Landslide risk reduction for sustainable land use direction in Tawangmangu District, Karanganyar Regency year 2023

Tawangmangu District, Karanganyar Regency has an area of 7,002.94 Ha consisting of 10 villages. Topographically located on the western slope of Mount Lawu with a predominantly steep slope, which has an altitude between 655 m and 3,265 meters above sea level. The development of agribusiness-oriented dryland agriculture, natural tourism destinations, and the establishment of residential buildings that increasingly provide job and business opportunities so that there is an increase in government income and surrounding communities. This condition impacts population pressure on land, so the risk of landslides is thought to be higher. Areas prone to landslides are in the central part of Bandardawung Village, Along Village in the west and central regions, Plumbon Village in the middle and east, and Tengklik Village in the west. The study’s purpose, located in Tawangmangu District, Karanganyar Regency, is to determine the reduction of landslide risk for sustainable land use. Descriptive quantitative research methods include determining area function, vulnerability, vulnerability, and landslide risk using scoring and weighting of observation data. The results of the research show that villages that have a high risk of landslides are areas that have a high risk of landslides, namely Blumbang Village, Kalisoro Village, and Tawangmangu Village.


Introduction
Land-use change due to urbanization significantly impacts the environment globally [1].The uncontrolled pace of urbanization will undoubtedly harm the ecosystem [2].The influence of extreme weather (high temperatures and rainfall) and tectonic activity in recent years has triggered geological disasters such as landslides [3].Climate change is just one possible driver of landslide hazards [4].Landslides occur when there is soil movement or movement of rock masses on a slope due to the influence of gravitational forces [5].The two critical factors for landslides are physical, natural, and socio-economic conditions [6].Anthropogenic factors are one of the causes of adverse landslides [7].The degradation of land use changes, causing landslides to increase [8].Losing primary vegetation on slopes can disrupt water catchment areas and soil balance, triggering movement [9].
Tectonic conditions in Indonesia form high morphology, faults, and volcanic rocks that are easily brittle and supported by the climate in Indonesia in the form of wet tropics, causing the potential for landslides to be high [10].The leading cause of landslides is the disruption of soil retaining forces and shear forces on a slope [11].Uncontrolled and increasing soil erosion caused landslides [12].Rainwater infiltration reduces the shear strength of soil masses, increases the weight of rocks and soil masses, increases shear forces, and decreases the stability coefficient [13].Landslides are one of the most 1314 (2024) 012026 IOP Publishing doi:10.1088/1755-1315/1314/1/012026 2 widespread, impactful, and destructive geological disasters worldwide, especially in mountainous areas [14] Changes in land use and land cover in mountainous areas can increase vulnerability to landslides due to modifications in topography, vegetation, and material characteristics [15].Karanganyar is an area vulnerable to natural disasters such as landslides, typhoons, floods, fires, land movements, collapsed houses, and accidents [16].There are 327 landslide-prone points, and in the last five years, there have been 300 landslides in Karanganyar Regency [17].Landslides have occurred in Indonesia, one of which is Karanganyar Regency, with an intensity that always increases yearly [18].The high level of landslide vulnerability means that the Area has the potential for high landslides, which is easy for landslides to occur, generally due to slope factors and rainfall intensity [19].
Tawangmangu District, Karanganyar Regency, has a high level of landslide vulnerability [20].Tawangmangu District is an area located on the slopes of Mount Lawu.Landslides are the most destructive natural disasters and cause heavy losses in mountainous regions [21].The survey results show that the existing land use of Tawangmangu District is tourism, settlement, and seasonal crops.Land with a steep slope for food crop cultivation causes landslides [22].Land use in an area reflects efforts (actions) and human interaction in utilizing and managing natural resources and accompanying environmental conditions [9].The absorption of rainwater through areas of rock cracks on the slope and the water that fills the rock cracks is compressive and further weakens the strength of the rock to remain stable; eventually, moving rock blocks slide down the slope and cause landslides [23].The emergence of problems of landslide hazards and risks and climate change will further worsen the situation of landslides [24].The use of steep slope areas planted with seasonal crops, which are the main livelihood of residents, will encourage landslides, so there is a need for reforestation with strong-rooted perennials as a direction for land use [25].This study aims to reduce landslide risk for sustainable land use by determining the function of the area, hazard, vulnerability, and risk of landslides using scoring and weighting data from observations in Tawangmangu District.

