The Seashore Life of the Brunei Heart of Borneo
Volume 1:
The Physical Environment
by
Roger McIlroy
and
John Elder
Photographs
by
Roger McIlroy (RM)
John Elder (JE)
Hans Dols (HD)
1st Edition: Nov 2008
Panaga Natural History Society
Panaga, Seria, Brunei Darussalam
This early morning view of the Heart of Borneo peatswamp rainforest captures the
tranquillity, mystery and diversity of this precious resource (RM)
Published by
Brunei Press Commercial Printing Services
Lot 72, Perindustrian Beribi II Gadong BE1118
Locked Bag No 2 MPC Berakas BSB BB3510
Negara Brunei Darussalam
Email: [email protected]
Website: www.bruneipress.com.bn
Tel: +673 245 6170
1st Edition published in Nov 2008
ISBN 99917-32-21-7
Copyright © 2008 in text: Roger McIlroy and John Elder
Copyright © 2008 in photographs: Roger McIlroy and John Elder or as credited
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted,
in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior
written permission of the copyright holders.
Contact the authors and find out more about this series via:
PNHS website: http://www.bsp.com.bn/PanagaClub/pnhs/index
Cover Photograph: Cumulonimbus on the horizon casting a huge aerial shadow on high cirrus clouds during an
April sunset over Heart of Borneo seashore. (RM)
Printed in Brunei Darussalam
Contents
The Heart of Borneo .............................................................2
The Peatswamp Rainforest .....................................................6
The Rivers ............................................................................11
The Beach ............................................................................16
Sand Transport and Longshore Drift ....................................19
Sand Bars .............................................................................24
The Geology ........................................................................25
The Weather ........................................................................30
The Tides .............................................................................31
The Sun ...............................................................................35
The Winds ...........................................................................38
The Monsoon (Seasonal) Wind Pattern ................................42
Temperature .........................................................................51
Waves ...................................................................................53
The Haze ..............................................................................54
The Future of the Heart of Borneo Coast .............................56
Teaching Resources ..............................................................59
References ............................................................................61
Foreword
Dr Grahaeme Henderson
Managing Director,
Brunei Shell Petroleum
C
are and concern for the environment is an integral part of Brunei Shell
Petroleum (BSP)’s business. Our efforts were duly recognised in 2008
when we won the prestigious Shell Chief Executive HSSE global award for
environmental performance. Everyone in Brunei Darussalam is proud of
this huge achievement.
BSP is the leader in the private sector in providing support for the
Government’s conservation efforts. We have contributed funds and shared
our expertise on the landmark Government-led biodiversity conservation
initiative, the Heart of Borneo. We also partner with our Government
stakeholders on a wide range of initiatives, including the Anduki forest
reserve biodiversity plan, Sungai Seria wetlands, PRYNSA schools’ outreach
programme, and numerous eco-tourism projects.
BSP is delighted to sponsor this series of books on the seashore life of Brunei
Darussalam. Written by our employees, along with contributors from Panaga
Natural History Society and others passionate about the environment, they
are well researched and attractively illustrated to promote this country’s
incredibly rich, hugely diverse and largely pristine environment.
Looking after our environment is vital…for today, tomorrow and for future
generations.
Preface
Hans Dols
Honorary President,
Panaga Natural History Society
(PNHS)
M
any who visit Brunei’s tropical seashore will be quickly aware they
are entering a very special place. This is a new world with much to
be seen, touched and explored. All will be fascinated by the diversity of our
coastal ecosystem and want to find out why it is so important to them and
to Brunei.
What started as short leaflets to illustrate our beach excursions has grown
into a series of booklets presenting a whole gamut of information dealing
with our coastal flora, fauna, and the physical environment we all share.
Roger McIlroy compiled the information from various sources and with
the help of contributors from the PNHS and others involved in preserving
Brunei’s environment has spent many hours distilling the best information
on a multitude of topics and has managed to write all this down in a very
handy and readable format fit for a wide audience.
This series of booklets are only a start and the PNHS hopes that many
will be inspired by this work to create further editions on the seashore life
and indeed on other wildlife of Brunei to help sustain these wonders for
posterity.
The Heart of
Borneo Initiative
T
he World Wildlife Fund (WWF) has for many years been driving
initiatives to protect the biodiversity of the Borneo rainforest. Notable
successes have been the protection of the Danum Valley, Tabin, Kalumba,
and Ulu Padas areas in Sabah, Lanjak-Entimau, Batang Ai and the Pulong
Tau in Sarawak, and Kayan Mentarang, Betung Kerihun and Sebangau in
Kalimantan. In addition, efforts to promote responsible forest trade have
reached new milestones.
In November 2003, the WWF brought to Singapore groups such as
Conservation International (CI), Wildlife Conservation Society (WCS)
and The Nature Conservancy (TNC); where it was agreed that the concept
of a transboundary conservation area in Borneo should be promoted, with
WWF taking the lead. This area became known as the Heart of Borneo,
and this programme is leading the way to conserve one of the world’s most
precious biodiversity treasures (Ref 1). The support of the three nations
involved, Brunei Darussalam, Malaysia, and Indonesia, was secured,
culminating in the Declaration on The Heart of Borneo Initiative signed in
Bali, Indonesia, in February 2007.
Declaration on
the Heart of Borneo Initiative
Three Countries, One Conservation Vision
W
e, the Governments of Brunei Darussalam, Indonesia and Malaysia,
recognizing the importance of the Island of Borneo as a life support
system, hereby declare that:
•
With one conservation vision and with a view to promote people’s
welfare, we will cooperate in ensuring the effective management of
forest resources and conservation of a network of protected areas,
productive forests and other sustainable land-uses within an
area which the three respective countries will designate as the “Heart
of Borneo (HoB)”, thereby maintaining Bornean natural heritage
for the benefit of present and future generations, with full respect
to each country’s sovereignty and territorial boundaries, and
also without prejudice to the ongoing negotiations on land boundary
demarcation.
•
The HoB Initiative is a voluntary trans-boundary cooperation
of the three countries combining the stakeholders’ interests, based
on local wisdom, acknowledgement of and respect for laws,
regulations and policies in the respective countries and taking into
consideration relevant multilateral environmental agreements, as
well as existing regional and bilateral agreements / arrangements.
•
We are willing to cooperate based on sustainable development
principles through research and development, sustainable use,
protection, education and training, fundraising, as well as other
activities that are relevant to trans-boundary management,
conservation and development within the areas of the HoB.
To support this Declaration, we, the three countries will prepare our
respective project documents incorporating the strategic and operational
plans, which will form the basis for the development of our road map
towards realizing the vision of the HoB Initiative.
Done at Bali, Indonesia on the twelfth day of February, two thousand and
seven in three original copies.
The signatories of the
Declaration on the Heart
of Borneo Initiative: Three
Countries, One Conservation
Vision. Brunei’s signatory,
Pehin Dato Dr. Awang Haji
Ahmad bin Haji Jumat, on far
left (Brunei Forestry Dept)
Since the signing, the Brunei Government has
been very active in implementing the Project.
His Majesty the Sultan and Yang-di Pertuan
of Brunei Darussalam reiterated Brunei
Darussalam’s commitment to the protection
of Brunei Darussalam’s environment and
to promote the sustainability of its forest
through the Heart of Borneo project at an
APEC (Asia-Pacific Economic Cooperation)
Summit. He was subsequently congratulated
by British Prime Minister, Gordon Brown
at the Prime Minister’s official residence, 10
Downing St, for Brunei’s commitment to the
HoB initiative (Ref 25).
HoB signatory, Minister Pehin Orang Kaya
Setia Pahlawan Dato Seri Dr. Haji Awang
Ahmad bin Haji Jumat set an example during
Global Community Day by planting a tree in
support of Brunei’s Heart of Borneo project,
and subsequently led a walk in the forest on
World Forestry Day.
The Ministry of Industry and Primary resources
set up a Heart of Borneo - Three Countries,
One Conservation Vision’ Brunei National
Planning Workshop, at which the Deputy
Minister, Dato Paduka Haji Hamdillah bin
Haji Abdul Wahab, who had been appointed
Chairman of the Heart of Borneo National
Council said the HoB will act as a catalyst for
more rapid developments in the eco-tourism
industry, and also enable further conservation
and protection of Brunei Darussalam’s rich
tropical rainforest and its biodiversity whilst
preserving the cultural and traditional rights
HoB signatory, Pehin Dato Seri Dr.
