10th Asian Regional Conference of IAEG (2015)

Landslide Susceptibility Always Happens Every Year In Banjarnegara, Central Java,
Indonesia
Novi Dian ANGGRAINI
Geological Engineering, Padjadjaran University, West Java, Indonesia
E-mail: nopiianggraini@gmail.com
Abstract
Landslides are a frequent natural disaster occurring in Indonesia, especially in Java Island
where few forests remain in this most populous island in the world. Village Jemblung,
Karangkobar, Banjarnegara, Central Java, Indonesia have a kind of rocks of volcanic
material dangerous if in the state of obsolescent. In the state of obsolescent, soil formed
from the weathering of volcanic material containing numerous loam. Worsening the natureof loam of being pulpy causing land not able to withstand the burden of the ground in aslope, than there was a landslide in the Banjarnegara. The morphology of steep hills with aheight of the 400 meters and having the form of a hill with a slope convex shaped circular
down with the slope of land reaching more than 30 degrees and supported with the flow ofwater that is also great because of high rainfall to the aspect of the trigger in this area.The
methodology that was used in this research was with secondary data and geology mapping.
Socialization needs to be done in a sustainable way to those who live in the point do
mitigation regional structural priority by doing rehabilitation and reconstruction withidentification areas prone to fall and rapid mapping from various sources data, maps source,
satellite images of weather data, and the location of settlement. We hope the government
need to apply technology early warning system landslide disaster detection to avoid theincident, as in Banjarnegara that always occurs every year. Early detection instrument isonly one component of mitigation efforts. For people who live in areas prone to disaster, ofinstitutional strengthening, structural mitigation, and social, far more important to improvealertness and minimize losses due to natural disasters.
.
Keywords: Landslides, Banjarnegara, every year
INTRODUCTION

interrelate is important in understanding what causes
landslides along with an understanding of the impact
humans have on these factors by altering naturalprocesses. Typically, a number of elements willcontribute to a landslide, but often there is one which
triggers the movement of material.
Java Island is located at the southern part ofEurasian plate margin. The India-Australian plate ismoving north-ward relative to southeastern Asia,
Subduction beneath the southern Indonesian Islands
along the Java trench. As a result, Java region

A landslide is the movement of rock, debris orearth down a slope. They result from the failure of thematerials which make up the hill slope and are driven
by the force of gravity. Landslides are known also as
landslips, slumps or slope failure. In general, thefactors which influence whether a landslide will
occur typically include slope angle, climate,weathering, water content, vegetation, overloading,geology, and slope stability. How these factors

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law. In general, slope failure is as result ofcombination both rainfall intensity and accumulated
rainfall. Some investigators have linked measures of
the cumulative event rainfall to the average rainfall
intensity, obtaining event-intensity (EI). Onodera et.
al (1974), who were probably the first to propose
quantitative rainfall thresholds for the initiation oflandslides, further proposed a set of thresholds
linking the hourly event intensity to the ratio between
the average and the maximum rainfall intensity perhour. Using the similar concept of power law andrainfall intensity – accumulated rainfall record, athreshold can be also devised between rainfall
intensity and accumulated rainfall.

witnesses a number of seismic and volcanic activities.
Banjarnegara district located on regions that haveto the topography of hills, namely the mountains ofnorthern and mountainous serayu longitudinal south
east and west - serayu separated by river that forms
the valley and the geology complex. The area of thevalley of the river forming a plain serayu is relatively
stable regions, while in a mountainous area south
serayu serayu northern and mountainous areas thatare unstable, because of steep and controlled bytopography as well as various kinds of rocks have ageological structure that complex.
The recent landslide of 12 december 2014 inhamletjemblung,
sampang,karangkobar,
Banjarnegara. Landslides happened is predicted tohappen at 17: 30 wib and fell on a a hamlet inhabitedby about 300 people of 53 the family .That occurs
due to an avalanche of, residents in three villages,
namely desa sletri, paweden village, and village
sampang were evacuated to avoid the possibility ofsupplementary landslide. It is estimated that the causeof a landslide, because high rainfall in the region
around, these landslides causing dozens of houses
were damaged and hundreds of people were reported
heaped up landslide material.

