Disaster Risk Management

Definition
Disaster management can be defined as the effective organization, direction and utilization of available counter-disaster resources involving several activities of prevention, preparedness, response, recovery, mitigation and risk reduction and rehabilitation. These activities are displayed as continuous cycle as displayed in the figure 6 below.

1. Prevention is measures taken to avert a disaster from occurring, if possible (to impede a hazard so that it does not have any harmful effects).

2. Preparedness is measures taken in anticipation of a disaster to ensure that appropriate and effective actions are taken in the aftermath.

3. Response is actions taken immediately following the impact of a disaster when exceptional measures are required to meet the basic needs of the survivors.

4. Recovery is the process undertaken by a disaster-affected community to fully restore itself to pre-disaster level of functioning.

5. Mitigation and risk reduction are measures taken prior to the impact of a disaster to minimize its effects (sometimes referred to as structural and non-structural measures).

6. Rehabilitation is actions taken in the aftermath of a disaster to: assist victims to repair their dwellings; re-establish essential services; and revive key economic and social activities.

In implementing the DRM approach, accurate and reliable hazard, vulnerability and disaster risk information is vital and relevant to all phases of the disaster management cycle which attaches great importance to hazard mapping and vulnerability assessment as a fundamental tool for good decision-making and efficient sharing of disaster risk information.

Hazard and Vulnerability Map for Mitigation
Hazard map is an effective tool in disaster management in term of providing the residents with the information on the range of damage and disaster prevention activities. There are two types of hazard maps:

1. Residents-educating type: This type of map has the main objective to inform the residents living within the damage forecast area of the risk of danger. The information on spots of danger or places of safety and the basic knowledge on disaster prevention are given to residents. Therefore, it is important that such information is represented in an understandable and very simple language.

2. Administrative information type: This type of map is used as the basic materials that the administrative agencies utilize to conduct disaster preparedness and mitigation service.

For giving the whole information of the disaster risk management, we shall take one example of risk assessment in the East Java province, in this case, tsunami hazard assessment in Pacitan coastal area.

Data needed
List of data needed in risk assessment process much depends on type of hazard that we want to assess. In term of multi hazards, the type of data needed and their availabilities are listed in the table 6 below.

Of all the data mention above, some of the data are not available. Thus, to fill the data needed for tsunami vulnerability map, we need to derivate some of the data as follows:

1. Landuse map is derived from topographic map

2. Road map is derived from topographic map

3. Irrigation map is derived from topographic map

4. Fresh water and electricity network can not be derived from the topographic map.

5. Tsunami historical data is derived from previous researches.

Tsunami historical data is needed to conduct the tsunami simulation. This historical data is derived from previous research conduct by Muhari et all as displayed in the figure 7 below. From these historical data, we define tsunami scenario of Pacitan’s coastlines is 14 meter.

The working procedure
In general term, this exercise is conducted through following flowchart displayed in figure 8 below. The following methodological steps are done in this study as follows based on the methodology done by Papathoma and Dominey-Howey (2003):

1. Identification of inundation area and inundation depth area

For this study, we do not consider tsunami source and seabed topography. To identify inundation zone, we use historical data and combining it with elevation data. Elevation data was derived from SRTM data (90x90 meter) downloaded from USGS (2009). The highest tsunami run-up for south coast of Java island was 14 meter from Banyuwangi tsunami event in 1994 (Muhari et all, 2007). This run-up data was used to determine the area between the coastline and the highest recorded tsunami. Since the highest tsunami used for this purpose was 14 meter, so the inundation zone will be the area between the coastline and the 14 meter contour. Since the depth of inundation area will be varied depend on the contour, so we divide this inundation area into four inundation depth zones (IDZ), as follows:

• IDZ 1 (High IDZ) : ground elevation 0 – 5 meter
• IDZ 2 (Medium IDZ) : ground elevation 5 – 10 meter
• IDZ 3 (Low IDZ) : ground elevation 10 – 14 meter
• IDZ 4 (Very low IDZ) : ground elevation > 14 meter

These inundation depth zones are used as a background for the maps in displaying the spatial vulnerability of element at risk, in this case settlement. The settlement located in high IDZ will have higher risk due to tsunami, so these areas should receive priority in mitigation action and also planning implementation.

