MODULE D

RISK ASSESSMENT AND MANAGEMENT

ANALYZING LANDSLIDE RISK IMPACT TO ROAD NETWORK

(Case Study on Samigaluh District, Kulon Progo Regency, Yogyakarta Province)

GROUP ASSIGNMENT

Lecturer:

Prof. Dr. Sutikno

By:

1. Afza Afgani Setiawan (14/370482/PMU/8131)

2. Ari fana Eka Hastuti (14/373988/PMU/8436)

3. Boby Setyawan (14/370650/PMU/8192)

4. Heni Masruroh (14/370614/PMU/8181)

GEO-INFORMATION FOR SPATIAL PLANNING AND RISK MANAGEMENT

GRADUATE SCHOOL GADJAH MADA UNIVERSITY

YOGYAKARTA

2014

GROUP ASSIGNMENT 2

ANALYZING LANDSLIDE RISK IMPACT TO ROAD NETWORK

(Case Study on Samigaluh District, Kulon Progo Regency, Yogyakarta Province)

Afza Afgani Setiawan*, Heni Masruroh*, Boby Setyawan*, Arifana Eka

Hastuti*, Prof. Dr. Sutikno**

Abstract:

Samigaluh is one of district which have potential landslide in Yogyakarta. The

element risk in this problem is road. The object of this research are calculate

the vulnerability value, hazard area and risk value. To calculate vulnerability

value, we use probability landslide area method and type road analysis. Based

on from analysis the vulnerability, we obtain the score of road vulnerability.

The score 0.9 is high (for collector road which located in high probability

landslide area), 0.7 is intermediate (for local road which located on

intermediate probability area), and 0.5 is low (for other road which located in

low probability area). To determine the risk value, we use three classifications.

These classifications are 1.02 for risk area I, 0.6 for risk area II, and 0.285 for

risk area III.

Keywords: Hazard, Vulnerability, Landslide, Risk, Road

A. INTRODUCTION

Indonesia is a tropical country that

has high intensity and frequency of

rainfall. This condition make Indonesia as

the prone area for landslide. Landslide is

one disaster that often occur in Indonesia.

It can cause claim many lives, destroy

infrastructures, buildings, and caused

economic and environmental loss. Kulon

Progo regency is one of regency in

Indonesia that has high vulnerability of

landslide, especially Samigaluh District.

Postgraduate Student of Geo-Information for

Spatial Planning and Disaster Risk

Management - UGM

** Professor of Geo-Information for

Spatial Planning and Disaster Risk

Management - UGM

Samigaluh District is located on the

Menoreh Limestone Mountain, which is

susceptible to landslide. It causes a large

amount of damage and even loss of life.

The damage of loss include farmland,

houses, main economic activity, and public

facilities.

Road network is the one of public

facilities that get impact of landslide in

Kulon Progo especially in Samigaluh

District. Road network is as a vital

infrastructure to support the public activity

in this area. Road will support the

transportation, it can affect the economic

activity. The ability of road network has

influence to growth and income the local

GROUP ASSIGNMENT 3

government. It really needs the road

availability to support regional

development and open access to the

surrounding area.

Many road networks were built by

cutting slope that can cause unstability of

it. In the other hand, many landslide

occurrences were caused by cutting slope

for roads, railways and housing

(Hardiyatmo.2006). Based on those facts

above, this research was focused on

landslide risk impact to road in Samigaluh

District, Kulon Progo Regency, and

Yogyakarta Province.

B. LITERATURE REVIEW

1. Hazard

Hazard is a potentially physical

damage, human activity which can

cause death or injury and damage of

property, social, economic, and

environmental. This event has an

occurrence probability in a specific

period and in certain areas, and intensity

(Van Western et al, 2009).

These definitions stated that hazard is a

threat to people and the things value

(property, infrastructure, facilities).

Roads were categorized as

infrastructure and the landslide hazard

threaten the existence of road.

Hazard have three components

which are probability within specified

period (temporal probability),

probability within certain areas (spatial

probability), and intensity (magnitude).

According to (Varnes, 1984) landslide

hazard consist of two major element,

namely landslide spatial probability and

landslide temporal probability which is

related to the magnitude, return period

of the triggering event and the

occurrence of landslide.