Methods
This study is located in Tawangmangu District, Karanganyar Regency.Tawangmangu District consists of 10 villages, namely Tengklik, Plumbon, Sepanjang, Nglebak, Kalisoro, Tawangmangu, Blumbang, Gondosuli, Karanglo, and Bandardawung.This research study aims to determine the risk of landslides based on vulnerability, vulnerability, and capacity parameters.The study's results were collected through observation, interviews, and documentation.The population of this research is all villages in Tawangmangu District with the unit of analysis being the Village.The sample used is a saturated sample.

Landslide Hazard
Landslide hazard uses six parameters: slope, rainfall, soil type, land cover, rock type, and fault [26].These parameters are in accordance with BNPB policy.The map of landslide-prone areas came from overlaying all parameters using ArcGIS software.Landslide hazards are classified into five classifications: very low, low, medium, high, and very high.Classification is based on the results of the analysis carried out by researchers.

Landslide Vulnerability
Landslide vulnerability is obtained from physical, social, economic, and environmental vulnerability parameters [27].Indicators of each of the parameters used are shown in Table 1 Physical Vulnerability Index.Indicators of physical vulnerability are the density of houses (permanent, semi-permanent, and non-permanent), public facilities' availability, and critical facilities' availability.The physical vulnerability index is obtained from the average weight of house density, availability of public facilities, and availability of essential facilities based on the Regulation of the Head of BNPB No. 02 of 2012 concerning General Guidelines for Disaster Risk Assessment.The parameters and weights of the physical vulnerability index are presented in Table 2.

Table 2. Physical Vulnerability Index Parameters and Weights
Source: [28]

2.2.2.
Social Vulnerability Index.Social vulnerability indicators are population density, sex ratio, poverty ratio, disabled person ratio, and age group ratio.The social vulnerability index is obtained from the average weight of population density (60%), vulnerable groups (40%) consisting of sex ratio (10%), poverty ratio (10%), disabled people ratio (10%), and age group ratio (10%).The parameters and weights of the social vulnerability index are presented in Table 3.

Parameter
Weight (%) Economic Vulnerability Index.Economic vulnerability indicators are the productive land area in rupiah (rice fields, plantations, agricultural land, and ponds) and GRDP.The value of the effective land area in rupiah is obtained from the contribution of GRDP and land use maps and sub-districts in numbers.The parameters and weights of the economic vulnerability index are presented in Table 4.

Community Capacity for Landslide Disasters
Capacity is the community's way or power to maintain and prepare for, prevent, overcome, and recover from disasters [29].The parameters used on community capacity are the Regional Resilience Index (IKD) and the Community Preparedness Index (IKM).The IKD value in each village is the same, while the IKM value depends on the indicators used.The IKM indicators used in this study are preparedness knowledge, emergency response management, the influence of community vulnerability, community dependence, and forms of community participation.The community preparedness index is obtained by conducting interviews.

Landslide Risk
Landslide risk overlays vulnerability, vulnerability, and capacity [30].Landslide risk values can be obtained using the following formula: R =H x

𝑉 𝐶
Information: R: Risk Index H: Hazard Index V: Vulnerability Index C: Capacity Index Landslide risks are classified into five classifications: very low, low, medium, high, and very high.Classification is based on the results of the analysis carried out by researchers.

Landslide hazard
Landslide hazard in Tawangmangu District is caused by mass movement on steep slopes.Factors causing landslides are rainfall, volcanic activity, river erosion, earthquakes, human activities, or a combination of these factors.The level of landslide vulnerability in Tawangmangu District is presented in Table 6.The red color in Figure 1 indicates that the area has a high landslide hazard level, so the potential for landslides if there is heavy rain for an extended period becomes more intense.The dominance of highclass landslide hazards in Tawangmangu District is on the slopes of Mount Lawu.Using land as agricultural land for annuals also increases the potential for landslides and can disrupt slope stability.The rapid land use change from non-developed land to developed in Tawangmangu District, which has recently experienced rapid tourism growth, exacerbates slope instability.Development in the upstream area, able to produce landslides, is a potential risk of flash floods.The main factor of the high level of landslide hazard in Tawangmangu District is the slope factor, dominated by classes IV and V. Landslide events in Tawangmangu District are presented in Figure 2.

