Level Of Landslide Hazard Research Articles

AGIHAN WILAYAH LONGSOR DI DAS JENELATA SUB DAS JENEBERANG KABUPATEN GOWA

This study aims to agihan the landslide hazard of Jenelata watershed, Jeneberang Sub-watershed, Gowa Regency. This type of research is quantitative research with a descriptive approach. Using the land unit analysis results of the overlay of two maps, namely the slope map, land shape, soil type and land use, so that 41 units of land were obtained. The sampling technique used in this study is based on land units. Sampling was carried out in nine land units which were the result of overlays from the land slope map and soil type map. The results showed that the Jenelata watershed sub-Jeneberang watershed Guat Kabuaten is a moderate level of vulnerability that is divided in each village, in part in pattallikang village, partly in Bontomanai village, part in mangempang village, part in tassese village, part in Jenebatu village sicini village, partly in parang lompoa village, partly in sapaya village, and paladingang. The level of landslide hazard of Das Jenelata Sub-Jeneberang sub-watershed is dominated by moderate danger level with a total score of 2.34 - 3.67. Jenelata Watershed Sub Das Jeneberang Gowa Kabuaten for its longitudinal vulnerability level is divided into two areas, namely low and medium areas.

Pemodelan Bencana Longsor Berbasis Spasial

Tanggamus Regency as one of the regencies in Lampung Province is also one of the areas to landslides. Most areas of Tanggamus Regency have the potential for disasters, especially in coastal areas, rivers and hilly areas. This study aims to create a spatial landslide disaster model in Ulu Belu District, Tanggamus Regency, Lampung Province. The method used is overlay and scoring with a spatial approach. The results showed that the level of landslide hazard in Ulu Belu District was divided into three, namely landslide areas with 11,736 ha or 11%. While areas that are to landslides are 81.319 ha or 77%. Then the high landslide area is 11,907 ha or 12%, and the village that has the highest area for high landslide criteria is in Gunung Tiga Village with an area of 1,930 ha. While the village with the highest area for medium landslide levels is Petay Kayu Village with an area of medium landslide areas is 4,803 ha. As for the area which has the highest area for medium landslide criteria is Sinar Galih Village with an area of 292 ha

Landslide dynamic process and parameter sensitivity analysis by discrete element method: the case of Turnoff Creek rock avalanche

The great diversity and complexity of geological hazards in terms of flowing materials, environment, triggering mechanisms and physical processes during the flow bring great difficulties to the numerical parameter selection for the discrete element method. In order to identity the significance of individual parameters on the landslides dynamic process and provide valuable contribution to the runout analysis of similar landslide, the dynamic process and associated microscopic mechanism of the Turnoff Creek rock avalanche in Canada are simulated. The present numerical results are compared with the field survey data and the results of depth-integrated continuum method. The final deposit range matches well with the field survey data. It is illustrated that the discrete element method is robust and feasible to capture the dynamic characteristics of large rock avalanche over a complex terrain. Besides, a new method to assess the landslide hazard level based on the discrete element method is proposed. According to the parameter sensitivity analysis, it is demonstrated that the basal friction coefficient and bond strength are essential to the final deposit while rolling coefficient and restitution coefficient have little effects on it.

Risk level of landslide hazard at Probolinggo district, East Java

Landslide is the third largest disaster in Indonesia, including in Probolinggo. Approximately 50% of Probolinggo regency area is a potential landslide region. This area is located in the southern part of Probolinggo regency with hilly terrain and slopes. The number of landslide events in 2015-2016 is recorded 21 events. Potential landslide hazard was analyzed by SINMAP (Stability Index Mapping) method using physic condition, slope, digital elevation model, and rainfall. The risk level of landslide hazard is derived from the crosstab between landslide hazard potential and vulnerability index covering exposure aspect, sensitivity, and adaptive capacity with variables consisting of population density, livelihood, the proportion of the vulnerable population, building quality, and the number of poor households. The high risk of landslide hazard in Probolinggo regency is found in four districts of Lumbang, Pakuniran, and Kotaanyar sub-district. Potential landslide areas are spread in the south of Probolinggo Regency, especially in Krucil subdistrict with 15-40 % slopes. Based on the spread of landslide location, as many as 81% of landslide locations occur in high and medium landslide potential areas.

