Pradesh | 00 | 01 | 01 | ||
| Bihar | 00 | 04 | 04 | ||
| 04 | 08 | 12 | |||
| 2 | Subernarekha | Odisha | 00 | 01 | 01 |
| Godavari | Maharashtra | 03 | 00 | 03 | |
| Telangana | 02 | 00 | 02 | ||
| 05 | 00 | 05 | |||
| 3 | Tapi | Gujarat | 01 | 00 | 01 |
| 4 | West Flowing Tapi to Tadri | Maharashtra | 02 | 02 | 04 |
| Goa | 02 | 00 | 02 | ||
| 04 | 02 | 06 | |||
| 5 | West Flowing Tadri to Kanyakumari | Tamil Nadu | 00 | 01 | 01 |
| Karnataka | 00 | 01 | 01 | ||
| 02 | 02 | ||||
| Subtotal | 14 | 13 | 27 |
Month and State wise summary
The maximum 12 HFL breach incidents happened in July followed by 9 in Sept and 5 in August.
Out of 12 states where these 27 HFL breach incidents occurred, 14 sites are located in 3 states of Maharashtra (7), Bihar (4), Uttarakhand (3). UP, Rajasthan, Telangana and Goa states have seen two HFL breach incidents, while MP, Odisha, Gujarat, Tamil Nadu and Karnataka have seen HFL breaching at 1 site each.
| Month | River basins | No. | |||||
| Ganga | Subernarekha | Godavari | Tapi | West Flowing Tapi to Tadri | West Flowing Tadri to Kanyakumari | ||
| May | 01 | 01 | |||||
| June | |||||||
| July | 04 | 01 | 06 | 01 | 12 | ||
| August | 05 | 05 | |||||
| Sept. | 03 | 01 | 04 | 01 | 09 | ||
| Total | 12 | 01 | 05 | 01 | 06 | 02 | 27 |
In addition to HFL breach, there have been atleast 7 level forecast sites where flood level almost touched the old HFL or reached close to HFL. Details and hydrographs of these sites are given below.
| SN | Site | River/ Basin | District State | WL | DL | Old HFL/ Date | This season level/ Date | Missed HFL breach by |
| 1 | Kalpi | Yamuna Ganga | Jalaun UP | 107 m | 108 m | 112.96 m 25.08.1996 | 112.84 m 09.08.2021 | 0.12 m |
| 2 | Ganghighat | Ganga | Patna Bihar | 47.6 m | 48.6 m | 50.52 m 21.08.2016 | 50.45 m 15.08.2021 | 0.07 m |
| 3 | Benibad | Bagmati Ganga | Muzaffarpur Bihar | 47.68 m | 48.68 m | 50.01 m 12.07.2004 | 49.99 m 31.08.2021 | 0.02 m |
| 3 A | 49.84 m 17.08.2021 | 0.17 m | ||||||
| 4 | Rajamahal | Ganga | Sahebganj Jharkhan | 26.25 m | 27.25 m | 26.94 m 03.10.2019 | 26.86 m 19.08.2021 | 0.08 m |
| 5 | Nandre | Yerala Krishna | Sangli Maharashtra | 540.17 m | 542.21 m | 548.445 m 08.08.2019 | 547.91 m 21.07.2021 | 0.435 m |
| 6 | Arjunwad | Krishna | Sangli Maharashtra | 539.2 m | 540.7 m | 544.345 m 09.08.2019 | 543.955 m 26.07.2021 | 0.39 m |
| 7 | Terwad | Panchganga Krishna | Kolhapur Maharashtra | 534 m | 536 m | 541.64 m 10.08.2019 | 540.93 m 26.07.2021 | 0.71 m |
There has been no major improvement in consistency, completeness, transparency and timeliness in CWC flood forecasting while maintaining and making public the HFL breach incidents as has been highlighted in earlier blogs on the issue by SANDRP.
Contrary to previous practice, CWC decided to upgrade HFL breach record even before the flood level recede below the old HFL in case of some of the new sites.
HFL breach is crucial point for better flood monitoring and forecasting. But publishing different HFLs for Kapsi, Dhanora sites on Wardha river and Tharnam on Penganga sites shows CWC’s inconsistency and negligence. There is no archive of its hydrographs.
The agency is only source of information on flood forecasting but has not put the records in public domain for scrutiny and independent assessment. Undoubtedly, CWC’s flood forecasting needs a lot of improvement.
Bhim Singh Rawat (bhim.sandrp@gamil.com)
References:
[i] https://sandrp.in/2021/09/30/sw-monsoon-2021-district-wise-rainfall-in-india/
[iii] https://sandrp.in/2018/11/08/hfl-crossing-flood-events-during-india-sw-monsoon-2018/
[iv] https://sandrp.in/2019/10/29/rivers-that-cross-highest-flood-level-during-sw-monsoon-2019/
[v] https://sandrp.in/2020/10/03/rivers-that-reached-new-highest-flood-level-during-monsoon-2020/
[vi] http://cwc.gov.in/sites/default/files/cfcrcwcdfb-13.07.2021-2_5.pdf
[vii] http://www.cwc.gov.in/sites/default/files/cfcrcwcdfb-16.08.2021-2_5.pdf
[viii] http://www.cwc.gov.in/sites/default/files/cfcrcwcdfb-17.08.2021-2_5.pdf
[ix] http://www.cwc.gov.in/sites/default/files/cfcrcwcdfb-18.08.2021-2-revised_5.pdf
SANDRP 