Flood Damage in Ampara District

DEPARTMENT OF CIVIL AND ENVIRNMENTAL ENGINEERING

FACULTY OF ENGINEERING

UNIVERSITY OF RUHUNA

CE6322: ENGINEERING HYDROLOGY

FLOOD DAMAGES IN AMPARA DISTRICT 2011

(02/01/2011 to 07/02/2011)

NAME : BANDARA K.A.J.M.

REG No : RU/E/2008/014

DATE : 13/06/2011


Faculty of Engineering Page 2

ACKNOWLEDGEMENT

I have taken efforts in this project. However, it would not have been possible without the kind support and help of many individuals and organizations. I would like to extend my sincere thanks to all of them. I am highly indebted to Dr. Amila De Silva for their guidance and constant supervision as well as for providing necessary information regarding the report & also for their support in completing the report. I would like to express my gratitude towards my parents & member of Faculty of Engineering for their kind co-operation and encouragement which help me in completion of this report. I would like to express my special gratitude and thanks to Eng. Saman S.L. Weerasinghe, Regional Director of Irrigation of the Ampara Range for giving me such attention and time. Bandara K.A.J.M

RU/E/2008/014

Faculty of Engineering

University of Ruhuna.



CONTENT Page No

ACKNOWLEDGEMENT i

CONTENT ii

1.0 SUMMARY 1

2.0 INTRODUCTION TO THE GAL OYA BASIN 1

2.1.1 PHYSICAL FEATURES OF SENANAYAKA TANK 1

3.0 FLOOD DAMAGES 3

3.1.1 OPERATIONAL ISSUES 4

4.0 DATA ANALYZING 6

5.0 CONCLUSIONS 11

REFERENCES 11

ANNEXES 12



1.0 SUMMARY

This report presents the results of an impact in flood during at January 2011 in Ampara District. Due

to heavy rains in Ampara District has become inaccessible through the Inginiyagala, Mahaoya and

Kalmunai routes, which have been submerged, access has been cut off to all Division. This is the

most devastating floods that hit the Eastern part of the country especially Ampara since 1913.

2.0 INTRODUCTION TO THE GAL OYA BASIN

Gal Oya, a reservoir-based irrigation system, lies on the eastern coastal plain of Sri Lanka (fig. 1).

Originally proposed just after Sri Lanka’s independence in 1948, the main reservoir was completed

in 1960, and the full irrigation system was transferred from the Gal Oya Development Board to the

Irrigation Department for routine operation and maintenance. The reservoir, Senanayake Samudra,

has a capacity of 979 million cubic meters. Immediately below the dam is a trifurcation that controls

water deliveries into the main divisions of the system: the Right side (11,741 ha), the River Division

(8,502 ha), and the Left side (16,328 ha). Its combined irrigated area makes Gal Oya the largest

contiguous irrigation system in Sri Lanka.

2.1.1 PHYSICAL FEATURES OF SENANAYAKA TANK

The reservoir has been classified as “deep, encompassing many valleys” as the wetland is a multi-

fingered lake with 4 major basins and surrounded by hills. The reservoir is located in the Gal Oya

basin, which covers an area of 179,200 ha. The catchment area of the reservoir alone covers about

100,000ha. The main river feeding the reservoir is the Gal Oya River. In addition to this, the

reservoir is fed with water from seven main tributaries and 23 unnamed minor seasonal streams. The

profusion of bays gives the reservoir an estimated shoreline of about 130 km at full supply level. The

capacity of the reservoir is 949x106 m3 with a maximum depth of 33m and an average depth of 12m.

The water level in the reservoir is subject to wide seasonal and annual fluctuations and is directly

related to rainfall in the region. The lowest level recorded in the recent past was 28m below spill

level in 1989; maximum depth in the reservoir at that time was 5m. The length of the dam is 1,093m

with a crest at 83 m above sea level. The entire reservoir area is situated in the Vijayan series, a

Precambrian formation prevailing in the eastern part of the country. The reservoir is situated in the

dry zone of the eastern low country of Sri Lanka in the agro-ecological region DL2, which is defined

as an area with a 75% expectancy of annual rainfall exceeding 900mm. Most rainfall is normally

recorded in the period October-February; the period May-September is usually dry. Mean annual

temperature is around 27.7 0C.



Figure No 01



3.0 FLOOD DAMAGES

The floods in Sri Lanka are most likely to occur in the months of May in the first cycle and in

December in the second cycle. With respect to spatial distribution floods are most frequent in the

districts of Ampara. Due to floods in Ampara at January,

24 dead,

4 lakhs destitute,

1 ½ lakhs acres paddy field destroyed.