Landslide Disaster Vulnerability
Landslide vulnerability in Tawangmangu District is influenced by social, physical, economic, and environmental vulnerability parameters.Each parameter has a different weight.The social vulnerability index weighs 40%, the physical vulnerability index weighs 25%, the economic vulnerability index weighs 25%, and the environmental vulnerability index weighs 10%.The level of social vulnerability in the Tawangmangu District is presented in Table 7

Community Capacity to Landslide Disaster
Community capacity against landslide disasters is the community's ability to deal with landslides in Tawangmangu District.Community capacity is obtained through the Community Preparedness Index (IKM), which has five parameters: preparedness knowledge, emergency response management, the influence of community vulnerability, community dependence, and community participation.The results of the community capacity analysis in Tawangmangu District are presented in Table 10.

Table 10. Community Capacity Level in Tawangmangu District
Source: Data analysis Based on Table 10, the village that has a high-class community capacity level is Tengklik Village.The Tengklik Village area, with a very steep slope, causes frequent landslide disasters.Hence, people already know about landslide disasters and their mitigation compared to other villages with low landslide intensity.The distribution of community capacity in Tawangmangu District is presented in Figure 4.  Regional Functions.Sustainable land use directives are the use or utilization of land to conform to the direction of regional functions.The area consists of protected areas, buffer areas, annual crop cultivation, and annual cultivation areas.Based on the scoring results, the functions of the Area in Tawangmangu District become four functions of the Area, namely, Protected Areas, Buffer Areas, Annual Plant Cultivation Areas, and Seasonal Plant Cultivation Area.The results of the analysis of the function of the Area in Tawangmangu District are presented in Table 12.  12, the villages that have protected areas are Blumbang Village, which covers an area of 15.07 ha; Gondosuli Village, which covers an area of 4.73 ha; Tawangmangu Village, covering an area of 0.14 ha, and Tengklik Village covering an area of 0.64 ha.Buffer areas, annual crop cultivation, and annual cultivation areas dominate every Tawangmangu District village.

3.5.2.
Evaluation of Land Use Directives.Evaluation of land use directives analyzes the function of the area with existing land use data.The map of the part of the area in Tawangmangu District is presented in Figure 6.

Figure 6. Regional Functions of Tawangmangu District
This evaluation is intended to determine land use in Tawangmangu District that is not by the function of the area and then can evaluate land use directions.Existing land use is presented in Table 13 Based on the results of the evaluation of the function of areas with landslide risk and existing land, it was found that the area according to the part of the area at a very high-risk level of 68.59% or 4440.47 ha, the medium area was not by the function of the area of 31.41% or 2051.95ha.According to the area's function at a high-risk level of 54.80% or 36,896.13ha, the medium area is not by the function of the area of 45.20% or 30,435.85ha.
The area with a very high level of landslide risk where there is a significant mismatch in the function of the area is Blumbang Village, covering an area of 801.54 ha.Blumbang village has buffer and protected areas on a 25-45% slope.Land use not by the buffer area's function reaches 801.54 ha.There is irregular land use in the buffer area of Blumbang Village, such as moor, built-up land, and shrubs.We recommend that buffer areas with 25-45% slopes be used for gardens with minimal land processing or with forest farming systems.
The area with a high level of landslide risk where there is a significant mismatch in the function of the area is Blumbang Village, covering an area of 7090.41 ha.Blumbang Village, on a slope of 15-25%, has buffer areas, protected areas, annual plant cultivation areas, and annual cultivation areas.Land use not by the buffer area's function reaches 4891.57ha.There is irregular land use in the buffer area of Blumbang Village, such as moor and bush.We recommend that buffer areas with 15-25% slopes be used for gardens with very minimal land cultivation or with forest farming systems, allowing for settlements or built-up land but very limited.Land use that is not by the function of the annual crop cultivation area reached 2198.84 ha.There is irregular land use in the yearly crop cultivation area of Blumbang Village, such as shrubs and moor.We recommend the annual crop cultivation area for plantations and annual cultivated plants, but if it is on a slope, it can be used as a settlement.