2. Identification of Element at risk

The spatial distribution of settlement is obtained from topographic maps. Actually, not only settlement that we should consider for element at risk due to tsunami but there are many elements which are vulnerable for tsunami also. For example: inhabitants, infrastructure, cultivated area, properties, etc.

3. Determination of tsunami hazard map for settlement

For this study, vulnerability of a settlement is determined based on its location. For the better result, actually we should also consider the building condition such as number of stories, material, construction, etc. In this case, the importance of the chosen criteria (settlement) is connected to the mitigation measures that may be taken. We divide the level of settlement risk into 4 based on inundation area, as follows:

• High vulnerability : located at ground elevation 0 – 5 meter
• Vulnerability : located at ground elevation 5 – 10 meter
• Less vulnerability : located at ground elevation 10 – 14 meter
• Very less vulnerability : located at ground elevation > 14 meter

4. Determination of vertical evacuation map

Pacitan is located in low-land area with sandy beach. At the occurrence of tsunami, escaping to the higher place would be not possible. Therefore, it is necessary to provide safety towers and artificial hills in a certain place. The criteria should be considered for this purpose including accessibility and the distance to the settlement and higher place.

5. Determination of soft structural countermeasures map

Structural tsunami countermeasures can be grouped into two types: namely, hard and soft structures. Typical hard structures are seawalls, breakwaters and groynes, while soft structures are mangrove green belts, coastal forests and land-use arrangements. For this purpose, we take into account the drainage pattern and existing landuse for mangrove using topographic map and geologic map.

As the result of these activities, we will have several maps as the basis to conduct disaster risk management activities, as follows:

1. Tsunami hazard map

2. Tsunami vertical evacuation map

3. Soft structural countermeasures map

These three maps are used to develop some threatment option to reduce tsunami impacts and effects (see in the enclosures).

Tsunami hazard map is not the final result of these activities, the main point is how to disseminate the hazard information to local communities in order to increase their awareness toward disaster occurrences. Local goverment and community based development must take into account when we dealing with local communities. Some of mitigation methods to avoid tsunami hazard can be carried out in form of structural and nonstructural measures as follows:

Non – structural measures
Several recommendations in the Pacitan area are conducted considering the result of this study through zoning policies as follows:

1. Restrict new development in this area to avoid loss of live and property damage. In the case of Pacitan district, Ploso and Sidoharjo villages are located in the high vulnerable and vulnerable zone. Thus, the villages and their inhabitants are prone to tsunami hazards. By restricting new development in this area and combining it with resettlement of existing inhabitants, we hope the number of loss and damage will be less devastating. Moreover, spatial coastal zone planning could be applied including set-back lines, mangroves green belts and roads connecting to upland areas for easy evacuation.

2. Mangrove plantation in the Pacitan’s coastal area for reducing the impact of tsunami’s waves. Some of experts have already proved that mangrove forest may as effective as concrete seawalls structure for reduction of tsunami effect on house damage behind the forest (Harada et all in Kathiresan).

3. Vertical evacuation. In the areas which are not possible for people to move to higher place i.e. hills, we must provide such high building for evacuate in the case of tsunami occurrences. The number of stories of the evacuation tower must consider the tsunami’s waves height. In case of Pacitan coastal area, the height of evacuation tower must be more than 5 m.

Structural measures
In addition to the recommendation above, we also recommend the other structural countermeasures that would reduce the tsunami impact, as follows:

1. Building codes. In Pacitan coastal area, building construction should consider tsunami waves force. For example, after tsunami struck Pangandaran village, fisherman house was built followed several building codes as:

a. The minimum number of stories is two, the first floor is open space allowing the tsunami waves flow without causing much damage on the houses and properties.

b. The foundation of the building using deep pier of concrete and heavy steel frames are likely to perform well in a tsunami case unless if tsunami is compromised by earthquake shaking.

