CASE BOX 4.3 FLOODS AND LANDSLIDES IN BRUNEI IN THE PAST DECADE

By Chi Shing Wong

In recent years, partly attributable to global climate change, the population of Brunei Darussalam, a small Southeast Asian country on northwest Bor-neo Island, has experienced, almost annually, the twin disasters of floods and landslides, causing extensive damage to property, infrastructure and the natural environment, as well as evacuations and other socio- economic disrup-tions. Floods and landslides are particularly severe in the monsoon season of January and caused huge chaos in 2009, 2011 and 2014 due to unpredict-able episodic deluges and flash floods. This presents a severe challenge to the meteorologically- induced disaster preparedness and management of the country, which has emphasised disaster response rather than preparedness and mitigation.

Although the National Disaster Management Centre (NDMC), chaired by the Crown Prince, was established in August 2006 to handle disaster operations and hold disaster exercises and workshops, it is made up mostly of Fire and Rescue Services officials who are responsible for the coordination of any rescue and other work caused by natural disasters. In addition, as of 2011, there had been no specific allocation in the national budget for disaster risk reduction in the country (Rahman, 2011; Brunei Darussalam Prime Minister’s Office, 2013).

The weakness in the infrastructure (the generally shallow urban storm- water drains, canalisation of streams and rivers in the city centre and inad-equate attention to slope stability and soil water retention characteristics prior to construction) adds to the country’s vulnerability to hydro- meteorological disasters (Ndah, Kumar, & Becek, 2015). In 2014, the government allocated 68 million Brunei dollars (US$55.4 million) specifically for flood mitigation projects in addition to a budget of 35 million Brunei dollars (US$28 million) for repair work on public infrastructure and government assets damaged by floods and landslides (Brunei Darussalam Prime Minister’s Office, 2014).

Despite improvements in drainage and infrastructure in some flood- prone areas, such as drainage works at Kedayan River in Kg Menglait and Kg Kum-bang Pasang, and the installation of hard drains to alleviate flood issues in Jalan Sg Tampoi, Jalan Mulaut and Kg Bebatik, there are still areas around the country like Tutong district that continue to be affected by the ongoing floods.

Similar problem exists in many countries where exposure of people and assets has increased faster than vulnerability has decreased (Mohamed, 2014).

Sources: Gupta (2010), Rahman (2011), Brunei Darussalam Prime Minister’s Offi ce (2013, 2014), Mohamed (2014) and Ndah et al. (2015).

Hydrological hazard: fl ood

Globally, fl oods are the most common type of natural disaster. They account for 40% of natural disasters worldwide and fl ooding is an annual event in many places.

It is the leading cause of natural disaster mortality, leading to 6.8 million deaths in the twentieth century (Doocy et al., 2013). Almost half of the fl ood- related fatalities in the last quarter of the twentieth century occurred in Asia. In many places, fl oods are an annual event.

The Center for Research on the Epidemiology of Disasters (CRED) defi nes a fl ood as a signifi cant rise of water level in a stream, lake, reservoir or coastal region.

Generally, fl oods can be classifi ed into three types: general fl ood, fl ash fl ood and storm surge/costal fl ood (CRED, 2009). General fl ood describes the accumulation of water on the surface due to long- lasting rainfall (water logging) and the rise of the groundwater table above the surface. It can be induced by the melting of snow and ice, backwater effects or special causes, such as the outburst of a glacial lake or the breaching of a dam. Flash fl ood is a sudden fl ooding episode which occurs within a short duration. It is typically associated with thunderstorms and can virtu-ally occur in any place. Storm surge/coastal fl oods are the rise of the water level in the sea, an estuary or lake as a result of strong wind driving seawater towards the coast. The areas threatened by storm surges are coastal lowlands.

Although a tsunami is not a fl ood but a series of waves generated by an (under-water) earthquake on the sea fl oor, as discussed in an earlier section, the sudden fl ooding of coastal areas and the potential damage on infrastructure may cause health impacts largely similar to those of fl oods. (Please also refer to Knowledge Box 4.3 on tsunami.)

What are the known risk factors associated with adverse health outcomes?

Flood types are associated with different impacts. For example, as fl ash fl oods occur quickly and leave people with little lead time to respond, they may result in higher mortality rates as compared to general fl oods. On the other hand, general fl oods, despite the slower onset, affect larger populations and a wider area. In addition, fl oods with higher water depth and greater fl ow velocity result in greater damage.

