India’s Aug Krishna Basin floods: Dams harming not helping

August 8, 2019 SANDRP
Krishna River Basin is in for worst floods than the previous big flood of August 2005. Already at eight sites, the water level has crossed the previous HFL – Highest Flood Level recorded by CWC (Central Water Commission), at four sites each in Maharashtra and Karnataka, almost all on different tributaries.Unprecedented nature This has happened just over the last three days. It and this is pretty unusual as you do not see HFL crossing at so many places simultaneously. Moreover, normally when HFL is crossed, the new level is at the most a few centimeters higher than the previous HFL. In current floods, the new HFL is upto unbelievable 5 mts above the previous HFL at more than one place. Additionally, normally the water level crosses HFL for a few hours at the most. In current floods, the water level has so far remained above the previous HFL for over two days in some instances. EVERYONE of these parameters show how unprecedented the floods are. Higher the duration, amplitude and sites, implies higher the damage potential of the floods.
High Rainfall There has been above normal rainfall in Upper Krishan Basin in Maharashtra, which mainly includes districts of Kolhapur, Sangli and Satara. In these three districts, the rainfall, as per IMD’s figures, till 0830 am on Aug 8, 2019, have been 2068.5 mm (70% above normal), 480.7 mm (60% above normal) and 1028.1 mm (78% above normal). These districts have received rainfall much above rainfall during Aug 1-8, with rainfall of 716.6, 177.6 and 363.6 mm respective, the rainfall being about 400% above normal in this first week of August. But this is not such an unprecedented high rainfall that cannot be managed without allowing it to create a disaster that these districts are now facing. Moreover, the high rainfall was distributed over eight days and was preceded by warning of high rainfall.
Role of dams Disasters, India’s, Aug, Krishna Basin, floods:, Dams, harming, not helping, Sandrp, The dam operators are likely to turn around and say that but the dams were full and we had no option but to release water. The question is WHY WERE THE DAMS FULL when monsoon is just about halfway through and IMD has predicted much higher rainfall in the remaining part of the monsoon compared to the first half?
If we look at the graph below, we see that three of the big dams in this region, namely Koyna, Radhanagari and Warna were almost 100% full by Aug 5, when the current flood wave started. The flood disaster has exactly coincided with the dams getting full, that is from Aug 5, 2019. But why were the dams full by Aug 5, 2019? Why did the dams not start releasing water from say July 25, 2019, when Koyna and Warna dams were only around 50% full. The Radhanagri dam should have started releasing water even earlier as that dam was already close to 80% full by July 25. If these dams had started releasing water from July 25, 2019, they would have had sufficient space during the first week of Aug 2019, when the districts received heavy rainfall and that would have helped reduce the floods rather than increased it as the dams ended up doing.
Koyna dam, by far the largest of the Upper Krishna basin dams in Maharashtra, in fact, has FRL (Full Reservoir Level) of 657.9 m and live storage at FRL of 2652 MCM (Million Cubic Meters) as per CWC’s weekly reservoir level bulletin. However, as per Maharashtra Water Resources Department website, Koyna FRL is 659.43 m, and was already filled upto 658.65 m, with live storage of 2742 MCM, higher than its live storage capacity.
The story of other dams in the Krishna basin in Maharashtra is similar with Ujani (89.8%), Khadakwasla (95.73%), Dhom (88.43%), Dudhganga (89.28%) full as on Aug 6. In downstream Karnataka too story is similar with Ghataparabha (95%), Malprabha (92%), Almatti (70%). Almatti, fortunately has reduced the storage level from 85% on Aug 1 (why it filled up to 85% on Aug 1 is another question) to 70% by Aug 7.
This indicates that if Krishna basin were to get another week of high rainfall, the flood situation in the basin would get much worse than was the case either in Aug 2005 or in Oct 2009 (Andhra Pradesh). And the large dams, that are supposed to help moderate the floods, would again be major contributor to the flood disaster. As has happened in numerous occasions in the past too.
The role of dams in the current Krishna basin floods is also apparent from the statements of Karnataka and Maharashtra Chief Ministers. The Karnataka CM wrote to Maharashtra counterpart to convey that because of sudden release of large quantities of water from Koyna dam contributed to floods in North Karnataka. Maharashtra CM, in turn, called up Karnataka CM to request to reduce the water level of Almatti dam to reduce the backwater impact in upstream Maharashtra.
No Lessons from the past? In fact, Maharashtra had set up a committee after the Aug 2005 floods, but the report of that committee remains a state secret till date! That reflects a lot on amazing transparency in our water governance.
It may be recalled, that just weeks earlier, large parts of Maharashtra faced drought that many described as worst than the drought of 1972. Why is it that so soon after that the state is facing the worst floods of the century? We may choose to sweep this under the climate change carpet, and there is no doubt there is role of climate change in worsening our rainfall pattern.
But we may also understand and acknowledge that capacity of our catchment areas to hold, to absorb, store the rainwater and recharge the groundwater in a decentralised manner is reducing, thanks to our indiscriminate and mindless development pursuits. We need to really work to improve the capacity of the catchment to hold, store and absorb the rainwater and recharge the groundwater. This includes increasing the capacity of our soils to hold and store moisture and having sufficient local water harvesting systems, wetlands, forests and other groundwater recharging mechanisms. That would help reduce the flood peaks and also drought frequency and intensity.
However, immediately, we need to ensure that the water stored in the dams is judiciously released to make way for possibly high rainfall incidents in coming weeks. The rule curves of all the dams need to be put out in pubic domain and accountability fixed when the rule curves are violated.
Himanshu Thakkar and Parineeta Dandekar, SANDRP (ht.sandrp@gmail.com)
Aug 2019 Krishna Basin Floods in Maharashtra – Karnataka: How dams harming rather than helping