©2018 Department of Geography Education, University of Jember 67 GEOSFERA INDONESIA p-ISSN 2598-9723, e-ISSN 2614-8528 Vol. 3 No. 2 (2018), 67-78 , August, 2018 https://jurnal.unej.ac.id/index.php/GEOSI DOI : 10.19184/geosi.v3i2.7992 LEVEL OF LANDSLIDE SUSCEPTIBILITY IN CIBAL DISTRICT OF MANGGARAI EAST NUSA TENGGARA Dominikus Victorius Bate1, Puguh Karyanto2, Moh.Gamal Rindarjono3 1,2,3 Sebelas Maret University, Indonesia Email : dominikusbate04@gmail.com Received: 6 July 2018/Revised: 19 July 2018/Accepted: 30 July 2018/Published online: 28 August 2018 Abstract This research aims to determine the degree of susceptibility of landslides in Cibal Districts. The method used in this research is descriptive survey method. The population in this research is all of the land in Cibal Districts. data collection technique is done by using observation technique and documentation study. Data analysis technique in this research uses crosstab technique. The results of this study can be seen that the level of susceptibility of landslides in Cibal based on crosstab results, there are three categories of vulnerability of landslide , they are low, medium and high. Low landslide susceptibility rate of 6.979,65 hectares or 64,09% is found in Nine sub-districts / village. The moderate landslide susceptibility rate has an area of 3.634,67 hectares or 33,38%, in seven villages. While the high landslide susceptibility rate is found only in one village with an area of 275,65 hectares or 2,35% of the total area of Cibal districts. Keywords : Susceptibility, Landslide, Cibal District 1. Introduction Natural disasters are disasters that caused by events or events that is caused by nature such as earthquakes, tsu-nami, eruption volcanoes, floods, dry, hurricanes, and landslides. Natural disasters can give effects on the economic, social and environmental sectors. Suripin (2002) defines landslides as a form of erosion where the transport or movement of the soil mass occurs at some point in a relatively big volume. In terms of movement, there are some erosion caused by the movement of the soil mass, creep, rock fall and mud flow. The mass that moves in the landslide is a big mass. Therefore, the occurrance of landslide will bring victims, such as environmental damage, agricultural land, settlement and infrastructure and property and even loss of human life. According to Minister of Public Works Regulation No. 22 of 2007, the process of landslide that starts from the absorption of rain water into the soil that will increase the weight of soil. If the water penetrates to the impermeable soil that acts as a slip plane, the soil 68 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 becomes slippery and the weathering soil above. It will move along the slope and out the slope. Landslide can occur if the intensity of rainfall is high, slope to steep slopes, thick weathering, rocks and geologic structure varies. Land use is less suitable with the characteristics of the land (Sutikno, 1994 in Permata, 2016). Susceptibility is a condition caused by human activities (the result of physical, social, and environmental processes) that causes the increasing Susceptibility of society to harm. The degree of vulnerability can be assessed from physical (infrastructure), social, demographic and economic susceptibility (Muta'ali, 2012). Susceptibility is the degree which society, structure, service or geographic area potentially or may be damaged or disturbed by a certain dangerous impact due to its nature, its construction, and its proximity to dangerous or vulnerable areas (Djaelani, 2008). Susceptibility is a condition of a community group that leads or causes inability to face the threat of danger (Nurjanah, 2011: 16). According to the Regulation of the Head of National Disaster Management Agency (BNPB) No. 04 of 2008 Susceptibility is a state or behavior of people or society that causes inability to face threats or danger. Cibal is one of the areas that often occur landslide . Recorded on March 3, 2007 occured a great landslide that cause 44 people died, 21 people were injured, 6 houses severely damaged, 500 people evacuated, along the road. There are 5 major landslide point, 14 medium landslide and 12 small landslide and total broke road. In 2016, there were 13 landslide occur in Cibal