2011/5/30

COMPARISON STUDY OF EXISTING FLOOD
MANAGEMENT SYSTEMIN JAPAN AND SRI LANKA

Janaki Mudalige
District Disaster Management Coordinator,
Coordinator
Disaster Management Centre, Ministry of Disaster Management,
Sri Lanka(ADRC Visiting Researcher)

9th March,2011

SPECIFIC AIMS OF MY RESEARCH:(1).Study all available flood mitigation methods, real time data acquiring
methods, flood early warning dissemination methodologies, quick response
and evacuation procedures in Japan.
(2) Make a comparison between Japan and Sri Lanka in terms of flooding(2).Makeand flood management activities.
(3).Identify all the appropriate ways, which can be used to upgrade theproposed early warning and flood management system in Sri Lanka withthe help of Japanese methodology.
(4).Introduce new methodology, which can be adapted in Sri Lanka todisseminate real time early warning to vulnerable communities in floodprone area.
Long term objective of this research is to adaptation of suitable
methodologies through its outcomes to the river network within the districtof Kegalle in Sri Lanka.

12011/5/30

RESEARCH ACTIVITIES:(1). STUDY OF DATA ACQUISITION METHODS;•Water level data acquiring methods•Rainfall data acquiring methods•Use of available air photos/satellite imageries etc.
were studied in Japan and Sri Lanka.

(2). STUDY OF DATA ANALYSIS•Analytical methods used to develop a prediction between increases inriver water level accordance with rainfall were studied in Japan andcompare it with the Sri Lanka.

(3). FLOOD EARLY WARNING•Methodologies used to disseminate real time flood early warning to thevulnerable community and,
•Flood forecastingfmethods in Japan were studied and compared it with
Sri Lankan scenarios.
(4). EVACUATION PROGRAMS•Evacuation methodologies in Japan were studied and they werecompared with Sri Lankan scenarios.

22011/5/30

FLOOD MANAGEMENT IN
JAPAN

Administration in Japan
National

Prefecture

Municipals(Cities, Towns and Villages, Tokyo Special Wards)
Wards

3

2011/5/30

4

2011/5/30

Geographic Condition and Climate
in Japan• 70% of land is covered with forests and mostly mountainous• Heavy rainfall occur during rainy season (June‐July) and in thetyphoon season (August‐October)• Rivers are short and steep, causing sharp hydrograph
The ratio of maximum/minimum discharge is extremely high(about 100 for Tone River)• 50% of population are concentrated in flood plains (10% of
land)• Japan is vulnerable for water related disasters

Causes of Flood in Japan•Rivers are steep and short distance, resulting rapid flow.
•Most of urban areas are located in low-lying areas that arelower than the water level during floods.
f•Population and city functions are concentrated in bellow
zero-meter sea-level in some areas (Coastal areas in threemajor bays). Catastrophic flooding can be anticipated oncethe embankments are failed•Half of the population and three-quarters of total assets
are concentrated in low-lying areas. Major damage can be
anticipated when flooding occurs.

52011/5/30

Causes of Flood in Japan…..
• Rapid Urbanization.
Normally, the flow rate of rivers in urban areas isextremely low, but urban‐type floods frequently
occur when typhoons hit . The rain water falls to thecatchments, flows down rapidly and overflows
within a short period.
• High intensity rainfalls.
(1961‐ 342 mm per day ;per dayy
Julyy 13, 2004 ‐ 421 mm p
Over 100 mm per hour in the Tokyo Metropolitan
Area
Over 600 mm per 24 hours in Okinawa in 2010
• Typhoons are landing

River Law Amendment(1997) in Japan• Establishment of comprehensive riveradministrationd i i t ti systemtffor flflood
d control,t l watert
use and environmental conservation.
– Improvement and Conservation of river environment– Introduction of river improvement planning systemdesigned to incorporate the opinions of local
residents.