Rainfall is a main cause of fl oods. Other factors contributing to this haz-ard include: human factors (lack of structural fl ood control measures, such as embankments, obstruction of river water fl ow due to debris and waste, and lack of drainage basins in urban areas), meteorological factors (solidifi ed ground surface after a drought reducing the ability of soil to quickly absorb excessive rain-water, and excessive precipitation over a prolonged period oversaturating the soil and increasing overland run- off), and topographical factors (landscape around a river infl uencing how quickly rainwater reaches the channel – e.g. a river channel surrounded by steep slopes and lacking in vegetation or woodland could easily lead to the river bank bursting and the overfl ow of water onto the fl oodplain since there

is a lack of trees and plants to intercept precipitation) (Associated Programme on Flood Management [APFM], 2013) (see Case Box 4.4).

What are the health impacts of fl oods?

The health impact of fl oods is complex and diffi cult to generalise across contexts.

High mortality is rare in fl oods. During the past few decades, only 58 events resulted in more than 1,000 deaths. Settlements in fl oodplains are more prone to fl oods than houses on higher ground. The size of fl oodplains can be varied. For example, Vietnam’s Mekong River delta fl oodplain covers an area of over 12,000 square kilo-metres. People living in a fl ood- prone area can mitigate the impact of fl oods by adopting fl ood- resistant designs in their houses, such as reinforcing walls with waterproof coatings and equipping homes with backup generators. In urban set-tings, fl ood damage is often more intense due to the higher population density and the high proportion of impervious surfaces and a lack of green infrastruc-ture to absorb excess precipitation. With the increasing intensity and frequency of cyclones due to climate change, urban areas are also becoming more susceptible to fl ash fl oods.

Floods may be caused by fresh water or salt water. Freshwater fl oods may leave mud and soil when the waters recede, saltwater can affect the salinity of ground water, making water undrinkable and harming the aquatic animals (Smith, 2009). Floods may cause water contamination by bacteria and viruses.

For example, fl oods in Mozambique in 2000 caused a rising number of diar-rhoea cases, fl oods in Mauritius in 1980 triggered an outbreak of typhoid fever, and fl oods in West Bengal in 1998 created a cholera epidemic (WHO, 2005).

Cholera is an infectious diarrhoeal disease, caused by Vibrio cholerae . It is esti-mated that there are 1.4 to 4.3 million cases of cholera annually, causing 28,000 to 142,000 annual deaths (World Health Organization [WHO], 2015a). Studies have shown that V. cholerae is native to coastal ecosystems, particularly in the tropics and subtropics (Colwell, Kaper, & Joseph, 1977; Lipp, Huq, & Colwell, 2002). Therefore, coastal fl ooding increases the risk of cholera infections. Fur-thermore, stagnant water, remaining for days or weeks after the initial fl ood, increases the risk of vector- borne illnesses by providing new breeding sites for vectors. Floodwater also destroys power lines and submerges electrical equip-ment, causing electrical shocks and increasing the risk of fi res. Table 4.3 summarises the health impact of fl ooding.

Flood- related mortality . Drowning and traumatic injuries are common causes of death during floods as fast-flowing floodwater carries vehicles, trees or building materials, causing orthopaedic injuries, trauma and lacerations. A study of 13 floods in Europe and the United States found approximately two- thirds of the 247 deaths occurred through drowning, and males were highly vulnerable to dying in floods, partially due to unnecessary risk- taking behav-iour (Jonkman & Kelman, 2005). Another review of relevant literature found mortality by drowning in the home occurred largely among the elderly. The

primary risk factors for immediate flood- related deaths depend on the charac-teristics of the flood: speed, depth and the extent of water. For example, flash floods are more hazardous due to their speed when compared with general floods (Ahern et al., 2005). In addition to drowning and injuries, victims are prone to hypothermia, especially in cooler weather, and animal bites if the floodwaters originate from rivers and other water bodies with snakes or other dangerous animals.