Evaluation of landslide hazard level on spatial pattern of Tanah Datar Regency

Natural disasters have caused much harm to human life. Migration through disaster based planning is one way to minimize risks. The purpose of this study is to evaluate the level of landslide hazard in the planning of spatial pattern in Tanah Datar Regency. To determine the landslide hazard level using the scoring method through the overlay of a thematic map. Indicators used are slope, rainfall, soil type, geology, landform, and land use. Furthermore, evaluation of landslide hazard on spatial planning is determined by overlaying hazard level maps with land use plans in spatial pattern planning. The results showed that the 26% landslide hazard rate was a high danger level, 46% moderate hazard level, and 38% low hazard level. In addition, hazard level evaluation of spatial patterns resulted in approximately 37.3% planning for residential areas having high hazard levels. Therefore, it is necessary to revise the pattern of regional space and include the element of disaster in the planning of spatial pattern.

Shear Strength Reduction in Progress of Shear Displacement on the Landslide Near Dam Reservoir

Landslides may cause enormous human casualties, economic losses, infrastructure damages and the change of physical environment and geomorphology. Landslides on the upstream of dam reservoir obviously occur when reservoir impoundment has affected groundwater level of the upstream slope that penetrates into the susceptible soil layers which can fall down to the reservoir. The falling landslide mass into reservoir would significantly reduce the reservoir capacity as sustainable water resource for human and agriculture needs. The study of shear strength reduction in landslide mass is important aspart of the landslide dynamics science which covers mobility after failure associated with landslide hazard level, risk assessment, landslide velocity and affected area. In this paper, the shear strength reduction in progress of shear displacement on the landslide near dam reservoir is obtained by means of ring shear tests. Examined samples were taken from the 2008 deep-seated large-scale landslide near Aratozawa reservoir that is located in Miyagi Prefecture, Japan. The observed data indicated that during eight months before landslide event on 14 June 2008, the Aratozawa reservoir was impounded significantly and caused high pore pressure in the suspected slip surface layer. The undrained cyclic loading tests and earthquake loading tests are conducted to explain the shear strength reduction in progress of shear displacement and high initial pore pressure from pre-failure state to the steady-state motion. The results of the tests implied that the sample from secondary collapse zone was the weakest specimen which is vulnerable to be mobilized in a long distant shear displacement. In addition, the ring shear test results indicated that the rapid shear strength reduction of landslide mass was mainly caused by initial high pore pressure and exacerbated by the 2008 Iwate-Miyagi inland earthquake as a main shock in the case of deep and large-scale landslide near Aratozawa dam reservoir.

Stochastic analysis of rainfall effect on earthquake induced shallow landslide of Tandikat, West Sumatra, Indonesia

On September 30, 2009, extensive landslides occurred in Tandikat, Padang Pariaman Regency, West Sumatra Province, Indonesia, burying hundreds of people, and flattening some villages after a Mw 7.6 earthquake hit West Sumatra coast. The landslides occurred during rainfall, and originated on mountains mantled with loose pumice. The probability of concurrent earthquake and rainfall event in this area requires landslide hazard evaluation by considering the effect of the unfortunate combination of rainfalls and earthquakes. To evaluate the landslide hazard level, the term of specific volume ratio (RSV) was used as the ratio of displaced volume to the maximum volume per unit width that could collapse from the slope. Combined analysis of groundwater model and slope stability was utilized to determine the landslide hazard level. Stochastic analysis using Monte-Carlo method was implemented to deal with uncertainties in determining slope stability. The stochastic analysis of the Tandikat landslide confirms that smaller earthquakes could possibly trigger catastrophic landslides during rainfall. Smaller peak ground acceleration of approximately 0.15 g could result in a more than 60% chance of Rsv >0.75, while the analysis of dry condition yields a 30% chance of catastrophic level of landslide hazard. This suggests that rainfall condition increases the probability of catastrophic landslide. The stochastic analysis of the Tandikat landslide confirms that smaller earthquakes could possibly trigger catastrophic landslides during rainfall. The results also suggest that peak ground acceleration of approximately 0.3 g is considered as the critical magnitude of ground acceleration that could result in a nearly 100% probability of catastrophic level of landslide hazard in the area.