6

2011/5/30

New System for River Improvement Planning
Includes procedures for incorporating the opinions of the head of the local govt. and the
local residents(1) Basic
B i RiRiver M
Managementt P
Policyli
Dealing with matters basis for river improvement.
・Unregulated peak discharge
・Design flood discharge(2) River Improvement Plan
DealingDli withi h matters specifics
ifi concerning
i riveri
improvement
River projects, River maintenanceComprehensive Flood Disaster Prevention Measures

River Improvement

Retention Areas

Runoff Control

Detention Areas

Mitigation Measures

Low‐Lying Areas•Channel Improvement•Construction
Construction of Retarding Basins
asins ,Flood ways

7

2011/5/30

Comprehensive Flood Disaster Prevention Measures…..
Retention areas• Maintenance of controlled urbanization districts• Conservation of nature• Construction of reservoirs and regulating basins• Installation of permeable pavements and seepage sumps
Detention areas• Preservation of urbanization control zones• Control of landfill• Promotion of conditions favorable to agricultural activities
Low‐lying areas• Development of drainage facilities• Construction of storage facilities• Encouragement of use of flood‐proof buildings

River Categorization in Japan• Class A rivers‐Rivers or part of river systems
considered to be particularly important for the
maintenance of the land or national economy.
• Class B rivers‐Rivers or part of river systems(not part of class A rivers) considered to beparticularly important for the interest of the
public.
public• Law applicable rivers

8

2011/5/30

River Management in Japan• Class A rivers‐ managed by the Minister of Land,p ( of the total length)g )Infrastructure and Transport(7%(some designated segments are manage by Governorof the prefecture or mayor of Municipality.)• Class B rivers‐ managed by governors of Prefectures
or mayor of municipalities for designated cities.
• Law applicable rivers (small‐scale rivers)‐ managed
p mayors.
y
byy the municipal

Tasks of River Administrator• Flood management• River water use management• River environment management
Activities of River Administration Offices• Observe rainfall, river water level, river water qualityqy• Conducting Research on improvement of environment andthe river• Plan, design and construct river structures• Patrol to observe problems of structures, illegal acts

9

2011/5/30

Japan Meteorological Agency(on the water related disasters)• One goal of JMA‐Prevention and Mitigation of
N t l Disasters
Natural
Di t• Responsibility‐ Issuing weather/tsunami
warnings and advisories, provide reliable andtimely information to governmental agencies
and residents for the ppurposespof natural
disaster prevention and mitigation.

FLOOD EARLY WARNING IN JAPANSustainable,
effective andReliable FLOOD
Early warning
systems areavailable inJapan throughcontinuous
monitoringprocedures102011/5/30

JMA’s Meteorological Services

2

1

2

Observations(1) Satellite Observation(2)U(2)Upper-air
i Ob
Observationti3(3)Radar Observation(4)Surface Observation by AMEDA systems (Automated Meteorological
Data Acquisition System)- Rainfall, Wind, Temperature, Sunshine(5)Ocean Observation(6)International Data Exchange(7)Measuring soil water Index
4

Framework of Forecast Operation (JMA)
Operates a number of observatories and whether stations across the country
National Forecast Center

Regional Forecast Centers (11)Local Meteorological Observatories (47)
LMO:
•LMO is responsible for provide information on weather for each prefecturaland sub- prefectural level as well as 8 weather stations.
• Numerical System for Weather Prediction•Real time information on rivers could be easily obtained through Internet.
• Internet Portal in Hyogo-weather warnings/advisories are readily available.
Through this, river Information (Rainfall, water level), road Information(rainfall, snow), Sea Information (elevation of tide) can be obtained.

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Main Objective of Local Meteorological Observatories(47)
Disaster Forecasting to save lives– Collecting weather and EQ data
– Analysis and Prediction of Weather– Issuing Warnings and Meteorological Information

Kobe Local MeteorologicalObservatory office

Methods used to acquire real time weather data by Kobe Local
Meteorological Observatory Office(1)Using AMeDAS (AutomatedMeteorological Data Acquision System)-Wind-Temperature-Rainfall-Sunshine
All the systems are computerized anddata can be monitored through thescreen.
There are 26 AMeDAS installed in Hyogo Prefecture.
There are 1,300 AMEDA Systems in Japan.

