This presentation is an attempt to describe the occurrence of floods in Sri Lanka, beginning from the great flood incidence of 1956. Data and other literature used to develop this presentation were obtained from published documents of Disaster Management Center of Sri Lanka

1. 1
Dr. Kingsley Guruge
Retired Senior Lecturer in Geography
Sri Lanka

2. ♥ The disaster event profile of Sri Lanka is based on the Sri Lanka
Historical Disaster Information System,designed by the Disaster
Management Centre (DMC), Ministry of Disaster Management, in line
with DesInventar system developed by the LA RED in Latin America.
♥ The relevance is based on the number of events and different effect
variables, such as
(a) Number of people affected,
(b) Loss of life,
(c) Number of destroyed or damaged houses/buildings,
(d) Loss of agricultural crops.
2
Sri Lanka National Report on Disaster Risk, Poverty and
Human Development Relationship

3. 3

4. ♥ The disaster event profile of Sri Lanka presents how
disaster events of different categories have been
distributed chronologically, seasonally and spatially.
♥ Distribution wise, the overall disaster typology in Sri
Lanka is not distributed evenly. In terms of annual time
series distribution, animal attacks seem to have
increased.
♥ However, disasters like floods seem to take place
every year.
♥ The seasonal distribution of disasters shows two
peaks; one from April to June and the other from
October to December, representing the two monsoon
seasons.
4

5. 5
Profile of Different Disaster Categories: 1974-2008
There are many types of disaster events in the country but the most
common are :
♦ Animal attacks (7,203 events),
♦ Fire (2,704 events urban and forest fire),
♦ Floods (1,397 events- riverine flood, urban flood,
flash flood, rain),
♦ Extreme wind events (1,263 events- cyclone, strong wind,
surge, gale),
♦ Drought (285 events),
♦ Landslides (1,156 events) and
♦ Lightning (295 events).

6. 6
Source : Sri Lanka National Report on Disaster Risk, Poverty and Human Development
Relationship
Profile of Different Disaster Categories: 1974-2008

7. 7
Chronological Trend of Disaster Events
Source: desinventar.lk

8. ♥ The sudden increase in animal attacks after 1998 is mainly due to the
commencement of systematic recording of events, rather than a sudden
outbreak of animal attacks.
♥ There are two main trends
First, from 1974 to 1997, there is gradual increase in the
number of disaster events fluctuating from 0 to 200 events
with several peaks.
Secondly, disaster events during the period 1997- 2006 show a
clear trend of very rapid increase of number of disaster events
from about 200 records in 1997 to more than 1,800
records in 2006, with the only break in the trend observed in
2001.
♥ There is a sharp break in this trend beginning 2007, but it is too early to
predict whether this is a start of a declining trend or not.
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9.  Droughts have been mostly responsible for agricultural loss,
followed by floods and wind events.
 Extreme wind events have caused the most number of deaths (926).
 Geological disasters like earthquakes, tsunami, volcanoes and
 landslides can cause massive destruction to lives and property
 In Sri Lanka, landslide is the most common geological hazard.
 Earthquakes of low to moderate magnitude have been recorded over
the past 400 years in Sri Lanka with very limited damage. No accurate
data is available

10.  Spatial distribution of disaster records is uneven. District
level ranging from 96 to 1887
 DS level from 9 to 74
 It can be observed that while taking the number of people
affected by disasters into consideration, the share of climate
related disasters is 96%, showing the dominating
importance of these disasters over the others.
 Most of the damage and destruction to houses has been
due to floods (232,236) and wind events (201,793).
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12. 12
Source : Sri Lanka National Report on Disaster Risk, Poverty and Human
Development
Relationship
Floods General Trend of Occurrence
1974-2007

13. Source: Towards a Safer Sri Lanka: A Roadmap for Disaster Risk Management
People Affected by Different Disasters in Sri Lanka
1974-2004

14. Source: Towards a Safer Sri Lanka: A Roadmap for Disaster Risk Management
Floods: Number of People Affected by Region- 1974- 2004

15. 15
Source : Sri Lanka National Report on Disaster Risk, Poverty
and Human Development Relationship
Profile of People Affected due to
Different Disaster Categories
without Tsunami : 1974 - 2008
Profile of People Affected due to
Different Disaster Categories
without Tsunami : 1974 - 2008

