A massive wave of flood is flowing down the rivers originating in Central India states from Odisha in East to Gujarat-Rajasthan in the west. At least fourteen river sites have seen breach of Highest Flood Levels (HFL) in last four days, a record by itself: 7 in Mahanadi, 5 in Godavari, 2 in JNarmada and one each in Suvarnarekha and Chambal. In at least four of these cases, the earlier HFL had survived for 26 years and has now been broken.
The flood wave that is traveling down is above above 35500 cumecs (12.54 lakh cusecs) in Narmada (at Indira Sagar Dam), above 25000 cumecs (8.83 lakh cusecs), in case of Mahanadi (at Hirakud Dam) and Godavari (at Gosikhurd Dam) rivers & over 15000 cumecs (5.3 lakh cusecs) in Chambal (at Gandhi Sagar Dam) River.
Several dams have crossed their Full Reservoir Levels (FRL) even as at least a month of monsoon remains, if not more, a sure sign of gross mismanagement and an invitation to disaster. The resultant floods have destroyed a yet to be inaugurated, but just completed bridge on Waingana river (Godavari basin) in Seoni district in Madhya Pradesh on Aug 30, 2020 and flooding of a hospital in Bhopal. Water level is several meters above the danger mark at several places along the rivers.
The downpour The current wave possibly started on Aug 26, when IMD (India Meteorological Department) reported in its daily district wise rainfall bulletin that at least 11 districts had close to or over 100 mm rainfall in the day (ending at 0830 hours, as per IMD daily practice). All of these were from Odisha, ranging from 178.7 mm in Kendrapara to 91.8 mm in Anugul.
The number of such districts were 6 (all Odisha) on Aug 27, 15 (12 Chhattisgarh, 2 MP and one Odisha) on Aug 28, 10 (all MP) on Aug 29 and 12 (11 MP and one Rajasthan) on Aug 30. Some of the districts were double centurions in a day, for example Chhindwara, Sehore (both MP) and Janjgir Champa (CG). Several districts were centurion on multiple days, for instance Anugu, Bauda, Deogarh (all Odisha), Raisen, Hoshangabad, Bhopal, Sehore, Narshimpura (all MP). This downpour has created a huge flood wave in major river basins like Brahmani, Chambal, Godavari, Mahanadi, Narmada and Suvarnarekha.
Dams Mismanagement However, besides heavy rainfall, the mismanagement of water reservoirs behind the large dams is also a major reason for the floods. It was great to see that Central Water Commission (CWC) had issued notice, for example, to respective engineers in charge of dams like Rengali dam in Odisha, Sanjay Sarovar in Madhya Pradesh, Upper Wardha and Pench Dams in Maharashtra for water level exceeding the levels specified in the rule curve or reservoir operation schedules for the respective dams. This necessitated that the dams had to release massive quantities of water even as the downstream rivers were in floods, thus adding to the flood disaster and in several cases creating an avoidable disaster. The dam operators and respective state water resources departments were certainly to be held accountable for this.
CWC flood forecasting However, CWC is also partly responsible for the situation, as their flood forecasting leaves a lot to be desired. As we can see from the examples of CWC hydrographs even for the crucial flood affected sites, many of them are missing even in crucial details of inflow-outflow, the data entries are so obviously wrong and so grossly wrong that one cannot make any sense of a number of hydrographs. The CWC forecasting does not take into account the even the imminent floods in view of upstream situations in several cases. Even when CWC has put on notice operating engineers of several dams, in case of several others, where the dams have clearly violated rule curve, we see no such consistent and persistent action from CWC to make an impact on the dam operators. CWC cannot hide behind % data entry errors, data entry errors in flood forecasting must have consequences and in any case must be corrected promptly. We see that the errors remain for several hours and days on other occasions. Clearly while CWC flood forecasting is improving, there a lot more that needs to be done.
We have given below some examples of seriously problematic CWC hydrographs to illustrate the point. There are many more such examples. In some cases, when SANDRP sent the defective hydrographs to the Director of CWC FF, there was corrective action, but there seems no self corrective system in place even for such errors that seem minor but has huge implication in terms of utility of the hydrogaph.