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2011/5/30

Methods used to acquire weather data by Kobe Local
Meteorological Observatory Office……..

(2) There are 258 Rain-gaugesiinstalled
ll d bby L
Locall G
Govt. withih
corporation with National
Govt. in Hyogo prefecture.
All the systems are computerized
and data can be monitored
through the screen.

Methods used to acquire weather data by Kobe Local
Meteorological Observatory Office……..

Method for Observe Weather Condition (Small
rain drops, snow…) – Can not measure theamountSnowfall observation13

2011/5/30

Methods used to acquire weather data by Kobe Local
Meteorological Observatory Office……..

Plants to observe variations
due to seasonal difference

Methods used to acquire weather data by Kobe Local
Meteorological Observatory Office……..
• (3) Using Radar Systems
There are 20 radar systems in Japan.
O in
One
i O
Osaka
k P
Prefecture.
f tArea information (Approximate Rainfall and Cloud information
can be observed from Radar.

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2011/5/30

Weather Analysis and Prediction System
in collaboration of Hyogo Prefecture & Kobe Local
Meteorological Observatory Office

Dots indicate therain-gauges
installed in Hyogo
Prefecture

Weather Analysis and Prediction System
in collaboration of Hyogo Prefecture & Kobe Local
Meteorological Observatory Office

Triangles indicate theWater level measuring
gauges in Hyogo
Prefecture15

2011/5/30

Weather Analysis and Prediction by Kobe Local MeteorologicalObservatory Office……..
• By analyzing data collected by AMeDAS, Rain‐gauges and Radar systems,
1 km2 pprecise data can be observed.

Show rainy clouds insome area

Hyogo Prefecture Govt. Office• Responsible for disaster prevention•••

684 rivers in Hyogoy g Prefecture.
Total Length : 3,494 km
Published Hazard map to the public through internet giving information ofinundation level and evacuation centers.

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2011/5/30

Dissemination of River Information by River Management
Improving Division ,Hyogo Prefectural Govt. Office• Automatic system to warn municipalities.
municipalities• 113 alarming systems to warn the public.
• 32 Cameras are fixed in Hyogo prefecture in major flood
points along major rivers. They are going to increased thenumber of cameras up to 124.
• Municipalities also fixed cameras along the river. 30 cameras
are fixed by Kobe Municipality.
• National Govt. installed cameras along A rivers.
But in heavy rainy situations it is difficult to observe camera
images from the screen.

Hyogo Prefecture Disaster Management Weather Information
Top Page: Warning and Advisory17

2011/5/30

Hyogo Prefecture Disaster Management Weather Information: Link (MLIT
Page)
Current Precipitation by Rain Gauge

Hyogo Prefecture Disaster Management Weather Information
Rain Cloud (Current Situation & Prediction)18

2011/5/30

Hyogo Prefecture Disaster Management Weather Information
Current Precipitation Data Through Radar

Hyogo Prefecture Disaster Management Weather Information:
Link (MLIT Page) Observation Station<-Rain gauge<-Water Level gauge

192011/5/30

Indication of Rainfall in the Screen• Blue color ‐ Normal rainfall• Yellow color ‐ Rainfall> 15 mm/hr• Red color –Rainfall> 20 mm/hr• Red color‐ Rainfall exceed 50 mm in 24 hours

Hyogo Prefecture Disaster Management Weather Information:
Link (MLIT Page)
Current Precipitation by Radar

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2011/5/30

Hyogo Prefecture Disaster Management Weather Information:
Link (MLIT Page)
Current Water Level by Water Level Gauge- Warning Level- Alert level- Normal Level•Calculation method isused to predict water level.
•Flood predictions updated
in every 10 minutes

Responsibility of Municipalities• Flood management of law applicable rivers.
• Flood observation and prediction.
• Issuing Evacuation orders.
Evacuation Procedure:• Municipalities work 24 hours in heavy rainypperiods.
• Each Municipality has fire dept.(7* 24 hr.)This take the necessary action for issuing early
warning to the public and evacuation.

