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Nineteen Years later…. Lessons learnt from Kantale Breach

Nineteen Years later…. Lessons learnt from Kantale Breach. D W R Weerakoon Former Director General of Irrigation. KANTALE IRRIGATION SCHEME. Constructed early 7 th Century Restored in 1875 - 37,124 Acft Augmented in 1954 - 87,750 Acft 1965 -110,000 Acft Data Height of Dam - 60’

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Nineteen Years later…. Lessons learnt from Kantale Breach

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  1. Nineteen Years later….Lessons learnt from Kantale Breach D W R Weerakoon Former Director General of Irrigation

  2. KANTALE IRRIGATION SCHEME • Constructed early 7th Century • Restored in 1875 - 37,124 Acft Augmented in 1954 - 87,750 Acft 1965 -110,000 AcftData • Height of Dam -60’ • BTW - 28’-50’ • Side Slopes - 1:3 ~ 1:2.5 • FSD - 42’ • Spillway – Radial Gated 10/(15’WX8’H)

  3. Kantale Dam Failure (Sunday 20th April 1986) • First information IE/Army /AGA • Warning the Public Police, Railway,CEB,NWS&DB • Efforts to reduce breach flow

  4. Prior Warning of Failure Prior Observation of signs of warning – none Recent Prior inspection (24th Nov,1985) - 65 runnels on D/S bund slope -No seepage observed at 22’8’’ of water -Bund overgrown

  5. Cause(s) of Failure • Failure of the LB sluice barrel • Deterioration of the sluice barrel • Effect of pile driving in close proximity for constructing the pump house

  6. Damage Caused • Loss of Human life - Dead bodies found 68 - Persons missing 59 • No of families affected 2,035 • No of persons affected 10,864 • Houses damaged -Completely 592 -Partially 628 • Crop destroyed -Standing crops 2,502 Ac -Harvested 627 Ac

  7. Some Issues Related to Kantale Breach • Observation of signs of prior warning ? • Equipped for satisfactory level of observation ? • Periodic Inspection - satisfactory ? • Standing Orders- Available ? Updated ? • Disaster management • Planned ? Awareness ? • Communication methods-satisfactory ? • Authority with the custodian of the reservoir ? • ……? ? ? ?

  8. Post failure Action • Immediate inspection of 11 reservoirs by a team of specialists • Hazard Rating of Dams • ID Circular on regular inspection- check list & reports – 1986 June • Establishment of a dam Safety unit in ID – 1997 • Preparation of standing Orders • Dam Safety Project under Mahaweli restructuring Project

  9. Dams Under ID Responsibility Total 281 Concrete Gravity 01 Earth 280 Large dams 54

  10. Modes of Embankment Reservoirs Failure (Statistics– Global) Source: ICOLD

  11. Issues for the Present & Future • Availability of Specialized Knowledge & Persons? • Prior Observations and capacity for inference ? - Training needs • Equipment for satisfactory level of observation? • Periodic Inspections/Follow up action ? • Preparation and updating of Standing Orders ? • Preparedness for Disaster management • Communication methods-satisfactory ? • Authority with the custodian of the reservoir ? • Adequacy of funds

  12. THANK YOU

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