sub-district which resulted in 14 damaged houses and also many people who suffered injuries . Then, there were 11 major landslides and 4 moderate landslides (BPBD Manggarai Regency, 2007, 2016) 2. The Methods The location of this research is in Cibal District of Manggarai Regency East Nusa Tenggara which is astronomically located between 80 22 '52' '- 80 32' 50 '' LS and 1200 29 '13' '- 1200 30' 48''BT and based on coordinates Universal Transfer Mercator (UTM) is located between 13396556 mT - 13400525 mT and 932037 mU - 950452 mU. The research was conducted from June to August 2017. The area has 17 villages , an area of 10.889,97 hectares and the population is 27.482 soul. 69 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 Figure 1: Administration Map of Cibal Districts 2017 The type of this research is qualitative descriptive research. The data used are the primary data in the form of measurement and observation results in the research sites includes population data and settlements (units). While the secondary data in this research is administrative map of Cibal districts, Manggarai Regency. The sampling technique is saturated side where the member of population as a sample (Sugiyono, 2016). The sample in this research is all sub-districts / village in Cibal Districts of Manggarai Regency. 70 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 The landslide Susceptibility analysis only uses population and settlements. Settlement is the density of settlements in areas that occur landslide. The population is obtained from Cibal District data in 2016 figures. Population and settlement density data were obtained from the Statistic Central Bureau of Manggarai Regency. Population density and settlements were classified into three classes. They were low, medium, and high class. To know the class interval of population density and settlement, it is used formula: = − 1k Exp : C = Estimation of Class Amount (Low, Medium, high) K = Class Amount Xn = Highest Value X1 = Smallest Value Source : (Supranto, J, 1996 ) After population density and settlement, the two parameters are classified again into three classes . the classes are low, medium, and high class. To know the class is used calculation in crosstab, as follows : Table 1. Matrix between Population and settlement Density Population Density Low Medium High S et tl em en t D en si ty Low Low Low Medium Medium Low Medium Medium High Medium Medium High Source : Aditya, Triyas,(2009) 3. Results and Discussion 3.1 Population Density The existence of the population is one of the parameters. It is very important in setting the level of susceptibility of landslides because community is a distinguishing factor determining whether the disaster landslide can be categorized as a disaster or just as a natural phenomenon. Administratively, Cibal districts area is one of area in Manggarai Regency which has a large number of residents. The population in Cibal Districts is 27.482 soul that consist of 13.588 male and 13.894 female population. 71 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 Classification of population density is divided into three categorie. The categories are low, medium and high population density. The calculation is obtained by using the formula: = − Exp : C= Approximation of Class Amount k= Class Amount Xn= Highest Value X1= Smallest Value Source : Supranto :1996 From the formula above, it can be obtained the amount of classes are 155 . Therefore , it can be known the clasification category as follows : Table 2. Clasification of Population Density Class No Class of Population Density 1. 150 – 305 soul/km2 Low 2. 305 – 461 soul/km2 Medium 3. 461 – 615 soul/km2 High For further related of Population Density can be seen on table 4 below : Table 3. Population Density of Cibal 2017 No Sub- Districts/Village Population Amount Large (km2) Population Density (soul/Km2) Category 1 Nenu 2.452 6,95 353 Medium 2 Wudi 1.477 3,55 416 Medium 3 Rado 1.694 2,76 615 High 4 Welu 2.152 5,60 384 Medium 5 Barang 1.310 5,83 225 Low 6 Pinggang 1.452 6,58 221 Low 7 Golo 1.312 5,01 262 Low 8 Pagal 2.703 8,27 327 Medium 9 Gapong 1.095 3,97 276 Low 10 Perak 1.432 9,54 150 Low 11 Beamese 1.250 3,78 331 Medium 12 Lando 990 4,85 204 Low 13 Langkas 1.416 7,90 179 Low 14 Kentol 1.081 3,90 277 Low 15 Riung 2.109 