Haji Awang Ahmad bin Haji Jumat
sets a fine example by planting a
tree in support of Brunei’s Heart of
Borneo project (Forestry Dept)
Borneo Bulletin headlines His
Majesty the Sultan and Yang DiPertuan of Brunei Darussalam’s
commitment at the APEC Summit
(Borneo Bulletin)
HoB signatory Pehin Dato Dr.
Haji Awang Ahmad bin Haji Jumat
leads a forest walk as part of World
Forestry Day 2008 (Forestry Dept)
of the people living within and near the forest
areas.
His Majesty the Sultan and Yang
Di-Pertuan of Brunei Darussalam
congratulated by Gordon Brown,
British Prime Minister, June 2008
(UK Prime Minister’s Office)
Deputy Minister of Industry and
Primary Resources, Dato Paduka
Haji Hamdillah bin Haji Abdul
Wahab (left), during the Heart of
Borneo - Brunei National Planning
Workshop, with Dato Mikaail
Kavanagh, WWF’s Brunei Advisor
(middle).
Deputy Minister of Industry and
Primary Resource, Dato Paduka
Haji Hamdillah bin Hali Abdul
Wahab receives the HoB education
pack from H.E. John Saville, British
High Commissioner
Her Royal Highness Paduka Seri Pengiran
Anak Isteri Pengiran Anak Sarah binti
Pengiran Salleh Ab Rahaman presented the
certificates and prizes to the winners of the
Heart of Borneo Photography and Painting
Competition.
The Heart of Borneo Project Implementation
Framework (PIF) funded by Brunei Shell
has been launched, and the British High
Commissioner commissioned educational
booklets and education packs about the Heart
of Borneo with support from the International
School Brunei.
Brunei also won the Standard Chartered
Greatest Race on Earth (GROE) 2007/08
Environment Challenge, and in the process
secured USD 500,000 of funding for the
‘Heart of Borneo’ programme. This is the
world’s only marathon team relay series, and
it allows people from all round the world
to make environmental pledges and which
country they wished to support. 3.4 million
pledges were made, and after the count, Brunei
with its HoB was declared the winner!
Key environmental dignitaries have come to
visit. Nobel Prize winner Professor Wangari
Maathai, and Professor David Bellamy OBE
came to The International School of Brunei’s
Borneo Global Issues Conference VI, also
graced by the presence of Her Royal Highness
HRH Paduka Seri Pengiran Anak Isteri Pengiran
Anak Sarah binti Pengiran Salleh Ab Rahaman
inspects the submissions at the HoB Photography
and Painting Competition, accompanied by BSP
MD Dr. Grahaeme Henderson.
Princess Sarah. The Ministry of
Industry and Primary Resources
organised a helicopter trip to view
the HoB rainforest. On the flight,
the passengers were briefed by Acting
Director of Forestry, Mahmud Hj
Yussof from the Forestry Department,
on the types of forests found in Brunei
Darussalam, and the ecological
uniqueness of each forest they visited.
The (ex) Belait District Officer
Awang Haji Mohammad bin Haji
Abdul Rahman led an expedition to
the Ingei Hot Springs and the Gua
Batu waterfalls on the upper reaches
of the Sungei Ingei in the deepest part
of the Belait district. This is where the
Sungei Ingei conservation forest meets
the Mulu National park near the
Brunei-Sarawak border, undisturbed
primary forest in the heartland of the
Heart of Borneo.
HRH Paduka Seri Pengiran Anak Isteri
Pengiran Anak Sarah addresses the delegates at
the ISB Conference
Prof Maathai (5th from left) and Prof. David
Bellamy (far right) on a helicopter visit to
the rainforest as part of the ISB Conference
(Borneo Bulletin)
Intrepid District Officer Awang Haji
Mohammad bin Haji Abdul Ahman in the Sg
Ingei demonstrating field trip skills (HD)
Acknowledgements
T
his book would not have been possible without the work of the Panaga
Sub Aqua Club, and their website, for which John Elder originally
prepared a major part of this material, the BSP Geomatics Dept Metocean
Section, under Wee Thiam-Yew from where much data originated, and
Svein T. Sandal and his co-authors for the “1996 Geology and Hydrocarbon
Resources of Negara Brunei Darussalam”.
Mention also to Marina Wong and Aziah binte Hj Ahmad and Esther Lee
for their inspirational “Common Seashore Life of Brunei” which can be
considered the foundation work on which this series is built.
Also thanks to Jackie Maskall for her dedicated editorial work in improving
the readability of the text, and Peter Engbers and Mark Tuttle for their
reviews, the BSP External Affairs Team, and the Brunei Press publishing
team, in particularly May Lim who prepared the layout of the published
version.
Last and not least, thanks to Hans Dols for support throughout the
project.
The Heart of Borneo Seashore is characterised by a broad sandy beach, an azure blue
sea, driftwood, and the battle against erosion. Billionth Barrel Monument Seria (RM)
The Seashore Life
of the Brunei Heart of Borneo
The Heart of Borneo
T
he Heart of Borneo project: “Three
Countries, One Conservation
Vision” covers a total of 220,000
square km of equatorial rainforest
through a network of protected areas
and sustainable-managed forest, and
through international co-operation
led by the governments of the three
countries of Brunei, Malaysia and
Indonesia that make up the island of
Borneo.
Brunei on NW Coast of Borneo (Ref 10)
Brunei is a relatively small but beautiful
country lying on the northwest coast
of Borneo, at 4° - 5° north of the
equator, at longitude 114° – 115° east,
and is unique and special in the Heart
of Borneo in that the rainforest has
survived into the lowlands. This means
the rainforest is never far from the
coast throughout Brunei, and uniquely,
and very specially, actually reaches the
seashore of the South China Sea in the
Belait District between Kuala Belait and
the border with Sarawak.
This first book in the series describes
the Physical Environment and is an
2
the physical environment
introduction to the seven further books dealing with the species that live
there.
Lowland rainforests are particularly important as they are the biologically
richest in Borneo (Ref 15) and contain many locally endemic plant and
animal species, found nowhere else in the world. Preserving the link
between lowland and highland rainforest is also important as many species
of Bornean birds and mammals move up and down elevational gradients
and among different lowland habitats in order to find enough fruit and
other food to survive. Borneo’s forests are home to 13 primate species, more
than 350 bird species, 150 species of reptiles and amphibians and about
15,000 species of plants. Scientists continue to make many new discoveries
in the forests: more than 50 new species were discovered in 2006 alone.
The conservation of so much rainforest in Brunei is to the credit of the
Brunei government and people when elsewhere in Borneo rainforest has
been disappearing at a rapid rate. In the 1980s and 1990s Borneo underwent
a remarkable transition. Its forests were levelled at a rate unparalleled in
human history (Ref 16). Large parts of Borneo’s rainforests were essentially
View northwards down the Baram River, with Kuala Belait and the Sungai Belait to the right, Miri
on left. The approximate boundaries of the peatswamp rainforest are in red, showing it reaching the
coast between the two rivers. (RM)
3
The Seashore Life
of the Brunei Heart of Borneo
transferred to industrialised countries in the form of a range of timber
products, and sold to consumers who were unaware of the unsustainability
and damage of the trade. Initially most of the timber was taken from the
Malaysian part of the island in the northern states of Sabah and Sarawak.
Later forests in Kalimantan became the primary source for tropical timber.
Today the forests of Borneo are but a shadow of those of legend. Since 1980
Borneo’s forests have been reduced by more than one-third, mostly as the
result of industrial logging and land conversion for oil palm plantations.
WWF projects that by 2020 less than one third of Borneo’s forest cover will
remain. Every second (Ref 14) in 2000-2002 the rainforest lost 400 square
meters. Every second…
The Heart of Borneo
will not just be a nature
reserve but will be
managed for the benefits
of local people on the
coast and inland like the
Kayan, the Kenyah, the
Kelabit, the Iban, the
Bidayuh, the Barito, the
Dusun, the Kadazan,
the Murut, and the
Penan.
Their local
knowledge will make
them guides, rangers
and teachers. They can
work with scientists and
pharmaceutical experts
to identify and describe
local remedies (and
poisons!) that can be of
medical benefit. Tourism
can be developed in a
sustainable manner.
