Chalakudy · Dam floods · Kerala

Reservoir Operations Fail People in Chalakudy River Basin in Kerala in 2020

Guest Article by S P Ravi

Kerala continues to witness unusual monsoon rainfall patterns for the third straight year in 2020. Kerala had witnessed its worst flood in almost a century in 2018. The 2019 flood was probably second only to the 2018 floods over the last 50 years, with many places experiencing larger floods than that in 2018. While the state did not face huge floods this year, tragedy struck in the form of the Pettimudi landslide near Munnar in Idukki district. It buried alive 70 members of plantation labourer families, making it the worst ever landslide in Kerala in terms of human causality. Kerala has also witnessed its wettest monsoon in September in this millennium with a rainfall of 601 mm, surpassing the previous highest of 526 mm recorded in 2007. The S-W monsoon period is now over and the state received 2227 mm rainfall, which is 9 percent above long term average.

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Monsoon · Rainfall

Monsoon 2020: District Wise Rainfall

India received 957.6 mm rainfall in Just concluded South West Monsoon 2020, during the scheduled 4 month monsoon from June 1 to Sept 30, 2020. This is 8.74% above normal monsoon rainfall of 880.6 as per India Meteorological Department (IMD). This is considered ABOVE NORMAL rainfall, since rainfall is in the range 4-10% above Normal rainfall. This sounds good at national level, but the situation on ground could be very different, if we see the rainfall across the country.

It is noteworthy as per even IMD, monsoon has not yet withdrawn from most parts of the country. But IMD closes its monsoon rainfall account at 0830 hours on Sept 30, so all rainfall after that hour has to be counted in “Post Monsoon” rainfall book, even though the rainfall is very much part of monsoon as per IMD.

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CWC - Central Water Commission · Dam Induced Flood Disaster · Kerala

ROLE OF DAMS IN 2018 KERALA FLOODS: Rejoinder of J Harsha to the response by Sudheer et al

Rejoinder Article by: J.Harsha

An article titled “Role of dams on the floods of August 2018 in Periyar River Basin” was published by Sudheer et al. (2019) in Current Science. A rebuttal was prepared and thanks to South Asia Network of Dams, Rivers and People (SANDRP), the same was published by SANDRP on 25th August 2020 (https://sandrp.in/2020/08/25/role-of-dams-in-kerala-floods-distortion-of-science/) for which Sudheer et al. (2019) has now furnished a response (https://sandrp.in/2020/09/19/response-of-sudheer-et-al-to-the-comments-by-mr-j-harsha-on-the-article-role-of-dams-on-the-floods-of-aug-2018-in-periyar-river-basin-kerala/).

In the rebuttal published by SANDRP, I had questioned the very basis of fitting HEC-HMS model for Periyar River Basin (PRB) by Sudheer et al. (2019), and also challenged the assumptions made by them, the methodology followed and the consequent voluminous inferences such as catchment response at Neeleshwaram (L2), virgin simulations, bank full discharges and particularly inferences that indicted nature for the flood calamity but exonerating the role of dams for the floods of Kerala in 2018. 

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Dam Induced Flood Disaster · Kerala

Response of Sudheer et al to the Comments by Mr. J. Harsha on the article, “Role of dams in the floods of Aug 2018 in Periyar River Basin, Kerala”

Sudheer, K P1,2,*, S. Murty Bhallamudi1,3, Balaji Narasimhan1,3, Jobin Thomas1, Bindhu, V M1, Vamsikrishna Vema1,4, Cicily Kurian1,
1Department of civil Engineering, Indian Institute of Technology Madras, Chennai – 600036,
2Department of Agricultural and Biological Engineering, Purdue University, West Lafayette, IN, USA.
3Indo German Centre for Sustainability, Indian Institute of Technology Madras, Chennai – 600036
*Corresponding Author: sudheer@iitm.ac.in

The authors of Sudheer et al. (2019) – hereinafter referred to as ‘authors’ – appreciate Mr. J. Harsha (hereinafter referred to as ‘commenter’) for his judgmental assessment (in his blog appeared on SANDRP website- “https://sandrp.in” on August 25, 2020, see: https://sandrp.in/2020/08/25/role-of-dams-in-kerala-floods-distortion-of-science/) of the authors’ work “Role of dams on the floods of August 2018 in Periyar River Basin, Kerala” (published in the Current Science in 2019: [DOI: 10.18520/cs/v116/i5/780-794]). As mentioned in Sudheer et al. (2019), the primary objective of the article was to examine whether the early release of the water stored in the reservoirs would have attenuated the flood peaks, and if so, what would have been the extent of the attenuation, in the context of debates and discussions in the social, political, as well as scientific domains based on non-sequitur speculations. Accordingly, the authors designed a scientific exercise using a widely used hydrological model (HEC-HMS) to understand the role of the dams in the Periyar River Basin (PRB) in the 2018 flooding situation.

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Indian Meteorological Department · Monsoon · Rainfall

District wise rainfall in June-Aug 2020 in India

In the ongoing South West Monsoon, India received 44 year old high surplus rainfall of 327 mm in just concluded Aug 2020, 26.6% above normal rainfall of 258.2 mm. This helped the total June-Aug 2020 rainfall to achieve 10% surplus, with actual rainfall 780.3 mm, 69.9 mm higher than normal rainfall of 710.4 mm. In June the country received 18% above normal rainfall and in July it received 9.9% below normal rainfall, the rainfall at the end of June was just 1.1 mm above normal. Thus almost the entire surplus rainfall is thanks to the rainfall during Aug 2020. The rainfall distribution has however, been far from normal that these figures suggest, as we can see from the state wise and district wise figures below.