2. Seawalls are one of the structural measures used in to prevent tsunamis, storm surge and high waves. This type of construction has a buffer zone to prevent coastal inundation due to overtopping waves.

3. Wave breaker is one of structural measures used for reducing the tsunami wave’s energy as they move toward land areas. Wave breaker in Indonesia is constructed by using simple construction.

4. Resettlement. Resettlement is the last option taken when we can not ensure that other structural measures will be able to reduce the impacts of tsunamis. The new settlement area must consider the worse scenario.

These recommendations need further research and must consider local community as a base of disaster reduction because of several reasons:

1. Pacitan’s coastline is a tourism area so structural measures built in that area must have double function as mitigation structure and as a tourism object.

2. Community Based Disaster Mitigation is one of the most effective ways to reduce the impacts of tsunami hazard in term of community empowerment toward tsunami hazard reduction.

DRMIS
Disaster risk management information system (DRMIS) can be defined as an information system designed to prevent the loss of lives, minimize human suffering, inform the public and authorities of risk and minimize property damage and economic loss, speed up the recovery process.

East Java Province DRMIS is a vital needed due to the intensity of disaster occurrences in that area from landslide to earthquake. Moreover, the development of internet makes the process of information dissemination broader than before.

Conclusion
Disaster risk management is efforts that prevent the impacts of disaster in the study area carried out in the series activities of prevention, preparedness, response, recovery, mitigation and risk reduction and rehabilitation. One effective tool to carry out disaster risk management process is definition of hazard and vulnerability maps which function as the basis map for all of disaster risk management activities. From the case of tsunami hazard assessment of Pacitan coastal line, we can see the usefulness of these maps for response, recovery and mitigation activities.

2008 Disaster Events in East Java

Some of disaster events in East Java province are explained as follows:

Landslides
Landslides most commonly occur in the southern and middle zones of East Java province. Some of landslide occurrences are shown in table 1 below (modified from www.pu.go.id).

Floods
Floods most commonly occur in the middle and northern zones of East Java province. Some of flood occurrences are shown in table 2 below.

Tropical Cyclones
Tropical cyclones most commonly occur in the middle and western zones of East Java province. Some of tropical cyclones’ occurrences are shown in table 3 below.

Drought
Drought most commonly occurs in the middle and western zones of East Java province. Some of drought occurrences are shown in table 4 below.

Tidal floods
Tidal floods most commonly occur in the middle and northern zones of East Java province. Some of tidal waves occurrences are shown in table 5 below.

East Java Province Hazards

Types of Hazard

According to historical data, East Java province has possibilities natural disaster occurrences such as landslide hazard, volcanic eruption, earthquake and flood explained as follows:

Mass Movement
Mass movement is movement in which bedrock, rock debris, or soil moves downslope in bulk, or as a mass, because of the pull of gravity. Mass movement includes from so slow movement to very rapid movement (McGeary et all). Mass movement can be categorized based on the movement mechanism as follows:

1. Flow implies the descending mass that moving downward is viscous fluid.

2. Slide means that the descending mass remains intact and moving along one or more well – defined structure. Two types of slide are transitional slide in which the descending mass moves along a plane approximately parallel to the slope of the surface while in rotational slide (slump), the descending mass move along a curved surface, the upper part moving downward and the lower part moves outward.

3. Fall occurs when material free – falls or bounces down a cliff.

Landslide is one type of mass movements in which the descending mass remains intact and moving along one or more well – defined structure. Landslide occurrence can be caused by two primary categories: internal and external factors or combination of both. Some internal factors triggering landslide occurrences are: lithology/material/soil, geological structure, relief and slope, stratigraphy and drainage pattern/density. Some external factor triggering landslide occurrences are climate controls, landform unit, hydrological condition, land use/land cover and human activity.