This damage’s occur after 1984 later year ago. People have become increasingly affected by floods

with the highest number recorded in 2011. Further, people located in the division of Ampara District

have been most affected by floods. However, the occurrence of deaths due to floods is quite high

except for the last years where it reached nearly 15 persons. Destruction and damage to houses and

buildings also appear to follow a similar pattern with most damage occurring in the districts of

Ampara. Damage to paddy has taken place mostly in the earlier years with the highest impact

recorded in 1984, while spatially the highest damage has incurred in the districts of Ampara.

Due to torrential rain resulting from recent weather condition, nearly 10 Divisional Secretariat

Divisions of Ampara district have been experiencing flooding since the 6th January 2008. The most

affected D.S. Divisions are Akkaraipattu, Aalayadivembu, Ninthavur, Thirukkovil, Pottuvil,

Sammanthurai, Saithamaruthu, Karaitivu, Addalaichenai and Kalmunai.

Over 70,000 children are among the affected. While some schools in the flooded areas are being used

as temporary camps, many of the school going children’s educational activities have been disrupted

due to present weather condition/flood situation. Most of the affected families are depending on

fisheries and daily earnings for their livelihood. As the heavy rain disrupted these families’

livelihood, children in the families are affected by shortage of food, drinking water and proper

sanitary care.



Table No 01

3.1.1 OPERATIONAL ISSUES

The torrential rains have caused main roads to be submerged reducing access to affected areas.

Additionally, heavy rains also resulted in the intermittent opening of sluice gates of tanks and reservoirs. Transport and telecommunications are disrupted across the districts.

All schools in the affected areas have been declared closed by the Government throughout the week and most of the displaced are accommodated in most of these sites.

0

50

100

150

200

250

300

350

400

450

500

1st Flood 2nd Flood

181159

497.8

248.9 No of Damages

Tentative EstimateCost(Million)

743512

816

207430

0 15 52

1285

2670 2580

39 95 15 12 27 0 2 0 18 3 20

500

1000

1500

2000

2500

3000

Partially DamagedHomes

Fully Damaged Homes

Funds required for the repairs the Damages in

2011

Rs. 300.0 Million

Table No 02: Homes Damaged During Flood



Population Density & Flood Preparedness

Figure No 02



4.0 DATA ANALYZING

Spatial Distribution of Rainfall D

ate

Am

para

Uha

na

Him

idur

awa

Wee

rago

da

Ann

amal

ai

Gon

agol

la

Blo

ck”J

”

Sina

wat

htha

Bok

keba

da

Dam

ana

Palla

noya

Nam

aloy

a

Am

bala

noya

Ekga

loya

Pann

alga

ma

1 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

2 13.9 3.8 7.6 8.1 17.7 3.0 8.8 _ 22.8 17.2 5.0 21.0 5.0 _ 31.7

3 33.0 45.7 27.9 48.2 50.0 82.5 40.6 78.0 27.6 29.2 10.0 17.7 21.5 6.3 17.7

4 7.6 11.4 7.6 36.8 40.1 22.8 24.1 41.9 30.4 9.1 7.0 19.3 15.2 3.8 7.6

5 19.8 29.7 36.8 13.9 10.1 12.7 16.5 22.8 33.0 26.4 17.0 23.6 44.1 10.1 30.4

6 11.4 11.4 15.2 10.1 8.8 14.4 7.6 8.0 8.1 10.1 5.0 16.0 7.6 3.8 5.0

7 21.5 _ _ _ _ _ _ _ _ 34.2 10.0 16.5 12.7 _ _

8 228.0 124.4 116.8 200.6 124.4 254.0 185.4 254.0 251.4 _ 122.0 193.0 190.0 139.7 119..3

9 21.5 27.9 27.9 47.7 53.3 44.4 24.8 41.1 50.8 20.3 20.0 22.8 12.7 7.6 22.8

10 63.5 54.6 55.8 _ 48.2 74.9 62.2 _ 33.0 55.1 46.0 40.6 33.0 27.9 27.9

11 236.2 165.1 124.4 144.7 200.6 143.5 201.0 _ 88.9 214.1 65.0 53.0 231.0 78.7 78.7

12 66.0 62.2 64.7 27.9 30.4 83.8 _ 68.5 60.9 _ 67.0 66.0 83.8 40.6 60.9

13 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

14 6.3 10.1 7.6 7.6 _ 21.3 6.3 _ 22.8 _ 5.0 10.1 _ 3.8 2.5

Table No 03: Rain fall data from 1st of January in mm (1st Flood)



=

15

Average Annual rain fall in Ampara District is 1250mm -1600 mm

By considering the daily rainfall data of January in 2011(1st flood)

Mean rainfall in the Ampara district (1st flood)

