Role of Dams on the Floods of August 2018 in Periyar River Basin, Kerala

Sudheer, K. P.; Bhallamudi, S. Murty; Narasimhan, Balaji; Thomas, Jobin; Bindhu, V. M.; Vema, Vamsi Krishna; Kurian, Cicily

doi:10.18520/cs/v116/i5/780-794

Cited by 87 publications

(29 citation statements)

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“…Flooding execrated due to the release of water from dams can be attributed to the underestimation of water management in the KFE case. A NASA report on the Kerala flood and this study demonstrate the role of water released from the dams, as well as water from heavy precipitation, resulted in it becoming the worst flood of the century in Kerala [7].…”

Section: Other Details Of the Extreme Flood Eventmentioning

confidence: 61%

“…The CWC (Central Water Commission) report adds that the dams did not help in mitigating the flood; however, dams are not to be blamed for KFE dams being at their full capacity before the KFE. In such a case, dams have to release excess water or they may collapse [7]. Dams, reservoirs, and wetlands are, in general, created for the generation of electricity, flood control, and maintaining a water supply.…”

Section: Other Details Of the Extreme Flood Eventmentioning

confidence: 99%

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Interaction of a Low-Pressure System, an Offshore Trough, and Mid-Tropospheric Dry Air Intrusion: The Kerala Flood of August 2018

et al. 2020

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The present study examines the Kerala Flood Event (KFE, 15–16 August 2018, in India) that occurred along the west coast of India and resulted in ~400 mm of rainfall in one day. The KFE was unique in comparison to previous floods in India, not only due to the rainfall duration and amount, but also due to the fact that the dams failed to mitigate the flood, which made it the worst in history. The main goal of this study is to analyze and elucidate the KFE based on meteorological and hydrological parameters. A propagating low-pressure system (LPS) from the Bay of Bengal (BoB) caused the streak of plenty of rainfall over Kerala, the west coast, central India, and the BoB. Additionally, the upper-tropospheric anti-cyclonic system over the Middle East region inhibited a northward advancement of LPS. On the western coast of India, a non-propagating (with diurnal fluctuations) offshore trough was observed over the west coast (from Kerala to Gujarat state). Therefore, a synergic interaction between LPS, an intrusion of dry air in the middle-troposphere, and the offshore trough was the main reason for KFE. However, after around ten days, rainfall saturated the dam capacities; thus, the released water, along with the amount of precipitation on the day of the event, was one of the other possible reasons which worsened the flood over Kerala.

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Section: Other Details Of the Extreme Flood Eventmentioning

confidence: 61%

Section: Other Details Of the Extreme Flood Eventmentioning

confidence: 99%

Interaction of a Low-Pressure System, an Offshore Trough, and Mid-Tropospheric Dry Air Intrusion: The Kerala Flood of August 2018

et al. 2020

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“…Further, the absence of spatial correlation may be related to the fact that the significant dam reservoirs [see Fig. 1(b)] were already full due to earlier rainfall throughout 2018, and the August precipitation led the dam to overtop [75]. Overtopping a dam is often a precursor to its failure, and thus excess water may be released through spillways to avoid the failure.…”

Section: Flooding and Precipitation Patternmentioning

confidence: 99%

Probabilistic Mapping of August 2018 Flood of Kerala, India, Using Space-Borne Synthetic Aperture Radar

Sherpa

Shirzaei

Ojha

et al. 2020

IEEE J. Sel. Top. Appl. Earth Observations Remote Sensing

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Synthetic aperture radar (SAR) imaging provides an all-weather sensing technique that is suitable for near-real-time mapping of disasters such as floods. In this article, we use SAR data acquired by Sentinel-1A/B satellites to investigate a flood event that affected the Indian state of Kerala in August 2018. We apply a Bayesian approach to generate probabilistic flood maps, which contain for each pixel its probability to be flooded rather than binary flood information. We find that the extent of the flooded area begins to increase throughout Kerala after August 8, with the highest values on August 9 and August 21. We observe no apparent correlation between the spatial distributions of the flooded areas and the rainfall amounts at the district level of the study area. Instead, larger flooded areas are in the districts of Alappuzha and Kottayam, located in the downstream floodplain of the Idduki dam, which released a significant volume of water on August 16. The lack of apparent correlation is likely due to two reasons: first, there is often some delay between the rainfall event and the flooding, especially for rather large catchments where flood waves need some time to reach floodplains from higher elevations. Second, rainfall is more abundant at overhead catchments (hills and mountains), whereas flood occurs further downstream in the floodplains. Further comparison of our SAR-based flood maps with optical data and flood maps produced by moderate resolution imaging spectroradiometer highlights the advantages of our data and approach for rapid response purposes and future flood forecasting.

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“…From August 1 to 19, 2018, Kerala experienced exceptionally heavy rainfall that lead to extensive flooding and landslides, and caused about $5 billion worth of damage and more than 500 causalities (Mishra et al ., ). This unprecedented and extreme rainfall generated a record 100‐year flood that forced officials to open nearly 80 dams at once, creating havoc, landslides, and significant damage to crops and livestock (CWC report, ; Sudheer et al ., ; Mishra et al ., 2018). Unlike the historical and localized flood events of Mumbai in 2005 (Vaidya and Kulkarni, ), Utharakand in 2013 (Vellore et al, ), and Chennai in 2015 (Srinivas et al ., ), the entire state of Kerala was inundated with heavy rainfall spells that lasted for several days.…”

Section: Introductionmentioning

confidence: 99%

A diagnostic study of extreme precipitation over Kerala during August 2018

Viswanadhapalli

Srinivas

Basha

et al. 2019

Atmospheric Science Letters

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The state of Kerala, located on the west coast of India, experienced a record 100‐year flood that resulted in major landslides from unprecedented prolonged and extremely heavy rainfall (50–480 mm·day−1) during August 1–19, 2018, causing extensive damage and about 500 causalities. Rainfall observations indicate that the heavy rainfall occurred over two spells (August 7–10 and 14–18) in association with an offshore trough, and a depression over the Bay of Bengal (BOB). High‐resolution 38‐year climatology data (5 km) and the ERA‐Interim reanalysis dataset show a strong low‐level jet over the Arabian Sea and a depression over the BOB with a southwestward tilt during the heavy rainfall. Very high‐resolution (2‐km) mesoscale model simulations suggest that this high convective instability due to the strong westerly jet along with the formation of offshore vortex, the transport of mid‐tropospheric moisture under the presence of conducive vertical shear of horizontal wind, and transport of mid‐tropospheric moisture from the BOB are the major factors (as shown in the schematic diagram) behind the extreme heavy rainfall over Kerala.

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Role of Dams on the Floods of August 2018 in Periyar River Basin, Kerala

Cited by 87 publications

References 0 publications

Interaction of a Low-Pressure System, an Offshore Trough, and Mid-Tropospheric Dry Air Intrusion: The Kerala Flood of August 2018

Interaction of a Low-Pressure System, an Offshore Trough, and Mid-Tropospheric Dry Air Intrusion: The Kerala Flood of August 2018

Probabilistic Mapping of August 2018 Flood of Kerala, India, Using Space-Borne Synthetic Aperture Radar

A diagnostic study of extreme precipitation over Kerala during August 2018

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