Though Indonesia is known for its susceptibility to natural disasters, with tsunamis, volcanic eruptions, and floods regularly making headlines, it is landslides that account for the highest disaster death toll throughout the archipelago, according to the Indonesia National Disaster Management Authority (BNPB). Last year, it claimed 248 lives.
According to the BNPB, the number of landslides in Indonesia have increased to 376 in 2014 from 291 in 2012.
Population pressure results in land-use change, road building, and deforestation, which along with climate change, are all factors in landslide frequency and strength.
The 2012 study also found that nearly half of Indonesia's 250 million citizens live in landslide-risk zones, with 40 million located in what they called “high-risk” zones mostly in Java, Sumatra, and Sulawesi islands.
BNPB spokesperson Sutopo Purwo Nugroho believes that land-use change is one of the primary causes of the December 2014 disaster.
“The subsistence farming systems done in the hilly areas [in Central Java] are not accompanied by good land conservation practices,” Nugroho says. "Population growth and greater volume of rain as a result of climate change have increased the potential for landslides, but the most dominant factor is land degradation from farming activities."
Around Banjarnegara, forests had been cut down to plant potatoes, and it is believed that the inability of the weakened root systems to hold wet soil contributed to the deadly landslide.
“Changes in vegetation — whether that be timber logging or wildfires — can increase landslide propensity and occurrence,” Jonathan Godt, coordinator of the landslide hazards programme at the US Geographic Survey, tells SciDev.Net.
Rainfall is also a factor, and climate change models used by the Intergovernmental Panel on Climate Change predict that, in most scenarios, rainfall intensity will increase in many parts of Indonesia, creating greater potential for flooding and, subsequently, landslides.
According to Godt, figuring out whether land-use change or climate change plays a larger impact on landslides, which also occur in situations with no human impacts, is hard.
“Heavy rainfall [caused by climate change] may play a role, but it is hard to disentangle,” says Godt.
Indonesia’s response to the regular landslides has been lacking, according to the government-funded Indonesian Institute of Sciences, which stated in a press briefing last month that the country’s mitigation efforts against landslides, despite its high occurrence, lagged behind those for more high-profile disasters such as volcanic eruptions and tsunamis.
Indonesian NGOs, including WAHLI (Friends of the Earth Indonesia) and KEHATI (The Indonesian Biodiversity Foundation), believe that Joko Widodo, Indonesia’s president who visited Banjarnegara and called for a “balanced environment”, must take strong steps to ensure that the disaster that befell the village does not become a regular occurrence in the whole country.
This article has been produced by SciDev.Net's South-East Asia & Pacific desk.