I= m + nRp(2)

where I is rainfall intensity, R is accumulated
rainfall, and m, n and p are empirical parameters. The
authors are requested to understand the following
points when preparing and submitting manuscripts ofthe paper.
Table 1 The rainfall – triggering landslides at
Banjarnegara from 2010 – 2014
RainfallMETHODSYear

The threshold is defined as lower boundary of
rainfall for a landslide to occur. Thus, anempirical-based model is applied to define the value.
Empirical thresholds are obtained studying rainfall
conditions, which resulted in slope failures. Most of
the proposed thresholds perform reasonably well in
the region where they were developed, but can not beexported to neighboring areas. Also, their temporal
accuracy remains largely untested Crozier (1999).
Most commonly, the empirical thresholds correlate
rainfall intensity and duration (I-D curve) andcumulative precipitation during an event. The
common expression for ID threshold has the generalform:
I= c + aDb(1)

Duration (day)Accumulation
(mm)

2010

255

6408

2011

241

6018

2012
2013

132
186

4429
5549

2014

273

6962

The rocks that affect the vulnerability of
the avalanche not only cover the type of violence andit rocks, but more important is the rocks structures.
Layered rock sloping in line with the direction of abevel angle would have the level of vulnerability thathigh.Hard rock and still relatively fresh can also
become vulnerable to the avalanche when she has
many cracks / joint are in line with the direction of abevel angle.Hard rock and many of the joint would be
more vulnerable again when staying in the soft rocks
that have the nature of the wrinkle. Areas of land andlies thick on the high also relatively vulnerable to an
avalanche of because the region is really potential forwhere I is rainfall intensity, D is rainfall duration,
and a, b and c are empirical parameters. The
parameters can be determined from the best-fit of therelationship. When c = 0 Eq. (1) is a simple power2

10th Asian Regional Conference of IAEG (2015)

seepage, and cutting the slope of that model
conservation must refer to the parameters.

increasing the burden of a mass land because
generally has the ability to absorb rainwater that is
relatively high compared with rocks. On the basis of
the understanding, the landslide vulnerability
assessment is based on an assessment of theparameters morphometric.
The condition of soil layer and rocks on theslopes in the research that included land residual
permeability relatively high with thick about three to
6 m on the surface and constituted by a hard layer ofrocks breccia.The form of the field after theavalanche gelincir including the type of flat, andoccurring in locations around the meeting between
layers of land around the hard layer and soil or rockat the bottom.
In morphometric slope, the point of thelandslide in the middle of the most mountainous, withthe slope, and on the upward slope. Type the flow of ,flow the ground , and all the upward slope inflowstone, type an avalanche of dominant ( 80percent lower at the slope ) happened, while there arein the upward slope neonatal type, the middle andlower .The aspect of the form of the 70 percent of thelandslide, there is a slope that is concave and adiposis
class slope 3% & 9%. Morfostruktur from the aspectresearch area has rock almost the same characteristics
that are reflected by the weathering of rock and thecondition of the structure of the relatively samelandslide disaster prone.The condition that is concaveand slanted slope to the point of the concentration of
the flow of surface water and away a large surface
expected to be an avalanche of the most decisive
factor.
From an analysis of landslides parametersof the land showing large more than the slope. Solumthe land the level of weathering rocks, structure layer
rocks, the presence of the stump, water seepage
cutting slope and indicating the level of danger
landslide land getting high. The condition of soil
texture, the permeability, drainage, and the use ofland larger not necessarily the level of danger
landslide their land is higher. From the observation
field in avalanche of any location, the factors thatcause an avalanche can happen this. Distinctive andnot the same factors the trigger landslide despite same
type, but the avalanche of increased with increasing
frequency the slope of a slope, solum the ground, therate of weathering, layer structure, the stout andTable 2 The landslides occurance in 5 years
Year

Date of occurance

2010

February 13th
March 17 th
May 14 thOctober 21 thApril 3 rdApril 9 th
May 4 thNovember 4 thNovember 5 th
January 12 thNovember 22 th
December 21 th
December 23 th
February 13 th
December 12 th

