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Integrating Local & Indigenous Knowledge with

Science & Technology for Flood & Landslide Control:

Case studies from Japan and other countries

1. Revival of indigenous methods of flood control in Japan

2. Validation of omens as indicators for early warning and theirpractical application

3. Development of hydrological equipment for community early

warning to monitor concentrated rainfall increasing as a result of

climate change

4. Education in Cuba19 April 2013

Hidetomi Oi

Ex-JICA Senior Expert on Water Resources Development and Disaster Reduction

19 April 2013


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1. Revival of indigenous methods for flood control in Japan

Retarding basin

Open levee

Ring levee

Base raisingForest beltMattress

Skeleton

Secondary levee

1600s-1800s (Feudal era)

Variety of indigenous methods

suitable for local conditions weredeveloped, encouraged by feudal

governments, as shown in the figure.

1896-1976 (Meiji era)

Long high levees were constructed

to confine floods in the river, applying

advanced technologies and using

heavy machines.

1977-

Comprehensive Flood Control including construction of rain water storage and infiltration

facilities in housing development areas to reduce flooding of urban rivers.

1996-

Revival of indigenous methods in view of theirresilience against extremes as well as

environmental merits, allowing inundation but avoiding total destruction and leading to early

recovery. In 2010 JICA prepared Handbook on Climate Change Adaptation in the Water

Sector :A Resilient Approach that Integrates Water Management and Community

Development which emphasized resilience. This shift is being accelerated learning from

lessons from the tsunami disaster on 11 March 2011.


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Example of indigenous methods

Ring leveeRing levees are seen in

deltas of Ganges-

Brahmaputra(Bangladesh),

Ayeyarwadi(Myanmar),

Kiso(Japan) etc.

Open levee


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Forest belts on the river side reduce

impact of floods and protect levees andhouses etc.

Forest belts on the inner side reduce

energy of overflowing floods and protect

levees and houses etc.

Forest beltForest belts


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Traditional river works

Skeleton works

Mattress worksMattress works Skeleton works


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Gabion works

Bamboo gabionswere used for

urgent rehabilitation

works in Japan.

Gabions are used

popularly in

developingcountries.


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River bank protection with used tires, Trinidad and Tobago

Slope protection works using

used tires, Sri Lanka


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Storage and infiltration have been given priority as a basin approach tomitigate flooding of urban rivers since 1970s

Storage : roof top, park, playground,

parking area etc.

Infiltration :porous pavement


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Example of storage

Playground

Small park and tennis court

Parking area


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0

200

400

600

800

1000

1200

1400

0 6 12 18 24 30 36 42 48

Time (Hour)

Discharge(m3/s) Qp = 880m3/s

States Quo

Qp = 1,090 m3/s

Year 2050 under Secenario B1

Qp=1,300m3/s

Year 2050 under Secenario A1FI

Study on Comprehensive Flood Mitigation for Cavite, Metro

Manila, Philippines (JICA 2009)An example to address flood problem of urban rivers due to urbanization

and climate change. The principle is basin approach with emphasis on

storage (retarding basin, storage ponds), in addition to river works

(widening, dredging, embankment).

2008 2050

Peak discharge 880 m/s 1,300m/s (1.5)

Inundated house 21,800 houses 74,200 houses (3)


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Storage ponds in housingdevelopment areas (Cavite, Philippines)

Retarding basins along rivers(Cavite,Philippines)


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2. Validation of omens (signs, symptoms) as indicators

for early warning and their practical application

Omens had long been used for early warning especially for sediment

related disasters, but as science/technology developed, such a

practice gradually diminished.

However, recent surveys disclosed that although people were

reluctant to evacuate even with instructions from mayors, they didevacuate if they perceive any omen. It was also disclosed that

instructions of mayors were not always appropriate in terms of timing

as well as contents of messages.

Accordingly, Government (Min. of Land, Infrastructure and

Transport) conducted a survey to validate omens from scientific pointof view in 2006. As a result of survey of 71 disaster cases, a total of

30 omens were identified as meaningful indicators for early warning.

Local governments are considering to incorporate the results of the

survey into Disaster Management Plan and school curriculum.


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2

Survey Sheet

Rainfall(hourly and

accumulated)Weather

conditions

Government

actions (centraland local)

Witnesses

on omens

Disaster


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SLOPE FAILURES

1. Cracks, Falling of cobbles, Swelling of slopes

2. Spout of water from slope; Springs become

muddy.3. Tilting of trees, Trembling of trees

4. Ground rumbling

DEBRIS FLOWS

1. Slope failures in mountain slopes, Falling of

cobbles

2. Decrease in river water while rains continue.

3. Ground rumbling, Sounds of trees being split

4. Smell of decay

LANDSLIDES1. Deformation of ground; Cracks in slopes, foot

path, pavement, walls

2. Water of wells, streams becomes turbulent.

3. Sudden decrease in water level (ponds etc.)

4. Sounds of trees being split

Progress of hazardous phenomena and omens perceived


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Supplementary reader for elementary school illustrating

omens for debris-flows, landslides and slope failures

respectively

Omens for the case of debris-flows


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3. Development of hydrological equipment for community

early warning

As a result of climate change, locally concentrated rainfall has been

increasing, causing flash floods and sediment related disasters.Such localized rainfalls can not be monitored by government

observation networks and should be monitored at each community

for timely actions.

Various equipment have been developed. The one shown below has

been developed in the Caribbean and Japan which is suitable forcommunity early warning due to following advantages:

Cheap in cost

Easy for assembly, operation and maintenance

Safe observation in the house

Short, heavy rainfall even in

the mid-night will be measured without fail due to the alarm device.


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Ordinary water level gage. It is

dangerous to go out to the observation

site to observe the sudden rise of water

level in the mid-night under heavy storm.

Workshop for assembling the equipment

for government staff in Fiji in 2012 (left)

and in Nepal in 2011(right)


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Community based landslide

early warning system,

developed by Gajamada

University, Indonesia

Community flood early warning with a

sensor of two stainless rods beneath the

floor, developed by a person of electrical

appliance shop, Mindanao, Philippines


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4. Disaster education in Cuba, which supports the most

advanced in the world in disaster management

management

Education startsas early as at

kindergarten

At elementary school using

paper TV

Disaster Management Club at

junior high school


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THANKS