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Dam Induced Flood Disaster · Kerala

Role of dams in Kerala floods: Distortion of Science

Guest Article by: J.Harsha

Introduction: In August, 2018, devastated floods occurred in the southern Indian state of Kerala that led to widespread death and destruction to livelihoods. One of the worst affected basins was Periyar River Basin (PRB). While investigating the role of dams in the devastating floods, an article titled, “Role of dams on the floods of August 2018 in Periyar River Basin, Kerala” by Sudheer et al., (2019) was first published in the Current Science1 Journal brought out by Indian Academy of Sciences, Bengaluru, India on 10th March 2019. The journal article by Sudheer et al., (2019) adopts hydrological model to investigate the role of dams in the occurrence of floods in PRB and concludes that dams had less or little role in the occurrence of floods in comparison to the natural reasons. However, when the article was reviewed, it was found that the authors Sudheer et al., (2019) had made fallacious assumptions, errors in their methodology, adopted poor data quality and they have arrived at erroneous inferences and conclusions such as exonerating the role of dams in Kerala floods but indicting the nature as the cause of floods. This review article therefore, using RS & GIS (Remote Sensing and Geographical Information System) techniques challenges their inferences that is based on fallacious assumptions, accumulated errors in their methodology and the poor data quality fed into the hydrological model.

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Monsoon · Rainfall

District wise Rainfall in India in June July 2020

During the just concluded first half of the South West Monsoon 2020, India received 453.3 mm rainfall, just 1.1 mm above the normal rainfall of 452.2 mm during the period. The Surplus of  18% rainfall that India received in June 2020 has thus been wiped out by the 9.9% deficit in July rainfall. Normal rainfall in July 2020 is 285.3 mm, while actual rainfall was 257.1 mm. IMD does not provide monthly figures of rainfall for different states, sub divisions and river basins, which it should along with comparison with respect to normal rainfall and rainfall last year.

To get July 2020 rainfall, we will need to use the figures given in this article along with the figures of June 2020 rainfall (see: https://sandrp.in/2020/06/30/district-wise-rainfall-in-india-in-june-2020/). The district wise figures of June-July 2020 rainfall can be seen in this PDF file from IMD: IMD DISTRICT WISE RAINFALL FROM JUNE 1 TO JULY 31 2020.

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Indian Meteorological Department · Monsoon · Rainfall

District Wise rainfall in India in June 2020

Here we present the rainfall figures from India Meteorological Department in the just concluded month of June 2020, the first month of SW Monsoon 2020. The overall rainfall at all India level in June 2020 was 196.2 mm, 18% above normal rainfall in the month at 166.9 mm. It was 33% deficit last year.

This is India’s wettest June 12 years, The Times of India reported on July 1, 2020. Agriculture Ministry Data shows that sowing is 68% higher at 31.56 m ha. The June rainfall was 202 mm in 2008, the rainfall this year is the highest since then. All four IMD regions (Northwest, Central, South, East & NE) have recorded surplus rainfall, the surplus is the highest in Central (30.5% surplus) and E-NE (15.7%) regions. North West India had the lowest surplus at 3.5%. IMD Head Mrutyunjay Mohapatra said that whole of India was covered by monsoon on June 26, 12 days ahead of the normal date of July 8.

State wise rainfall Three states had large excess rainfall (above 60% surplus rainfall), namely Bihar, Madhya Pradesh and Sikkim. Eight states/UTs (Union Territories) had excess rainfall (20-59% surplus): Assam, Meghalaya, UP, Chhattisgarh, Maharashtra, Telangana, Andhra Pradesh & Andaman and Nicobar. Nine had deficient rainfall (20-59% deficit): Lakshadweep, Mizoram, Manipur, J&K, Ladakh, Himachal Pradesh, Delhi, Dadar & Nagar Haveli. Rest of India had Normal Rainfall. Continue reading “District Wise rainfall in India in June 2020”

Rainfall

State wise rainfall Pre Monsoon 2020 & Post monsoon 2019

India Meteorological Department (IMD) divides a water year (June 1 to May 31) into four seasons: Monsoon: (June 1 to Sept 30), Post monsoon (Oct 1 to Dec 31), Winter (Jan 1 to Feb 28/9) and Pre Monsoon (March 1 to May 31). For rainfall during all these seasons, IMD’s hydro-meteorological website[i] provides a lot of data on daily basis, including daily district wise rainfall, state-wise, sub division wise and river wise daily rainfall maps among many other weekly, monthly and seasonal products. However, one problem with it is that none of this information is achieved. So if you missed seeing or downloading available data on any date, there is no way to look at it even next day. This is even true of the seasonal rainfall maps, unfortunately.

Most observers look at the monsoon rainfall data, which is clearly the most important season, without doubt. However, the rainfall in other seasons is also very important from a number of perspectives.

Here we are giving a detailed account of the pre-monsoon season rainfall that India received in the season just ended on May 31, 2020, including state wise, sub division wise, river wise and also district wise figures. Along with it, we also provide the figures of post monsoon figures for the just concluded water year. For the winter season (Jan-Feb 2020) we have only the figures for Jan 2020 since we missed downloading the Feb 2020 figures. We had already provided the monsoon 2019 figures through two blogs in October 2019[ii].

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