16. 16
Source : Sri Lanka National Report on Disaster Risk,
Poverty and Human Development
Relationship
Profile of Loss of Life due to
Different Disaster Categories
Without Tsunami : 1974-2008
Profile of Loss of Life due to
Different Disaster Categories
With Tsunami : 1974-2008

17. 17
Source : Sri Lanka National Report on Disaster Risk,
Poverty and Human Development
Relationship
Profile of houses Destroyed
and Damaged due to Disasters
Without Tsunami : 1974-2008
Profile of houses Destroyed
and Damaged due to Disasters
With Tsunami : 1974-2008

18. 18
Source : Sri Lanka National Report on Disaster Risk,
Poverty and Human Development
Relationship
Profile of Agricultural Losses Due
to Disasters (in Hectares)
Without Tsunami :1974 - 2008
Profile of Agricultural Losses Due
to Disasters (in Hectares)
Without Tsunami :1974 - 2008

19. ♥ Mainly drought (52.2%), flood (38.9%) and Extreme wind
events (4.2%) cause damage to agricultural crops.
♥ 1987, 2001 and 2004 and damage appears to be mainly
caused by drought and flood.
♥ The seasonal distribution of loss to agricultural crop shows a
cyclical distribution with two peaks. One peak takes place in
the months of November, December, January and February
due to both drought and flood.
♥ During this period, most damage is caused by floods which
can be attributed to the monsoon rains. The other peak can
be seen in August and September mainly due to drought.
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20. 20
Spatial Distribution
of Events by Districts
and DS Divisions :
1974-2008
Source : Sri Lanka National Report on
Disaster Risk, Poverty and Human
Development Relationship

21. 21
Source : Sri Lanka National Report on
Disaster Risk, Poverty and Human
Development Relationship
Agricultural Loss Due to
Disasters (in Hectares) -
Spatial Distribution:
1974 - 2008

22. ♥ The spatial distribution shows that the districts of Kurunegala
and Ampara appear to have the highest loss of crop. In
districts such as Colombo, Kandy and Kalutara the loss is
somewhat low. This is because the agricultural sector is not as
significant in these districts as in other districts.
♥ Further, the most affected DS divisions are located in the
Southern and Western parts of the island, while certain DS
divisions in the Northern and Eastern parts of the island are
less affected.
♥ Mainly drought (52.2%), flood (38.9%) and Extreme wind
events (4.2%) cause damage to agricultural crops. In 1987,
2001 and 2004 and damage appears to be mainly caused by
drought and flood.
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23. ♥ Flood was identified as the most common and hazardous
natural event in Sri Lanka.
♥ Floods in Sri Lanka are mainly due to excessive rainfall
received during monsoons and received as a result of
development of low-pressure systems in the Bay of
Bengal. (Cyclonic Floods)
♥ Floods are directly related to the amount of rainfall and
therefore a proper understanding about the distribution of
rainfall becomes important.
Floods in Sri Lanka

24. ♥ Major floods are associated with the two monsoon
seasons. During south-west monsoon (May – Sept.) The
western, Southern and Sabaragamuwa provinces are
vulnerable for floods during this period.
♥ During north-east monsoon (Dec. – Feb.) the
Eastern, Northern and North-Central provinces are at
risk of flooding.
♥ Since the beginning of the 20th century major floods
that affected extensive areas of the country, appear to
have occurred about 9 times.
(1902, 1913, 1925, 1931, 1940,1947, 1957, 1963, 1978)
Monsoons and Floods

25. ♥ Bank-full discharge – most important in terms of
incidence and impact.This type of flood occurs when
surface run-off entering the river exceeds the discharge
capacity of the river channel.
♥ Flash Floods: Sudden accumulation of water on low-lying
areas leads to flash floods. ( common occurance in urban
areas)
♥ Breaching of reservoirs and channel bunds: mostly
seen in the dry zone
♥ Tsunami: along coastal areas
Types of Floods in Sri Lanka