2. Vulnerability

Vulnerability is the degree of

loss of certain elements at risk which is

caused by the natural phenomena of

given certain size and shown in scale

from 0-1. Landslide vulnerability is

concept mainly depends on run out

distances, volume of landslide, sliding

velocity, the element at risk, the nature

of the element at risk type and

proximity to a slide.

Based on (Berdica on Eka,

2012) the vulnerability of the road

transport system relates to the incident,

which may reduce the functionality of

the road network. There are several

method to determine the vulnerability

of road. To determine the road

vulnerability we use value from 0-1

which were assigned to each road type.

High vulnerability (score 1) if road lies

on slope >250 and low vulnerability

(score 0.3) if road lies on slope <250

GROUP ASSIGNMENT 4

3. Landslide

Landslide are recognized as the

third type of natural disaster in terms of

worldwide importance. Due to natural

conditions or man-made actions,

landslide have produced multiple

human and economic losses. In

literature a wide variety of names have

been used for the denudation process

whereby soil or rock is displaced along

the slope by mainly gravitational forces.

The most frequently used are: Slope

movements; Mass movement; Mass

wasting; Landslide. In the last decade

Landslide is the term most used.

Landslide is the movement of a mass of

rock, debris or earth, down a slope,

when shear stress exceeds shear

strength of the material.

4. Risk

Risk consists of three elements,

namely vulnerability, hazard and

exposure are the possibility of damage

or loss. Element of risk associated with

each other’s when one of the elements

increase. There are several methods

purpose to determine landslide risk.

Distinguished risk based on the level of

quantification, there are the landslide

risk assessment methods in qualitative,

semi qualitative and quantitative.

Qualitative method based on risk

classes which are categorized by expert

judgment. Risk classes’ high, moderate,

and low, semi-quantitative based on

ranking weighted by given criteria.

5. Types of Landslide

Landslide can be classified in

many ways, there are many attributes

used as criteria for identification and

classification including:

a. Rate of movement

This ranges from very slow creep

(millimeters/year) to extremely

rapid (meters/second).

b. Type of material

Landslide are composed of bedrock,

unconsolidated sediment, and/or

organic debris.

c. Nature of movement

This moving debris can slide, slump,

flow, or fall.

6. Roads Networks

A road networks are system of

interconnecting lines and points that

represent a system of roads. Roads are

the link between the locations of the

other locations. The pattern of the road

network is one of the most important

elements of the morphology of the city.

Several patterns of the road network

according to Johannes (in Yunus, 2004)

are as follows.

a. System irregular street pattern. In

this system seen any irregularity road

system in terms of width and

GROUP ASSIGNMENT 5

direction of the road. These

irregularities seen in the pattern of

swirling, its width varies with many

branches.

b. System of concentric radial street

pattern. In this system there are some

special properties that have

concentric and radial street pattern,

its center is the main activity area at

the same place last defense of a rule,

have a geometric regularity, as well

as major roads branching from a

central point and form the "asterisk-

shaped pattern"

c. System angled elbow street pattern

or grid. In cities with a system of

street patterns angled elbow or grid

(rectangular or grid system), parts of

the city is divided in such a way into

blocks rectangles with streets that

parallel longitudinal and transverse

forming a right angle.

7. Road classifications

Based Indonesian Republic

Laws of the Road No.38 2004 on Eka,

2010, classification of road according to

their functions are:

a. Arterial road is public roads with

the main function to serve the

major transportation which has

characteristics such as; travel

distance, high average speed and

limited number of entrance in the

most efficient.

b. Collector road is public roads

which has function to serve freight

collector or deal with the

characteristics of medium range

travel, medium average speed, and

the limited number of driveway.

c. Local road is public roads having

function to serve local

transportation with the

characteristics of travel a short

distance, low average speed, and

the number of entry is not

restricted.

d. Environment road is public roads

having function to serve transport

environment with close distance

travel characteristics, and low

average speed.

8. Road Network Analysis

This function refers to the spatial

data points or lines as an integral

network. This function is often used in

the fields of transportation and utilities

(e.g. cable network applications, water

pipes, gas, and disposal). For example,

to calculate the shortest distance

between two points using ways that are

within the scope of the network. That is,

find the whole combination road linking

the starting point and end point. At any

combination calculate the distance from

GROUP ASSIGNMENT 6

the starting point to the end point with

the accumulated distance segment

(road) that shape it. Choose the

combination that has the smallest

accumulated.