4
the physical environment
The HOB rainforest reaches the South China The last tree turns out to be two trees in a final
Sea (RM)
embrace before they fall victim to the erosion by
the voracious sea (RM)
5
The Seashore Life
of the Brunei Heart of Borneo
The Peatswamp Rainforest
A
peatswamp
is
where
the soil is composed
of undecomposed or partly
decomposed organic matter as
high acidity of the water restricts
organisms that would normally
decompose plant material.
Originally the Belait plain from
the Lumut Hills to the Labi Hills and to
the Baram River was entirely covered by
peat swamp, up to 20m thick (Ref 23).
Nowadays, from Kuala Belait eastwards,
much of the peatswamp along the coast
has been reclaimed for development.
These peat swamps in the Belait basin have
formed over some 5,000 years (Ref 5) since
the last time the sea covered the basin, and
have gradually formed large domal shapes,
where the centre of the dome is 3-4
metres higher than the edges. A survey was
6
the physical environment
carried out with a
series of boreholes
across the dome
separating
the
Baram and Belait
rivers along the
now
disused
Pagalayan Canal
showing the dual
convex shape and
underlying sands
and clays.
There are six
communities of plants first described by Anderson, (Ref 18) on the domes
that change proceeding from the edge to the centre of the dome with
decreasing fertility as the acidity of the water increases with poorer run-off.
Mixed peat swamp forest occurs on shallow peat over sand at the periphery
of the peat domes, with a rich diversity of trees but in Belait in places
dominated by kapur paya Dryobalanops rappa (rappa being derived from
the Iban kerapa = a shallow swamp.
Alan batu forest (batu = stone) is next with the appearance of very tall (to 60
m.) emergent individuals of the alan tree Shorea albida, with hollow trunks
and heavy buttressing. “Batu” refers to the heavy weight of the wood.
Alan bunga forest (bunga=flower) is next, with the canopy totally dominated
by Shorea albida, with few understory trees, but at a lower height of 50 - 60
m, and now solid trunks, no buttressing, and lighter timber.
Padang alan forest follows with considerably stunted alan trees indicating a
harder struggle for survival. Their height is now reduced to 35m-40 high.
Padang selunsor forest appears as the centre of the dome is approached,
7
The Seashore Life
of the Brunei Heart of Borneo
An alan (Shorea albida) tree dominates the view from this peatswamp clearing (RM)
8
the physical environment
and alan almost disappears.
The dominant trees are
the selunsor tree Tristania
spp., Parastemon sp., and
Palaquium spp. The trees
are small in girth and the
forest very dense but with a
canopy of only 15 - 20 m.
high.
Mixed winged dipterocarp seeds (Ref 20)
Finally at the centre of the
dome padang keruntum
is sometimes found, which
more
resembles
open
woodland with small and
stunted trees.
Some of these peatswamp
communities may be the
only examples in the world.
(Ref 24).
Shorea (alan) tree in Seria peatswamp forest (RM)
Both the kapur paya and
alan are “dipterocarps” (
from the Greek (di = two,
pteron = wing and karpos
= fruit), and are famous
for simultaneous flowering
and fruiting when the
canopy bursts into colour
as countless emergent
dipterocarp trees flower
almost simultaneously with
a vast number of blooms:
around four million per tree.
9
The Seashore Life
of the Brunei Heart of Borneo
This may be a strategy to intermittently starve and swamp seed predators so
that at least some seeds survive to germination. The trees produce so many
seeds that the forest floor is literally carpeted during a five week period
(Ref 16). Shorea albida has been declared a threatened species by the World
Conservation Monitoring Centre (Ref 23).
Profile of peatswamp near Seria showing two of the six peatswamp zonations (Ref 24 after Edwards
et al 1998)
As the peatswamp domes reach the rivers, another community emerges,
that of the Freshwater swamp, comprising luagan and empran. Both are
completely flooded by river water when water levels are high and so receive
good supplies of alluvium. Luagan is the name for the occasionally water
filled alluvial valleys, of which the Luagan Lalak in Belait is a good example,
which becomes a mass of wind-blown grass when water levels are low, while
empran describes the narrow levees along the rivers, colonised by Syzygium
spp. and valuable timber species Belian Eusideroxylon zwageri and merbau
Intsia palembanica.
10
the physical environment
The Rivers
Schematic of the depositional environment of the Heart of Borneo Coast. (BSP) (Note the dominant
longshore current actually goes west to east.
T
he schematic shows the main topographical features of the Heart of
Borneo coast in Belait and into Sarawak where the Baram River is
the dominant feature. This river is located just across the border although
historically the river and hinterland was part of Brunei. It is a massive river,
and its drainage basin covers some 21,500 sq km. The Belait has a drainage
area of about 2,300 sq km. and is separated from the Baram catchment
area by the Belait hills formed by the Belait anticline. Rainfall is high in
the catchment areas averaging over 3.2 m per year giving an annual average
discharge rate from the Baram of some 1600m3/s (Ref 5) which is about
a cubic kilometre per week, or 50 cubic km per year! The Belait averages
11
The Seashore Life
of the Brunei Heart of Borneo
Baram river and delta and key locations (BSP) Baram River and delta. Plumes of sediment and
tannin water can be seen extending into the sea
(BSP Landsat)
around a tenth of this amount at 150m3/s, (even this is more than twice the
amount of water carried by the River Thames in London!) (Ref 17).
Nowadays both rivers have low gradients in their lower reaches and meander
through extensive peatswamp covered alluvial plains. The Baram has an
extensive delta protruding into the South China Sea.
The rivers bring down high concentrations of suspended solids to deposit in
the sea. This is clearly visible in aerial photographs where plumes of brown
coloured water with high tannin concentration from the peat extend long
distances into the sea. Suspended solids in the Belait show an average of
50mg/l which leads to some 200,000 –250,000 tonnes of sediment being
discharged each year (Ref 5). It can be assumed that the Baram brings down
2 million tonnes per year or more.
Baram River showing its geographical features along its length and low gradient along the delta plain,
before the seabed drops sharply at the edge of the continental shelf (Ref 5)
12
the physical environment
Brunei Bay
Baram Delta
N
Take the South China Sea away and this seabed image from BSP shows the Brunei continental shelf
and the huge pile of sediments laid down by the Baram river via the “Baram canyon”
Tannin coloured water from the Belait clearly shown against the blue seawater. (BSP)
13
The Seashore Life
of the Brunei Heart of Borneo
Mouth of the Tutong River showing sand bars , sand spit and coastal lagoons (Ref 5)
Sungai Seria preserves its mangrove fringed lagoons and mudfeats despite being peppered with oil
wells dating back to 1929, and is still a wildlife haven (BSP)
14
the physical environment
How to break down a mountain: what Mt. Kinabalu might have looked like during the Ice
ages. Perito Moreno Glacier, Patagonia. Luca Galuzzi. (Ref 9.13)
15
The Seashore Life
of the Brunei Heart of Borneo
The Beach
T
he Brunei Heart of Borneo coast is
characterised by a fine golden sandy
beach which continues the length of Brunei
to Tanjung Pelumpong in Muara, a distance
of some 120km.
The source of the sand can be surmised
from the heavy minerals present (Ref 5
P215). These heavy minerals can be found
in concentrated grey layers and contain
zircon, ilmenite, rutile and magnetite. The
accumulations are small with (perhaps
thankfully) no commercial value. These
minerals are the erosional products of igneous
rocks, or reworked from older sandstones.
They will probably have come from erosion
of the Crocker-Rajang range and foothills
running from Sabah to Sarawak. A direct
source could have been the famous Gunung
(Mt) Kinabalu (4,100m) in Sabah, the
highest mountain in SE Asia.
Mt Kinabalu is now known to have been
formed from the youngest granite pluton
in the world. A pluton is a giant plume
of molten granite that has forced its way
upwards through the Earth’s crust, in a
16
the physical environment
similar manner to the local clay diapirs discussed later. This pluton came
to the surface only a million years ago, and in fact is still growing at a rate
of 5mm per year. The overlying sands and shales and the top of the pluton
itself have been eroded away, partly by the freezing and thawing of ice and
the erosion by glaciers that covered Mt Kinabalu during the Ice Ages (Ref
21). The erosion products would be carried down by the glaciers and then
by rivers to the sea.