Landslide Risk on the Farmland at the Arjuno Volcano Complex of East Java

The purposes of the study are (1) studying the characteristics of the landslide hazard level, vulnerability, and capacity dealing with the seasonal plant farmland, and (2) developing the conceptual model disaster risk of landslide for the seasonal plant farmland at the stato volcano area. Sampling of the land factor was carried out in a purposive way and the sampling of the people was carried out accidentally. The analysis was conducted descriptively, parametric and non-parametric statistics, and spatial analysis of ecological map, land shape, slope, soil and land use. The findings showed that the extremely high landslide risk occurred at the cone shape of the incised volcano and the slope of the incised volcano. The economic vulnerability of one-seasonal crop farmland was about Rp. 8,879,310 ha/year-Rp. 44,036,061 ha/year. While, the socio-economic factor of the farmers was generally characterized by a transition into a periurban area. The conceptual model tated that the resources of seasonal plant farmland with the high risk of landslide can be cultivated with the acceptable risk if the vulnerability of agricultural commodity is low in economic value and the capacity of farmers cultivating it is high.

MITIGASI DAERAH RAWAN TANAH LONGSOR MENGGUNAKAN TEKNIK PEMODELAN SISTEM INFORMASI GEOGRAFIS; STUDI KASUS: KECAMATAN SUMEDANG UTARA DAN SUMEDANG SELATAN

Landslide is the main natural disaster in the study area of North Sumedang and South Sumedang sub-districts. The spatial distribution of landslide hazard and risk are not available yet that important for decision making. The aim of research is to providegeographic information system technology for developing a model for landslide hazard mitigation. The results show that a part of the area in the North Sumedang and South Sumedang subdistrict has moderate class covering 8.460,41 Ha (65,5%) and high landslide hazard is covering 2.798,44 Ha (21,67%), low landslide hazard zone = 1.570,25 Ha (12,16%) and very low landslide hazard 85,69 Ha (0,66%). By combining landslide hazard and property value, a prediction of landslide risk was produced. Despite the majority of the area has low risk class (9.564,16 Ha/74,07%), but the highrisk area occurred in minimal places (86,44 Ha/0,67%). This phenomena showed that area with high potential level of landslide hazard is not always having a high value of risk. Since the risk calculation is determined by properties value such as:infrastructure, road network and land use. While the landslide hazardous level is determined by natural factors such as : slope, soil type, geology and land use.

PEMETAAN BAHAYA LONGSORAN BERDASARKAN KLASIFIKASI STATISTIK PEUBAH TUNGGAL MENGGUNAKAN SIG: STUDI KASUS DAERAH CIAWI-PUNCAK-PACET, JAWA-BARAT

