Impact News

Written by: Abimanyu A. Atmaja, Dekka D. Putra, Kharis A. Alam, Muhammad Asa, Muhammad A. Dzulfikar

Edited by: Chelsea Patricia

For the past few weeks, the Indonesian Agency for Meteorology, Climatology, and Geophysics (Badan Meteorologi, Klimatologi, dan Geofisika/BMKG) has issued warnings to most of Indonesia’s higher latitude regions, highlighting the potential for extreme weather events. One such event is due to wind shear and atmospheric convergence, which lead to a subsequent buildup of air masses and convective clouds (Info BMKG, 2024). This condition ended up being the triggering mechanism of secondary hazards that happened all over Indonesia, including what we saw in West Sumatra and South Sulawesi.

Mt. Marapi Flash Flood and Cold Lahars

Marapi volcano has exhibited a significant increase in activity over the past year, characterised by two distinct eruptive episodes, which resulted in not-so-stable deposits on the mountain slopes and upstream fluvial channels (PVMBG, 2023). The developing atmospheric conditions culminated in extreme rainfall on May 11th, impacting the surrounding regions, which usually experience low-intensity rainfall (mean rate: 9.8 mm/year), including Marapi Volcano. This intense precipitation triggered a catastrophic flood and cold lahars, bringing volcanic deposits ranging from debris to boulders to green and residential areas downstream (BNPB, 2024c).

The disaster has unfolded with at least 67 confirmed fatalities, 20 people unaccounted for, and a growing number of displaced communities (DPR RI, 2024). The scale of this tragedy is likely to escalate, with extensive residential areas experiencing near-complete collapse, as reported in Agam, Tanah Datar, Padang Panjang, and Padang Pariaman Districts (Prasetyo, 2024). Silaiang and Malalak, the roads connecting Bukittinggi and Padang, are currently impassable due to deposits of cold lahars (Caniago, 2024a). Additionally, the closure of Sitinjau Lauik Road (Padang-Solok) due to an unanticipated landslide leaves residents with the option of utilising the precarious and narrow Kelok 44 Road (Figure 1) (BNPB, 2024b). 

Early post-disaster efforts have focused on clearing landslide debris from Malalak Road and successfully re-establishing access (Efison, 2024a). However, recurrent hazards have hampered similar interventions on other roads, re-emerging during the clearance process (Efison, 2024b). 

Figure 1. Roads connecting Bukittinggi to other areas in West Sumatra
Source: Analysis on BIG Data and Open Street Map, 2024

Luwu Flash Flood and Landslide

A similar weather pattern triggered a separate disaster in South Sulawesi roughly a week before West Sumatra’s flooding. The prolonged rainfall caused the water to exceed the river’s capacity, resulting in a maximum of 3-metre-deep flash flood (BNPB, 2024a; Rusdianto, 2024). The consequences of this event were visible in the surrounding areas of Mt. Latimojong’s river system, with the most impacted area being the Luwu Regency, where the flood impacted 13 sub-districts (Figure 2) (Fajar, 2024). According to the latest reports, the floods, accompanied by landslides, caused at least 14 deaths, damaged over 1,000 homes, and blocked road access (BNPB, 2024a).

Apparently, heavy rain is not the whole story behind the floods and landslides in Luwu. Excessive mining activities and land conversion have also played a role in the miserable scenes we witness in the area (WALHI, 2024). In addition, looking at the constituent materials, most of the Luwu area is dominated by soils with moderate to high landslide sensitivity, some of which are latosol and grumusol soils. These soils have a clayey structure and are able to bind water, increasing the potential for partial collapse of the terrain (Usman, 2021). 

Figure 2. Subdistricts impacted by flash floods and landslides in Luwu Regency visualised based on BNPB’s report
Source: BNPB, 2024

Mitigating post-disaster cascading impacts

The development of recent events in West Sumatra and South Sulawesi highlights the potential for systemic risk, impacting interconnected aspects of life beyond immediate needs. Restoring transportation access is crucial to prevent economic disruption and support displaced residents, particularly mitigating health risks in non-ideal conditions. WASH interventions (water, sanitation, and hygiene) offer a valuable approach, some of which have been implemented in both cases, although yet to be evenly distributed (Priyasmoro, 2024; Radlis, 2024). In Luwu Regency’s flash flood, the urgency was reflected through the escalation of flu, indigestion, and skin disease risk due to destroyed springs and other essential service infrastructures (Ariadi, 2024; Caniago, 2024b). To support this, implementing humanitarian aid, including water and sanitation, demands local data to conduct a need assessment for its provision.

Towards disaster resilience

The future looms uncertain due to the threat of escalating natural hazards, particularly intensified meteorological events. The escalating threats demand a shift in our current strategies, which have fallen short in addressing the growing challenges. Based on experiences promoting resilience in Indonesia, the following areas are crucial for collaborative efforts to build a more resilient future:

Collaborative knowledge-sharing aims to bridge the gap between scientific understanding and traditional wisdom, empowering the establishment of disaster-resilient communities.
Integrating climate change projections into development regulations and strategies and preparing for the most extreme scenarios means ensuring an adaptable future.
Nature-based Solutions, particularly those implemented in riparian zones, are being promoted to reinforce land capacities and alleviate infrastructure collapse.

Further Readings:

Climate Change on Migration and Displacement

Urban Community Resilience Assessment

Gender Equality and Social Inclusion (GESI) Assessment for Water, Sanitation, and Hygiene (WASH)

Nature-based Solution for Flood Risk Reduction

Risk Perception Towards Flood Disaster Mitigation



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The post An Early Analysis of How Extreme Hydrometeorological Settings Prompted Flash Floods and Cascading Disasters: Lessons Learned from West Sumatra and South Sulawesi appeared first on Resilience Development Initiative.

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