13,87 152 Low 16 Ladur 1.965 12,32 160 Low 17 Goloncuang 1.592 4,22 377 Medium Total 27.482 108,90 4.908 Source : Research Data Analysis 2017 72 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 Based on table 3 above, it can be seen that Cibal has three classes of population density . They are low, medium, and high. There are ten villages that have low population density. The villages in Barang, Pinggang, Golo, Gapong, Perak, Lando, Langkas, Kentol, Riung, and Ladur Village. Six sub-distric/ Villages in Medium category are Nenu Village, Wudi, Welu, Pagal, Beamese, and Goloncuang Village. One Village with high category is Rado Village. Perak Village is the village with the lowest population density of 150 soul/km2 while Rado village is the highest population density of 615 soul/km2. Population density can be seen in the below map: Figure 2 : Population Density Map of Cibal 2017 73 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 3.2 Settlement Density The density of settlements has an effect on the susceptibility of landslide is the addition of load on the land which is in high danger zone so with the addition of this load can potentially the occurrence of landslide. The density of the settlement is the number of houses, schools, and other buildings on a certain land area expressed in units/km2. Classification of settlement density equal to population density is divided into three categories; low, medium, and high. The calculation of settlement density classification also uses the same formula as population density. From the formula , it can be obtained the number of classes is 19 so it can be known classification category, as follows: Table 4. Clasification of Settlement Density No Settlement Density Class of Settlement Density 1. 20 – 39 Units/km2 Low 2. 39 – 58 Units/km2 Medium 3. 58 – 76 Units/km2 High For further related to the density of settlements can be seen in table 6 below: Table 5. Settlement Density of Cibal 2017 No Sub- districts/Village Settlement Amount( Unit) Large (km2) Settlement Density (Unit /Km2) Category 1 Nenu 430 6,95 62 High 2 Wudi 268 3,55 76 High 3 Rado 184 2,76 67 High 4 Welu 322 5,60 57 High 5 Barang 199 5,83 34 Low 6 Pinggang 265 6,58 40 Medium 7 Golo 225 5,01 45 Medium 8 Pagal 458 8,27 55 Medium 9 Gapong 236 3,97 59 High 10 Perak 222 9,54 23 Low 11 Beamese 208 3,78 55 Medium 12 Lando 95 4,85 20 Low 13 Langkas 255 7,90 32 Low 14 Kentol 192 3,90 49 Medium 15 Riung 296 13,87 21 Low 16 Ladur 310 12,32 25 Low 17 Goloncuang 318 4.22 75 High Total 4.483 108,90 797 Source : Research Data Analysis 2017 Based on table 5, the density of the settlements is classified into three classes. The classesare low, medium, and high. There are six sub-districts / villages with low 74 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 density categories .They are Barang Village, Perak, Lando, Langkas , Riung , and Ladur Village . Five sub-districts / village with medium category that is Pinggang Village, Golo , Pagal , Beamese , and Kentol Village. Six other villages with high category are Nenu Village, Wudi, Rado, Welu, Gapong, and Goloncuang Village. Lando village is the village with the lowest density of settlements .There are 20 units/km2 while Wudi Village is the village with the highest density of settlements of 76 units/km2. For more details can be seen on the following map: Figure 3 : Settlement Density Map of Cibal 2017 75 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 3.4 Landslide Susceptibility After knowing the condition of population and settlement, so it can be counted density of population and settlement in every Village. The calculation is divided into three classes. The classes Low, Medium, and High class. To search the landslide susceptibility class using Crosstab, it can be seen in table 7 below: Table 6. Class Count of Landslide Susceptibility Cibal Districts 2017 No Sub-districts/Village Population Density Setlement Density susceptibility of landslides 1 Nenu Medium High Medium 2 Wudi Medium High Medium 3 Rado High High High 4 Welu Medium High Medium 5 Barang Low Low Low 6 Pinggang Low Medium Low 7 Golo Low Medium Low 8 Pagal Medium Medium Medium 9 Gapong Low High Medium 10 Perak Low Low Low 11 Beamese Medium Medium Medium 12 Lando Low Low Low 13 Langkas Low Low Low 14 Kentol Low Medium Low 15 