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2011/5/30

Kobe Municipality Precipitation Information System
Current Precipitation by Radar

Kobe Municipality River Monitoring System
Location of Observation Cameras

22

2011/5/30

Early warning activities in the Toga River in Kobe Municipality

CC Cameras (CLOSED –CIRCUIT TELEVISION) fixed to the river banks
to monitor the river water

23

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Water level measuring gauges and senses are fixed
to the river banks
Dangerous level

Warning level
Alert level

Speakers are installed along the riverto give announcement242011/5/30

Flash lights are installed along the river to warn community

Sign Boards are fixed to the river banks

25

2011/5/30

Kobe Municipality River Monitoring System
The Image taken by Monitoring Camera in the TOGA river

Water Level

Current condition

Normal Situation

The Image taken when a flash flood occurred at the TOGA river in 200926

2011/5/30

The Image taken when a flash flood occurred at the TOGA river in 2009

Flood Mitigationg
Activities
in Japan27

2011/5/30

River Zoning inJapanRiver Improvement
Tsurumi River

Before improvement

After improvement282011/5/30

River Improvement
Tsurumi River

Retarding basin

Multipurpose Retarding Basin for Tsurumi River

Dike

Overflow type dike

Dike

Overflow typedike

Example of Use as Multipurpose Facilities
Kirigaike regulating reservoir ,Kanagawa Prefecturenormally used as atennis court

Kirigaoka Regulating Pond
(Tsurumi River)In flood times

29

2011/5/30

Aerial view of a group of storm water detention ponds

Storm water detention ponds covered with bluish green screens

Basin Measures
Example of general storm water detention pond30

2011/5/30

River management activities at
Amagasaki in Hyogo prefecture. Land surface is lower than the sea
l l inlevel
i thisthi area.

Sea‐gates to prevent sea water intrusion in
Amagasaki in Hyogo Prefecture
Lock 2

Lock 1
Kyuu samondo River mouth31

2011/5/30

Wall around the sea beach to preventsea water intrusion

Pump Kyu samondo river water tothe sea
Control Center of Lock in Amagasaki

Tohin drainage pumping station(Water pumping capacity 72 m3 /s)32

2011/5/30

Water‐gauge beside of the water
control centre

water levels in 1934 and 1950 are marked
in this gauge.

Samondo River in Hyogo Prefecture
Matsushima Drainage pumping station topump river water to sea
Water pumping capacity : 91 m3 /s

Gate across the river to prevent
garbage flow down to the sea

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2011/5/30

Low‐height old dam across the Shoge river to overflow
water

Keep water levelsteady in upside.
This provide facility
to catching fish.

Primary stage of construction in upper part of Shoge river

Instruction Board fixed to the river bank34

2011/5/30

Underground Drainage Channel
to retain and circulate flood waterThis is situated in upper
part of Shoge river

Koyagawa Drainage Pumping
Station
4p
pumps
p are in here
Drainage capacity:
25 m3/s
Water pumps to the
Inagawa river .

35

2011/5/30

Construction of Inagawa river

FLOOD MANAGEMENTIN SRI LANKA

36

2011/5/30

TYPES OF FLOODS IN SRI LANKA
 RIVER OVER FLOW FLOODING DUE TO SEA WATER-Storm Surge/Cyclone-Tsunami FLASH FLOODS URBAN FLOODS FLOODING DUE TO BREAKINGRESOURVORS AND RIVERS

OF

DAMS

IN

RIVERS IN SRI
LANKA
Out of the 103 river basins,
Kelani Kalu,
Kelani,Kalu Gin , Nilwala and
Mahaweli experience floods
every year.

