Prone to Landslides on the Slopes of Mt. Wilis

MADIUN, KOMPAS — Landslides, floods and ground movements have hit East Java areas in the past two weeks. High intensity and frequent rainfall as well as changes in land use in some of those areas have reportedly triggered such disasters.

A thorough effort and early preventive measures are required to avoid similar disasters. An area on a slope of Mount Wilis is one of the areas prone to landslides.

Some landslides and ground movements had been detected in that area. But there was no thorough handling to minimize the disaster. In fact, the protective role in the areadecreased.

Monitoring in the past week showed that some areas on the slope of Mt. Wilis became farming fields. The slope along the road from Mojo district to Jugo village in Kediri regency, for example, was turned into a farming field. Local residents used the cliff and valley for farming despite the inclination of the slope being at a more than 50 degree angle in some spots.

The area from Jugo village through Selopanggung in Semen district, Kediri, was planted with coarse grains, pulses, roots and tuber crops. There were also pines. Some minor landslides were seen in several spots. Warning signs were installed in that area.

Elsewhere, the Selorejo hamlet in Surat village, Mojo district, is also prone to landslides. The latest landslide occurred last Thursday. As of Thursday (13/4) noon, 41 residents from 12 families whose houses were damaged and affected still took refuge at the Surat village administration office.

Residents said it was the first time seeing a landslide in their area. Along the small road in the village, Kompas saw signs of digging activities in the yards of the residents. But residents denied there were digging activities below the landslide spots.

Mapped

Based on Kompas records, a landslide occurred in Joho village, Semen district, Kediri, in December 1981, after heavy rains on the slopes of Mt. Wilis lasted for 10 days. High intensity rainfalltends to trigger incidents, such as landslides.

Cracked ground was also detected in the Selopura and Kepel villages in Ngetos district, Nganjuk regency. Nganjuk Disaster Mitigation Agency (BPBD) head Soekojonto said the landslide in Kepel village started with cracked ground in 2005.

The 50-centimeter-long and 10-centimeter-wide crack grew to 100 meters long and 15 centimeters wide. At that time, the landslide hit the slope of Mt. Wilis with a length of 7 meters long at 15 meters high.

The heavy rain caused the cracked ground to grow to 100-150 meters long. Eventually, on April 9, 2017, the cracked ground collapsed and triggered a landslide from the height of 300 meters.

Hendro Prasetyo, a Natural Resources and Environment lecturer with the Agriculture Faculty at Brawijaya University, Malang, said the cracked ground in Ngetos had been detected long ago.

Aside from that area, other areas in East Java are also prone to landslides, such as the area below Mt. Arjuno and Welirang – an inclined area in Cangar village, Bumiaji district, Malang regency.

The area used to be forested but was then transformed into a horticulture farm. The landslide prone area includes West Malang in Pujon district, Ngantang, Kasembon. The area was transformed from forests into cultivated lands.

In Banyuwangi, a landslide-prone area is located on the slope of Mt. Argopuro and Pesanggaran, with ground movement having once been detected in Pesanggaran. Land transformation has not been drastic because the area was part of the protected and production forest.

Hendro said there were several ways to avoid repeated landslides. For the area around Mt. Wilis, the government needs to declare the forest on the slope of Mt. Wilis a protected forest so that there would be no more tree cutting.

Second, even if the area remained a production forest, state forestry company Perhutani must regulate when to grow and when to cut the trees. People must immediately grow trees after cutting down trees.

“Perhutani must report to the local administration of its activities so that the administration could anticipate possible landslides during the tree-cutting session,” Hendro said.

So far, Hendro said the local administration had no idea about the tree planting and tree-cutting schedules. Most of the time, the schedule was set by the central office of Perhutani.

Third, the local administration needs to build embankment around the area prone to landslides, which is located near the river or water source, so that the potential landslide would not affect the river or water source.

Adi Susilo, Brawijaya University geology and disaster studies center head, said the forest transformation into farming in some areas needed to be limited. Adi said there must be reforestation by planting big trees. Usually, erosion occurs on soft soil of which the below part is sand.

Taking refugees

As of Sunday (16/4), from 341 people who sought refuge, only 18 families are still staying at Dayakan village in Badegan district. The ground movement spanned 300 meters with a width of 40 centimeters and a depth of 3 meters. Some residents had returned to their houses after the Volcanology and Geology Disaster Mitigation Center deemed the area safe from cracked ground.

Dayakan village head Kateno said 78 buildings, mostly houses, were affected by the cracked ground. Twenty-two buildings, including a school, mosque, health clinic and houses, were damaged. The damage mostly comprised cracks on the wall, floor, foundation and roof, which could potentially collapse. “Our residents are still taking refuge to anticipate cracked ground. They fear their houses could possibly collapse,” Kateno said.

Local residents worry about the cracked ground mainly at night. The cracks produce thunderous sounds and small tremors.

“I had to bring everything, including home appliances and the cattle,” said Toimin, a resident of Watuagung hamlet, Dayakan village, whose traditional-style limasan house has the potential to collapse due to the cracked ground.

(WER/INK/BRO/DIA/GER/SYA/ADY)