Heart of Borneo Coast beach west of Kuala Belait with Nypah palm debris and fringed by
Casuarina trees (RM)
17
The Seashore Life
of the Brunei Heart of Borneo
The sands could also have come from
Gunung (Mt) Mulu (2,377m) near the
Mulu Caves in Sabah where an original
thickness of 4,000 to 5000 metres of
sands and shales of the Mulu formation
have been eroded. In both cases, the
long transport distance over 200km and
the frequent reworking of the sand has
resulted in the very fine grain size seen
today. When you pick up a handful of
sand from the shore here it is fascinating
to think that some of it may have
originated from a glacier at the top of Mt
Kinabalu or traveled through the Mulu Caves!
The beach sand extends about 500 metres offshore to about 5m water depth
and as it gets deeper and less affected by the wave energy, the sediments get
finer and muddier (argillaceous) until eventually at about 8m water depth,
the sea bottom is dominated by muds.
At the upper shore face,
there is often a jumble
of logs, an unfortunate
product of logging in the
Baram hinterland, and
Nearshore depositional environment, showing sand gradually other washed up debris
transitioning to mud offshore. Vertically, sand and muds often being colonised
alternate as water levels have changed historically
by
beach
creepers
like Centipede Grass
Ishaemum muticum, Sea Bean Canivala maritime and Beach Morning
Glory Ipomea pes-caprae. This soon gives way to the Casuarina Casuarina
equisetifolia, Sea Lettuce Scaevola tacada, Sea Hibiscus Hibiscus tiliaceous
and Screwpines Pandanus spp. of the near shore vegetation, characterised by
the ability to withstand salt spray and root in sandy nutrient-poor soils.
18
the physical environment
Sand Transport
and Longshore Drift
T
he strength of the waves and the direction of their arrival on the beach
affect the movement and hence the level of sand on the beach.
The strong NE
Monsoon
waves
disturb the sandy
bottom creating a
large “swash zone”,
where sand grains
are mobile, and an
associated
strong
longshore current
drives
sediment,
bathers and surfers
to the west. As
these waves also
strike the beach
obliquely, sand is
carried up the beach
at an angle; however
the backwash goes
straight down the
beach. This means there is a net movement of sand in a westerly direction
along the beach during the NE Monsoon. This process is called longshore
drift.
Longshore drift has a significant affect on the mouths of the rivers in Brunei.
19
The Seashore Life
of the Brunei Heart of Borneo
Sungai Lumut showing westerly trending spit and potential “breakthrough” point (BSP Roadmap)
These are pushed to the west during the NE Monsoon and back to the east
during the SW monsoon. The dominance of the NE monsoon in terms of
wave strength, means that the net effect is the push west, and so many rivers
in Brunei enter the South China Sea via a long spit which trends to the
west, good examples being the Sungais Tutong, Liang, and Lumut. Even
the Belait and Baram show this phenomenon. The Sungai Seria unusually
seems to be the exception to this rule, as it currently has a spit trending
east. It is suspected that here the current channel is a relatively recent
“breakthrough” where a bend in
the river short cuts its way to the
sea at a time of particularly high
rainfall. The Sungai Lumut for
instance, has a loop which runs
only 100m from the sea before
returning inland, reaching the
sea some 3 km further west.
Moving sand may completely
close off the mouths of minor
rivers exacerbating flooding
inland during the Landas
20
the physical environment
season. The Sungai Belait has its breakwaters to prevent this sanding up,
and the Sungai Seria is powerful enough to maintain its mouth open during
this period, but minor rivers often have to be kept open by using mechanical
excavators.
Paradoxically at the highest tides, the excavators are sometimes used to
actually pile up sand to close off these minor rivers as flooding inland from
fresh water causes less crop and garden damage than an inundation of
seawater from the King Tide.
Sand erosion is very noticeable at this NE Monsoon time, with much of the
log debris swept away and the foundations of the protective dyke exposed.
The level of sand on the beach drops by a meter or more due to the erosion
meaning tides reach further up the beach than a tide with the same height
during the summer. This means winter tides appear even higher than
they really are, and the beach itself offers less protection from King Tide
flooding.
Between the monsoons, sand is deposited rather than being eroded and the
beach looks its best, with colonisation by coastal plants, and shells and seeds
accumulating for collectors.
Sand scoured away exposing timber formwork at base of Ringers’ Dyke during the NW monsoon in
Dec 2007 compared with sand piled up in April 2008. Weathering on the concrete reveals evidence
of the different sand levels (RM)
21
The Seashore Life
of the Brunei Heart of Borneo
The root spread of this discarded logging offcut offers a stunning sand sculpture against this April
2008 sunset (RM)
Ripple Marks
Ripple marks are caused by friction of moving water or wind on the sand
substrate. In the quiet periods between monsoons, sand can be deposited
up the beach, drying out between high tides. Wind blown ripples are then
formed and stunning sand “sculptures” can be formed around logs.
Much of the beach is flat and ripple free as water is never flowing continuously
in one direction, it generally only experiences the in-out swash of the surf.
However in the sand bar channels and where the rivers flow into the sea
ripples can be observed, often quite dramatic megaripples, with a wavelength
of 2-3 metres covered with regular sized ripple marks.
22
the physical environment
April 2008: between the monsoons the sand piles up on the beach, and lovely wind blown
ripples appear on sand dried out between high tides as highlighted by the setting sun(RM)
Two orders of ripples (ripples and megaripples) visible near the Sungai Seria (RM) 23
The Seashore Life
of the Brunei Heart of Borneo
24
the physical environment
The Geology
I
Schematic of the string of oilfields formed on top of the
Seria anticline (red line) (Ref 5)
Geological Map showing anticlines (red) and synclines
(green) (Ref 5)
it’s not just the visible
seashore that’s special.
The rocks underlying the
Heart of Borneo coast are
also special in that they are
folded into an extended
anticline (a fold system in
the form of an arch), and
house extensive oil and gas
reserves.
The Seria anticline extends
along the length of the
Heart of Borneo Coast and
contains the Miri Oilfield
(discovered 1910) and Seria
Oilfield (1929) which were
the start of the oil industries
in Sarawak and Brunei. The
Seria anticline is parallel to
two other anticlines: the
Belait anticline forming the
Labi Hills where the first oil
strike in Brunei was made
in 1913 (Well Belait-2) and
the Ampa anticline where
the SW Ampa oilfield
25
The Seashore Life
of the Brunei Heart of Borneo
accumulated, and where the first
offshore oil development in Brunei
was installed, the structures of which
are visible offshore from the HoB
coast.
The Seria Field has produced
more than one billion barrels of
oil over eighty-nine years, and its
development has been followed by
other fields along the Seria anticline, including Rasau and Asam Paya.
The petroleum, or oil, has formed from the remains of plants and animals
that lived in the South China Sea up to 15 million years ago. When the
organisms died and sank to the bottom, they were covered in mud, and where
the conditions were right, slowly decayed into carbon-rich compounds,
and along with pressure and heat produced a “source rock”.
The big three oil bearing anticlines, green-Upper Miocene rocks, (5-10 million years ago), yellow,
Pliocene rocks (1.6-5 million years ago) (Ref 5)
Over time, the oil has travelled upwards from the source rock as oil is
lighter than water, and accumulated in sandstone rocks that have spaces, or
pores, to hold it. The oil stays in place when the rock has an impermeable
cap which prevents the oil from travelling higher. Extracting oil therefore
involves drilling through the cap rock in order to access the trapped oil.
Anticlines are one of the best oil traps. To find anticlines and other traps
26
the physical environment
Schematic of seismic acquisition process (BSP)
geologists use shock waves
in a process called “Shooting
Seismic”, which involves sending
a sound wave into the earth from
a controlled explosion or sound
source and measuring and timing
the sound waves reflected from
the underlying rocks.
The anticlines locally have
been formed as a result of two
processes, compression, and clay
or shale diapirism.
Compression is due to plate
“tectonics” which is movements
in the continental crust associated
with mountain building and
illustrated dramatically by the
famous Indonesian “ring of fire”
of volcanoes.
27
The Seashore Life
of the Brunei Heart of Borneo
A clay or shale diapir is an intrusion of soft rock caused by buoyancy and
pressure differentials. Plastic clays of the Setap formation underlying the
oil-bearing sands are squeezed upwards much like toothpaste squeezed out
of a tube. As they push the overlying rocks up, these rocks can retain their
pressure, which is then significantly higher than that of the shallower strata
they get pushed into. Such “overpressured” rocks pose a significant risk to
drilling and blowouts can occur. Thankfully, in Brunei these events, such
as at Rasau in 1989, have been rare, with minimal environmental damage.
