Dams

Rivers that crossed Highest Flood Level in Monsoon 2021

(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.

SNSiteRiverDistrict StateWLDL  Old HFLDateNew HFLDate/ TimeRise
1GangotriBhagirathi-I  Uttarakashi Uttarakhand  3054.1 m29.07.20193054.58 m27.07.2021  0.48 m
2PipalkotiAlaknandaChamoli Uttarakhand  1051.78 m19.08.20191051.86 m27.07.2021 05:00 hrs0.08 m
3KalsiAmlav YamunaDehradun Uttarakhand  511.2 m18.08.2019512.4 m11.07.2021 06:00 hrs1.2 m
3AKalsiAmlav YamunaDehradun Uttarakhand  511.2 m18.08.2019511.47 m12.07.2021 12:00 hrs0.27 m
4AuraiyaYamunaAuraiya Uttar Pradesh112113118.19 m25.08.1996118.51 m06.08.2021 16:00 hrs0.32 m
5BarodiyaNAKota Rajasthan  322.46 m15.08.2019322.75 m07.08.2021 06:00 hrs0.29 m
6KhatoliParwatiKota Rajasthan201202207.55 m23.08.1996209.05 m04.08.2021 02:00 hrs  1.5 m
7SeondhaSindDatia Madhya Pradesh134.42 m135.42 m141.73 m24.07.1991143.7 m04.08.2021 15:00 hrs1.97 m
8BansiRaptiSiddharth Nagar, UP83.9 m84.9 m85.88 m20.08.201785.95 m03.09.2021 08:00 hrs0.07 m
9SakraBurhi GandakMuzaffarpur Bihar49.58 m50.58 m50.87 m15.08.201751.02  m12.07.21 01:00 hrs0.15 m
      50.87 m15.08.201751.40  m28.07.20200.53 m
10LalganjGandakVaishali Bihar49.5 m50.5 m51.75 m25.07.202051.83 m02.09.20210.08 m
11HathidahGangaPatna Bihar40.76 m41.76 m43.17  m21.08.201643.52 m16.08.2021 11:00 hrs0.35 m
12BhagalpurGangaBhagalpur Bihar32.68 m33.68 m34.72 m26.08.201634.86 m18.08.2021 07:00 hrs0.14 m

More details on HFL breach in Ganga basin

SNSites
1The HFL at Gangotri site at Bhagirathi-I is breached after 2 years. CWC has upgraded new HFL.
2The HFL at Pipalkoti level monitoring site on Alaknanda river is breached after 2 years. CWC has upgraded new HFL.
3The 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.
4Flood 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.
5River 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.
6The 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.
7The 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.
8The 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.
9In 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.
10Flood 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.
11Flood 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.
12Flood 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.

SNSiteRiverDistrict StateWLDL  Old HFLDateNew HFLDate/ TimeRise
1Mathani Road BridgeJalkaBaleshwar Odisha5.5 m5.5 m7.05 m27.08.2020 04:00 hrs7.31 m22.09.2021 10:00 hrs0.26m

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.

SNSiteRiverDistrict StateWLDL  Old HFLDateNew HFLDate/ TimeRise
1LasurShivnaAurangabad Maharashtra  511.6 m11.08.1998512.6 m08.09.2021 08:00 hrs1.0  m
1A       513.5 m28.09.21 18:00 hrs1.9  m
2KapsiWardhaWardha Maharashra  204.91 m30.08.2020205.71 m08.09.2021 13:00 hrs0.8  m
2A       205.96 m09.09.2021 23 hrs1.05 m
3DhanoraWardhaChandrapur Maharashtra  171.44 m30.07.2020174.09 m23.07.2021 14:00 hrs2.65 m
3A       174.53 m08.09.2021 14 hrs3.09 m
4TharnamPengangaAdilabad Telangana  215.28 m15.08.2020215.59 m23.07.2021 06:00 hrs0.31 m
5SomanpallyManerKarim Nagar Telangana  127.344 m24.07.1989127.65 m08.09.2021 02:00 hrs0.306 m

More details on HFL breach in Godavari basin

SN Site
1The 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.
2The 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.
3The 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.
4Old 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.
5At 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.