Discussions
Landslides are one of the disasters that often occur in Tawangamngu District.Previous studies have used morphology and lithology to explain landslides spatially [31].Understanding landslide characteristics will provide insights for estimating landslide vulnerability that can provide land use planning information [32].The development of Tawangmangu District towards development towards tourism certainly encourages changes in land use.Planting annuals on hillsides or sloping land is one factor that increases the potential for landslides.Land with a steep slope for food crop cultivation caused landslides [22].The use of steep slope areas planted by seasonal crops, which are the main livelihood of the population, will encourage landslides, so there is a need for reforestation with strong-rooted perennials as a direction for land use [25].In disaster mitigation, local communities in landslide-prone areas are often overlooked [22].Sustainable development planning in Tawangmangu District is essential to maintain the upstream ecosystem.Disaster risk assessment in Karanganyar Regency is vital for more IOP Publishing doi:10.1088/1755-1315/1314/1/01202613 targeted, integrated, and comprehensive disaster risk reduction management [33].An alternative effort to mitigate landslide disasters through long-term planning is spatial planning with a zoning system [6].The study of landslides is essential for development planning, decision-making, and disaster impact reduction efforts [11].After the landslide disaster, the area arrangement is vital to reduce disaster risk and build a safe area [8].Landslide risk analysis is essential for development planning and landslide disaster mitigation.

Conclusion
Tawangmangu District, characterized by its steep terrain, requires a thorough landslide risk assessment to mitigate potential losses.The findings indicate varying levels of landslide vulnerability across villages, with Gondosuli Village standing out as the most vulnerable.Additionally, Blumbang Village, Gondosuli Village, and Tengklik Village exhibit high vulnerability.Community capacity ranges from low to high, with Tengklik Village demonstrating strong capacity.Lastly, landslide risk spans from very low to very high, with Blumbang Village, Kalisoro Village, and Tawangmangu Village facing very high risk.In summary, it's imperative to align land use with area functions to reduce landslide risk in Tawangmangu District.
. The high class dominates landslide vulnerability in Tawangmangu District with an area of 9,170.71ha spread throughout villages in Tawangmangu District.The village with the highest class is Gondosuli Village, covering an area of 3,805.92Ha.The factor causing the increased vulnerability of landslides in Gondosuli Village is the steep slope.The distribution of landslide vulnerability in Tawangmangu District is presented in Figure 1.

Figure 1 .
Figure 1.Landslide Hazard Map of Tawangmangu District

Based on Table 9 ,
the level of landslide vulnerability in each village in Tawangmangu District varies, which is influenced by social, physical, economic, and environmental vulnerability indices.Villages that have a high landslide vulnerability class are Blumbang Village, Gondosuli Village, and Tengklik Village.Blumbang Village has a high class covering an area of 984.0818 ha, Gondosuli Village has a high class covering an area of 1175.4728ha, and Tengklik Village has a high class covering an area of 997.9819 ha.The distribution of landslide vulnerability in Tawangmangu District is presented in Figure 3.

Table 3 .
Parameters and Weights of the Social Vulnerability Index

Table 4 .
Parameters And Weights for the Economic Vulnerability Index Indicators of environmental vulnerability are land cover.The environmental vulnerability index is obtained from the average weight of land cover types based on the Regulation of the Head of BNPB No. 02 of 2012 concerning General Guidelines for Disaster Risk Assessment.The parameters and weights of the environmental vulnerability index are presented in

Table 6 .
Landslide Vulnerability Level in Tawangmangu District

Table 6
shows that landslide vulnerability in Tawangmangu District has deficient, low, medium, high, and very high levels

Table 7 .
. Social Vulnerability Level in Tawangmangu District

Table 7 ,
it is known that social vulnerability in Tawangmangu District has a medium class.Medium vulnerability classes are derived from population density, sex ratio, number of vulnerable age groups, poor people, and people with disabilities.The highest population density is in Nglebak Village, the highest number of poor people is in Tawangmangu Village, and the highest number of people with disabilities is in Kalisoro and Nglebak Villages.Vulnerability is measured also by looking at losses.The level of losses due to landslides in Tawangmangu District is presented in

No Village Loss Economics (IDR) Loss Physical (IDR) Total Loss (IDR) Environmental Losses (ha)Table 8
It is known that Kalisoro Village suffered the most significant total loss of Rp 322,895,100,673.However, the most critical potential for environmental damage is in Gondosuli Village, which has an area of 873.26 ha.The results of landslide vulnerability analysis in Tawangmangu District are presented in Table9.

Table 9 .
Landslide Vulnerability Level in Tawangmangu District

Table 12 .
Regional Functions in Tawangmangu District

Table 13 .
. Regional Functions in Tawangmangu District