Maharashtra
Upper Krishna Basin Flood 2019
Vadnere
Committee -2: A report with
“difference”!
Pradeep
Purandare
SANDRP published my article entitled “Maharashtra
Floods 2019: Don’t waste the crisis” on 26th May 2020.In that
article I had explained the reasons behind my resignation from the Flood Study
Committee. Exclusion of my chapter from the committee’s report was one of the
reasons. Now, the said report is available in public domain & surprisingly
enough, it includes my chapter; thanks to SANDRP!
In this note, I would like to draw the
attention of all concerned towards the erroneous data, strange analysis &
weird logic employed by the Vadnere Committee - 2 in its report without discussing
the serious issues in the committee meetings
The Vadnere Committee -2 report concludes
(p 8, Vol. 1): “It can be seen that the contribution of free catchment, in the
discharge observed in river Krishna, at Irwin Bridge at Sangli, was 49%... The
discharge from free catchment, which was substantial and had no control.” This
is used by the committee to suggest that dams did not contribute to flood
disaster. However, it is shown below how factually wrong these figures are and
hence, all their conclusions on such wrong data are clearly baseless
Irwin bridge (Sangli), Rajaram weir
(Kolhapur) & Rajapur weir (Maharashtra state border) are the River Gauging
Stations (RGS) in Krishna basin where discharge measurement is done using Stage
Discharge Curves (SDC).
SDC
is a graph / rating curve which shows the average discharge for a particular stage
(water level) at a particular RGS for a given cross section. Rating curves are
developed based on observed flow & surveys of the gauge site. The curve is
the empirical relationship & can change over time. Extrapolating beyond the
limits of the rating curve can lead to erroneous discharge values.
In
view of above, it would be logical to verify following:
(1) Whether
the SDCs at RGS at Irwin bridge, Ankali Bridge & Rajapur weir have been
revised?
(2) Whether any extrapolation was done?
The
answer is stranger than the fiction! Read the observations (Annex-1) made by
the Flood Study Committee during its field visit to flood affected area on 23
&24 Sept 2019
The
observations are self-explanatory and speak volumes. Forget revising SDC; the
report says (p 34, Vol II): “It is observed that there is no river gauging
station near the Irwin bridge.”
And “officials told that the SDC at
Rajapur Weir is prepared with reference to the SDC available at CWC site at Kurundwad” (p37 & 38,
VolI) The point to be noted is Kurundawad is approximately 10 km u/s of Rajapur
Weir.
Moreover, the report accepts that the
river cross sections inputs for the model have not been updated since 2012 (P
341, Vol. 2): “For input of river cross sections in the model, survey was
carried out in 2012, changes in the cross sections over the years have not been
taken into consideration”
Given the situation, the data generated at
the so called RGS simply does not have any sanctity. The values are not the
outcome of any scientific process to say the least!
Logically speaking, WRD & the report should
have stated that in absence of reliable & accurate data no scientific
conclusions can be drawn. But instead of that WRD & the report has ventured
in carrying out the analysis of erroneous data. And this even contradicts one
of the important findings. Let us see how committee has landed itself in a
soup!
Real
Time Decision Support System (RTDSS) for Krishna basin is dealt with in Section
4.4 of the Report of Flood Study Committee, titled: “Study Report by Water
Resources Department, GoM: Real Time Decision Support System for Krishna Sub
Basin” The details of observed & simulated discharge & water levels at
Irwin Bridge, Ankali Bridge & Kurundwad RGS sites are given in Tables
4.4.3, 4.4.5 & 4.4.7 in the said section. Based on this data it is claimed
that “…….values are well within acceptable limit” [Table 4.4.9, Page 336 of
RTDAS report, Vol 2] & hence, “All is well” about RTDSS. Let us see the
“acceptable values”
From above mentioned tables in the report,
it is seen that the difference between observed and
simulated water levels is quite significant. Its summary is given in Table-1
below
Table
– 1: RTDSS “with difference”!
Difference
(Meters)
|
Irwin
Bridge
|
Ankali
Bridge
|
Kurundwad
(CWC)
|
Average
|
1.1
|
1.8
|
1.8
|
Max
|
3.7
|
4.5
|
4.5
|
Min
|
-1.7
|
-0.1
|
-0.1
|
Note:
Difference is positive when Observed water level is higher than simulated water
level and negative when observed water level is lower than simulated water
level, as given in Table 4.4.3 (Irwin Bridge, see pp 335, Vol. II), Table 4.4.5 (Ankali Bridge, see pp 337, Vol.
II) and Table 4.4.7 (Kurundwad-CWC, see pp 339, Vol. II).
Similarly,
the gist of observed & simulated runoff (in TMC or Thousand Million Cubic
Feet) at above-mentioned G D Sites is presented here in Table – 2. These figures for total runoff for
the 20 day period of highest rainfall event from July 25 to Aug 13, 2019 as per
the Vadnere Committee – 2 Report
Table-2:
Runoff contradictions
Runoff (TMC)
|
Irwin
Bridge
|
Ankali
Bridge
|
Kurundwad
(CWC)
|
1.Total
|
|||
(a) Observed
|
188
|
218
|
325.5
|
(b) Simulated
|
170
|
216
|
274.2
|
(C) Difference [(a) - (b)]
|
18
|
2
|
51.3
|
2.Total
from free catchment (Simulated)
|
47
|
69
|
134.2
|
3
Contribution from free catchment
(% wrt 1(a))
|
25
|
31.5
|
41.23
|
4
Contribution from free catchment
as reported in Table - 4.3.17, WRD
Report (4.3)
|
97.39
(49)
|
-
|
-
|
From Table -2, it is clear
that
· There
is significant difference between observed & simulated runoff at Irwin
Bridge (18 TMC) & Kurundwad (51.3 TMC)
·
Simulated free catchment Runoff is 47 TMC
i.e.25% of total observed runoff at Irwin Bridge.
·
However, contribution from free catchment
as reported on page 77 of Vadnere
Committee – 2 Report WRD Report (4.3) is
97.39 TMC i.e, 49%of total observed runoff
It
is claimed, time & again, by WRD officials, and uncritically reproduced by Vadnere
Committee – 2 Report, that contribution of free catchment in the
outflow was far greater than that of dam catchment. Above statistics given by
them, however, contradicts their own argument! Contribution from free catchment
is hardly 25%, their own report says.
Strangely,
for Vadnere Committee – 2 and WRD a difference of average 1 to 2 meters in
water levels and 18 to 51 TMC in runoff is not a `significant difference’! In
order to substantiate it’s claim that “…….values are well within acceptable
limit” the committee has resorted to “Nonsense / Spurious Correlation” which
reminds me the famous proverb “"Lies, damned
lies, and statistics".
As per the weird logic of the Committee the
Observed & Simulated Data with such huge differences are correlated!
I
earnestly request the distinguished members of the committee, especially those
who are from the premium institutes like IIT, IITM, IMD, CWC, MRSAC & MWRRA
to give their studied opinion in this matter.
In
Conclusion: It is clear from this brief note that the
Vadnere committee -2 analysis is full of contradiction, the simulations are
based on assumptions and extrapolations, they do not match with the observed
values. More worryingly, the conclusions of the committee are contradicted by
the details given by the WRD in the report itself. The attempt of the committee
hence to show that the dams could not have played a significant role in flood
moderation has no basis.
Annex-1: Not given here due to some technical problem
Screenshot
from the report of Committee’s field
visit on 23-24 Sept, 2019
(Source:
Vol. 2 of Vadnere Committee – 2 Report)