9. Rainfall

Rain is a precipitation (the fall of the

liquid from the atmosphere in the form

of liquid or frozen to the earth surface)

tangible fluid. Rainfall is the climatic

variables which affect the level of

landslide susceptibility areas.

10. Slope

Slope is a surface that lies at an angle to

the horizontal so that some points on it

are higher than others. Slope

classifications based on score which

shows the influence level on the

landslide hazard. The higher score the

higher level of influence on the

landslide hazard (Hadmoko et al, 2010).

11. Landslide Risk to Road

Landslide risk to road can be divided

into direct and indirect impact. (Smith,

1992) state that direct loss is the first

order consequence which occurs after

an event, such as death, injuries, cost of

repair building, cleanup cost.

Meanwhile indirect loss is consequence

occurring a latter to the event such as:

loss of income, reductions in business,

mental illness, bereavement. These

impacts related with the cost of each

element at risk.

C. METHOD

1. Study Area

Samigaluh District located on 110° 7’

00’’E - 110° 13’ 00’’E and 7° 38’ 40’’S -

7° 43’ 15’’S, is one of the most northern

districts in Kulon Progo regency,

Yogyakarta. Samigaluh District has a

total area of 6.736,78 Ha which consist of

seven villages (e.g. Pagerharjo 1.055,98

Ha, Ngargosari 715,48 Ha, Gerbosari

1.093,65 Ha, Banjarsari 1.043, 04 Ha,

Sidoharjo 1.115, 84 Ha, Purwoharjo

1.003, 61 Ha and Kebonharjo 709, 18

Ha). (Source: Data analysis). Samigaluh

is very strategic location, because it is

located at the cross roads of trade traffic

between Yogyakarta Province and

Central Java Province.

2. Determine Probability Landslide

To determine probability landslide, we

use landslide inventory and landslide

density. The data which use in this

research are rainfall data, soil data, and

slope. All of data obtained by the

recorded data. Landslide can damage

house of property and cause death. To

analysis each data we use scoring

analysis:

a) Scoring for rainfall intensity

GROUP ASSIGNMENT 7

Source: Taufik, et al (2008)

b) Scoring for slope area.

No Slope Score

1 0-8% 1

2 8-15% 2

3 15-25% 3

4 25-45% 4

5 >45% 5

Source: Taufik, et al (2008)

c) Scoring soil types

According Rahim (1995) on Bagus

Sulistiarto classify types of soil based

on sensitiveness soil towards erosion.

Class Soil Types Score

I Aluvial,

Gleysol,Lanosol,

(No sensitive)

1

II Latosol (rather

sensitive)

2

III Mediteranian 3

IV Andosol,

Grumosol, Laterik,

Podsol (Sensitive)

4

V Regosol Lhitosol

(Very sensitive)

5

3. Analysis Probability Landslide and

Mapping Unit

To analyze probability landslide, we use

ArcGIS application and scoring for each

data. From the data availability (rainfall

data, slope data and soil types), we

calculate score each data categories. We

use these data because it have influence

for probability landslide in this area. To

determine the final probability landslide

we use intersect all of the data which

given scored in each category.

4. Vulnerability analysis of element risk

To determine road vulnerability consider

considered type of the road and

probability landslide area. In this case

there are two type of road that are

collector road, local road and

environmental road. We assume that

collector road which located on high

probability landslide area have higher

vulnerability than local road which

located in intermediate probability

landslide area.

5. Determine the Hazard Area

To determine interval of classes the

hazard area, we use this formula:

I = ℎ𝑖𝑔ℎ𝑒𝑠𝑡 𝑠𝑐𝑜𝑟𝑒−𝑙𝑜𝑤𝑒𝑠𝑡 𝑠𝑐𝑜𝑟𝑒

3

I = 12−6

3

This classification based on the sum of

three classes (Slope, Soil types and Rain

Fall) Hazard class:

No Class of

Hazard

Interval Value

1 11-13 2 0,8

2 8-10 2 0,6

3 5-7 2 0,4

No Rainfall

(mm/year

Score

1 < 100 1

2 1000-1500 2

3 1500-2000 3

4 2000-2500 4

5 >2500 5

GROUP ASSIGNMENT 8

6. Framework

D. RESULT

This paper purpose to determine value

of risk assessment and hazard map. To

know the value of risk assessment we have

to know:

1. Vulnerability

Vulnerability can be seen from

location of road. If the road located on

high hazard area, this road include in

high vulnerability. If the road located on

low hazard area, this road include in low

vulnerability. The next step we

calculate the value of vulnerability from

the proportion where the road located

on the high hazard or low hazard.