26. ♥ The most destructive flood in the wet zone during the
past 100 years, occurred in August 1947.
♥ Unusual heavy rainfall within the upper catchment areas
of the Mahaveli and Kelani rivers was the main cause for
this flood
♥ Daily rainfall figures for, Blackwater Estate 485 mm,
Watawala 478 mm, Oonagaloya 475 m.m., Maskeliya
462m.m., Lucombe Estate 457m.m., Nawalapitiya 447
m.m., ( Highest ever recorded)
♥ In several areas along the windward side of the central
highlands, the total rainfall in August 1947, was also the
highest ever on record.
Floods in Sri Lanka– Historical Perspective- 1947 flood

27. Station Total Rainfall
in August
1947 (m.m.)
Previous Highest August
Total (m.m.)
Kandy 722 434
Peradeniy
a
813 363
Madulkelle 1280 365
Dickoya 1263 788
Hatton 1359 1047
Maskeliya 1493 1259
Norton
Bridge
1556 n.a
Watawala 1584 n.a.
Blackwater 1612 n.a.
Source: Report of the Colombo Observatory 1947
Rainfall in August 1947

28. ♥ High runoff rate ( as high as 60%, according to Maddumabandara)
♥ The narrowness of the river valleys,
♥ Excessive sedimentation along the river channels
♥ Presence of sand bars, that obstruct the river outlets to sea.
♥ Flood levels: Nagalagam Gauge (Colombo) 12’.6” (Previous highest
level was 11’.4”)
♥ Extensive areas along Mahaveli , Kelani and Kalu Ganga have been
submerged to a depth of 30 feet.
Flood Damage
♥ Floods destroyed at least about 40,000. private dwellings.
♥ Rendered more than 400,000, people homeless.
♥ Extensive damages to roads, bridges and railways.
♥ Deaths, loss of Personnel possessions, not comprehensively
estimated
Other causes for flooding

29. ♥ The setting: by the end of November1957 majority of irrigation tanks
of the dry zone was spilling over or was near full capacity
♥ In early December rainfall was concentrated mainly on the North
Eastern parts of the dry Zone
♥ From about 17th of December the zone of highest rainfall expanded
gradually from a core area in the North East to encompass the entire
Northern plains, and the Northern segment of the central highlands.
♥ The torrential rainfall that led to flooding began on 23rd December ,
and continued unabated until the 26th.
♥ Rainfall was heavily concentrated on Northern and Eastern parts of
the dry zone. Daily total rainfall exceeded 400 m.m.
Floods of 1957

30. ♥ Flood Levels: according to reports prepared by GA s, extensive areas
in A’ Pura, Polonnaruwa, Vauniya, Mannar and Puttlam districts were
submerged at places upto 30 feet or more.
♥ Localised floods in other parts of the country, excluding Southern
Region
♥ Apart from the floods, landslides were reported in
Kurunegala, Matale, Kandy Nuwara Eliya and Badulla
♥ Deaths: 171 (Annual Report for 1957- Dept. of Social Services)
♥ About 65,000, houses were either partially or totally damaged
♥ Irrigation Dept. reported serious damage to 35 major irrigation
works, and minor damage to 53 others, in addition to breaching of
more than 1300 village tanks.
♥ Exclusive damage to roads, bridges, railways, and to crops
Floods of 1957 ( Continued)

31. ♥ According to Asian Disaster Reduction Center (ADRC) the 1978
cyclone alone affected
♥ More than one million people,
♥ Killed nearly a thousand persons,
♥ Partially and completely damaged nearly 2,50,000 houses,
♥ Destroyed 90 percent of the coconut plantation in the Batticaloa
district
(The government spent over Rs.600 million to bring immediate relief
to those affected.)
♥ Also cyclones and floods of severe intensity struck Sri Lanka
in 1922, 1931 and 1964.
♥ Cyclone of 1978 incurred damages amounting to nearly 3.78
percent of the GDP while floods of 1992 caused losses close to
1.03 percent of the GDP.
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Floods of 1978