Modern subsurface visualisation and drilling technologies keep the risks to
a minimum but constant vigilance is required. Sometimes these pressures
breach the cap rock naturally and oil and gas seepages, and mud volcanoes
form at the surface. Mud volcanoes are present in Brunei, such as the Bukit
Pantai mud volcano, 7 km south of Jerudong, which is also surrounded
by hydrocarbon seepages. Clay intrusions into the cap rock in the form
of localised shale dyke swarms can also be seen in outcrop at the Jerudong
anticline in northern Brunei.
Clay diapir rising and disrupting the overlying rocks (Ref 5)
Mud volcanoes can form at surface
28
Lava lamp: clay diapir analogue
(Ref 9.12)
the physical environment
Blowout in Rasau Field 1989
(BSP)
Natural Oil seepage to surface at Seria (Ref 5)
Clay diapir injection forming a dyke on the east flank of the Jerudong anticline (Ref 5)
29
The Seashore Life
of the Brunei Heart of Borneo
The Weather
T
he Heart of Borneo seashore and its inhabitants, are hugely affected by
the daily influences of the sun and the moon as the Earth rotates, by
the seasons created by the Earth’s orbit round the sun, and by the rainfall
and winds created by these effects. These will be explored in more detail in
the following sections.
Typhoon tracking across the Philippines with its spiral “tails” affecting the Brunei coastline
(NASA 28 Oct 2006)
30
the physical environment
The Tides
The effect of the Sun’s and Moon’s gravity causing spring and neap tides (Ref 9.1,2)
T
he daily ebb and flow of the
tide has an enormous effect
on the seashore, constantly moving
and reworking the sand, providing
food for the seashore inhabitants
and occasionally buffeting and
thrashing the shore with wild
intensity.
Tides are caused by the gravitational
pulls of the moon and the sun on
the sea. The moon, with a large
gravitational pull (17% of Earth’s),
31
The Seashore Life
of the Brunei Heart of Borneo
drags a sizeable “bulge” of water as it orbits the Earth. The spin of the
earth-moon system creates another bulge on the other side of the Earth due
to centripetal force. The gravitational effect of the sun being 46% of the
moon’s, it pulls round a smaller bulge.
Brunei Tide Table Example from Sep 2006 showing the cycle of single spring tides and double
(though much smaller) neap tides (BSP TSM/3) (height in metres above chart datum, which is about
the water level at its furthest out during the year)
This means the South China Sea should experience two (high tide) tidal
bulges each day. However, because the South China Sea is a relatively small
and confined body of water, it cannot easily accommodate the flow of two
tides a day and for most of the month only one tide exists. Only at neap
tides, when water movements are relatively small do two tides take place.
This can be seen in the chart of monthly tides.
Incidentally, this tidal drag over millions of years has caused the moon to
Tide table for December 2006 from BSP showing King Tides at 2.2m around 11.00 pm on the
21/22nd Dec. Extra low tides also occur at this time (red boxes, only 0.2m above datum) (BSP
TSM/3)
32
the physical environment
stop rotating and so
it is always the same
face of the moon we
see from Earth!
At full moon and
new moon the tidal
bulges coincide as
moon and sun align,
consequently
the
tide is extra high.
Such tides are called
“spring tides”. At
half moons the tidal
range is smallest as
the sun’s and moon’s
pulls are at right angles to each other. These tides are called “neap tides”.
A peculiarity of the single spring tide is that it goes out twice as fast as it
comes in. In the example shown , it takes 8 hours from 2 a.m. till 10 a.m. to
go out and 16 hours from 10 a.m. till 2 a.m the next morning to come in!
During
December
and January Brunei
experiences
the
infamous
“King
Tides”, the highest
spring tides of the
year. As the Earth’s
orbit round the sun
is slightly elliptical,
when the Earth is
closest to the sun,
the sun’s gravitational
effect is higher and
Daily tide level showing the tide going out between 02.00 and 10.00
twice as fast as coming in between 10.00 and 02.00. (BSP TSM/3)
33
The Seashore Life
of the Brunei Heart of Borneo
the tides are higher. The Earth is closest to the sun in early January (3rd Jan
in 2008). This is called its perihelion and it is 5,000 km closer than at its
furthest away (aphelion) in early July. So in Dec/Jan, the sun’s gravitational
pull and thus its tidal “bulge” is at its greatest. If accompanied by heavy
rainfall or a storm surge from the edge of a typhoon, as may occur at the
December King Tide, then significant flooding can occur as the Sungais
cannot drain the rainfall. At the same time, waves can overtop the dyke, and
unprotected beaches can experience severe erosion.
Another tidal feature that those
visiting the beach in the evening
will know that at certain times
of the year, the tide seems always
to be in, while at other times of
the year it is always out. This
can be seen in the annual tide charts (see below) that show the tide-level
at specific times of the day during the year. For instance, the annual tide
chart for 18.00 in the evening shows the tide is low from May to October,
while at 07.00 in the morning it is low from November to April. So beach
joggers, beachcombers and shell collectors have more beach available in the
morning during the winter months and in the evening during the summer
months.
Position of tide at 18.00 (BSP TSM/3)
34
Position of tide at 07.00 (BSP TSM/3)
the physical environment
The Sun
B
runei is certainly a
sunny place, and
the sun can almost be
guaranteed to shine
every day. It averages
about 6-7 hours per
day at the Airport but
on the coast it will be
more than this. This
is sometimes a surprise
to visitors who expect
the weather in a
rainforest to be raining
all the time!
There are other interesting misconceptions: for instance, many people
believe that the Brunei day must be the same length all year round because
Brunei is on the Equator. But Brunei is actually slightly north of the
Equator at 4-5o north, so day length does vary. The longest day is actually
12 hours and 23 minutes in midsummer (22nd June) and the shortest is
11 hours and 51 minutes in midwinter (21st December). This half hour
difference is not noted by many, but beach strollers and golfers know they
have a much better chance of getting their exercise or 9 holes in after work
in June-August with sunset as late as 6.40 p.m compared to November/
December when sunset can be as early as 6.04 p.m.
Another question you might ask is why December 21st has the shortest day,
35
The Seashore Life
of the Brunei Heart of Borneo
but not the earliest
sunset? The answer is
because sunrise and
sunset are governed
not just by the seasons
(caused by the tilt of
the Earth relative to
the sun) but also by
the ellipticity of the
Earth’s orbit.
Sunrise times (blue) and sunset times (red) in Brunei. showing
that for 7 ½ months of the year the day is longer than 12 hours
(JE)
Up at European
or down at New
Zealand
latitudes,
the effect of the
seasons (many hours)
greatly
outweighs
the ellipticity (+/- 15
minutes), however,
as we move towards
the tropics, the effect
of the seasons is
diminished and the
ellipticity
becomes
dominant.
For sure, the longest day is the Summer Solstice on or around the 21st June,
and the shortest day the Winter Solstice on 21st December, however, in
December, mid-day is later due to the elliptical component thus moving
the ‘earliest sunset’ backwards in date and the ‘latest sunrise’ forward, the
amount depending on your latitude.
In London, for example, the ellipticity still has a small effect and the earliest
evening is 9th December and the darkest morning, 29th December. The
weather is normally so foul that most people wouldn’t observe the subtlety,
but in the tropics, it is more obvious.
36
the physical environment
When is Noon?
S
olar noon is when the sun is at its highest point in the sky but because
of the effect of time zones, the timing of this in Brunei is never exactly
12.00 although it is actually quite close. Based on sunrise and sunset
times, assuming solar noon to be exactly in between, it is closest in Oct/
Nov at around 12.07, while it is latest in February at 12.37. Solar noon
is also called the “celestial meridian”, the highest point in the sky, which is
the origin of the terms a.m or ante meridian and p.m. or post meridiem.
Mind you, even at the solar noon in Brunei the sun is not usually directly
overhead. This is because of the tilt of the Earth. The latitude at which the
sun is directly overhead swings between the Tropic of Cancer (latitude 23°
26′ 22″ N) on the June solstice, to the Tropic of Capricorn (23° 26′ 22″ S)
on the December solstice. The sun is actually only directly overhead at solar
noon in Brunei near the equinoxes; March 20th and September 23rd.
