Rapid Field Investigation on Flooding in Rajang Delta

Corus Hotel, KL 8 June, 2015

Alex K Sayok, Mah Yau Seng, Lee Guan Heng,

Wong XY, & Yong WL.

PRESENTATION FORMAT

• INTRODUCTION

• METHODS

- STUDY AREA

- MEASUREMENT METHODS

-ANALYSES/CALCULATIONS

• RESULTS

• DISCUSSIONS

• CONCLUSIONS & RECOMMENDATIONS

INTRODUCTION

Malaysia as part of the World: Climatewise Published: Monday January 19, 2015 MYT 12:00:00 AM Columnists: Martin Khor is executive director of the South Centre, a research centre of 51 developing countries, based in Geneva.

This increase could be associated with natural variability in sea surface

temperatures of the equatorial Pacific Ocean (El Niño/La Niña events) and the

Indian Ocean (Indian Ocean Dipole).

Recent events and climate science strongly indicate that 2014 downpour and

floods are not one-off events but part of a national, regional and global pattern

linked to climate change and extreme weather events. And that the situation

worsen, more and more, in future years and decades.

According to data in a 2012 Malaysian Meteorological Department, Malaysia has

experienced increase in temperature, consistent with the global warming trend,

leading to changes in weather (major wind patterns, amount and intensity of

precipitation, and increased frequency of severe storms and weather extremes)

Recent great floods

The new weather pattern in Malaysia includes both heavier rainfall and dryer

spells – even within the same year causing water shortages in various states

with high-rainfall and flooding months in other states or even the same states.

The lesson - pay more attention to increasing extremes and extreme events in

the weather, counteract their causes and deal with their effects - having plans

for mitigation, adaptation and loss-and-damage.

Top on the list is to stop further deforestation. The widespread chopping of

trees, especially in highland areas, is a major reason why intense rainfall causes

so much flooding.

-The natural tree cover breaks the falling rain and allows the gentler drip of water to seep into the ground, providing ground-water to flow into reservoirs.

-When trees are removed, the rain falls heavily onto the ground, removes the soil, and water plus the soil is swept into streams and rivers, which get clogged up with soil and which are also filled quickly with the high volume of rain water.

Flood situation getting worse in Sarawak Published: Wednesday January 21, 2015 MYT 12:00:00 AM

Nation

• Most of the flood hit victims were in the south and north of Sarawak.

• In areas like Matu, where flood waters were about one metre above ground level, electricity supply was cut off as a safety measure.

What about Flood in peat swamps & development and impacts

METHODS

The Team

Objectives

• Evaluate whether oil palm plantation areas are flooded - how frequently, how long, to what depth, through field assessment in the wet season and discussion with local inhabitants / workers.

• Determine status of OP plantations in areas suspected to suffer from waterlogging and possibly flooding.

Scope of work • field inspection at oil palm plantations

• Measurements at each location Location

• General (GPS-coordination, concession license holder (if possible), municipality)

• Date of plantation establishment and palm oil age

Peatland in Sarawak

- 850,000 ha peatland

Peatland in Sarawak Total = 1,800,000 ha

Rajang Delta

Rajang Delta

Rajang Delta

Rajang River

.

Rajang Delta

• almost entirely of peatland with a negligable area of mineral soil and is already largely drained by industrial oil palm plantations

• already largely been cleared and drained by industrial oil palm plantations in the last decades.

Land Use - have largely been cleared and

drained for oil palm plantations in the last decades.

- In 2014 half occupied by large-scale oil palm (and a few sago) -Smallholder oil palm, and degraded forest

Flood prone (Blue) – flood plain, lowlying areas Extreme Floods (Green) - extreme weather conditions

SIBU

MATU

IGAN

OYA MUKAH

DARO

SARIKEI

BALINGIAN

B A

C

D

E F

G

H

K

L M

J

O

N

P R Q

S T

Z Y

X

V

U

Area Sampled

Sibu

Mukah Oya

Igan

Measurement of water level

Stream channel, main drains, canals

Measurement of water level

Stream channel, main drains, canals

Peat Depth, Groundwater Level measurements

Peat Clay

Palm Height & Diameter Measurement

OBSERVATIONS IN SAGO AREAS

RESULTS

SIBU • Floods occurred in riverine areas upto 1.5m, upto > 10 days

• Caused by heavy rain during wet monsoon

• Upstream development activities

• Siltation in Rajang and poor drainage in Sibu Town

• Initial Flood Mitigation (Phase 1 and 2) and Bakun Dam did little to ease flooding in Sibu

• Subsidence are evident in many parts of the town (roads, buildings)

MUKAH • Floods occurred in riverine areas upto 1.5m, upto more than

2-3 days

• Caused by heavy rain during wet monsoon

• Not much upstream development activities but tidal

• Subsidence not evident but many rusty man-hole covers

Urban Sibu and Mukah Floods

Sibu Town

Jalan Rambutan Sibu

Subsidence in Sibu Town

Floods in Rajang Delta: Kpg Tian Matu

Matu Flood

Riverine villagers

Coastal villages

Flood in oil palm plantation

Water management/control

UPSTREAM

DOWNSTREAM

Water level maintained at collection drain

Water level at main drain

Peat Depth and Ground water Level

Peat Clay

14ft = 4.75m mark

Even close to 15 feet (5m), it was still peat. In such areas, water also fluctuated quite drastically especially drains nearby the Stream site.