Regarding environmental degradation in Puncak and its surrounding area due to the rapid landuse changes during 1981-1994, some mitigation schemes for soil erosion have been implemented but landslides. Data on landslide and its causative factors (landuse, soil, geology, slope, climate, and terrain mapping unit) and their relationships in the area are still not available. The objective of this research is to develop the method and procedures to map landslide hazards by using GIS (Geographical Information System) univariate-statistical analysis applied to the area as a case study. For this purpose, three methods to classify and to map landslide hazards were evaluated. They were respectively developed by considering: (a) unweighted density total number of the landslide, Method#1, (b) density total number, weighting value, and age of landslide, Method#2, and (c) density total number, weighting value, age, and activity level of the landslide, Method#3. The density number is counted by overlying· each of the landslide maps and each of the causative factors maps used, and from this step, the weighting value is derived. The resulting density number of landslide given as a cumulative percentage and the corresponding weighting value were then plotted on an X-Y graph. From the graph, the level of landslide hazard is classified by applying: (1) standard classification procedure as the default statistical analysis given by the software used, and (2) natural classification procedure as it based on the nature of the curve slope of the cummulative graphic. The result given by the three methods were varied but in general, they gave landslide hazard maps with a similar pattern in which the very high and very low hazard levels in the study area increased during the period of 1981-1994. Of the three methods, applying the natural classification gave a better result than that of the standard classification procedure. Method#2 and Method#3 were better than Method#1 in predicting the future landslide occurrence. Apparently, Method#3 should show the best result but the effect of conversion from raster to vector data in GIS significantly reduced the quality of the resulting map.

Analisis Morfometri dan Morfostruktur Lereng Kejadian Longsor di Kecamatan Banjarmangu Kabupaten Banjarnegara

The aims of this research are: (a) to study and classify the landslide hazard level, and (b) to analysis morphometry and morphostructure slope at occurrence slides in the research area. The sampling method applied in this research was stratified sampling, landform units were applied as strata. The sample within strata was determined according the landslide hazard based factor that caused landslides. Analysed of morphometry and morphostructure conducted in described of landform units. The landslide location was mapped by determining landslide point with Global Position System (GPS), and morphometry slope analysis in three images with Digital Elevation Model (DEM) analysis. The results showed that the degree of landslide hazard in the research area could be classified into 9 units landform with 5 landslide hazard level, from very low until very high. At very high landslide hazard existed occurrence landslides at most, whereas at very low landslide hazard existed occurrence at least. From slope morphometry aspect, the point of the most landslide case is in mountain midle slope (11), lower slope (9), and upper slope (5). Flows type, soil fall, and rockfall all happen in lower slope. Landslide types almost (80%) happen in lower slope, whereas slump type happen in upper, middle, and lower slope. From slope form aspect, 70% landslide cases happen in concave slope position and slope classes 3-5 (>9%). From morphostructure aspect, the research area hasn’t difference because of weathering level and litology structure condition which is relatively similar. Concave and aslant slope condition become the concentration point of surface flow water and under surface which are predicted be the most influence factor that cause landslide.

GIS-based spatial analysis and modeling for landslide hazard assessment in steeplands, southern Honduras

Landslides are a serious concern in steepland areas where intensive storms are common. The level of landslide hazard is not only dependent on storm and land physical attributes, human activities, especially agriculture practices, are also important considerations. Hurricane Mitch was one of the strongest hurricanes of the 20th century; it generated intense rain that triggered widespread landslides and flooding throughout Honduras and Nicaragua. The objective of this study was to develop and test a heuristic approach for predicting spatial distribution of landslide hazard. Four variables, slope, aspect, stream proximity, and land cover type, generated from available topography and remote sensing data, were used in the model. This model was developed and verified in southern Honduras based on data from the Namasigue watershed and validated in the adjacent El Triunfo watershed. Results of GIS analyses showed that the likelihood of landslide was significantly influenced by slope and land cover. As slope increased, the percentage of land affected by landslides, when the soils were saturated, increased sharply on land used for crop production, indicating that agricultural activity and the associated removal of deep-rooted permanent vegetation increased the landslide hazard on steep sites. Consequently, sites covered by shrub fallow and forests had relatively low incidence of landslides regardless of the topographic features. The model was effective in predicting landslide hazard and generating landslide hazard maps; this model has been found to be a useful aid for soil and water conservation organizations in the region to target conservation investment.