Position of the Setting Sun
W
Position of the sunset on the Brunei HoB coast during the year (JE)
inter visitors
complain
that they can’t see
the sun dipping into
the sea at sunset,
while during the
rest of the year they
can.. why is that?
The reason is that the position of the sun as it sets (and rises) on the horizon
varies due to the 23.5 degree tilt of the Earth’s axis. In the summer, the
North Pole is tilted towards the sun and the position of the sunset moves
north, while in the winter, the South Pole is tilted towards the sun and
the sunset moves south. This means that in Brunei for much of the winter
the sun sets over the land, and only sets over the sea in its full glory from
February to October.
37
The Seashore Life
of the Brunei Heart of Borneo
The Winds
T
he winds experienced on the seashore are caused by daily temperature
changes and by seasonal changes. The winds affect the waves and also
the height of the tides, and also the presence of those annoying sand flies..
the windier the fewer!
Daily (Diurnal) Wind Pattern
T
he daily (“diurnal”) variation in
temperature difference between
land and the sea creates movement
in bodies of air. During the day, the
land warms up faster than the sea,
and so the air rises from the land to
be replaced by the cooler air from the
sea. A morning walk on the beach
will often enjoy clear skies, clear
water (sometimes even good enough
for snorkelling), and small waves
lapping the shore.
Just before midday the land has
usually warmed sufficiently for an
onshore breeze to start and by mid afternoon this is well developed, causing
large bright white thunderhead clouds (cumulonimbus) to form inland as
the humid air from the sea is forced up over the mountains. These huge
clouds extend from 3 to 20 km in height and are often visible inland from
Seria and Panaga.
38
the physical environment
Cumulonimbus forming above Baram Delta seen from Panaga (RM) June 2008
39
The Seashore Life
of the Brunei Heart of Borneo
Clouds building up inland in the afternoon (Ref 9)
They can cause heavy
rain inland with dramatic
lightning in late afternoon
and evening.
Labi
regularly experiences a
downpour at 4 o’clock
in the afternoon! On
rare occasions a dramatic
sunset occurs when a stray
cumulonimbus cloud on
the horizon casts a shadow
on high cirrus clouds.
As the land temperature
falls in late afternoon, the
onshore breeze decreases
and by midnight the sea is
sufficiently warmer than
the land for the air to rise
over the seas, replaced
by cooler air from the
land creating an offshore
breeze. This breeze can
sometimes carry the inland
thunderheads to the coast
and cause heavy rain and
thunder and lightning
during the night.
Cumulonimbus on the horizon casting a huge shadow on the
high cirrus clouds during an April sunset (RM)
40
the physical environment
Lightning strike from cumulonimbus over Kuala Belait beach, July 2007,
with a torrential rain downpour to the right (RM)
41
The Seashore Life
of the Brunei Heart of Borneo
The Monsoon
(Seasonal) Wind Pattern
T
he cycle of seasons becomes less pronounced the nearer you get to the
Equator, so although Brunei is some 4.5 degrees north it is essentially
summer all year round!
However, the winter and summer cycle in northern and southern latitudes
causes the monsoons felt in the Tropics. The popular misconception,
associated with Hollywood films of torrential rains in India, is that a monsoon
is a wet season. This is not so, it is purely a wind direction that may (in
the case of India), or may not, bring rain, and in fact the word ‘monsoon’
actually comes from the Arabic word ‘mausim’ meaning “season”.
Near the Equator,
the air is warm
all year round
and rises forming
a low pressure
area. Wind from
high
pressure
areas will flow
towards this belt
of low pressure.
In winter, the
denser, colder air
flows south from
the area of highest
pressure which is
in China, while
42
Monsoon wind patterns (Ref 9.4)
the physical environment
Satellite photograph of Typhoon Cimaron in Northern South China Sea, Nov 2006 (NASA)
in summer, the highest pressure is in Australia, and so colder air flows north
from there. This annual cycle is a scaled up version of the diurnal winds
described earlier; wind simply blowing from warmer to cooler areas.
However this simple north-south (winter) and south-north (summer) air
flow is influenced by the rotation of the Earth as shown in the illustration,
and so it actually blows towards Brunei in the winter from the north-east
(NE monsoon) and in the summer, south-east winds dominate, although
these twist south-west as the winds cross the equator to form the SW
monsoon felt in Brunei.
In Brunei the NE Monsoon (The Landas Season) brings the heaviest rain
of the year, but by February the rain is exhausted and the remainder of the
monsoon is dry until the seasons change in March.
The NE monsoon starts in the early autumn when China cools down
enough and is normally established by November. The early months of the
43
The Seashore Life
of the Brunei Heart of Borneo
Panaga flooding in Dec 1995 during NE Monsoon and King Tides (BSP TSM)
NE Monsoon bring heavy rain having picked up moisture from the long
fetch across the South China Sea. In conjunction with the King Tides at
end December they can cause extensive flooding such as that in 1952-1954
which caused British Malayan Petroleum (predecessor to BSP)(Ref 8) to build
Ringers’ Dyke, the sea-wall stretching 11km between Panaga and Sungai
Bera. The dyke, built between 1954 and 1957, mitigates against wave damage
and erosion, but floods still occur. In 1962, the tail of “Typhoon Mary”
caused sea swells up to 12 feet high, which coincided with six continuous
days of rainfall, with 60cm falling. In the resulting extensive flooding all
houses in Seria G13 were evacuated, and Jalan Tengah in Seria was two feet
Panaga-Seria
road flooding during King Tide Dec 1995 (Ref 4)
44
the physical environment
underwater. Ironically,
with such a surplus of
water, domestic water
supplies were also cut
as the Sungai Belait
flooded the Badas Pump
Station to a depth of 3
metres.
In
more
recent
years problems have
continued,
with
extensive flooding in
Miri in 1981, and Belait
in December 1995, as
shown in the map of the
flooded areas in Panaga
at the time.
By
February
each
year, although the
NE Monsoon wind Rainbow from Panaga Beach, 8 April 2006 (RM)
is stronger with surf
pounding the beach, the wind direction becomes more easterly and warmer
and contains less moisture because of the rain shadow effect of Sabah and the
Philippines. It is also now strong enough to prevent the nightly ‘back-flow’
of air. The two conditions combining cause a marked decline in rainfall.
A by-product of the NE monsoon winds is that every piece of rubbish in
the South China Sea, ranging from massive timber to thousands of plastic
bottles, gets washed up on the beach. Stranded jellyfish are commonly seen,
as are a wide variety of nuts and seeds making it the best time of year for
beachcombing as the sand flies are much less of a pest. Overall, with a
varied cloudscape and clear sky, the later stages of the NE monsoon offer
the best time of year for after work beach activities and dramatic sunsets.
45
The Seashore Life
of the Brunei Heart of Borneo
Sunlight reflecting and refracting from the back of
rain drops. (Ref 9.14)
The high tides and high runoff
from the rivers at this time bring
many marine animals such as fish
and shrimps into the estuaries to
lay their eggs, accompanied by
their associated predators such as
grouper. This is the time of the year
when there are more fishermen on
the rivers than on the shore.
The transition between NE
and SW monsoon brings calm
conditions in April-May and the
water becomes clear with high
visibility. The eggs have hatched in
the rivers and the juvenile fish and
shrimp and other small fish like
anchovies are abundant along the
shore, as are the shore fishermen!
High thin cirrus clouds may be
seen at this time, and a particular
feature to look out for at this time
is a sun halo. Due to ice-crystals,
light is reflected and refracted and
may split up into colours because
of dispersion, similar to what
happens in a rainbow.
Double reflection of light in a raindrop causing a
double rainbow. (Ref 9.15)
46
Rainbows are also a common
feature
in
late
afternoon
throughout the year. The low
sun from the west causes any
showers observed looking east to
the physical environment
be transformed into a
spectacle. Rainbows are
caused by the reflection
of the sun from the back
of raindrops. This means
that you have to have
the sun at your back to
see them. The reflected
image is split into
constituent colours by
refraction as light passes Double rainbow, Panaga E8 August 2008 (RM)
through the surface
of the raindrop as it enters and leaves. Occasionally, a second, dimmer,
and thicker secondary rainbow is seen outside the primary bow. Secondary
rainbows are caused by a double reflection of sunlight inside the raindrops,
and appear at an angle of 50°–53°. As a result of the second reflection, the
colours of a secondary rainbow are inverted compared to the primary bow,
with blue on the outside and red on the inside. The dark area of unlit sky
lying between the primary and secondary bows is called Alexander’s band,
after Alexander of Aphrodisias who first described it. (Ref 11.2)
Water spout from West Pelaut Oil Rig offshore Brunei 24 Jul 2007 (Ref 4)
47
The Seashore Life
of the Brunei Heart of Borneo
As spring progresses
to summer and
China warms up and
Australia cools, the
airflow over Brunei
reverses and from
June to August the
wind blows from
the southwest as the
south-west monsoon.
