Disaster Risk and Hazard Map Analysis for Timor-Leste:
An overview of existing risk maps
Disaster Risk Management Institutional and Operational Systems
Development in Timor-Leste Project, UNDP
January 2010
Table of Contents
1
Introduction and context ................................................................................................................ 3
2
Hazard and Risk Mapping products available in DRMInfo .............................................................. 3
2.1 Landslide Risk .............................................................................................................................. 3
2.2 Flood Risk .................................................................................................................................... 5
2.3 Fire risk ........................................................................................................................................ 6
2.4 Drought risk ................................................................................................................................. 7
2.5 Tsunami Risk................................................................................................................................ 8
3
Other hazards and risks .................................................................................................................. 9
3.1 Cyclone Hazard ............................................................................................................................ 9
3.2 Earthquake Hazard ...................................................................................................................... 9
4
Conclusions ................................................................................................................................... 10
Produced with financial support provided by the European Commission Humanitarian Aid
department (ECHO) and the United Nations Development Programme (UNDP)
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
1
Introduction and context
This document was produced by the project entitled “Disaster Risk Management Institutional and
Operational Systems Development in Timor-Leste”, co-funded by UNDP and the Disaster
Preparedness Programme of the European Commission’s Humanitarian Aid department (DIPECHO).
The project has been supporting the National Disaster Management Directorate (NDMD) to address
the immediate needs as identified by the Council of Ministers for the development of necessary
institutional and standard operational systems to support the operationalisation of the National
Policy for Disaster Risk Management, the decentralization of services, and the strengthening of the
link between district and central levels, as well as among various Government structures.
One of the project outputs is a mapping and analysis tool to assist national and local officials to
understand and manage disaster related risks. The computer based tool, which has been named
DRMInfo, facilitates assessment, presentation and knowledge management of disaster risks in a
Geographic Information System (GIS) package that requires only modest computing skills to operate.
The map layers in DRMInfo are divided into hazards (also known as “sources of risk”) such as
landslide potential, tsunami potential and flooding potential; and vulnerable elements in the
community (also known as “elements at risk”), such as households, schools and bridges. The
information can be displayed at various levels (national, district, sub-district or suco level) to provide
an indication of the level of disaster risk as the maps show the intersection between sources of risk
and elements at risk.
This document is based on available information to provide a basic analysis of the natural hazards
which are most relevant in Timor-Leste. The broad analysis and recommendations in this document
are drawn primarily from data and analysis conducted initially in 2002 under a UNDP project on
hazard maps for Timor-Leste. The hazard data was revalidated in 2009 and combined with
vulnerability data to produce these maps. Information about the methodologies used for the
development of each map is available in the project report on the development of DRMInfo. Higher
definition maps are also available from UNDP DRM Project.
2
Hazard and Risk Mapping products available in DRMInfo
2.1 Landslide Risk
Landslides are events where material such as rock and earth moves down a slope, often with very
destructive force. Landslides are driven by gravity and important contributing factors include slope
stability and water content. They are often triggered by heavy rainfall and/or runoff and are more
common in areas where the vegetation providing stability and reducing the speed of runoff has been
degraded.
Interpretation:
The maps below show the distribution of landslide hazard across the country and categorize the
hazard into five levels (very high, high, medium, low and no-data). It shows that the eastern half of
the country has almost all the areas of “very high” and “high” landslide hazard, based on the
available data. The second map shows how one of the hazard layers within DRMInfo can be
combined with one or more of the layers representing elements-at-risk. In the map “Houses at
Landslide Risk Timor-Leste”, landslide hazard has been combined with the national household
3
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
location data. Only households that sit within the boundaries of the “very high” and “high” landslide
hazard regions are depicted on this map.
The maps inform national resource managers and planners how landslide risk is distributed across
the country and quantify the risk in terms of the numbers of households exposed to the hazard.
Such information has the potential to support several strategies for risk reduction. In the high risk
areas the design of roads and bridges could incorporate means to prevent adjacent soils from
becoming unstable due to water saturation. Houses, schools and other vulnerable infrastructure
should be located to avoid exposure to the hazard wherever possible. High risk districts could be
4
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
prioritized in terms of access to heavy equipment for road repair and emergency rescue that could
be located there in anticipation of landslide damage. Reforestation and sustainable agricultural
techniques should also be considered to stabilize potentially dangerous terrain.
2.2 Flood Risk
Flooding in Timor-Leste occurs as flash-flooding when heavy seasonal rain higher in catchment
basins converges in tributaries as it descends, resulting in rapid rise of discharge in the water
courses.