PHYSICAL FEATURES Point

Canal Dept (m)

Physical features Water

Level (m) Peat Depth

(m) Calculated

subsidence1 (m)

Estimated Original

Peat surface2

(m)

Max Flood level (m)

A -0.05 0 3.0 1.62 4.62 1.45 B -0.40 -0.40 0.90 1.56 2.46 1.45 C -0.40 1.15 1.45 1.56 3.01 0.45 D -0.25 0 >3.0 1.50 >4.50 1.0 E -0.25 -0.30 >2.0 1.56 >2.56 1.0 F -0.30 0 >3.0 1.56 >4.56 0.75 G -0.60 -0.54 >3.0 1.56 >4.56 1.0 H -0.50 -0.33 2.83 1.30 4.13 1.5 I -0.70 -0.70 >3.0 1.30 >4.30 1.5 J -0.90 -0.75 >3.17 1.24 >4.41 1.5 K -0.70 -1.10 4.28 1.24 5.52 1.0 L -0.40 -0.50 >4.12 1.24 >5.36 1.25 M -0.45 -0.07 >4.72 1.24 >5.96 1.25

PHYSICAL FEATURES Point

Physical features

Canal Dept (m)

Water Level (m)

Peat Depth (m)

Calculated subsidence1

(m)

Estimated Original

Peat surface2

(m)

Flood Level (m)

N -0.90 -0.50 >1.6 1.62 >3.22 1.0

O -1.2 -0.70 >1.5 1.62 >3.12 0.85

P -1.0 -0.35 >2.0 0.72 >2.72 0.90

Q -0.60 -0.35 >2.55 1.62 >4.17 0.75

R -1.2 -0.38 1.40 0.72 2.12 0.50

S -1.2 -0.45 >1.96 1.62 >3.58 0.50

T -0.95 -0.48 >2.0 0.66 >2.66 1.45

U -0.95 -0.56 >5.0 0.66 >5.66 1.45

V -1.2 -0.31 >4.0 0.66 >4.66 1.20

W -1.2 -0.47 >2.0 0.72 >2.72 1.20

X -1.2 -0.88 >2.2 0.72 >2.92 1.25

Y -1.1 -1.34 >5.3 0.66 >5.96 1.30

PALM CHARACTERISTICS Point

Palm Characteristics Remarks Palm

age, year

Diameter (cm)

Height (m)

% Lean

ing4

% Fruit ing4

Productivity5

(ton/ha/yr) Min Ave3 Max min Ave3 Max

A 17 59 79.5 67.95 3.6 7.56 9.9 10 22.2 18 with peak of 24

100% healthy, 30% with exposed roots 46.1 cm of visible subsidence

B 16 56 72.8 87.5 7.2 8.82 9.9 15 40

C 16 64 80.4 95.5 7.2 9.63 10.8 15 10 100% healthy, 80% with roots exposed

D 15 63 69.05 81 0.9 3.96 5.4 20 20 100% healthy, 50% with roots exposed

E 16 59.5 65.8 70.5 5.4 7.56 9.9 20 60 100% healthy, 20% with roots exposed

F 16 57 62.95 69 3.6 5.4 7.2 20 60 90% healthy, 10% with roots exposed

G 16 61 72.7 79.5 3.6 6.12 9 15 90 100% healthy, 40% with roots exposed

H 10 57 72.4 84.5 2.3 2.87 3.5 10 100 14 100% healthy, 20% exposed roots

J 10 58 66.35 73 2.6 3.34 3.8 10 100 100% healthy, 40% with roots exposed

K 9 61.5 74 84.5 0.9 1.34 1.5 15 70 5 100% healthy

L 9 63 70.8 84.5 1.7 2.71 3.6 15 70 100% healthy, 40% with roots exposed

M 9 51.5 58.35 79.5 0.8 1.41 2 15 90 100% undersize N 9 57 62.6 70 0.8 1.75 2.2 15 70 100% undersize, 70% yellowish,

30% unhealthy

PALM CHARACTERISTICS Point

Palm Characteristics Remarks Palm

age, year

Diameter (cm)

Height (m)

% Lean

ing4

% Fruit ing4

Productivity5

(ton/ha/yr) Min Ave3 Max min Ave3 Max

N 17 64.5 72.65 77.5 2.5 4.11 10.8 50 100 14 100% healthy but all with exposed roots

O 17 48.5 65.1 78.5 7.2 10.17 12.6 20 100

P 2 52.5 77.55 89.5 0.7 1.02 1.2 0 100 - Healthy but yellowish

Q 17 51 72.2 85 5.3 7.04 10 20 60 14 Healthy but 100% are yellowish, exposed roots