SNSiteRiverDistrict StateWLDL  Old HFLDateNew HFLDate/ TimeRise
1KholwadTapiSurat Gujarat  11.5 mNA11.92 m29.09.2021 11:00 hrs0.42  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. 

SNSiteRiverDistrict StateWLDL  Old HFLDateNew HFLDate/ TimeRise
1Belne BridgeGadSindudurg Maharashtra  19.3 m06.08.201920.0123.07.2021 09:00 hrs0.71 m
2NiivaliBavRatnagiri Maharashtra9.4 m11 m12.465 m05.08.201915.155 m23.07.2021 05:00 hrs2.69 m
3MahadSavitriRaigad Maharashtra10 m11 m11.93 m25.07.200513.46 m23.07.2021 03:00 hrs2.03 m
4MuradpurVashistiRatnagiri Maharashtra  8.22 m04.08.20199.63 m23.07.21 05:00 hrs1.41 m
5CollemKhadeparSouth Goa Goa  72.89 m21.07.198273.5 m23.07.2021 06:00 hrs0.61 m
6GanjemMadaiNorth Goa Goa  12.52 m29.07.198214.5 m  23.07.21 06:00 hrs1.98 m

More details on HFL breach in West flowing rivers basin from Tapi to Tadri

SNSite
1At 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.
2At 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.
3At 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.
4Old 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.
5At 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.
6The 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.

SNSiteRiverDistrict StateWLDL  Old HFLDateNew HFLDate/ TimeRise
1ThiruvarambuKodaiyar  Kanyakumari Tamil Nadu11 m12 m14.58 m15.08.201814.68 m26.05.2021 14:00 hrs0.10 m
2SanteguliAghanashiniUttara Kannada Karnataka14 m17 m19.66 m18.08.200820.2 m  23.07.21 11:00 hrs0.54 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.

SNBasinStatesLevel MonitoringLevel ForecastingTotal
1GangaUttarakhand030003
  Uttar Pradesh000202
  Rajasthan010102
  Madhya Pradesh000101
  Bihar000404
   040812
2SubernarekhaOdisha000101
      
 GodavariMaharashtra030003
  Telangana020002
   050005
3TapiGujarat010001
      
4West Flowing Tapi to TadriMaharashtra020204
  Goa020002
   040206
5West Flowing Tadri to KanyakumariTamil Nadu000101
  Karnataka000101
    0202
 Subtotal 141327

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. 

MonthRiver basinsNo.
 GangaSubernarekhaGodavariTapiWest Flowing Tapi to TadriWest Flowing Tadri to Kanyakumari 
May     0101
June       
July04 01 060112
August05     05
Sept.03010401  09
Total12010501060227

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.

SNSiteRiver/ BasinDistrict StateWLDLOld HFL/ DateThis season level/ DateMissed HFL breach by
1KalpiYamuna GangaJalaun UP107 m108 m112.96 m 25.08.1996112.84 m 09.08.20210.12 m
2GanghighatGangaPatna Bihar47.6 m48.6 m50.52 m 21.08.201650.45 m 15.08.20210.07 m
3BenibadBagmati GangaMuzaffarpur Bihar47.68 m48.68 m50.01 m 12.07.200449.99 m 31.08.20210.02 m
3 A      49.84 m 17.08.20210.17 m
4RajamahalGangaSahebganj Jharkhan26.25 m27.25 m26.94 m 03.10.201926.86 m 19.08.20210.08 m
5NandreYerala KrishnaSangli Maharashtra540.17 m542.21 m548.445 m 08.08.2019547.91 m 21.07.20210.435 m
6ArjunwadKrishnaSangli Maharashtra539.2 m540.7 m544.345 m 09.08.2019543.955 m 26.07.20210.39 m
7TerwadPanchganga KrishnaKolhapur Maharashtra534 m536 m541.64 m 10.08.2019540.93 m 26.07.20210.71 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/

[ii] https://ffs.tamcnhp.com/

[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

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