nineteen years later…. lessons learnt from kantale breach
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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’ - PowerPoint PPT PresentationTRANSCRIPT
Nineteen Years later….
Lessons learnt from Kantale Breach
D W R Weerakoon
Former Director General of Irrigation
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)
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
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
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
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
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 ?
……? ? ? ?
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 JuneEstablishment of a dam Safety unit in ID – 1997
Preparation of standing Orders
Dam Safety Project under Mahaweli restructuring Project
Dams Under ID Responsibility
Total 281Concrete Gravity 01
Earth 280
Large dams 54
Modes of Embankment Reservoirs Failure
(Statistics– Global)
Overtopping
Internal Erosion
Structurl Insatability
Other
40%
20%
20%
20%
Source: ICOLD
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
THANK YOU