R 2 68 80.35 90.5 0.5 0.7 0.8 0 100 - Healthy but 100% are yellowish

S 17 52 63.55 78 4 5.5 6.5 20 100 14 100% healthy but with yellowish & exposed root

T 1 0 0 0 0 0 0 - - New, so no harvesting yet

Healthy young seedling At Sg Baoh

U 1 0 0 0 0 0 0 - - Healthy young seedling At Sg Baoh

V 1 0 0 0 0 0 0 - - Healthy young seedling. At Sg Narub

W 2 44 62.05 73.5 0.4 0.62 0.7 - 80 Healthy young seedling. At Sg Kelid

X 2 48 82.5 96 0.6 0.75 0.9 - 90 Healthy young seedling. At Sg Kelid

Y 1 0 0 0 0 0 0 - - Healthy young seedling. At Sg Sabrasau

Flood Impacts

HEALTHY H J L

10 10 10

1.5 1.5 1.0

7 7 10

10 10 15

100 100 90

72.4 66.35 70.80

2.87 3.34 3.60

14

14 14

UNHEALTHY K M N

9 9 9

1.5 1.25 1.25

>20 >20 >20

15 15 15

70 90 70

74.00 58.35 62.60

1.34 1.41 1.75

5

5 5

Location

Age (years)

Max Flood level (m)

Duration (days)

Leaning (%)

Fruiting (%)

Ave. Diameter (cm)

Ave. Height (m)

Productivity (ton/ha/year)

Sg Rasau

Flood Impacts

HEALTHY P R T

17 17 17

0.85 0.75 0.50

10 10 10

20 20 20

100 100 100

65.1 72.20 63.55

10.17 7.04 5.50

14

14 14

UNHEALTHY

O

17

1.00

>10

50

100

72.65

4.11

14

Location

Age (years)

Max Flood level (m)

Duration (days)

Leaning (%)

Fruiting (%)

Ave. Diameter (cm)

Ave. Height (m)

Productivity (ton/ha/year)

Sg Mudan (Oya)

He i gh t

Location of sampling points

Oil palm Height & Diameter Vs Groundwater Groundwater

Di ame t e r

Oilpalm height (m) and groundwater level (m) for each sampling location/point

Oilpalm diameter (m) and groundwater level (M) for each sampling location/point

Groundwater

Location of sampling points

LEANING

OCCURS IN BOTH FLOODED N NONFLOODED AREAS

LEANING

HIGHER % NEARBY DRAINS

LEANING (MUDAN)

LESS FREQUENT FLOODS

FREQUENT FLOODS

Height and Fruit (Sg Rasau)

HEALTHY UNHEALTHY

Height =2.87m Fruit = 100% Productivity= 14

Height =1.34m Fruit = 70% Productivity= 5

Sg Rasau

SILTATION/SEDIMENTATION

Frequently flooded site (Mudan)

Height =4.11m Fruit = 100% Productivity = 14

Frequently flooded

Less Frequently flooded

Sg Baoh

CONCLUSIONS

URBAN FLOODS

• Floods in urban areas (Sibu & Mukah) are more publicised

• Floods in Sibu – caused by rains, discharged from upstream, wet Monsoon & king tide aggravated the situation

• Floods in Mukah are mainly tidal

CONCLUSIONS PEAT SWAMPS

• Peat depths = 1.40 – more than 5.0m (deep to very deep)

• Water level = 0.00 – 1.2m

• Subsidence = 0.66 in one-year to 1.62m in 17-yr

• Leaning = in all sites but higher 50% in flooded Flooding = 5-15% of plantation areas (upto 15 days, more than 1.0m)

• Flooding can affect/reduce upto 67% of the palm yield

Development in peat caused subsidence. In more frequently flooded areas, %leaning are higher, decreased health (growth) of oil palms and thus decrease productivity.

THANK YOU

lessons of recent great floods

• Besides conserving the forests, there are many other ways to mitigate and adapt better.

• The damage begins in the upper reaches of the river and is transformed into devastation as the engorged river reaches town areas, breaches its banks, and the raging waters sweep along houses, cars and everything else in its way.

• These include replanting of trees in deforested areas; soil conservation as a strategy and major activity all over the country; de-silting of rivers and streams; the vast improvement of drainage in urban and rural areas; climate-proofing of buildings, including building new schools and houses on stilts or on pillars in flood-prone areas; protecting coastal areas from storms, winds and high waves including through conserving and replanting mangroves.

• There is also the whole set of activities for better management of floods and other disasters, including establishment of permanent evacuation centres; early warning systems; earlier and better systems of evacuation; stocking and distribution of food, clean water, medicine and other essentials to victims; plans for repair and rehabilitation; and the up-front allocation of financing.

• If we treat the “great floods” not as once-in-20-years or once-in-a-lifetime events, but as part of the “new normal”, then the plans for a better eco-system and for managing the disasters can be made more systematically, and a significant budget for regular financing can also be set aside.

• Let’s hope that we do learn the lessons of the recent great floods and prepare comprehensively to prevent, mitigate and manage them effectively. We may not be able to achieve “Never the floods again”, but we must achieve “Effectively manage the heavy rains and floods that are sure to come”.