Volcanic Eruption
Volcanic eruption is a natural event resulting from the activities of the Earth’s inner core that may release some of the Earth’s energy accompanied by volcanic material i.e. ash, magma and pyroclastic lava. There are three types of major volcanoes that are marked distinctively based on size, shape and composition as:

1. Basalt dome or Shield volcanoes are broad, gently sloping volcanoes constructed of solidified lava flow. During eruptions, lava spreads widely and thinly due to its low viscosity. Because the lava flows from a central vent without building up much near the vent, the slopes are usually between 2° and 10 i.e. Kilauea, one of the volcanoes that form Hawaii Island.

2. Cinder cone or pyroclastic cone is a small volcano between 100 and 400 meters tall, made up of pyroclastic fragment ejected from a central vent. In contrast to the gentle slope of shield volcano, cinder cones commonly have slopes of about 30° i.e. Cerro Negro.

3. Composite volcano or stratovolcano is volcano constructed of alternating layers of pyroclastic fragments or solidified lava flows. Composite volcanoes are built over long spans of time. Eruption is intermittent, with hundreds or thousands of year’s inactivity separating a few years of intense activity. This type of volcano is the larger and better known volcanoes of the world i.e. Mount Fuji and Anak Krakatau.

From three types of volcanoes, the most hazardous and devastating volcano is stratovolcano because it has high explosive eruption involving pyroclastic lava flows which usually flows faster due to steep slopes and often combine with hazardous gas explosion. East Java province has 12 volcanic mountains, most of them categorize as composite or stratovolcano meaning that this area is highly prone to volcanic eruption disasters

Earthquake
Earthquake is a trembling or shaking of the ground caused by the sudden release of energy stored in the rocks beneath earth surface. Earthquake usually occurs in the area where plate boundaries meet and interact. Southern zone of East Java province is one area prone to earthquake and tsunami hazard since it is directly facing the subduction zone in the Indian Ocean and un-solidified soil properties.
According to Harian Sore, some historical data of earthquake shows that Banyuwangi and other areas around it was stricken by an earthquake struck with 4.9 Richter scale in September 10^th, 2004, ten years after tsunami disaster struck that area in 1994.

Drought
There are three types of drought known which are explained as follows:

• Meteorological drought, involves reduction in rainfall a specific period (day, month, season, year) below a specific month-usually.

• Hydrological drought, involves reduction in water resources (stream flows, lake levels, groundwater, underground, and aquifers) below a specific level for a given period of time.

• Agricultural drought is the impact of meteorological and hydrological drought on this particular area of human activity. Crops have particular temperature moisture and nutrient requirement during their growth cycle in order to achieve optimum growth.

Northern zone of East Java consist of topographic Karsts which mainly dominated by groundwater table, thus, in the dry season, this area may facing all of drought’s types above.

Tropical Storm
A tropical storm is a storm system characterized by a low pressure center and numerous thunderstorms that produce strong winds and flooding rain. Tropical cyclones feed on heat released when moist air rises, resulting in condensation of water vapor contained in the moist air (www.en.wikipedia.org). Some areas in East Java province suffer from this type of hazard causing some damages and losses.

Flood
A flood is an overflow of an expanse of water that submerges land, a deluge which may result from overflowing of water volume within a body of water, such as a river or lake escaping its normal boundaries. Some types of flood hazard based on the sources and the material carried out are:

1. Riverine floods are floods that triggered by monsoonal rain and high tide, categorized in:

• Slow kinds: Runoff from sustained rainfall or rapid snow melts exceeding the capacity of a river's channel. Causes include heavy rains from monsoons, hurricanes and tropical depressions, foreign winds and warm rain affecting snow pack.
• Fast kinds: flash flood as a result of e.g. an intense thunderstorm.

2. Estuarine floods (tidal floods) are floods that caused by a combination of sea tidal surges caused by storm-force winds. A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category.

3. Coastal floods are flood caused by severe sea storms, or as a result of another hazard (e.g. tsunami or hurricane). A storm surge, from either a tropical cyclone or an extratropical cyclone, falls within this category.

4. Catastrophic floods are flood caused by a significant and unexpected event e.g. dam breakage, or as a result of another hazard (e.g. earthquake or volcanic eruption).