No Class

vulnerability

Type of

Road

Value

1 High Collector

road

0,9

2 Intermediate Local road 0,7

3 low Other road 0,5

2. Coping capacity

Coping capacity is the ability of

people, organizations and systems,

using available skills and resources, to

face and manage adverse conditions,

emergencies or disasters. Coping

capacity is the ability of a system

(natural or human) to respond to and

recover from the effects of stress or

perturbations that have the potential to

alter the structure or function of the

system.

The magnitude of the risk can

be reduced by capacity. It show that the

conditions of community which have

the power and ability to review and

assess the threatness and how

community can manage the

environment and their resources.

Community based on disaster

management is main factor to reduce

the risk of disaster. Based on the

historical and areal conditions of

Samigaluh district, the score of coping

capacity is 0.7.

The formula of risk:

R : Risk

H : Hazard

V : Vulnerability

C : Capacity

R I = 0,8 X 0,9 / 0,7 = 1,028

R = H X V / C

GROUP ASSIGNMENT 9

R II = 0,6 X 0,7 / 0,7 = 0,6

R III = 0,4X0,5 / 0,7 = 0,285

Generally, disaster causes a risk.

High or low risk of disaster depends on

the threats, vulnerability and the ability

of communities to cope with disasters

mentioned. The higher the value of

capacity, the lower the value of risk, but

for the value of hazard and vulnerability

is directly proportional to the value of

risk. The value of risk assessment are

extent of damage and loss. The higher

value of risk the higher damage and

loss. Then this value is very useful as

disaster mitigation. So in this research,

we can determine that area R I have

more damage and loss than other area.

Road of the R I also have damage and

loss than road in other area.

GROUP ASSIGNMENT 10

GROUP ASSIGNMENT 11

GROUP ASSIGNMENT 12

GROUP ASSIGNMENT 13

Referencess

Ahmad, Fadly. Studi Indentifikasi Penyebab

Longsor di Botu. (online)

(http://repository.ung.ac.id/hasilris

et/show/1/364/studi-identifikasi-

penyebab-longsor-di-botu.html)

diakses 16 Noveber 2014

Das, Chandra. 2011. Spatial Statistical

Modelling For Assessing Landslide

Hazard And Vulnerability. Thesis

is not published. Netherland.

University Of Twente

Jenelius, Erik. 2006. Road Network

Vulnerability Of Area-Covering

Distruptions: A Grid-based

Approach With Case Study. Journal

Transportation Research Part A:

Policy and Practice Volume

40,Issue 7,August 2006, Pages 746-

760.

Jenelius, Erik. 2006. Transportain Reseach

Part A: Policy and Practice.

Journal Transportation Research

Part A: Policy and Practice

Volume 40,Issue 7,August 2006,

Pages 537-560.

Kingma, N.C, et al. Multi Hazard risk

assessment. 2011. ITC: Faculty Of

Geo Information And Earth

Observation

Rahman, abdur. 2010.Penggunaan Sstem

Informasi Geografis Untuk

Pemeaan Kewaranan Longsor Di

Kabupaten Purworejo. Jurnal Bumi

Lestari,Volume 10 No.2, Agustus

2010,hlm.191-199

Santha,Damodaran. 2010. Population

Vulnerability and Disaster Risk

Reduction: A Situation Analysis

Among The Landslide Affected

Communities In Kerala,India.

Journal Of Disaster Risk Studies,

Vol.3. No.8.June 2010.

Sartohadi Junun. 2004. Tingkat Bahaya

Longsor di Kecamatan Samigaluh

dan Daerah Sekitarnya, Kabupaten

Kulon Progo, Provinsi Daerah

Istimewa Yogyakarta. Jurnal

Seminar Nasional Degradasi Hutan

dan Lahan, Pacasarjana UGM: 10-

11 Desember 2004.