Sardar Sarovar As we can see from the hydrograph below, dated Aug 30, 2020, a data entry mistake at 1900 hours the previous day makes the whole hydrograph problematic as we cannot read any of the inflow or outflow figures on a crucial day when the inflow and outflow were exceeding 25000 cumecs during several hours. The lack of correction till for over 24 hours showed there is no corrective system in place.
Tawa In this hydrograph, while dam level is updated hourly basis, the inflow is given only for two instances inn this graph that covers four days. And NO outflows are given. Just one inflow forecast is given.
Bargi In this hydrograph, we can again see a data entry mistake did not get corrected for over 30 hours. The hydrograph provides no outflow figures and only two instances of inflow figures and one instance of forecast inflow.
Indira Sagar In this hydrograph, again one can see that there are not outflows. Only two instances of inflows and one instance of forecast of inflow. It is also notable how the water level has been going up and up and has now reached FRL level, in complete violation of the rule curve.
Pench This hydrograph firstly shows that water level at this reservoir was even higher than FRL on Aug 29, 2020. Secondly, it shows that till Aug 28, the outflows were zero, this also shows total failure of the forecasting and also violation of rule curve by dam operator. The notice from CWC to the Chief Engineer in Maharashtra on this (and also upper Wardha dam in Maharashtra and Sanjay Sarovar Dam in MP) dated Aug 28 is too late and should have been sent earlier. It is also not clear what will be the consequence of the notice.
Upper Wardha Dam The hydrograph shows that till Aug 28, the outflow from the dam was paltry 26 cumecs and there was no attempt by the dam operator to reduce the water level to bring the dam level in tune with the Rule Curve and also ensure that dam does not create avoidable flood disaster in the downstream area.
Sanjay Sarovar The hydrograph shows that in case of Sanjay Sarovar Dam, till the morning of Aug 28, the outflow was very low and there was no attempt to either take any advance action in view of the forecasts or even to reduce the dam level to bring it in line with the Rule Curve. It was only after the inflows went up that suddenly the outflows were also increased over a hundred fold high.
Gosikhurd Dam In case of this major dam on Wainganga river in Maharashtra that also get all the outflows from upstream dams like Upper Wardha and Sanjay Sarovar, there was no attempt to take any advance action to ensure that dam does not end up contributing to downstream disaster as it ultimately did. Outflows were increased massively only in the morning of Aug 28, when inflows jumped up.
Upper Indravati Reservoir The hydrograph shows data entry error makes it present a totally wrong picture. It is also notable that the outflows are way below the inflows.
Rengali Dam Another example of serious violation of the dam operation led to avoidable flood disaster in Brahmani River in Odisha. We can see in this hydrograph that the outflows were so low, leading to the dam level going above the FRL next day, and then shooting up of the outflows while the downstream river was flooded, leading to a disaster that could have been avoided with advance action by the reservoir operator. It is not clear if this dam operator has been served notice for the violation and if any action will follow. It never does.
Let us see the situation at various sites where HFL has been crossed.
MAHANADI HFL has been crossed at seven locations in Mahanadi basin so far as per our information, including Four locations in Chhattisgarh and Three in Odisha.
CG: Pathardihi At this site on Kharun River in Raipur district of CG, the old HFL of 279.21 m (July 21, 1994) was breached on Aug 28-29. The new HFL was huge 2.47 m above the old HFL, this is a huge jump, the highest among the 14 sites being reported here. The water level remained above the HFL for 22 hours.
Kalma At this site located in Janjgir Champa district of CG, the old HFL of 201.04 m on Mahanadi was submerged at 1200 hrs on Aug 28, new HFL reached is 1.39 m above the old HFL. The water level is still above the old HFL even as we write this at 1900 hours on Aug 30, 55 hours after it was breached.
Surajgarh At this site on Mahanadi River in Raigarh district of CG, the old HFL of 199.9 m (Aug 13, 2003) was breached at 0000 hours on Aug 29. The new HFL is 1.16 m above the old one, and water level continues to remain above old HFL even 43 hours later as we write.
Kurubhata Located on Mand river in Raigarh district of CG, the HFL at 220.35 m (Aug 10, 2004), water level rose 5 cms above the HFL and remained just three hours above the HFL past midnight on Aug 28.
