Landslides are becoming more frequent in West Java. Why?

The Jati Radio Village, Cililin Village, West Bandung Regency (KBB), West Java, was affected by another landslide disaster on Sunday, March 12th, 2017. TNI/Polri and the Regional Disaster Management Agency (BPBD) and volunteers began removing landslide debris from the area, helped by residents.

As reported by Mongabay, the landslides from Geger Pulus Hill left behind big rocks and dirt strewn across residential areas and roadways. The estimated mud and rock thickness is 20 centimeters, and the water level at the time of the landslide was 60 centimeters, or around waist high.

Five homes were damaged when a 100-meter-high cliff at the foot of Bukit Pulus fell on them. Following the removal of trees from Bukit Pulus, the unstable soil on the cliff caused the landslide, according to Herman, a local resident. In 2015, a landslide did reach homes, however it was only mud and pebbles. Even if teak and albasia trees were planted, a large landslide actually happened afterward.

“Because albasia was regularly chopped down, bamboo gombong was planted after teak bodas were removed, and this caused a large landslide. In Cililin, landslides were also triggered by the recent heavy rains “he stated.

At least 151 families have been relocated as a result of the West Bandung Regency BPBD’s efforts so far. He said that one individual was critically injured and four others were slightly injured.

According to Dicky Maulana, head of BPBD’s Logistics and Emergency Division, the landslide was caused by the conversion of land on top of the cliff from bamboo to agricultural land for local residents. Residents were asked to plant hard trees on the land in the future, he said.

“The debris from the landslide will need to be cleaned up as a follow-up. A technical office in the Housing and Settlement department of KBB should determine the area where gabions should be installed to prevent subsequent landslides, we hope. But we’ve also done geological investigations in the past, and it turns out that the soil is extremely unstable,” he explained. Residents were on high alert for any additional landslides until this report was published.

In Waled District, Cirebon Regency, West Java, a flash flood calamity occurred last week upstream of the Ciberes River. The Ciberes River overflowed due to heavy rains upstream, according to a press release that was received. This is assumed to be the cause of the banjir bandang.

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More than 1,000 people were forced to flee their homes after four villages were submerged in muck. A total of 40 hectares of land and fields were drowned as the water rose to a height of 50 – 180 centimeters.

In West Java, a number of land movement disasters have occurred as well. There was no way via Cireki Village in Tomo District of Sumedang Regency to reach the Cirebon-Bandung national route since the road had collapsed.

A similar occurrence occurred in the Babakan Block, Wanahayu Village, Majalengka District, Majalengka Regency; the Majalengka-Cikijing route was also disrupted. Due to the recent road collapses, this catastrophe impacted the economy, which had already been affected.

Awful Possibility

According to the Geological Agency’s Center for Volcanology and Geological Hazard Mitigation (PVMBG), there has been a considerable increase in ground movement disasters in early 2017. According to PVMBG data, there were 177 incidences across the country. This year’s total of natural disasters is close to previous year’s total of 220 events.

Disasters are more likely to occur when a situation is examined in depth. With only two months of 2017 remaining, there may be more additions, and the weather, which can still change at times, could affect the total number of events “Head of PVMBG Kasbani made the remarks in Bandung’s Geology Office, Jalan Diponegoro.

According to Kasbani, 108 land movement catastrophes occurred in West Java in 2016, with a prevalence of 38%. A total of 213 people were killed, 69 were injured, and 1121 buildings collapsed as a result of the disaster.

Only two months before, the landslide disaster in Indonesia, especially in the western half, had reached 177, with 16 deaths and 25 injuries. In the eastern part of Priangan, where national routes were cut off, the majority of the fatalities perished in flash floods, while infrastructure was damaged by a creeping ground movement.

He said that while the landslide was a local calamity, the impact was worldwide. Consequently, he and his party are hoping that district and city stakeholders will acknowledge their domain as a first effort to mitigate disasters. Despite the fact that the terrain is steep and prone to disasters, land conversion typically poses a difficulty in upstream or green zones.

According to him, every province has a geological map that depicts the topography and risk for landslides in a particular area. The most recent landslides are shown, as well as a map indicating the region’s potential landslide susceptibility, which is updated once a month. There are warnings for each district or city in Java, “which means this is an early warning for ground movement,” Kasbani said.

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Recognized Early

An Indonesian soil geologist, Imam A. Sadisun, says that landslides are triggered by regulating factors and triggering factors, respectively. In more detail, both natural and non-natural factors might contribute to the occurrence of the disaster’s symptoms.

Catastrophes can be triggered by a variety of factors, such as natural disasters, man-made disasters, or a combination of both. Whether or not it’s a result of nature depends on the soil conditions in each place, which are largely influenced by the volcanic rock beneath, which hasn’t weathered and can’t properly absorb rainwater when it falls.

Other non-natural variables include human activity such as the construction of infrastructure, the expansion of land use, or the mining of steeply sloped terrain….

Land and help, on the other hand, are the deciding variables. It is possible for landslides to occur in rock or soil, or even a mixture of both.

It can also be triggered by slope cutting that disregards environmental regulations and development that neglects soil stability. Changing the contours of a cliff or slope, for example, from a moderate slope to a steeper one, is an example of this “in the office of the Faculty of Earth Sciences (ITB), stated Imam.

Landslides are prevented by the shear strength of the soil or rock, according to him. However, as water seeps into the ground, the strength of the soil decreases because the water pushes the soil particles in the direction of the water.

There is no effect on the ground before it hits water, but when the water is pushed it just moves.” Because of the help of water, it was able to happen. Landslides occur more frequently during the rainy season because falling water can increase to the weight, making the lines of the landslide area appear to be lubricated “he went on to say.

To understand a tree, it is necessary to look at it from multiple angles. Water storage is one purpose of trees, but they also serve as a mechanical structure for holding things in place. Slope stability can be compromised by tree stands that aren’t optimal for slope stability.

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Ideally, the tree should be situated above and below the slope for mechanical purposes. Tree roots should be able to sustain the weight of the soil when the water level decreases in fields that are at risk of landslides.

“If the tree is located in the middle of the slope, it should not be a hard tree because its mechanical function does not play a role in the slope’s stability. To ensure that rainwater does not just wash off into the ocean, trees are required to slow it down and allow it to seep into the earth “he asserted, according to her.

Imam further stated that current environmental degradation is a direct result of population increase and the need for land. Wherever there is an increase in activity and population, the city/regency reaches the village/village.

It is also possible for me to employ landslide-prone locations for this purpose. Because it is possible to evaluate the movement potential of each slope. First and foremost, the study must be proven before any construction or planning may begin. Soil and rock can be strengthened with technical means, and a planned structure can be created that is more resistant to landslides “Imam, who is also the Deputy Dean of the Faculty of Earth Science and Technology, noted this.

The PVMBG concept, he said, is a suitable way to undertake geological research in city and district areas. Red, yellow, green, and blue are all designated color zones on this map. In addition, each color has a distinct meaning, such as red, which signifies an increased chance for land movement, while green denotes a safe area of land.

Using this map as a starting point, the government may get a sense of the population distribution in its area, and individuals who live in the red zone should keep an eye out for signs of ground movement in the near future.

Public awareness and education are necessary in this instance. That people will begin to notice the abnormalities in nature is his goal. An example of a landslide initiation sign is a formerly upright tree that has become slanted. In order to decrease disasters, the community should be employed as the most significant mitigation component.