Flood occurrences in theeastern slopes and plainscoincide with the North-East
rainfall season,season September toJanuary.
In western slopes floods occurs
during North-East rainfall
season, but more common inSouth-West season from May
to August.

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2011/5/30

Flooding in Sri Lanka

Physiography of Sri Lanka• There are three major
j ppenne-plainspin terms of elevation in Sri
Lanka and the area between each adjacent penne-plains
usually consists of steep slopes, steep and narrow valleys,
spurs.
• All major rivers start from the central hills. When themountainous areas receive intensive rainfall,, all flatten areasthat are situated surrounded by this hilly region gets flooding
within a short period of time because of rapid water flow down
steep valleys to increase the water level suddenly in highly
populated downstream planer areas

In Sri Lanka, sudden floods are experienced by lowland areas due
to its Geomorphological existence

3rd Penne Plain

2nd Penne PlainSTEEP SLOPES

1st Penne Plain

SEA

SEA

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2011/5/30

VERY FAST FLOOD WATER FLOWDOWN STEEP VALLEIESSUDDEN FLOODING OVER LOWLAND AREAS

Recent Flooding in Sri Lanka‐ February, 2011

39

2011/5/30

10.0

10.0

9.5

9.5

9.0

9.0
1400 mm

8.5

1200 mm8.5

3500 mm3000 mm1000 mm8.0

2000 mm

8.0
800 mm

1500 mm
7.5

7.5600 mm
1000 mm
7.0

400 mm
7.0

500 mm

200 mm
6.5

200 mm
6.5
0 mm
0 mm

6.0

6.0

5.5
79.5

80.0

80.5

81.0

81.5

82.0

5.5
79.5

NORTHEAST MONSOON (DECEMBER TO FEBRUARY)

NE Monsoon-( December-February)

80.0

80.5

81.0

81.5

82.0

SW Monsoon- (May- September)

SOUTHWEST MONSOON (MAY TO SEPTEMBER)

Second Inter monsoon

First Inter Monsoon
10.0

10.0

9.5

9.5

9.0

9.0

3500 mm3500 mm1000 mm

8.5
700 mm

8.5

800 mm

600 mm
8.0

8.0

700 mm

500 mm
7.5

7.5

500 mm

300 mm
7.0
200 mm

7.0

400 mm

200 mm

100 mm
6.5

6.5

0 mm

0 mm
6.0

6.0

5.5

5.5
79.5

80.0

80.5

March-April

81.0

81.5

FIRST INTERMONSOON (MARCH TO APRIL)

82.0

79.5

80.0

80.5

81.0

81.5

82.0

October- November

SECOND INTERMONSOON (OCTOBER TO NOVEMBER)

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2011/5/30

Precipitation and irrigation map of Sri Lanka
Wet zone of SRI LANKA :•This area is prone to severe flooding
frequently.
•A large number of major rivers are
fl i throughflowingthh thisthi Zone.
Z•Human settlements located on theriverbanks and low-lying areas aremainly subjected to flooding.

During the heavy rain in 2011, most of earth bunts of ancientirrigation tanks (lakes) were broken causing damages toagricultural lands, properties and even to human lives. (NorthEast part of the country)
School41

2011/5/30

MAN MADE CAUSES

Deforestation in catchments has drastically reduced water
retention capacity and has increased the silt in down stream area42

2011/5/30

Poor Cultivation Practices on Upper Catchments has caused severe soil erosion tolower the water retention capacity of downstream area to increase rate of flooding

Mud water during flooding indicates how
much soil erosion takes place

Severe Silt through Soil erosion in Catchments

43

2011/5/30

Construction by blocking water ways

ILLEGAL LAND FILLING

44

2011/5/30

A recent land fill has caused flash flood toadjacent populated area

Zoning must be done along the River Valley‐ Flood Prone area45

2011/5/30

Unplanned and Illegal settlements in flood prone area in Sri Lanka‐ (Restricted
and Prohibited area)