2011

2012
2013
2014

RESULTSThe empirical thresholds are a basic
element of the landslide early warning system.
However, when using them, it should be combinedwith a real-time rainfall monitoring andinstrumentation. A basic limitation that can be definedas conceptual 46 Reichenbach et al. (1998) is thatthresholds inevitably represent a simplification of therelationship between rainfall and landslide occurrence.
Rainfall is not the direct cause of failures which, infact, are caused by the build-up of high pore waterpressure in the slope, a phenomenon that is also
related to hydraulic, physical and mechanicalproperties of terrain and to other environmental
factors like slope, vegetation cover, and climaticcharacteristics of the area
The avalanche slopes related to the 100
meters tall and 500 meters wide. Landslide Typerotational may , which makes tongue of an avalancheof jumping and ripped up to as far as 600 meters .35
houses and 1 mosque ( al-iman mosque ) along withthe take off the highway Banjarnegara-dieng heapedmaterial until a few hundred feet landslide .308 of the
population, 200 of them managed to escape .An
avalanche of terrible jemblung is the largest in
between the 34-point landslides other was
found .Wholly situated in the region karangkobar.

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10th Asian Regional Conference of IAEG (2015)

factors
that
contribute.
In
the
case
karangkobar-merawu Banjarnegara especially in thearea, the first factor is a unique geological condition.
The second factor is of extreme rain and heavy rain.
And the third factor is clogged up drainage so water
could not be free to the potential of the landslide.
First and second factor is a factor that given or isalready so. So that no human can be controlled. But
different from the third factor. Humans can manage
the drainage of a slope, the water could be reduced sothat the level of saturation. Drainage channels simple
can be built for that purpose. In addition, a crack that
had been formed must be buried again until flattened.
Also there is no good in the excavation and the slopes,
both petty let alone great, for whatever reason.
Disaster landslides always overshadow
banjarnegara geology as the implications of destiny
are unique. The destiny which makes land here isvery fertile and can overgrown with diverse plants
cultivation. The destiny that also makes them views
area beautiful and cool. If managed well the twothings able to raise banjarnegara gemah ripah loh
jinawi. But the high risk of the high gains behind all
the advantage count also hidden talent distress. In thehundred up to thousands of years ago, disaster
potential landslides may not become a major problem
as the number of people who it was rarely. But now
the population has doubled, so that the greater the risk.
The UGM team should be welcomed the effort tomap and other institutions down to the potential
landslide banjarnegara ( sub-district ) hamlet. Should
also welcomed the idea of central java governor to
local jemblung hamlet of the remaining population.
The notion of local or the relocation of transmigration
which still remain within the scope should be
developed not only for banjarnegara jemblung hamlet
after the disaster. But also for other someday somehamlets are known to have the potential of the highavalanche. One day to the victims no longer fallingFig. 1 A panorama jemblung hamlet, village sampang
Banjarnegara and mountain telagalele based in theillustration google earth image with the direction ofview to the south. Dotted line showing the estimate of
the position of the origin of an avalanche of material.
An arrowhead mark yellow indicate the direction ofground motion in an avalanche of the terrible disasterof the. Source: sudibyo, 2014 with the base of google
earth and the information azizah, 2014.

Fig. 2 The image view of a wide ( wide-field ) the
disaster location landslides terrible jemblung( sampang ) 2014, taken central vulcanology andgeological disaster mitigation per 13 December 2014
repaid. The direction of view to South East. Seems
the position of the crown fall and the watering hole /a puddle right underneath it. Source: pvmbg, 2014.
Disaster potential still overshadow
hamlet jemblung forward. The first came from a goodfamily of the stem a river of lightning. If it rains, thisdam will obstruct the river for a few moments before
it collapsed into the deluge. While the second comingof a landslide. So here was the great pool along 30
meters was flooded as deep as 1 meter. If heavy rain
pouring down, can suppress this pool of water in thesoil beneath it has a soft and delicate so that erosion
can happen again. Even in the worst of it, disasterscale could exceed what was hamlet jemblung.

ACKNOWLEDGEMENTS
We would like to thank 10th Asian Regional
Conference of IAEG for permitting author to publish
this work and Mr. Dicky Muslim for allowing author
to write the paper. I also say thank you to Rachmanda
Anandita putra and Muhammad Pasya Nugraha who
all contributed during various stages of the project.

CONCLUSIONSIn the landslide, in general, at least three410th Asian Regional Conference of IAEG (2015)

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