Odisha: Mahulpali Located on Bheden river in Sambalpur district of Odisha, the old HFL of 252.6 m (July 6, 2007) was breached on Aug 27. The new HFL is 58 cm above the old one and water level remained above HFL for four hours.
Padampur Located on Ong river in Rayagada district of Odisha, the HFL of 178.74 m (Aug 16, 2018) was breached by 0.5 m on Aug 27-28. The water level remained above HFL for 8 hours.
Kanas This site on Mahanadi in Puri district was breached by just 1 cm and water level remained above HFL for 4 hours on Aug 29, it is notable that the coastal site had old HFL of 5.47 m which was achieved on Aug 7, 2014.
Deogaon At this site on Mahanadi river in Sambalpur district of Odisha the old HFL of 130.16 m has not been breached as yet, but came within 4 cms of being reached, with water level stationary for 13 hours at 130.12 m, before it lowered from that level.
GODAVARI In still evolving situation in this river basin HFL has already been reached at three locations, two in Madhya Pradesh and one in Maharashtra.
MP: Keolari The HFL of 440.8 m at this site on Wainganga river in Seoni district of Madhya Pradesh was achieved on July 21, 1994. It has taken over 26 years to breach that level, and now it has been breached by a huge 2.23 m on Aug 29. The Wainganga river water level remained above HFL for 17.5 hours.
Balaghat The Highest Flood Level of 297.3 m (July 22, 1994) in Balaghat district of MP here was breached on Aug 30, 2020 by 15 cms and water level remained above HFL for eight hours.
Maharashtra Satrapur/ KR Bridge The HFL of 277.61 m (Sept 6, 1994)) on Kanhan river in Nagpur district of Maharashtra was breached on 29-30 Aug 2020. The new HFL of 278.43 n was achieved, 0.82 m above the old HFL and water level remained above HFL for 11 hours.
NARMADA: MP: Gadarwara Located on Shakkar tributary of Narmada river in Jabalpur district of MP, this site currently holds HFL of 330.26 m, achieved on July 15, 1999. This was breached over 21 years later on Aug 29, 2020, the new HFL is a huge 2.36 m higher and water level remained above the HFL for 14 hours.
Handia Located in Harda district in MP on Narmada river, this location had an HFL of 274.46 m (date not available on CWC FF site). This was breached on Aug 30, 2020, the new HFL is 274.9 m, 44 cm above the previous HFL and water level remained above HFL for 10 hours.
SUVARNAREKHA Odisha: Mathani Road Bridge This site in Baleshwar district in Odisha had HFL of 6.8 m, the new HFL now is 7.05 m, reached on Aug 26-27, 2020, water level remained above HFL for 25.5 hours.
CHAMBAL MP: Astha This site on river Parwati in Chambal basin in Sehore district of MP had HFL of 100.32 m (Sept 2019). This was breached on Aug 29-30, 2020, the new HFL of 100.95 m is 0.63 m higher than previous HFL. Water level remained above HFL for 23 hours. This site, strangely, has breached the HFL for the second time, almost within a week. On Aug 22, the site has already established a new High of 102.4 m[i].
In conclusion, one can see that that the Central Indian belt is seeing very high rainfall intensities repeatedly, spread over large area, creating massive flood risks. Climate scientists would see a footprint of climate change in this. But the key for us is to understand that we need to be prepared for such a situation, and as soon as we see any indication of this, take all possible steps for which actionable information is available, promptly. We need to improve our structural and non structural responses. We need to take all possible steps to PREVENT or REDUCE the extent of flood disasters and then also be ready for rescue and relief. We have a long way to go as far as PREVENTION and REDUCTION part is concerned. Evaluations through independent assessments, apportioning responsibilities and learning lessons from each such event are key ingredients to achieve that.
Himanshu Thakkar (firstname.lastname@example.org)
POST SCRIPT: 1. TOI video showing the submergence due to Gosikhurd dam in Nagpur. https://timesofindia.indiatimes.com/videos/city/mumbai/nagpur-villages-submerged-in-gosikhurd-dam-water-350-people-rescued/videoshow/77850680.cms?from=mdr