Interpretation:
The map above shows the areas where water accumulates in lowland or upland floodplains when
river banks have insufficient capacity to contain the flow. National resource managers will note the
preponderance of flooded land on the south coast where population and infrastructure are sparse
relative to the north coast. Implications for planners would be similar to those described for the
landslide risk map. Overlay of elements of risk is more useful in smaller scale maps, such as suco.
Suco river flood risk
The map shown on the following page illustrates how DRMInfo can usefully display smaller
administrative areas in high detail.
Interpretation:
This map is useful for local level flood risk reduction because it identifies specific households at risk
and suggests where households and infrastructure should or should not be located. Land use
regulations intended to reduce losses due to river flooding could be based on such a map. It could
indicate candidate locations for flood shelters in places with many households at risk. The map could
be improved with representation of essential infrastructure elements such as health clinics, schools,
roads and administrative offices and any other features that would help the user visualize the risk
situation, such as topography. These layers are available in DRMInfo
5
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
2.3 Fire risk
The fire hazard map below was created based on the fuel mass available in different land-use
classes. For the purpose of the map urban areas were determined to have high fuel availability.
Interpretation:
The map below shows the areas at higher risk of unintentional and uncontrolled fire and the
vulnerable households within those areas. This map indicates that the highest numbers of
households at risk from fire are in the districts of Ermera, Liquica, and Covalima.
6
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
Such a map could be improved with representation of essential infrastructure elements such as
health centers, schools etc., particularly for district level maps and below. Related maps could
indicate the location of emergency services such as fire stations, medical services, and shelters for
emergency rescue operations. It could also distinguish buildings that are less susceptible to fire due
to their construction. More detailed maps at lower administrative levels may support decisions for
controlled burning to reduce fuel mass near areas with potential for high property losses.
2.4 Drought risk
The criteria for drought usually include the degree to which rainfall in dry years is different from
normal years, measured by the ratio of the rainfall in driest 10% of years to the normal (median)
rainfall. However, that degree of detail cannot be obtained from the limited data available for TimorLeste at present. Instead, a drought hazard map was produced by combining the annual rainfall map
with the groundwater occurrence map.
Interpretation:
This map shows three classifications of drought affected areas within Timor-Leste; high, medium and
low. The majority of high and medium risk areas are close to the northern coast, which agrees with
widely held understanding and anecdotal evidence. The map would be improved with
representation of land use types such as rice and maize fields and village gardens, and existing
groundwater irrigation systems. It could indicate likely locations for cultivation and development of
irrigation resources such as dams, aqueducts and wells. It could potentially support decisions about
agricultural microcredit, giving an indication of loan risk and discouraging inappropriate
development in drought-prone areas. Maps such as these are particularly relevant when factoring in
the expected consequences of climate change; which in Timor-Leste are expected to include
increased rainfall variability during growing seasons, and, therefore, potentially more droughts.
7
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
2.5 Tsunami Risk
For a tsunami to build up into a wave of destructive power it needs a stretch of shoaling where the
waves can grow in amplitude. It is therefore important to investigate where around Timor the
underwater gradient is sufficiently gradual to cause the shoaling effect. The greatest destructive
tsunami hazard occurs along the stretch of coast where the underwater gradient is lowest and the
shoaling stretch is longest.
A Tsunami Hazard Map was produced, based on the degree of shoaling offshore and on the inland
boundary formed by the 30 contour line. This was overlaid with households falling within the higher
risk area.
Interpretation:
The above map shows that there is much greater shoaling along the south coast, making this coast
more vulnerable to destructive tsunamis. On average, in the tsunami danger areas along the south
coast, the 30 m contour line is about 3 km inland. This means that in the event of a tsunami hitting
the South coast the danger zones are doubly vulnerable because: one, the wave can build up to a
great height due to the wide shoaling stretch, and two the swash of the breaking wave will enter far
inland as a result of the flat topography. It is the swash followed by the backwash that then causes
death and destruction when everything in its path is dragged back out into the sea.
According to the map above the entire coastline of Viqueque District is vulnerable to potentially
destructive tsunamis because of the relatively wide shoaling stretch in combination with a flat
topography inland from the coast.
8
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
3
Other hazards and risks
3.1 Cyclone Hazard
Timor-Leste is situated in the cyclone belt, however, this hazard is not mapped because the entire
country is in the “One Cyclone per Decade” zone (source: Natural Hazards Potential Map of the
Circum-Pacific Region, 1995). Besides cyclones, Timor-Leste is affected annually by tropical storms.
These tropical storms can be as devastating as a cyclonic activity as they can deposit extremely high
amounts of rainfall in short time periods. Warning communities in the path of tropical storms is an
important role of the NDMD and local officials. Therefore, developing systems and procedures for
warning systems down to community level (that would also be used for other hazards such as
tsunami) could be expected to be a high priority for government.
