On April 14, a severe flash flood invaded Oman from an extreme precipitation event that lasted until April 17. The highest rainfall record over the entire period was 302mm, while the peak hourly record reached 180.2mm. This weather event is not an extraordinary case considering the topography of Oman represented by the lofty Al Hajar mountains. Advection from hot and cold air masses during this transitional season and moisture flow from the surrounding water basins are all a recipe for severe thunderstorms, especially when combined with an external trigger such as surface low pressures and extended upper level-troughs. However, the interaction of humans with natural hazards created susceptibility to a disaster. Up to April 18, 21 people were found dead, including 11 pupils and infants. The final number of lost bodies is not yet confirmed. At least 1200 people including kids were trapped in schools and buses rescued by the Civil defence. Many people were isolated on the road or in their houses as flash floods invaded their homes and gardens, cutting off transportation links.

The loss was tremendous despite the issuance of warnings and forecasts. The root cause of this disaster was inadequate decision-making which led to the loss of life and enormous damages by increasing the risks, exposure, and vulnerability. Communities live on the floodplain and the flood-prone areas in the valleys (locally known as Wadis) that connect the mountains and the coastal plain. Intensive floodplain land use and a poor urban planning system aggravated flooding incidence. However, no statistics are available to the public indicating the extent and nature of property damage. The absence of a sufficient drainage system amplified the calamity during this case due to the saturation and flooding of the ground from the persistent precipitation.

Are we prepared for more extreme precipitation and intense tropical cyclones in the future as a consequence of climate hazards and cloud seedings operations? How can we mitigate and reduce the risks from extreme future scenarios when the precipitation record is broken?

Call for Action

Day and Fearnley (2015) divided mitigation systems into three main strategies based on when and how actions should be taken: permanent mitigation, responsive mitigation, and anticipatory mitigation. Their study showed how important it is to integrate and coordinate these three strategies, which also need to be tested to see how well and resilient they work. For these strategies to work well together, paying close attention to how they affect each other is essential. The most important thing to consider is how the vulnerable population understands the decision-making processes, how they react to the warning messages regarding their awareness, and what they expect these strategies to do. For example, the limited ability of permanent mitigation strategies to deal with rare hazards under poor responsive and anticipatory strategies leads to disastrous results. The historical record was ignored during the northeast Japan earthquake and tsunami on March 11, 2011, despite the high standards of permanent mitigation measures. The same thing could happen under irresponsive actions toward the issued warnings. The schools and workplaces would have been moved online, and the announcement should have been made at least 48 hours before the approach of the significant weather cases.

Successful mitigation systems require four key components: a map of the hazards, an early warning system, a control structure and non-structure measures, and regional planning and development (Wieczorek et al., 2001; Larsen, 2008). Non-structural measures can include reorganising, removing, converting, discouraging, and regulating growth (Wieczorek et al., 2001). For example, preventing, and minimising the redevelopment of areas susceptible to the future hazards. Hazard-prone areas can be utilised as an open space or certain type of farming taking in consideration the relevant factors.

A structural measure could include designing and constructing parallel to the flow direction and constructing multi-story buildings where the second floor can be used for living instead of the first (Kelman, 2001). Unfortunately, no public building census data is available to determine the number of stories in existing buildings in Oman. Other engineering solutions, such as large debris flow impoundment dams and their regular maintenance, could offer some protection even for the alluvial fan regions. More research must be conducted in each watershed to answer specific design questions, including the size of the event for which they should be built (Larsen, 2008).

Although the warning system does not prevent property damage, it protects lives by predicting flood-prone areas. It relies on radar, ground, and upper-air observations, as well as a robust model to identify the thresholds that trigger flood risk for each place with a rapid and practical link between Ministries of education, higher education, labour, civil defence, police, and the relevant authorities. Using general flash flood forecasts for fear of false alarms reduces the credibility and practicability of the warning system. On the other hand, the use and value of a warning are inversely proportional to the size of the geographical area covered by the warning (Larsen, 2008).

Regional planning and policy formulation need to involve multidisciplinary experts. For example, developing a flood hazard management policy requires technical expertise, public education and awareness, and good communication between scientists, policymakers, and politicians. Local communities should be involved alongside physical and social scientists. Post-event decision-making about recovery and reconstruction involves an exemplary dialogue between the government, experts, and the local population. Different options must be considered, such as balancing flood risk reduction against loss of livelihood and social considerations, and a compromise must be reached between the different groups. This measure guarantees that local voices and narratives are heard, ensuring resilience can only be accomplished by appreciating human livelihoods. 

With the increasing responsibilities and capability of efficiently responding to warnings, the study of how decision-makers and people receive and react to a warning has become essential to warning design. Educational programmes should be developed to increase familiarity with the warnings and the appropriate response (see Towards the “perfect” weather warning from the WMO), which is also emphasised in Target G of the Sendai Framework to “Substantially increase the availability of and access to multi-hazard early warning systems and disaster risk information and assessments to people by 2030”.

There is a need to develop disaster risk reduction strategies and systems that allow for the large uncertainties in the region’s hazard frequency-intensity distributions. No one can deny the complexity of Oman’s topography or the flood risks in the Al Hajar mountains, but this topography can be a boon if properly engineered and utilised.

Finally, a comprehensive national flood hazard management strategy is urgently required, along with urgent actions to be implemented to tackle the cascading flood risks. With each further delay, the total cost of the bills will go up even further in the future.

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Salma Al-Zadjali is a PhD candidate at IRDR, researching decadal climate variability of precipitation in order to assess the feasibility of a cloud seeding project over the Al-Hajar mountains in Oman. 

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The views expressed in this blog are those of the author.

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