CONSTRUCTION IN BUFFER ZONES- RATHNAPURA-SRI LANKA

46

2011/5/30

FLOOD PRONE AREA OFGURUGODA STREAMFUNNY CONSTRUCTION

47

2011/5/30

Effect of urbanization on flood runoff

BeforeAfter

In the recent past, highly populated areas wereseverely affected by flash floods, which were totallycaused byUnplanned human activities such as illegal and inappropriate
construction, blocking of water ways through unplanned
construction, poor waste dumping procedures,Unplanned land use practices,Low land reclamation
River sand miningcultivation on hill slopes without applying soil erosion
prevention practices

Flooding in 2011 caused by heavy rainfall due tosudden change of climatic condition. Improper
land use practices worsened the situation.

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2011/5/30

EVEN THOUGH INFORMATION ON RAINFALL DATA
AND WATER LEVEL DATA ARE COLLECTEDREGULARLY, FLOOD EARLY WARNING SYSTEMSNEED TO BE FURTHER IMPROVED
NEED OF BETTER COORDINATION,
COMMUNICATION AND INFORMATION SYSTEMAMONG DATA COLLECTORS, GOVERNMENT,VULNERABLE COMMUNITIES AND PEOPLE LIVING
IN CATCHMENT AREAS
FLOOD EARLY WARNING DISSEMINATION ARE STILLNOT IN PROGRESSFLOOD EARLY WARNING IN SRI LANKA

Every year,
year during rainy seasons people who are living in thedownstream areas are severely affected by flood. However,
unfortunately, there is still no proper early warning system established
to issue flood warning to people escape from the incidence. Timely
Warning, Quick response, evacuation procedures are yet to becommencedup

49

2011/5/30

PROBLEMS ENCOUNTERED IN MITIGATION OF FLOODS IN SRI
LANKAAll the riverbanks are highly populated Construction of flood retentionlleveesi a difficult
isdiffi lt task.
t k•Negligence of the people
Although, the institutions are carrying out public awarenessprograms, public participation is still unsatisfactory.
•Although, Government has introduced several favorable construction
methodologies for flood prone areas, people never follow such
construction methodologies.
methodologies
Reason : Most of the people living in flood prone areas are not having
the required financial strength.
•Currently, river gauging stations are operated in most of the rivers but
their use is still limited to measuring of discharge and rainfall intensity.

Early warning can be issued by measuring Precipitation in Catchments
and Flood Level in Flood Prone area
Catchment area
Rain Gauge

Flood Prone Area
Flood Gauge*Threshold Value for Rain-fall and Time taken
to Flood the Low Land area can be easily
calculated. Early Warning to vulnerable people
can be disseminated easily.

50

2011/5/30

Flood Management in Sri Lanka• Irrigation Department is responsible forplanning,li ddesign,i construction,t ti
operationti anddmanagement of all major and medium
Irrigation schemes and works related to flood
control, drainage and salinity extrusion.
• Disaster ManagementgCentre is responsiblepfor Dissemination of warnings to the public.

Rain gauges and Water level gauges are installed in
Kalani River catchment512011/5/30

Flood Gauge at Tuntota,
Gurugoda Stream
Flood Gauge at Flood
Prone Area of Gurugoda
StreamOne of the rain gauge incatchmentsofGurugoda Stream. This
type of rain gauges areoperated by Plantationcompanies since theperiod of British Rule52

2011/5/30

Daily Rainfall Recorded byaRubberPlantation
Company
situatedinCatchment Area

•Need of proper coordination
between data collectors, govt.
departments community in flood
departments,
prone areas and community in thecatchments .
Timely Warning, Quick response, evacuation•Timely
are yet to be commenced .

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2011/5/30

RESULTS

Output of this research is immense help forestablishing a real time early warning methodology to
all flood prone areas in Sri Lanka since at present;such a sophisticatedpand effective systemyis notpresent in the country.

Thank You for your attention

54