As the Australian
winter never gets as cold as the Chinese winter, the pressure does not get so
high and so the resulting south-westerly monsoon winds are weaker.
Line squalls can occur offshore in early morning as the diurnal offshore
breeze meets the SW monsoon winds at right angles. These lines move
along parallel to the coast and due to the difference in wind directions can
whip up waterspouts. These are actually mini tornadoes, but they rarely
come ashore to cause damage, with only one being recorded in Panaga, in
1993, which deposited a Hobie Cat on the golf course!
Hobie cat lifted onto Panaga Golf Course by 1993 waterspout (JE)
48
the physical environment
Maurice Davidson gives this account of a waterspout in Laut Brunei (Ref
2): “We encountered a waterspout in Brunei Bay, just off the Spit in 1997.
It was below a huge line squall. Strangely there was no wind, it was all
being sucked into this long dark finger, the spray and hissing from its 10m
diameter base was impressive! It slowly ripped 50m through the sea from
side to side, as the whole waterspout snaked down from its cloud. Having
got quite close to this, so everyone could see this amazing scene, the line
squall suddenly got darker and cooler. A very excited passenger then pointed
upwards. We were heading towards a second waterspout forming out of the
clouds over our head! A very evil long black finger tried to hit the water on
our left but failed, retracted and quickly disappeared back into the cloud
above us.”
As the land heats up and the onshore wind develops, these line squalls are
blown ashore and can cause heavy rain from midday onwards.
Typhoons
T
owards the end of the SW
monsoon, the typhoon
season starts in the west Pacific.
Brunei is one of the ‘the Lands
below the Wind’ (although this
title has now been appropriated
by Sabah for tourism purposes)
meaning that it lies south of the
typhoon belt, so it is never (at
least in recorded history) directly
hit by typhoons. However, the
effect of the typhoons to the
north is felt as their extreme
“sinkholes” of low pressure drag huge quantities of air around the South
China Sea, disrupting the normal monsoon wind patterns, and spin off
numerous squalls that chop up the seas and cause unseasonally high surf on
its HoB beaches.
49
The Seashore Life
of the Brunei Heart of Borneo
Rainfall
Average rainfall in Brunei in 250 cm bands, 2.5-2.75 m on the coast, to 4-4.25 m inland (Ref 5)
T
here’s no doubt that the volume of rain that falls in Brunei is very large,
yet because it falls intermittently, albeit in impressive downpours, the
much longer intervening periods of sunshine make Brunei a very pleasant
place to live, especially at the coast.
On the coast, the annual rainfall averages some 2.8 metres or less, while in the
Labi hills, it is over 4 metres per annum. On the coast, 2007 was far and away
the wettest recorded year since 1960 in Panaga with nearly 150 inches (3.8m)
of rain.
The statistics
show
that
the
NW
monsoon is
the dominant
event causing
the highest
rainfall
in
Nov-Jan. February and March are the driest months (although still receiving
3 times as much rain as London).
50
the physical environment
Temperature
B
runei is essentially hot
all year round averaging
some 27°C, (81°F), with
midday temperatures at
32°C, (90°F), and nighttime
temperatures
at
23°C, (74°F). However,
there is a noticeable drop
in temperature towards
the last quarter of the year,
with the coolest conditions being when the NE monsoon is at its height in
January and February, when the temperature drops towards late afternoon
and it is very pleasantly cool in the evenings and at night.
Humidity
H
umidity
is
a
measure of the
amount of water vapour
dissolved in the air, is
closely related to air
temperature, and is
expressed as a percentage,
relative to the maximum
the air could hold at that
temperature. Humidity
rises as the temperature
51
The Seashore Life
of the Brunei Heart of Borneo
falls (clouds have 100% humidity). It reaches its highest in Brunei just
before dawn, its lowest at mid day and early afternoon.
Sea Temperature
A
pleasant surprise for visitors to the HoB beaches is the lovely warmth
of the sea for paddling or bathing. The South China Sea is a mainly
enclosed area baked by the near equatorial sun and, apart from the Palawan
Trench 40 miles off the coast where the ocean drops to over 3,000 metres
deep, the sea is relatively shallow, sloping gently from the beach with
numerous reefs and shoals. The sea therefore maintains a constant, tropical
temperature of 30°C until the northeast monsoon winds kick in around
late November when the motion of the sea from the northeast picks up
the colder water from the offshore trench and the sea drops quickly to a
still warm 26°C, a temperature maintained until the change of monsoon in
April/May.
Sea temperature in deg Celsius in Brunei South China Sea taken from John Elder’s dive records in
Borneo (yellow) and specifically Brunei (red) (JE)
52
the physical environment
Waves
W
ave heights provided by BSP (Metocean Services TSM/3) are used
by the Panaga Sub Aqua club all year round to give guidance for
dive boat trips. The table shows the
roughest times during the NE monsoon
from November to February with waves
reaching 5.5 metres. Wave strength is
determined by the strength of the wind
that has created it and the distance for
which the wind acts on the wave before
it reaches land. Consequently the
largest waves at 1 ½ -2 m high occur in
late afternoon during the NE Monsoon
when the onshore breeze and monsoon
winds which have crossed the full length
of the South China Sea combine.
High surf can also occur when waves
stirred up by a typhoon reach Brunei.
Five metres high waves were generated
by Typhoon Cimaron in Nov 2006 with
these waves still nearly 2 metres high
when they reached the coast of Brunei.
The SW monsoon, which tends to
blow along the shore, rather than onto
it, produces smaller waves than the NE
monsoon.
53
The Seashore Life
of the Brunei Heart of Borneo
The Haze
A
n unfortunate
but thankfully
still
uncommon
environmental
phenomenon
in
Brunei is atmospheric
haze. Because of its
location, Brunei is
generally not only
“the land below te
wind” but also “the
land above the haze”
Haze from fires in Kalimantan and Sumatra is usually blown to the
West affecting Singapore and KL (Ref 12)
Haze is made up almost entirely of
very small smoke particles (less than
10 microns in diameter) produced
by wood/peat fires. It is measured
and reported as PSI or API (Pollutant
Standards Index or Air Pollution
Index) based on solid particulates,
SO2, CO, O3 and NO2.
Smoke from forest burning in Kalimantan seen
During periods of dry weather, from a satellite (Wikipedia ex NASA) Oct 2006
especially August-October, illegal
loggers and palm oil plantation developers in Kalimantan take the opportunity
to burn logged areas of jungle prior to planting oil palm or other cultivated
crops. The haze is mostly blown westwards and Singapore and peninsular
54
the physical environment
Malaysia are often badly affected, although
satellites show winds even take the smoke
right across Africa! Malaysia had to declare a
State of Emergency” in 2005 because the air
pollution index had reached 500.
Only unusually do wind patterns bring this
haze over Brunei.
Effect of smoke from Kalimantan
being felt as far as Africa (NASA)
However, there are locally produced hazes
in Brunei, mostly caused by fires that appear to start near roads, probably
caused by the careless disposal of cigarette butts. The smoke (or haze)
caused by this burning can drift over Seria and Panaga, seriously reducing
air quality.
Bomba extinguishing an extensive fire near the Badas Road, Belait. Peatswamp forest clearing
alongside the road here has created a secondary growth much more prone to fire caused possibly by
cigarettes thrown from cars. (BSP)
55
The Seashore Life
of the Brunei Heart of Borneo
The Future of the
Heart of Borneo Coast
I
t is easy to think that beaches are permanent features, yet we know from
geological mapping of the sediments in the area that the Heart of Borneo
coast is continually changing.
Twenty thousand years ago, at the height of the ice age, so much water was
locked in the ice sheets that the sea level was 130m lower than today and
would have resulted in a coastline some 50 km further offshore than at
present. By 2,000 years ago, the ice had melted but the coastline was still 1 –
2 km further out to sea with offshore islands and lagoons along the coast.