3.2 Earthquake Hazard
While it is not possible to predict the exact location or intensity of likely earthquakes, it is possible
to calculate the expected return period for earthquakes within various intensity ranges. Past studies
on likelihood of earthquake damage to locations in the Pacific Rim put Timor in classification VIII1.
This classification indicates that the country is exposed to earthquakes with intensities classified as
“Destructive”2 and which could cause significant damage and loss of life. The classification also
indicates a 20% probability of exceeding level VIII and experiencing a “Ruinous” to “Catastrophic”
intensity earthquake within a 50 year period.
It is also possible to map locally where seismic shaking can have higher relative impact. Data on
potential for ground-shaking exists due to previous analysis in Timor-Leste, as does data for
potential for soil liquification (Wine Langeraar, 2002). This type of data can be used to strengthen
risk reduction measures in specific localities or districts that are considered more prone to these
effects. It is understood that there are very few structures in Dili or district capitals that have been
built with seismic resistance incorporated, and that almost all private dwellings being constructed
are non-engineered concrete/masonry buildings. Such buildings could be expected to have very high
rates of failure in a strong earthquake (6.0-6.9 magnitude) and devastating levels in a major
earthquake (7.0-7.9) or above that was to have an epicenter close to Dili or any of the district
capitals.
As was recommended in the National Disaster Risk Management Plan of 2006, there are many
possible interventions to reduce the risks associated with earthquakes; these include: introduction
of appropriate building codes; enforcement of codes, building permits and inspections; availability of
basic construction standards to the public; training of masons and carpenters; and awareness raising
regarding personal safety during earthquakes.
The map below shows the locations of earthquakes in the vicinity of Timor-Leste over a 34 year
period. The available data suggest that there is considerable risk from a destructive earthquake. In
1
"The World Map of Natural Hazards", Munich Reinsurance Company - Geoscience Research Group
2
Damage slight in specially designed structures; considerable in ordinary substantial buildings with partial
collapse. Damage great in poorly built structures. Fall of chimneys, factory stacks, columns, monuments, walls.
Heavy furniture moved.
9
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
terms of risk analysis the probability of a significant magnitude earthquake would be classified as
having low probability (over a relatively short time period) but extremely high consequences. Over
time, the probability of an earthquake of significant magnitude impacting Timor-Leste becomes
higher. Therefore, if risk reduction measures were not implemented then the consequences from
such an event would remain extremely high.
4
Conclusions
The national level risk maps covered in this report indicate that Timor-Leste faces high levels of
exposure to disaster hazards and that there are many vulnerable elements exposed to these
hazards. The maps provide guidance for government officials and planners as they give an indication
of which districts have higher exposure to risk related to particular hazards. To assist further analysis
more detailed maps can be produced at district, sub-district and suco level where the data indicates
high levels of risk.
It should be noted that the methodologies used to produce these maps do not equate to absolute or
certain risk. Direct observation is required to survey the high-risk locations that are pre-identified
and to confirm the level of risk identified. Given this, district level authorities can use such national
risk maps to identify areas for examination and can cross-reference with local residents
understanding and historical perspective. The DRMInfo mapping tool also requires regular updating
of datasets to allow risk analysis to remain current.
The support requested by the Government for conducting a National Disaster Risk Assessment
would provide decision makers with a more comprehensive picture of the levels of disaster risk in
10
Disaster Risk and Hazard Map Analysis for Timor-Leste
January 2010
different districts and sucos, as well as at the national level. UNDP is committed to support the
process of conducting such a national risk assessment that would train and actively involve officials
both at the national and local levels; develop their knowledge of disaster risk and lay the
foundations for the development of risk reduction plans within government other agencies.
The current level of disaster risk analysis that is available provides some indications of where the
government could prioritise risk reduction activities in the absence of a more comprehensive
national risk assessment. This is particularly applicable when there are a number of large scale
infrastructure projects that are in early phase (e.g. heavy oil power plants and transmission lines,
roads projects, port upgrading, new government buildings, social housing, etc.). Many of the risks
described in this document can be expected to increase substantially over the coming years due to
rapid increases in population, urbanization, environmental degradation and climate change.
Much risk reduction work requires integration within planning timeframes that are annual or longerterm. However, there are many potential risk reduction activities that could be started in the shortterm if the government were to indicate they were a priority and allocate resources. These include:
 Warning systems – A system could be developed for disseminating disaster warning
information to district and suco level in a timely manner.
 Public awareness – There are many basic messages relating to disaster preparedness that
can be given to the public at large. Targeted messages can also be given to specific groups,
e.g. those living in areas considered vulnerable to tsunamis. Awareness raising on longerterm risk reduction, e.g. location and style of house construction, would also be very
valuable.
 Give stronger attention to land-use planning and oversight of the built environment.
11