Riung Low Low Low 16 Ladur Low Low Low 17 Goloncuang Medium High Medium Source : Data Analysis 2017 Based on the calculation of the class of population density and the density of settlements, it can be obtained level of susceptibility landslide in each Sub-districts or village in Districts Cibal Manggarai Regency. For the class of susceptibility is divided into three classes namely low, medium, and high landslide susceptibility classes. As for explanation of each class of landslide susceptibility, as follows: a. Low Landslide susceptibility level (L) Areas with low landslide susceptibility have little or no impact on landslides. The relatively small population and settlement density makes the area relatively vulnerable. Population density in this area ranges from 150 - 305 soul/km2 while the density of settlements ranges from 20 to 39 units/km2. Low landslide susceptibility rates are found in village Barang, Pinggang, Golo, Perak, Lando, Langkas, Kentol, Riung, and Ladur. 76 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 Low landslide susceptibility can occur due to low population densities and clasified settlements. The area of low landslide susceptibility is 6.979,65 hectares or 64,09% of the total area. b. Medium Landslide susceptibility level (M) Areas that has medium susceptibility landslides are having moderate effects on landslides. The medium of Population density and settlements that are making the area relatively has medium susceptibility. Population density in this area ranges from 305 - 461 soul/km2 while the density of settlements ranges from 39 to 58 units/km2. The level of landslide susceptibility in Pagal, Nenu, Wudi, Welu, Gapong, Beamese and Goloncuang villages. The area of moderate avalanche susceptibility is 3.634,67 hectares or 33,38% of the total area. c. High landslide susceptibility level (H) Areas with high landslide susceptibility have a high or large influence on landslides. Population density and high settlement make the area classified as having high susceptibility. Population density in this area ranges from 461 - 615 soul/km2 while the density of settlements ranges from 58 to 76 units/km2. The high landslide susceptibility rate is found only in Rado Village. The high landslide susceptibility area is 275,65 hectares or 2,35% of the total area of Cibal Districts. Based on the analysis of landslide susceptibility level, the distribution can be seen on the map below: 77 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 Figure 4 : Landslide Susceptibility Map of Cibal 2017 4. Conclusion Based on the results of this research, it can be concluded that the susceptibility of landslide in Cibal Districts , Manggarai Regency of 2017. There are three classes of susceptibility, low, medium, and high. The low landslide susceptibility was found in Barang Village, Golo Village, Pinggang Village, Perak Village, Lando Village, Langkas Village, Kentol Village, Riung Village, and Ladur Village with 6.979,65 hectares or 64,09%, the susceptibility level of landslide is located in Nenu Village, Wudi Village, Welu Village, Pagal Village, Gapong Village, Beamese Village, and Golo Ncuang Village with an area of 78 Dominikus Victorius Bate, et al / GEOSI Vol. 3 No. 2 (2018) 67-78 3.634,67 hectares or 33,38%. While the high landslide susceptibility rate only found in Rado Village with an area of 275,65 hectares or 2,35% of the total area of Cibal Districts. References Aditya, Triyas & Marjuki, Bramantyo, (2009) Preparation of DIY Province Risk Map. Yogyakarta: Provincial Government of DIY & PPMU SCDRR Regional Disaster Mitigation Agency (BPBD) of Manggarai Regency in 2017 Nurjanah. 2012. Disaster Management. Bandung: Alfabeta Regulation of National Agency for Disaster Management 04 of 2008 on guidelines for the preparation of disaster management Ministry of Public Works Regulation No. 22 of 2007 Muta'ali. 2012. Environmental Support Capacity for Regional Development Planning. Yogyakarta: Faculty of Geography Gadjah Madah Univercity. Gems, S. 2016. Risk Management And Landslide Mitigation. UGM: Yogyakarta Sugiyono. 2016. Quantitative Research Methods, Qualitative, And R & D. Bandung: Alfabeta Supretno, J. (1996). Statistics, Theory and Applications. Jakarta: Erlangga Suripin.2002. Preservation of Land and Water Resources.Yogyakarta.