Miri-Belait coastline.2,000 years ago (Ref 5)
56
The Miri-Belait coastline at present (Ref 5)
the physical environment
The sea level has risen 20 cm
in the last century and is still
rising, at a rate that is expected
to increase as global warming
further depletes the ice sheets.
The last high sea level, some
5000 years ago, resulted in a
large bay extending up the
Baram River, with the South
China Sea lapping against the
Lambir and Labi hills.
If global warming does cause a continual and progressive melting of the polar
ice sheets the over a century or two this could happen again! It could happen
even faster unless we learn more about how to control global warming.
Coastal erosion locally is a major
concern as the sea level rises. A
casuarina stump on the HoB seashore
acts as a sentinel marking the position
of the coast perhaps only 10-15 years
ago. Nearby, a peat layer is exposed
near the mouth of Sg Teraban
confirms the retreating coastline . If
global warming continues then the
coast will continue to erode despite
our best efforts to prevent it, and in
a century or two our descendants
could well be living in the Labi and
Lambir Hills enjoying the sunset over
the broad lagoon where our Heart of
Borneo peatswamp now flourishes!
Miri/Belait coastline 5,400 years ago (Ref 5)
57
The Seashore Life
of the Brunei Heart of Borneo
Casuarina tree stump between Sg Teraban and Sg Tujoh, showing the position of the coastline
perhaps only 10-15 years ago. Sep 2008 (RM)
58
Peat layer exposed at mouth of Sg Teraban due to coastal erosion (RM)
the physical environment
Teaching Resources
Oil and Gas Discovery Centre
https://www.bsp.com.bn/ogdc/
The Oil & Gas Discovery
Centre (OGDC) symbolises
the long-term commitment
of Brunei Shell Petroleum
Company
Sdn
Bhd
(BSP) towards sustainable
development of Brunei
Darussalam and its people.
OGDC introduces visitors
to the world of science and
engineering and the oil and
gas industry in Brunei, while
promoting environmental
awareness, highlighting the necessity of nature conservation.
With lots of informative displays and hands-on experiences to maximise the
learning opportunities, OGDC strives to promote fun education to enrich
visitors knowledge while they explore the seven galleries that showcases over
100 exhibits.
Bruneian children keen to learn more about the Heart of Borneo (BSP OGDC)
59
The Seashore Life
of the Brunei Heart of Borneo
Heart of Borneo Student Support Site
http://brunei.cfbt.org/bn/heartofborneo/hobmenu.html
There is a student support site created by the
British High Commission in association with
the World Wildlife Fund (WWF), CFBT
Education Trust and the International School
Brunei (ISB).
There are information, animated clips, links and
other teaching materials downloadable from this
excellent site.
Natural History Societies
Joining a local natural history society is a good
first step in learning more by getting involved in
saving the Borneo rainforest.
It’s amazing what you can do
with a plastic bottle! (OGDC)
The Panaga Natural History Society are active
in the Belait area in the south of Brunei, based
at Seria.
http://www.bsp.com.bn/PanagaClub/pnhs/
index.htm
The Brunei Nature Society are in the north
of Brunei based at the capital Bandar Seri
Begawan.
http://bruneinaturesociety.org/
It’s fun! (OGDC)
The Malaysian Nature Society have branches in
Miri and Kota Kinabalu.
http://www.mns.org.my/index.php
60
the physical environment
References
1) 2)
3)
4)
5)
6)
7)
8)
9)
The WWF Heart of Borneo Website
http://www.panda.org/about_wwf/where_we_work/asia_pacific/our_
solutions/borneo_forests/index.cfm
Laut Brunei The Brunei Sea: Maurice Davidson, Brunei Sub Aqua Diving
Club 2000 ISBN 99917-908-0-2
Tide Charts: Intrepid Yachting
http://www.bruneibay.net/tidecharts/seria.html
Brunei Meteorological Service Website:
http://www.civil-aviation.gov.bn/bms/satellite/
John Elder: The Panaga Sub Aqua Club Website
www.panagadivers.com
The Geology and Natural resources of Negara Brunei Darussalam. 1996 Revision edited by S.T. Sandal, Syabas BSB.
The Nine Planets; a multimedia tour of the Solar System, Bill Arnett http://www.nineplanets.org/luna.html
BSP Geomatics Department (TSM) and Metocean Services section
(TSM/3)
G.C. Harper: History of the Seria Oilfield, Brunei Muzium 1975
Wikipedia public domain images, and licenses. To reuse these images
please check the Wikipedia site for license terms.
9.1 springtide.jpg, public domain
9.2 neaptide.jpg, public domain
9.3 Diagrama_de_formacion_de_la_brisa-breeze.png
9.4 Earth_Global_Circulation.jpg
9.5 Storm_surge_graphic.svg, public domain
9.6 Longshoredrift.gif, Gnu
9.7 Recent_sea_level_rise.png, Gnu
9.8 Orbit3.gif, public domain
9.9 CumulonimbusFlorida.jpg, Gnu
9.10 Anticline.jpg Gnu v. 1.2
9.11 Ring of Fire, public domain USGS
9.12 Lava Lamp in the Dark Aaron Kuhn Creative commons
attribution sharealike V2.5
9.13 Perito Moreno Glacier Luca Galuzzi Luca Galuzzi - www.
galuzzi.it Wikipedia commons
10) Borneo Tour Specialists http://www.borneo.com.au/
61
11) Wikipedia
11.1
Tide
11.2
Rainbows
12) 13)
14)
15)
16)
17)
18)
19)
20)
21)
22)
23)
24)
Borneo Bulletin
Stripersurf.com
British High Commission booklet, using WWF material
http://brunei.cfbt.org/bn/heartofborneo/index.asp
Association for Tropical Biology and Conservation (ATBC)
http://news.mongabay.com/2007/0523-borneo.html
Deforestation in Borneo
Kalimantan at the Crossroads: Dipterocarp Forests and the Future of Indonesian Borneo
Tina Butler, mongabay.com
http://news.mongabay.com/2005/0417c-tina_butler.html
Floating down the river. The River Thames website:
http://www.the-river-thames.co.uk/thames.htm
Anderson J.A.R. 1963 The flora of the Peat Swamp Forests of Sarawak
and Brunei Gardens Bulletin Singapore, vol 20 p 131-228
SERIA LAND FIELD ASSESSMENT : Detailed Descriptions of
Vegetation and Wildlife in Selected Areas of the Seria Land Field –
Brunei Darussalam 1998-99
Australian Centre for International Agricultural Research
http://mycorrhizas.info/info.html
Mt Kinabalu Geology
http://www.mount-kinabalu-borneo.com/mount-kinabalu-geology.html
Andrew A. Snelling, Rapid Melting of Source Rocks, and Rapid
Magma Intrusion and Cooling
http://www.answersingenesis.org/articles/arj/v1/n1/catastrophicgranite-formation
Wong, K.M. et al, Forests and Trees of Brunei Darussalam. Universiti
Brunei Darussalam, 1999
Marina Wong and Aziah binte Hj Ahmad 1996, Common Seashore Life
of Brunei, Muzium Brunei
About the Authors:
R
oger McIlroy has lived in Brunei Darussalam
with his wife and children since arriving
from their home country of Scotland in 2001.
Roger holds degrees in Geology and Petroleum
Engineering and has managed to combine his
work in this field with a keen interest in the
environment. This series of books draws on his
documentation of the facts and images of the
natural history around the Panaga area of Brunei
which has been their home.
He sees this series as a fitting gift to the people
and wildlife of Brunei Darussalam in recognition
of their hospitality and friendship during his
stay.
J
ohn Elder is a British oil industry geophysicist,
whose work has taken him to some of the great
dive locations in the world. He learned to dive
in Oman in 1978 and became an instructor in
Plymouth, England in 1988. He has been Diving
Officer of BSAC branches in Lensbury (London),
Cairo and Brunei. His passion has always been
wreck diving, however, 11 years working in
Borneo fostered an abiding interest, for obvious
practical reasons, in the fascinating and sometimes
violent weather systems of the South China Sea.
In 2005, John was part of the team that won the
BSAC Duke of Edinburgh Prize for the “Life
beneath the Platforms” project. John, who still
dives whenever possible, lives in Hampshire with
his wife. He has two grown-up children who are
also qualified divers.