728.7

546.3

492.3

545.6583.6

757.3

577.3

514.3

629.7

415.7379

499.6

656.9

322.3

404.5

0

100

200

300

400

500

600

700

800

Figure No 04: Total Rainfall 1st flood (mm)

{728.7+546.3+492.3+545.6+583.6+757.3+577.3+514.3+629.7+415.7+379+499.6+656.9+322.3+404.5} mm

= 536.9 mm



D

ate

Am

para

Uha

na

Him

idur

awa

Wee

rago

da

Ann

amal

ai

Gon

agol

la

Blo

ck”J

”

Sina

wat

htha

Bok

keba

da

Dam

ana

Palla

noya

Nam

aloy

a

Am

bala

noya

Ekga

loya

Pann

alga

ma

25 68.5 93.9 55.8 _ 25.4 45.7 _ 49.5 40.6 39.3 30.0 22.8 27.9 12.7 3.8

26 16.5 49.5 38.1 7.6 17.7 30.4 _ _ 73.6 27.9 35.0 80.0 53.3 10.1 53.3

27 30.4 28.0 20.3 26.6 12.7 25.4 24.1 _ _ 25.4 20.0 12.7 33.0 7.6 28.0

28 36.8 49.5 54.6 49.5 20.3 25.4 50.8 20.3 27.9 _ _ 45.7 38.1 44.4 53.3

29 27.9 22.9 33.0 17.7 17.7 30.4 8.8 27.4 38.1 _ 10.0 31.7 5.0 8.8 8.8

30 3.8 4.5 8.8 5.0 _ 11.4 _ _ 15.2 _ 30.0 30.4 10.1 6.3 6.5

31 25.4 29.2 17.7 29.2 20.3 _ 24.8 _ 10.1 _ _ _ _ _ 3.8

1 217.4 167.6 187.9 111.7 114.3 330.2 204.4 _ _ 203.0 160.0 168.9 142.2 71.1 119.9

2 104.1 128.2 114.3 119.3 114.3 203.2 102.8 _ 200.6 114.3 187.9 138.4 134.6 177.0 97.7

3 33.0 30.4 _ 58.4 66.0 53.3 44.4 45.7 17.7 30.4 32.0 30.4 15.2 5.0 5.0

4 52.0 34.2 46.7 54.6 53.3 65.0 50.2 76.2 76.2 _ 19.0 39.3 40.6 11.4 6.3

5 9.6 15.2 11.4 5.0 3.8 _ _ _ _ 5.8 6.0 13.9 2.5 _ _

6 30.4 32.7 33.0 35.0 33.0 38.8 39.3 35.0 43.1 31.7 29.0 30.4 38.1 11.4 25.4

7 11.1 8.8 _ 10.1 15.2 5.5 5.0 15.2 17.7 28.7 21.0 _ 53.3 11.4 30.4

Table No 05: Rain fall data from 25th of January in mm (2nd Flood)



By considering the daily rainfall data of January and February in 2011(2nd flood)

Mean rainfall in the Ampara district (2nd flood)

1395

1241

11141075 1098

1622

1132

784

1191

922959

1144

1251

700

847

0

200

400

600

800

1000

1200

1400

1600

1800

Figure No 04: Total Rainfall 2nd flood (mm)

(1395+1241+1114+1075+1098+1622+1132+784+1191+922+959+1144+1251+700+847) mm

= 15

1098.3 mm =



Figure No 05: Flood damage map



5.0 CONCLUSIONS

The incidence of flooding seems to be most frequent in the latter years, with the most flooding

occurring in the year 2011 in Ampara District. Further, the floods in Sri Lanka are most likely to

occur in the months of May in the first cycle and in December in the second cycle. With respect to

spatial distribution floods are most frequent in the divisions of Ampara. People have become

increasingly affected by floods with the highest number recorded in 1984.. However, the occurrence

of deaths due to floods is quite high except for the latter years where it reached nearly 24 persons.

Destruction and damage to houses and buildings also appear to follow a similar pattern with most

damage occurring in the division of Thirickovil and Adalachchinei. Damage to paddy has taken

place mostly in the earlier years with the highest impact recorded in 1984, while spatially the highest

damage has incurred in the districts of Ampara. In some instances with respect to DS divisions, some

impacts have been reflected as low (Table No02).

REFERENCES http://www.rdiampara.weebly.com/ampara-division.html

http://www.dmc.gov.lk

http://www.meteo.gov.lk



Aligalge Tank Konduwattuwana Tank

Alahena Tank Weeragoda Tank

ANNEXES

6.1.1 Spilling Tanks during flood period

Ekgaloya Tank Pannalgamuwa Tank



6.1.2 Flood Damages Area’s

Senanayaka Tank Nawagiri Tank

Ampara Town Ampara municipal building

Gemunupura Area Rajawewa Tank

Documents

Flood Damage in Ampara District