Flood- related morbidity . Floods cause various morbidities directly or indi-rectly. Injuries, communicable diseases, and mental health problems are found to be associated with fl oods. Injuries : Flood- related injuries, such as contusions and lacerations, may occur as individuals attempt to remove themselves and their fam-ily from danger. Secondary injuries are also commonly associated with post- fl ood,

TABLE 4.3 Direct and indirect health impact of fl ooding

Type of effect Health impact

Direct impacts –e.g. direct exposure to fl oodwater

• Drowning and injuries from walking or driving through fl oodwater, contact with debris in fl oodwater, falling into hidden manholes, injuries from submerged objects, injuries while trying to move possessions during fl oods

• Building collapse and damage (injuries)

• Electrocution

• Diarrhoeal, vector- and rodent- borne diseases

• Respiratory, skin and eye infections

• Chemical contamination, particularly carbon monoxide poisoning from generators used for pumping and dehumidifying

• Water shortages and contamination due to loss of water treatment works and sewage treatment plants

• Stress, short- and long- term mental health issues, including the impact of displacement

Indirect impacts –e.g. impacts on other health determinants

• Loss of access to health care

• Damage to health care infrastructure and other vital community facilities

• Damage to water and sanitation infrastructure

• Damage to crops, disruption of food supplies

• Disruption of livelihoods and income

• Population displacement

• Mental and social health problems due to length of fl ood recovery and fear of recurrence

Source: Adapted from Ahern, Kovats, Wilkinson, Few, and Matthies (2005).

clean- up operations – for example those related to unstable buildings. Commu-nicable diseases : The risk of outbreaks after fl ooding is small in industrialised countries due to established water, sewage and public health infrastructure. In developing countries, these infectious disease risks are increased. Waterborne disease : Flooding presents a community with an increased risk of waterborne diseases (e.g. cholera, leptospirosis and hepatitis A) that are transmitted through the faecal- oral route since the drinking water source may be contaminated with pathogens. Heavy rainfall can damage the water and sanitation infrastructure, triggering sewage overfl ows into drinking water. Vector- borne disease : Although fl oodwater initially washes away mosquito breeding sites, standing water may be a perfect breeding site for mosquitoes, thus increasing the risk of vector- borne diseases, such as dengue and malaria. For example, the fl ooding in Costa Rica in 1991 and in the Dominican Republic in 2004 led to malaria outbreaks. Mental health problems : There can be an increase in the incidence of mental health problems, which results directly from the experience of living in the fl ooded areas and indirectly from geographic displacement, damage to houses and assets, and stress in the restoration process.

Uncertainties in assessing health impacts of fl ood

The true health impact of fl ooding is diffi cult to estimate as it is diffi cult to quantify health impacts as the adverse human health consequences of fl ooding are complex.

Understanding the vulnerability of population subgroups may help guide appropri-ate solutions to reduce the impact of fl ooding. The elderly, the disabled, children, women, ethnic minorities and those with low incomes are particularly at risk (Hajat et al., 2005). Additionally, displaced populations often experience compromised access to clean water and sanitation.

In short, floods are characterised by the accumulation of water on the sur-face. There are three types of floods: general floods, flash floods and storm surges. Drowning, hypothermia, animal bites, injuries, electrical shocks and waterborne and vector- borne illnesses are the common health impacts result-ing from floods.

What are the responses needed?

In general, fl oods and high winds do not result in high levels of mortality. Search and rescue, and evacuation of the affected population are the primary responses needed in a fl ood disaster. Specifi c attention needs to be directed towards reducing the risk of exposure to waterborne and vector- borne diseases. Sewage and other pollutants might contaminate water supplies, potentially leading to the transmission of waterborne diseases. Damage to crops, housing and infrastructure may affect food production and can lead to economic loss. Clean- up activities, maintenance of clean water and food security are key public health response needs for the affected population.

Climatological hazards: drought and famine

Droughts and famines are disasters with impact that may last for prolonged periods.

Droughts are climatological events that can last from a couple of weeks to several years and famines are a subtype of disaster that slowly affects a large population over months and years. Both of these calamities have a devastating impact on the health and livelihood of people as well as the ecosystems of the affected communities.

Drought is usually a preceding factor of famine but not every drought results in a famine. These two disasters will be discussed together in this section because they often go hand in hand.

What is a drought?

A drought is a climatological natural disaster defi ned as a defi ciency in a region’s water supply for an extended period of time as a result of persisting below- average

CASE BOX 4.4 FLOODS IN PERU AND CHILE, MARCH 2015