Natural VS Man Made Disasters

Disaster is an event that has negative impacts to society and environment by causing widespread of human, material and environmental losses that exceed community’s ability to cope using their own resources and need for national or international assistances.

Disaster results from the combination of hazard, vulnerability of affected community and lack of capability of affected community to cope with certain disaster. According to Centre for Research and Epidemiology of Disaster (CRED), an event can be categorized as disaster if that event fulfills at least one of these following criteria: ten or more people reported killed, 100 people reported affected, declaration of a state of emergency or call for international assistance. Based on the triggering factors, disaster can be categorized as natural and man – made disaster.

Natural disaster
Natural disaster is a type of disaster caused by forces of nature resulting from the consequence of a natural hazard which moves from potential into an active phase. Natural hazards will never result as a natural disaster in the areas without vulnerability i.e. tsunami in uninhabited areas. Natural disaster can be caused by physical factors known as non – biological disaster and non physical factors known as biological disaster.

Types of natural disasters

Non – biological Disaster
Non – biological disaster has physical factors triggering its occurrences and this type of disaster can be categorized in five major types based on the factors triggering it, as follows:

• Hydrological disaster is a disaster having water as its major deriving factor including tsunami, flood, etc.
• Climatic disaster is a disaster caused by the climatic changes from its usual pattern for instance: drought, hail storm, tornado, hurricanes or tropical cyclones, lightning and wild fires.
• Geological disaster is a type of disaster triggering by endogenic forces from the Earth’s inner corner i.e. earthquake, lahar, landslide and mudflow

Biological Disaster
Biological disaster is one type of disasters that caused by an organism, or substance derived from an organism, that poses a threat to human health. One form of biological disasters is epidemic which is unusual increase in the number of cases of an infectious disease which already exists in a certain region or population. Some examples of biological disaster are: avian flu, cholera, dengue fever, Ebola and Marburg, malaria, measles, meningococcal meningitis, HIV/AIDS and tuberculosis.

Man Made Disaster

Disasters caused by human action, negligence, error, or involving the failure of a system are called human-made disasters. Human-made disasters are in turn categorized as

• technological disaster i.e. industrial disaster and structure collapses
• sociological disaster i.e. arson, civil disorder, terrorism and war,
• hazardous material such as radiation contamination, chemical, biological and radiological disasters
• transportation i.e. aviation.

Types of man made disasters

Overview

In overall, Indonesia is located in the area “ring of fire” in which prone to natural disasters ranging from the one coming from endogenic process i.e. earthquake and tsunami to the one coming from the interaction between endogenic and exogenic process i.e. landslide, erosion and drought.

East Java province is one of the most crowded provinces in Indonesia after West Java Province. Geographically, East Java Province is bordered by Java Sea in the north-ward, Bali Strain in the east-ward, Indian Ocean in the south-ward and Central Java Province in the west-ward.

In physiographic term, East Java province can be categorized into three zones: southern zone (plateaus), middle zone (volcanic mountains) and northern zone (fault zones) (www.en.wikipedia.org). Southern zone which is directly facing subduction zone between the India-Australian Plate and Eurasian Plate leading this zone prone to geological hazard i.e. earthquake and tsunami. The Middle zone has relative fertile land due to volcanic eruption while northern part consists of topographic Karsts that may lead to water shortage.

As one of central industrial developments in Indonesia East Java, Province has high demand of infrastructure and settlement area for supporting its economic activities. Thus, overpopulation and overdevelopment increase pressure to environment as well as triggering environmental degradation leading the vulnerability of the population due to the natural and manmade hazards that may occur in the area.

In order reduce the impact of disaster occurrence i.e. loss of lives, property damages and economic losses, stakeholders including all level of governments, non – government and community based organization should conduct disaster risk management involving several activities of prevention, preparedness, response, recovery, mitigation and risk reduction and rehabilitation.

Disaster risk management information system (DRMIS) is a system function as a useful basis for planning, monitoring, controlling and reporting activities due to the efforts of reducing disaster’s impact. Hopefully, DRMIS can give both spatial and statistical data related to disaster occurrences in the study area.