32. ♥ Several flash floods occured recently, without giving much time
for evacuation, and diminished within two to three days. In
2008, there were three flood events one in 29th April, 30th May
and other in 19th July in Kelani, Kalu and Gin basins.
♥ Floods in Kelani river are important due to its outfall being near
the capital city of Colombo.
♥ Flood area mapping in the lower reach of the Kelani river basin
became a top necessity with frequent floods in Kelani River
♥ When the flood levels of Kelani are in between 5.0 ft. and 7.0 ft.
at the Nagalagam Street gauge, they are within the limits of
minor floods.
♥ When the level exceeds 7.0 ft. the flood is defined as a major
flood
♥ When it exceeds 9.0 ft. the flood is considered to be dangerous.
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33. ♥ Affected areas – Central, Northern, Eastern provinces,
(specially Batticoloa and Trincomalee)
♥ Duration – One week (Due to Monsoon Rains)
♥ Deaths due to Flooding = 23 persons
♥ Over 541,000 persons were displaced and had to take shelter in
275 camps set up by the Government.
♥ This is stated to be worse than the Cyclone of 1978, which
devastated the low-lying district of Batticaloa and displaced
nearly one million persons. The worst disaster in the districts of
Batticaloa and Ampara since 1913.
♥ The most devastating floods that had battered the Eastern
coast of Sri Lanka and wreaked havoc in most parts of the
island had cost the emerging economy a staggering Rs. 30bn or
US $ 27mn.
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January 2011- Floods of Sri Lanka

34. Estimated precipitation over Sri Lanka for
January 3 - 9. Up to 18 inches (525 mm) fell
over eastern Sri Lanka. Image credit: NASA
Earth Observatory.
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35. ♥ Recent past several flash floods occur, without giving much
time for evacuation, and diminished within two to three days.
So far, in 2008, there were three flood events one in 29th of
April, 30th of May and other in 19th of July for Kelani, Kalu and
Gin Ganga basins.
♥ Floods in Kelani river are important due to its outfall being near
the capital city of Colombo.
♥ When the flood levels of Kelani are in between 5.0 ft. and 7.0 ft.
at the Nagalagam (Colombo) gauge, they are within the limits of
minor floods.
♥ When the level exceeds 7.0 ft. the flood is defined as a major
flood
♥ When it exceeds 9.0 ft. the flood is considered to be dangerous.

36. ♥ Affected areas – Central, Northern, Eastern
provinces
♥ Duration – One week ( Due to Monsoon Rains
♥ Flooding in Sri Lanka has resulted in deaths of
about 23 persons during a week of monsoon
floods in the Central, Northern and Eastern
provinces especially Batticaloa and Trincomalee.
♥ Over 541,000 persons were displaced and had to
take shelter in 275 camps set up by the
Government, bringing the total number of
displaced persons to about 1,081,000.
January 2011- Floods

37. ♥ The most devastating floods that had battered the Eastern
coast of Sri Lanka and wreaked havoc in most parts of the
island had cost the emerging economy a staggering Rs.
30bn or US $ 27mn.
♥ Affected areas – Central, Northern, Eastern provinces,
(specially Batticoloa and Trincomalee)
♥ Deaths due to Flooding = 23 persons
♥ Over 541,000 persons were displaced and had to take
shelter in 275 camps set up by the Government.
♥ This is stated to be worse than the Cyclone of 1978, which
devastated the low-lying district of Batticaloa and
displaced nearly one million persons. The worst disaster in
the districts of Batticaloa and Ampara since 1913.

39. ♥ During the period of 1974-2008, the highest
number of people affected was due to floods and next
highest number of people affected has been due to
drought, even though it was apparent as very insignificant in
the Profile of Different Disaster Categories.
39

40. ♥ The highest number of flood events was reported in 2003
totaling 255, and the average for the period was 77.
♥ The greatest number of people was affected by fl oods in
1994, 2003, 1990, and 1993. The largest number of
houses damaged during the floods in 2003 totaled to
37,721 and in 1994 totaled to 19,857.
♥ The greatest damage to paddy occurred in 1994 (53,021
hectares), 1984 (51,034 hectares) and 1986 (47,564
hectares).
♥ Relief distribution was highest in 2003 (Rs.265,400,390)
and in 2005 (Rs. 243,271,924).

41. ♥ While the largest number of disaster events recorded; the
largest number of houses damaged or destroyed and the
largest amount of resources spent on flood relief was in 2003,
the largest number of people affected was in 1994, and the
greatest damage to paddy occurred in 1994.
♥ The Districts most prone to floods include: Kalutara,
Ratnapura, Colombo, Gampaha, Puttalam, Matara, Galle,
Ampara, Polonnaruwa and Hambantota.

42. The End